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BALTIC GAS Final scientific report
Reporting period:
January 1, 2009 – December 31, 2011
Report compiled and edited by Bo Barker Jørgensen and Henrik Fossing
2
Table of content
page
1. Executive summary 3
1.1 BALTIC GAS main results 3
1.2 Project management, research cruises, and data collection 5
1.3 Methane gas and seismo-acoustic mapping 8
1.3.1 Spatial mapping of shallow gas using a low frequency multibeam echosounder 9
1.3.2 Towards quantification of shallow free gas in Baltic Sea sediments 10
1.3.3 Rising of methane gas bubbles through the water column and pockmark distribution in
the Gdansk Basin
13
1.4 Sediment and water column biogeochemistry and physical characters 15
1.4.1 Methane in Baltic Sea sediments 16
1.4.2 Holocene mud deposits and presence of free methane gas (an example from Aarhus Bay) 19
1.4.3 Distribution and temporal variability of dissolved methane in the water column of the
Baltic Sea
20
1.4.4 Continuous measurement of surface methane concentrations – ships of opportunity 22
1.4.5 The role of the inshore and littoral region for methane emissions from the Baltic Sea 24
1.5 Modelling methane dynamics in the Baltic Sea 26
1.5.1 Climate-related effects on past and future methane dynamics 26
1.5.1.1 Hindcasting methane dynamics during the Holocene 26
1.5.1.2 Forecasting the impact of climate change on methane gas inventories 27
1.5.2 Environmental controls of gaseous methane production in the Baltic Sea (an example
from Aarhus Bay)
28
1.5.3 Regionalization and budgeting of methane cycle 29
1.6 Deliverables 31
2. Further research and exploitation of the results 33
2.1. Further research 33
2.2. Exploitation of the results 34
3. Work package overview 36
WP 1: Project management, coordination and dissemination 36
WP 2: Data mining and GIS-mapping 37
WP 3: Gas and seismo-acoustic mapping 40
WP 4: Biogeochemistry 43
WP 5: Modelling and data integration 49
4. BALTIC GAS Science team 53
5. Educational activities 55
6. Stakeholder events and other related activities 57
6.1 Stakeholder and scientific committees 57
6.2 Other related activities 59
7. Meetings and conferences 60
8. Peer reviewed scientific papers 63
9. Submitted scientific papers 64
10. Statistics for the performance assessment of the Programme 64
3
1. Executive Summary
BALTIC GAS is a research project funded by BONUS (i.e The Baltic Organisations Network for funding Science)
that addresses methane in the Baltic Sea and its mutual coupling to climate change and eutrophication. Through
application of seismo-acoustic techniques and geochemical approaches BALTIC GAS mapped shallow gas in the
Baltic Sea seabed and water column and analysed methane production, consumption, gas accumulation, and
methane fluxes for a better understanding and quantitative synthesis of the dynamics and budget of methane in
Baltic Sea.
The BALTIC GAS research project brought together a multidisciplinary team of scientists from 12 research institu-
tions (see 4. BALTIC GAS Science team) with the goal to (1) quantify and map the distribution and flux of me-
thane in the Baltic Sea, (2) analyse the controls on the relevant key biogeochemical processes, (3) integrate
seismo-acoustic mapping with geochemical profiling, (4) model the dynamics of Baltic Sea methane in the past
(Holocene period), present (transport-reaction models), and future (with predictive scenarios), and (5) identify
hot-spots of gas and potential future methane emission in the Baltic Sea.
The research project applied modern advanced technology and novel combinations of approaches to pursue the
listed goals i.a. multibeam bathymetry and seismo-acoustic profiling to map gas distribution and escape struc-
tures in combination with gravity coring. Further methane ebullition was identified and analysed by acoustic
flare imaging and sea surface emission by floating methane-gas flux chambers and “ferry box” monitoring. Al-
ready existing data were mined and combined with new observations to generate the first well-constrained
methane budget of a coastal sea, to map gas appearance in the seabed and to generate a predictive model to
understand and forecast methane fluxes as a function of environmental gradients, climate change, and contin-
ued eutrophication.
The BALTIC GAS research project was divided into 5 work packages (see also 3. Work package overview)
WP1: Project management, coordination and dissemination,
WP2: Data mining and GIS-mapping,
WP3: Gas and seismo-acoustic mapping,
WP4: Biogeochemistry,
WP5: Modelling and data integration,
The vast majority of the new and existing knowledge obtained during BALTIC GAS, however, was reached
through a tight (interdisciplinary) cooperation between work packages.
A short introduction that outlines the coordination of the BALTIC GAS research project is given below followed
by a presentation of the major outcome of the project. Additional information may be read on the BALTIC GAS
homepage (www.balticgas.au.dk, i.e. Deliverable 1.1) where all BALTIC GAS Deliverables are accessible (except
for two submitted manuscripts, i.e. Deliverable 4.4 and 5.3).
1.1 BALTIC GAS main results
• A novel approach was developed for the monitoring of gas in the seabed. Low frequency multibeam
backscatter data provided unique mapping capabilities of the distribution and depth of free gas. Com-
4
bined with geochemical analyses of deep sediment cores this has yielded new high-resolution maps of
methane and gas distribution in selected areas of the Baltic Sea sediments.
• A novel approach was developed to quantify gas in the seabed by a Parasound sediment echosounder
using three individual wavelengths. By this use of multichannel seismo-acoustics combined with ad-
vanced data analysis it was possible to determine the gas volume in the sediment as well as the size of
gas bubbles and the vertical extent of gassy sediment. Such data are now used to verify model results on
methane accumulation and cycling.
• A novel application of a multibeam swath mapping system for sediment visualization was used to detect
and quantify gas bubbles rising from the seabed. A new cross-correlation technique similar to that used
in particle imaging velocimetry has now yielded impressive results with respect to unambiguous bubble
detection and remote bubble rise velocimetry.
• A detailed transect of seismic and geochemical data from non-gassy to gassy sediment in Aarhus Bay
combined with reactive-transport modeling has now provided strong evidence that free gas bubbles in
the Baltic Sea sediments migrate slowly upwards. When approaching the sulfate zone the gas re-
dissolves and the methane is effectively broken down sub-bottom.
• Hot-spots of methane outgassing from the sediment, often accompanied by pock-marks on the seafloor
found by multibeam bathymetry, have now been detected and mapped in several areas of the Baltic
Sea, in particular in the Polish and Russian sectors.
• Long-term monitoring of methane in the surface water throughout the central Baltic Sea by a “ferry-
box” mounted on a ferry between Travemünde, Gdynia and Helsinki has revealed the seasonal dynamics
and geographical distribution of methane. Combined with a transect through the entire water column
from the Bay of Bothnia to the Kattegat this has yielded a unique data set on methane in the Baltic Sea
and on the source strength of this green-house gas to the atmosphere.
• Based on data mining and on new data an extensive database on methane and related parameters has
been compiled and made publicly available through the BALTIC GAS homepage and the database, PAN-
GAEA. The data have also been used to develop new GIS-maps of the distribution of gas, the depth of
the methane zone, and the subsurface methane fluxes in the central basins of the Baltic Sea.
• Studies in the central basins were supplemented with detailed analyses of methane cycling in the Swe-
dish archipelago. Experiments indicated that 30-84% of the total methane flux in the sediment could be
attributed to bubbles. Yet, 98% of this methane was oxidized in the oxic water column, thus preventing
emission to the atmosphere. The remaining water-air flux was still 10-fold higher than in the central ba-
sins.
• Based on the large geophysical and geochemical data base compiled by BALTIC GAS, a transient reac-
tive-transport model was developed to understand the past and present methane cycle in the Baltic
seabed and the accumulation of gas. The model results now explain quantitatively how gas in the sea-
bed is controlled by the thickness of Holocene mud which is the main modern source of methane.
• Model predictions of future methane fluxes and the potential for accelerating gas emissions from the
seabed have shown a large robustness of the biogeochemical processes towards breaking down the me-
thane. This robustness could not have been predicted without the large amount of new data that could
verify the model and has been a key result of the project. The general model forecast is thus that the
predicted temperature increase of 1-2 oC and salinity drop in the Baltic Sea, together with an unchanged
level of eutrophication, is not expected to lead to a dramatic increase in the gas ebullition from the sed-
iments during this century.
5
Fig 1. Baltic Sea geographical areas investi-gated during 15 BALTIC GAS cruises. Aarhus Bay (A), (B) Mecklenburg Bay, (C) Arkona Basin, (D) Bornholm Basin, (E) Gdansk Bay, (F) Baltic proper, (G) Gotland Deep, (H) Both-nian Sea, (I) Bothnian Bay), (J) Gulf of Fin-land, (K) Himmerfjärden. See also Table 2.
1.2 Project management, research cruises, and data collection
A total of 52 scientist, post docs, Ph.D-students, master students, and technicians were engaged in BALTIC GAS.
They participated during the project period (1/1/2009 – 31/12 2011) in BALTIC GAS workshops (Table 1; Deliver-
able 1.3), meetings between two or more BALTIC GAS institutions, Baltic Sea integrated seismo-acoustic training
courses (see 5. Educational activities), (see 6. Stakeholder events and other related activities), conferences and
stakeholder events (see 7. Meeting and conferences), and 15 cruises to the Baltic Sea (Deliverable 1.5) covering
in particular Aarhus Bay, Mecklenburg Bay, Arcona and Bornholm Basin, Gdansk Bay, Baltic proper, Gotland
Deep, Gulf of Bothnia, Gulf of Finland, and Himmerfjärden (a Swedish fjord about 50 km SSW of Stockholm; see
Table 2 and Fig. 1). See also BALTIC GAS scientific Reports (Deliverable 1.2).
Table 1. BALTIC GAS workshops organized during the project period: 1/1/ 2009 – 31/12 2011
Locality dates Hosting institution
Number of
participants
Bremen
Germany
February 4-6 2009 Max Planck Institute for Marine Microbiology 29
Warnemünde Ger-
many
September 16-17
2009
Baltic Sea Research Institute Warnemünde 24
Askö
Sweden
June 7-9
2010
Stockholm University
Department of Geological Sciences 24
Kaliningrad-region
Russia
February 23-24
2011
Shirshov Institute of Oceanology
Atlantic Branch, Russian Academy of Sciences 25
Aarhus
Denmark
November 1-3
2011
Center for Geomicrobiology
Department of Biological Sciences
Aarhus University
26
The research cruises were the backbone of the BALTIC GAS re-
search project where targeted sediment sampling was done based
on seismo-acoustic measurement, the water column was sampled
and flux measurements across the water-atmosphere interface
were conducted (WP3 and WP4). Additionally mining of existing
seismic data was performed (WP2) mainly from BALTIC GAS institu-
tional ‘hard copy’ data i.a. The Baltic Sea Research Institute
Warnemünde, The Geological Survey of Denmark and Greenland,
Atlantic Branch of the P.P.Shirshov Institute of Oceanology Russian
Academy of Sciences, and Department of Geosciences at the Uni-
versity of Bremen. Also professor emeritus Dr. T. Flodén from The
University of Stockholm contributed with important interpretation
of seismic data from a large area offshore Gotland. The collected
seismic data were loaded to seismic workstations by the data own-
ers, the distribution of free gas was digitized, and the data com-
piled at GEUS as basis for GIS-mapping carried out by Alfred We-
gener Institute for Polar and Marine Research (see below and De-
liverable 2.1, 2.2, and 2.3) Table 3 and Fig. 2 gives an overview of
the seismic lines recorded or mined from archived data during BAL-
TIC GAS.
6
Table 2. Cruises accomplished during BALTIC GAS (2009 – 2011). Investigations performed comprised i.a. seismo-acoustic measurements, sediment sampling and concomitant analyses to depict chemical and physical profiles, water column studies, and air-water flux measurements (see cruise reports for further details). Number of participating BALTIC GAS scientists and institutions are listed together with name of chief scientist.
Research vessel Region Date Investigations Chief scientist
persons /institutions
2009
RV Oceania Southern Baltic
Gulf of Gdansk
Vistula River mouth
Feb
20-27
seismo-acoustics Zygmunt Klusek
8 pers/2 inst
RV Aranda1)
Gulf of Finland
Northern Baltic proper
Apr
21-25
sediment Harry Kankaanpää
2 pers/2 inst
RV Limanda Himmerfjärden May
12 -17
sediment Volker Brüchert
6 pers/3 inst
RV Aranda1)
Gotland Basin
Bothnian Sea and Bay
Jun
4-17
sediment Alf Norkko
2 pers/2 inst
RV Ladoga Gulf of Finland
(i.e. Vyborg Bay)
Jun 30 -
July 2
seismo-acoustics
sediment
water column
Nikolay Pimenov
6 pers/1 inst
RV Merian1)
Gotland Basin
Bothnian Sea and Bay
Aug 28 -
Sep 9
sediment
water column
Falk Pollehne
1 pers/1 inst
RV Susanne A Aarhus Bay Oct 6 sediment Henrik Fossing
5 pers/3 inst
RV Oceania Southern Baltic
Slupsk Furrow
Gdansk Deep
Hel Peninsula region
Nov
5-16
seismo-acoustics
sediment
Zygmunt Klusek
14 pers/4 inst
RV Poseidon MecklenburgBay Arco-
na Basin Bornholm
Deep
Stolpe Foredelta Got-
land Deep
Nov 27 -
Dec 17
seismo-acoustics
sediment
water column
Rudolf Endler
11 pers/4 inst
2010
RV Susanne A Aarhus Bay May
5-7
sediment
Henrik Fossing
5 pers/3 inst
RV Limanda Himmerfjärden Jun
10 -14
sediment
water column
Volker Brüchert
5 pers /2 inst
RV Prof Shtokman Russian Sector of
Gdansk Basin
(i.e. NW pers)
Jun
20-27
seismo-acoustics
sediment
water column
Vadim Sivkov
2 pers/2 inst
RV Merian Mecklenburg Bay
Arkona Basin
Bornholm Basin
Gotland Deep
Bothnian Sea and Bay
Jul 31 -
Aug 21
seismo-acoustics
sediment
water column
Gregor Rehder
29 pers /7 inst
2011
RV Limanda Himmerfjärden
Jun
10-16
water column
air-water flux
Volker Brüchert
5 pers/2 inst
RV Limanda Himmerfjärden Oct
20-21
water column
air-water flux
Volker Brüchert
2 pers/1 inst 1)
BALATIC GAS scientist(s) invited to participate on cruise organized by other BONUS-project partner
7
Sediment parameters were measured during 12 out of the 15 cruises and comprised a vast amount of both bio-
geochemical and physical observations in combination with sediment characterization and occasionally rate
measurements of methanogensis, anoxic oxidation of methane, and sulphate reduction (see cruise reports for
details: http://balticgas.au.dk/balticgasaudk/project/workingareasandcruises/ Deliverable 1.5). The number of
parameters recorded differed between sediment cores but as a key parameter to BALTIC GAS methane (CH4)
was measured in all sediment cores and sulfate (SO4
2-) in most. Thus sediment data submitted to the common
database PANGAEA (http://pangaea.de/) comprised (when measured) (Deliveable 1.4):
A) Pore water chemistry: CH4, δ13
CH4, SO4
2-, H2S, Cl
-, Fe
2+, Mn
2+, NH4
+, PO4
3-, alkalinity, dissolved inorganic
carbon (DIC), δ13
DIC, acetate and other volatile fatty acids (VFA),
B) Solid phase chemistry: acid volatile sulfide (AVS), chromium reducible sulfur (CRS), ‘metals’, nutrients,
Fe(solid phase), Pb-210, total nitrogen (TN), total carbon ( TC), C/N-ratio, total organic carbon (TOC),
δ13
TOC,
C) Process rates: methanogensis, anoxic oxidation of methane, and sulphate reduction
D) Physical parameters: temperature, density, porosity
Sampling of the water column comprised CH4, δ13
CH4, and H2S and was always accompanied (i.e. initiated) by a
conventional CTD cast. The water column data were likewise submitted to PANGAEA.
Fluxes of methane from the sediment to the bottom water and across the sea surface in coastal and open-sea
Baltic waters were determined by modelling from concentration data and by direct flux measurement. Sea-air
exchange was quantified by data from an autonomous measurement system mounted on the ferry M/S FINN-
MAID in November 2009 commuting regularly between Travemünde (Germany), Gdynia (Poland) and Helsinki
(Finland) to measure methane and carbon dioxide concentration in the surface waters. Direct sea-air fluxes of
Fig. 2. Seismo-acoustic lines (i.e. data) complied in a common database by GEUS. Black lines are ar-chive data. Red lines show seismo-acoustic data measured during Baltic Gas.
Table 3. Seismo-acoustic data (measured and archived) complied in a common database by GEUS. See Fig. 2.
Data source
Acoustic
line
length
(km)
Archive data University of Stockholm 2,700
Archive data Shirshov Institute of
Oceanology
Atlantic Branch, Russian
Academy of Sciences
18,300
Archive data Baltic Sea Research Insti-
tute Warnemünde 5,100
Archive data The Geological Survey of
Denmark and Greenland
(GEUS)
1,900
Archive data Department of Geoscienc-
es , University of Bremen 900
Acoustic data measured during Baltic Gas 4,600
Total seismic database 33,500
8
methane were determined with floating chambers in near-shore areas of the Southern Stockholm archipelago,
in particular theHimmerfjärden estuary.
The BALTIC GAS coordinators organized that the modellers received seismo-acoustic data and results from in situ
sediment measurements on a regular basis and that data were exchanged between BALTIC GAS scientists, par-
ticularly at BALTIC GAS workshops. Here also new ideas, hypotheses, and theories were discussed based on the
most recent findings and the modellers’ knowledge base’ was improved leading to the development of robust
algorithms and models. These models proved highly valuable in bringing the many point observations into a
larger context and in confirming hypotheses concerning, e.g. the transport-reactions models.
1.3 Methane gas and seismo-acoustic mapping
During the BALTIC GAS research project seismo-acoustic surveying was the initial and most efficient method to
find and map free methane gas in the sediment and water column. In particular when combined with direct
methane measurements in sediment cores and water column samples.
In BALTIC GAS, acoustic monitoring of sediments was performed by use of a broad spectrum of acoustic tech-
niques and equipment i.a. singlebeam echo-sounders with frequencies of 12, 38 and 200 kHz, low frequency
multibeam echo-sounder (50 kHz ELAC), parasound sediment echo-sounder (4.2, 18,5 and 42.8 kHz) , Innomar
sediment echo-sounder (5, 10 and 15 kHz), high resolution broadband chirp echo-sounder (1 – 10kHz), single-
channel Boomer (2 – 4kHz), single-channel Sparker (1kHz), and multichannel Airgun seismics (200 Hz).
The echo-sounder transmits high frequency sound waves down to the sea floor and further into the seabed.
Depending on the frequency, more or less of the energy is reflected at the sea floor, which enables a precise
Fig. 3. A seismo-acoustic transect crossing methane gas saturated sediment in Bornholm Basin across a distance of about 8 km (about 90 m water depth) between site 374200 (55o14.973N/ 15o26.147E) and site 374180 (55o20.329N/ 15o26.237E). Methane gas bubbles efficiently absorb the acoustic energy and thus ‘blanks’ information from the under-lying sedimentary strata. Yellow vertical lines show position and length of gravity cores sampled (see also Fig. 11).
9
determination of the water depth with an accuracy of a few centimeters. Lower frequency sound waves pene-
trate deeper into the sediment depending on the hardness of the seabed due to differences in mineralogy and
other geological features. The sound waves penetrate relatively easy into fine grained sediments as mud, silt,
and clay, whereas penetration depths are very limited in sand, gravel and glacial till. Thus, the seismo-acoustic
data obtained give an acoustic cross section of the seabed where the sediments and sediment strata are seen by
‘acoustic imagery’ as a vertical reflector pattern profile (Fig 3). Methane gas bubbles, however, efficiently absorb
the acoustic energy and thus ‘blank’ information from the underlying sedimentary strata. Hence by ‘acoustic
imagery’, free methane gas is observed as a conspicuous, more or less homogeneous blanking on the seismic
‘picture’ or ‘scan’ (Fig 3).
During most BALTIC GAS cruises and at most stations studied hydroacoustic singlebeam echo-sounders were
used as the standard tool for remote sensing of free methane gas in the seabed and water column. However,
during BALTIC GAS also new seismo-acoustic techniques were introduced and demonstrated as superior solu-
tions for shallow gas mapping compared to singlebeam techniques as explained below.
1.3.1 Spatial mapping of shallow gas using a low frequency multibeam echosounder
Bornholm Basin in the Baltic Sea (80m) hosting free methane gas was surveyed with low and high frequency
multibeam acoustic equipment accompanied by standard sub-bottom profiling.
The gathered multibeam backscatter data (Fig. 4a) revealed distinct differences between areas with and without
gas. Compared to standard technique singlebeam data (Fig. 4b) and geochemical analysis (Fig. 4a, cs1 and cs2)
BALTIC GAS scientist for the first time demonstrated a perfect match in regard to sensing free methane gas with
Fig. 4. (a) Backscatter amplitude chart of EM120 with a transition zone between bluish/no gas and yellowish/shallow gas areas; the inlet shows amplitude data gathered from the 95 kHz system not showing any transition, (b) PARA-SOUND sub-bottom data recorded along the blue and red line in (a) starting at 08:15 UTC. The transition zone between shallow gas (right) and no shallow gas (left) plots exactly at the same time as seen in the multibeam data (a). On figure (a) and (b) the blue and red line indicate the two sediment types ‘mud’ and ‘mud hosted with shallow gas’, respectively.
10
this method (Deliverable 3.3). In contrast no data patterns were observed in the high frequency multibeam sur-
vey (Fig. 4a insert). This emphasized the superior potential of our low frequency approach where the low fre-
quency pulses not only penetrated the seafloor up to 10 m but the ‘acoustic gas front’ also mimicked the gas
front observed form direct measurement in gravity cores. Even small gas pockets clearly emerged as “bright
spots” in the backscatter data on the very outer swath at 140° (Fig. 4a, patch in northeasterly region) making the
multibeam system a reliable tool for 2D wide-angle/spatial mapping of shallow gas.
The technique just introduced was further tested in
the Botnian Sea (Fig. 5). The respective survey
shows more complex morphology with outcropping
till on the seafloor and subbottom channels within
the Holocene mud locally hosting pockets of shal-
low gas. The multibeam was run in parallel with the
subbottom profiler. Till, mud, and gas-bearing mud
clearly plotted as different features in both da-
tasets. The till appeared as real bathymetric high
(Fig. 5), the mud caused deeper bathymetric meas-
urements due to penetration; whereas the shallow
gas within the mud caused a sudden bathymetric
increase in the transition zone.
Even though earlier studies demonstrated the feasibility of backscattering strength analysis in regard to sensing
shallow gas, no multibeam studies exist revealing subbottom gas submerged several meters below the seafloor
in two dimensions. Given the high sensitivity and the large coverage shown in our study we attribute low fre-
quency multibeam sounders a great potential in soft sediments in regard to spatial mapping of shallow gas, iden-
tifications of individual gas pockets, and to locate buried objects.
1.3.2 Towards quantification of shallow free gas in Baltic Sea sediments
The presence of free gas bubbles introduces fundamental changes in the properties of sediments and their re-
sponse to seismic sound waves. While high frequency acoustic waves are strongly attenuated, lower frequency
seismic waves are able to penetrate gas-charged sediment layers. However, the speed in gas-bearing sediment is
significantly reduced due to lower wet bulk density and modification of other elastic and sediment physical
properties. Thus by careful determination of interval velocity from raw multichannel seismic data, we were able
to estimate the amounts of free gas in the sediment.
Recording the reflected seismic waves with an array of hydrophones/channels allowed an indirect measurement
of their velocity from the curvature of reflection hyperbolae (conventional interactive velocity analysis). In addi-
tion, we performed velocity analysis on pre-stack time migrated data, which, although time consuming and
computationally intensive, allowed the determination of the velocity field over gassy areas more accurately and
more extensively in space than hitherto done. Depending on stratification (identifiable reflectors), the accuracy
and resolution varied significantly. In general, velocities dropped from about 1450 m/s in non-gassy fine-grained
surficial sediments down to a few hundred m/s in the gas-charged zone. Beneath the gas patches, in the post-
glacial and glacial sediments, velocities again increased (>1500 m/s).
Fig. 5. Pseudo bathymetric presentation after application of a slope filter (Botnian Sea) Red areas show outcropping till seafloor, wheras blue and green data represent soundings reflected from subbottom features like gas and submerged till.
11
To quantify the gas content based on the velocity field, we used Anderson & Hampton’s geoacoustic model
(1980), which described the relationship between compressional wave velocity and the physical properties of
gas-bearing marine sediments. In the model, gas bubbles were assumed to be fully contained within the pore
space, thus modifying its compressibility. Taking the interval velocity values between reflectors, free gas content
in the pore volume could be estimated (Fig. 6). Values of the free gas content at the test location in the Born-
holm Basin ranged from 0.1 to 2%, where sensitivity becomes reduced. These numbers were basically in agree-
ment with the modelling results.
When excited, gas bubbles in the sediment resonated at a fundamental frequency, which was mainly deter-
mined by the bubble size and physical properties of the surrounding medium. As a result, acoustic behaviour
Fig. 6. High resolution multichannel seismics performed with a GI gun with a central low frequency of 200 Hz and a 50 m long streamer with 48 channels (seismo-acoustic transect GeoB10_044). (a) The interval velocity values between reflectors (m/s) showing significantly reduced velocities in the gas charged sediment (dark blue pixels in the white framed sediment section) compared to gas free sediments outside the frame. Depth below surface is expressed in m/s as the two-way travel time (TMT) i.e. travel time from source and back to receiver. The offset shows the distance (m) from the start of transect in the south to the endpoint in the north. The vertical solid line shows the depth of the sea-floor. (b) The interval velocity values between reflectors in the gas charged sediment (i.e. white frame in panel (a)). (c) Free gas content estimated from ‘interval velocities’ up to 2% gas of the sediment pore volume (i.e. gas replacing pore water).
12
was different below, at and above the resonance frequency but attenuation due to the scattering effects would
be strongest close to the resonance frequency.
By imaging shallow gassy sediments at a broader frequency range, gas bubbles could be physically characterized
from their acoustic response. In the Bornholm Basin, gassy areas were surveyed with three frequencies of the
Parasound sediment echo-sounder (4.2, 18.5 and 42.8 kHz). High reflection amplitudes from and strong signal
attenuation beneath the gas front occurred at the lowest imaging frequency of the Parasound, although natural
attenuation increased with frequency. Accordingly, this effect could be attributed to bubble resonance behav-
iour, which was not observed at the two higher frequencies (Fig. 7). Based on the theoretical considerations of
Anderson and Hampton (1980) and for typical sediment properties, bubble size distribution was likely to peak
near a diameter of approx. 2 mm (4.2 kHz) with the smallest bubbles larger than 0.2-0.4 mm (42.8 and 18.5 kHz,
respectively).
These new results obtained by the BALTIC GAS project represent major scientific progress in the quantification
of gas distribution and gas volume in marine sediments based on geophysical analyses. Using a diverse suite of
seismic and acoustic equipment in parallel together with advanced methods of data processing and analysis,
remote profiling measurements come within reach for routine gas quantification. While larger uncertainties still
exist and basic physical concepts still have to be developed and tested, the acquired results for gas content and
bubble sizes seem to be in good agreements with evidence from biogeochemical measurements and modelling.
Fig. 7. Seismo-acoustic signal received from a Parasound sediment echo-sounder operated at frequencies of 4.2, 18.5, 42.8 kHz along an appox. 700 m transect in Bornholm Basin from NW (left) to SE (right). Amplitudes at 4.2 kHz, close to the resonance frequency of about 2 mm bubble size, show scatter in the gas-charged layer and decrease beneath. The can be considered as horizontal variation in this decrease can be considered as a measure of the gas content. At the 18.5 and 42.8 kHz, above resonance frequency, the effect of gas is only revealed in generally lower amplitudes than values observed in adjacent gas-free sediments. Depth below surface is expressed in m/s as the two-way travel time (TMT) i.e. travel time from source and back to receiver. The offset shows the distance (m) from the start of transect in the NW to the endpoint in the SE.
13
1.3.3 Rising of methane gas bubbles through the water column and pockmark distribution in the Gdansk Basin
State of the art multibeam seismo-acoustic techniques were used to remotely investigate gas bubbles rising
through the water column. BALTIC GAS scientists successfully deployed a prototype multibeam ecco-sounder
that allowed us to image the rising of methane gas bubbles through the water column and to sense the respec-
tive rise pattern of individual gas bubbles released from the sediment i.a. from pock marks in the seafloor (Fig. 8,
Deliverable 3.3).
Investigations were carried out in the Gdansk Basin by the Institute of Oceanology, Polish Academy of Science
and the Atlantic Branch of the P.P.Shirshov Institute of Oceanology, Russian Academy of Sciences. Acoustical
surveys with multi-beam and side scan sonars were focused on mapping of pockmarks and detection of gas bub-
bles released from the seafloor. The presence of shallow gas in the Gdansk Basin area was manifested by differ-
ent indications such as gas-saturated mud (including gas pockets), pockmarks, and gas outflow within pockmark
(Fig. 9). The total area covered by pockmarks in the Gdansk Basin was about 27 km2
(25.1 km2
in the Polish sector
and 1.7 km2
in Russian sector, Table 4).
One area with pockmarks was located in the north-eastern part of the Gdansk Deep slope. Seven pockmarks of
various morphologies, typically elongated from the southwest to the northeast, were revealed in this area. The
horizontal length of the structures varied from 200 to 900 m, with a mean width of about 150-200 m and depths
of 1-3 m below the surrounding seafloor. Apart from individual pockmarks, groups of 2-3 of these depressions
were also observed. Usually, pockmarks were surrounded by gassy mud or located at its periphery. This distinct
pockmark area was situated on a cross-section of different fracture zones with weakened zones of the sedimen-
tary cover (supply channels, such as faults and furrows), which serve as a pathways for deep gas.
Fig. 8. (a) Successive echo-image frames recorded during water column imaging with SB3050 showing Rosette (RWS) downcast, contact with gassy sediments, and induced bubble escape into the water column. (b) “Beam-Slice” presentation with the x-axis representing the ping times in seconds where the y-axis is two-way-travel time [s]. Hori-zontal features represent non-buoyant microbubbles (I) where to the right some ascending bubbles occur (II).
14
A relatively large single pockmark of 3 km length and 0.4 km wide elongated in south-north direction was dis-
covered and mapped in the Polish sector of the Gdansk Deep (54.738N/19.186E, center position). Additionally
pockmarks were identified between 55.197N – 55.072N and 18.907E – 19.018E by use of broad banded echo-
sounding. Acoustically recognized pockmarks cross sections ranged from 20 to 200 m in diameter.
Fig. 9. Distribution of gas outflow (at arrow), pockmarks and shallow gas in the Polish and Russian EEZ of Gdansk Bay. The gas outflow is also shown on Fig. 10.
Table 4. Pockmarks in Gdansk Basin Polish and Russian EEZ.
Polish EEZ Russian EEZ (offshore Kaliningrad)
Positions Area, km2 Positions Area, km
2
55.18N/18.94E Pockmark 1,5 55.36N/19.81E Pockmark 0.06
55.14N/18.99E Pockmark 15,0 55.36N/19.81E Pockmark 0.29
54.82N/18.84E Pockmark 1,4 55.36N/19.82E Pockmark 0.18
54.57N/19.16E Pockmark 6,7 55.35N/19.79E Pockmark 0.32
54.57N/19.16E Gas outflows 0,5 55.35N/19.78E Pockmark 0.49
55.32N/19.76E Pockmark 0.30
55.32N/19.74E Pockmark 0.07
total 25.1 total 1,71
15
An active gas outflow within pockmark (Fig.10)
was documented in the southern part of the Gulf
of Gdansk, with the center positioned at the
54.571N/19.165E (Table 4). The size of the struc-
ture was determined using a 12 kHz echo-
sounder to be about 250 – 300 m. Gas bubbles
emanating from the sea floor at 80 m water
depth were observed to ascent at least up to a
water depth of 30 m. An interesting feature of
this pockmark was that the older and bigger low
gas flux pockmark area confined the more active
and deeper structure. Using calibrated echo-
sounders the radius of the raising gas bubbles
was estimated to range from about 2 mm up to
10 mm.
The largest identified acoustical anomaly, presenting gas-saturated muds, was located in the central part of the
Gdansk Deep at depths of 104-106 m. As known from literature the sub-horizontal pre-Quaternary surface here
is complicated by valley furrows, associated with a system of latitudinal extended faults. The basement of the
geoacoustical anomalies reached the underlying Mesozoic layers and was usually associated with faults. Weak
fluid fluxes and/or abundant supply of sedimentary material from nearby underwater slopes and the coast may
have caused partial or full burial of the local seabed depressions and thus explained the absence of pockmarks in
this area.
In the Polish sector gas pockets, included in ‘shallow gas’ areas(Fig. 9), were mostly localized in the area of the
Gdansk Basin, especially in the vicinity of the Hel Peninsula. Occurrence of such structures was associated with
muddy sediments and high sedimentation rates of organic-rich matter at rates from 1.5 to over 2 mm per year.
Most of the gas generated in this area was mostly produced by bacteria in the Holocene sediments. The total
area in the Polish sector covered by gas-bearing sediments was about 440 km2.
1.4 Sediment and water column biogeochemistry and physical characters
For an extensive quantification of methane concentrations in Baltic Sea sediments and in order to depict other
chemical and physical profiles direct measurements were performed in the sediment (Deliverable 4.1). Based on
the seimo-acoustic surveys targeted sediment sampling was done along transects reaching from sediments with
deep or no ‘methane-reflection’ of the seismic signal (i.e. non-gaseous sediment) to sediments with methane
saturation and thus a sharp reflection (i.e. gaseous sediment Fig. 3 and Fig 11). Depending on stations and cruis-
es a variety of sampling equipment was applied, i.a. gravity corer, Rumohr Lot corer, Frahm Lot corer, and multi-
ple corer. An important part of the characterization of gas-bearing sediments was done both by a general core
description (Deliverable 4.3) and by physical property studies (Deliverable 3.1) on cores obtained during an ex-
tensive coring program of the Baltic Gas expeditions. Multisensor core logging was used to estimate basic physi-
cal properties of gas free and gas charged sediments. The results (Fig.12) were used for interpretation of sedi-
Fig. 10. The acoustic transect through the gas outflow within the pockmark showing gas bubbles emanating from the sea floor (at 80 water depth) ascending up to a water depth of about 30 m. The image was obtained with a 12 kHz echosounder. See location at Fig. 9.
16
ment echo-sounder records. From these data the thickness of the Holocene mud (deposits of the Littorina Sea
from the past ca. 9000 years) and of the older deposits from earlier Baltic Sea Stages can be estimated.
Other ‘highlights’ from the sediment and water column studies as well as methane flux measurements across
the sediment-water-atmosphere interfaces are presented below and on the BALTIC GAS home page.
1.4.1 Methane in Baltic Sea sediments
Methane (CH4) was produced in great quantities in Baltic Sea sediments by methane-producing microorganism
when organic matter was degraded through a process named methanogenesis. However, sulfate-reduction
dominated the upper sub-surface layers because sulfate reducing bacteria are energetically more effective in the
degradation of organic matter than methane-producing microorganisms. Therefore methanogenesis only took
over deeper in the sediment, below the sulfate-methane transition (SMT) zone, where sulfate was exhausted or
occurred at very low concentration (Fig. 13).
In the Baltic Sea methane was continuously formed in the seabed and gas bubbles developed at sediment
depths where the methane concentration exceeded saturation at ambient hydrostatic pressure. However, by far
most of the methane was effectively scavenged before it reached the sediment surface. In the sub-surface sedi-
ment, where there was no oxygen, sulfate was the oxidant for methane which was converted to carbon dioxide.
Most methane was oxidized at the depth to which sulfate penetrated also known as the sulfate-methane transi-
tion (SMT)-zone (Fig. 13). This microbially mediated anaerobic methane oxidation accounted for >90% of the
entire methane flux in the sea floor and, therefore, played a critical role as a barrier against methane emission to
the water column and further into the atmosphere.
Fig. 11. Methane concentrations profiles determined in sediment cores sampled along a transect in Bornholm Basin crossing the methane gas saturated sediment shown on Fig. 3. (a) Site 374200 (depth 93 m), (b) Site 374190 (depth 91 m), (c) Site 345175 (depth 93 m), and (d) Site 374170 (depth 93 m). Solid line and stipulated line show in situ CH4 satu-ration and CH4 saturation at 1 atm, respectively. Methane is rapidly lost from the sediment core when brought on deck due to a pressure decrease. Thus the scattered appearance of the CH4 concentration profile at Site 374190 (b) – i.e. sediment from the gas saturated sediment – is due to a significant loss of CH4 before the sediment was subsampled. At the Sites 374200 (a) and 345175 (c) the in situ CH4 concentration was below saturation and not detected at all at Site 374170 (d).
17
Fig. 12. Results of multisensor logging of gravity core 374200-06GC in Bornholm Basin (see also Fig. 3 and Fig. 11). The deposits of the different Baltic Sea stages are separated by yellow lines and named in red letters. The measured parameters are:" vp" - pwave velocity, "dwb" -wet bulk density, "vsh" - vane shear strength torsional moment , "con-ductivity" - electrical conductivity, "Water cont" - gravimetric bulk water content, "suszeptibility" - magnetic volume suszeptibility, "Ignition loss" - loss of ignition, "colorvalue H S V" - from core photo extracted color values of the HSV model. A short sediment echosounder record (SES) is attached at the right side for comparison.
Fig. 13. Concentrations of dissolved methane (CH4) and sulfate (SO4
2-) in pore waters from Station 011 (Mecklenburg Bay) obtained during RV Merian cruise Jul 31 - Aug 21, 2010. In situ CH4 concentration at 40 m water depth (10 ‰ salinity, 9.3oC) and CH4 saturation at 1 atm (on deck) are shown on left figure. Expanded figure (right) show the SO4
2- and CH4 flux gradients, blue and red solid lines, respectively. At this station the upward CH4 flux (red arrow) of 430 µmol m-2 d-1 is balanced by the downward SO4
2- flux (blue arrow) of 460 µmol m-2 d-1 when CH4 is oxidized (con-sumed) in the sulfate-methane transition zone (yellow box) by reduction of SO4
2-.
18
Fig. 14. GIS-map of the spatial distribution of the sulfate-methane transition zone’s (SMTZ) depth (m) in Baltic Sea sediments. Observations of concomitant presence of both sulfate and methane were predominantly done in muddy sediments with a SMTZ median value of about 0.35 m caused by a high content of particulate organic matter and thus increased production of methane. Signatures of SMTZ-depth show the performed observations.
19
In the close vicinity to the SMT-zone, concentration gradients of sulfate and methane were steep and well de-
fined and the sulfate flux down to this interface balanced the methane flux from the deep sub-surface (Fig. 13).
From the perspective of biogeochemical analysis and sampling techniques, the depth of the SMT-zone was de-
fined by pore water studies, whereas determinations of methane fluxes from sediments into the water column
or atmosphere were much more demanding. Therefore, the depth of the SMT-zone provided a robust proxy – in
terms analytical accuracy and data availability –for identification of regions at the Baltic Sea seafloor where high
or low methane production as well as methane
fluxes into the water column were to be expected.
Figure 14 shows GIS-maps of the spatial distribu-
tion of the SMT depth with respect to sediment
types; bedrock, hard bottom, hard clay, mud, and
sand (Deliverable 2.2 and 2.3). As expected the
analyses revealed that shallow SMT-zone depths
were predominantly observed within muddy sedi-
ments with median values of about 0.35 m due to
the high content of particulate organic matter and
thus increased sulfate reduction and production of
methane. Additionally Fig. 15 shows a compilation
of pore water methane fluxes to the sediment sur-
face based on the various sediment surveys con-
ducted during Baltic Gas (Deliverable 4.2). The
highest benthic flux rates were measured in the
inshore areas of Himmerfjärden followed by the
central Gotland Basin and the Arkona Basin. Low
rates, with the exception of a seep site in the Both-
nian Bay, were measured in the northern Baltic.
In conclusion BALTIC GAS scientists observed (with very few exceptions) that free methane in the Baltic Sea in
general was restricted to Holocene marine mud areas and that a minimum threshold thickness of mud was re-
quired before free methane gas was observed in the seabed (see 1.5 Modelling methane dynamics in the Baltic
Sea below). Further, detailed sediment studies in combination with seismo-acoustic investigations at a variety of
locations in the Baltic Sea showed that the Holocene mud deposits in general were thinner than the threshold
thickness for bubble formation and that the existing areas with free methane could be characterized as geologi-
cal sediment traps.
1.4.2 Holocene mud deposits and presence of free methane gas (an example from Aarhus Bay)
Based on extensive acoustic survey and sediment sampling programs performed during previous projects, i.a.
METROL (EU 5th
Framework), Aarhus Bay sediments were proven ideal to BALTIC GAS scientist for a detailed
study on the control mechanisms of methane accumulation in Baltic Sea sediment and their relation to Holocene
mud thickness. Seismic studies had previously shown accumulation of free CH4 gas in the central area of the bay
Fig. 15. Compilation of the diffusive methane flux rates towards the sediment surface determined during BALTIC GAS. Fluxes were calculated form the methane concentra-tions gradients in the pore water samples (see Fig. 13).
20
where more than 4-5 m thick homogenous mud had accumulated. The lithology suggests that most CH4 is
formed in the Holocene mud with little contribution from deeper layers of organic-poor glacial clay1.
Thirteen 3-7 m long sediment cores were collected in October 2009 and May 2010 by gravity coring at very close
distances of 20-200 m along a 600 m transect crossing from gas-free into gas rich sediment (Fig. 16). The Holo-
cene mud thickness increased gradually
along the transect and the measured pore
water gradients CH4 and SO4
2- increased in
steepness (Fig. 17 Deliverable 4.4). The
SMT-zone shifted up closer to the sediment
surface when moving from the gas-free into
the gas-rich area with a SO4
2-/CH4 flux ratio
close to 1 and thus in accordance to the
theoretical value. We extrapolated the
depth trend of organic carbon mineraliza-
tion rates deep down into the methane
zone to estimate the total depth-integrated
rates of methanogenesis. From these results
we conclude that the thickness of the organ-
ic-rich Holocene mud layer, and thus the
sedimentation rate, was the main parameter controlling the initiation of sub-surface methane accumulation and
free gas formation (Fig. 18). The relationship between these factors is, however, non-linear due to a positive
feedback whereby a small upward displacement of the SMT exposes sediment with more reactive organic mat-
ter to methanogenesis and thereby enhances the overall methane production. A higher sedimentation rate has a
similar effect by increasing the burial of reactive organic matter down below the SMT where it strongly stimu-
lates methanogenesis. Due to the positive feedback, the SMT is further shifted upwards and the methane fluxes
are increased by the transition from non-gassy to gassy sediment. This mechanism of free gas formation in Baltic
Sea sediments were further confirmed through sediment modeling as explained below (see 1.5.2 Environmental
controls of gaseous methane production in the Baltic Sea (an example from Aarhus Bay below).
1.4.3 Distribution and temporal variability of dissolved methane in the water column of the Baltic Sea
The distribution of dissolved methane in the water column of the Baltic Sea was extensively investigated based
on analysis of data gathered prior to or during the BALTIC GAS project by partner IOW. A strong correlation be-
tween the vertical density stratification, the distribution of oxygen, hydrogen sulfide, and methane was identi-
fied (Fig. 19). A widespread release of methane from the seafloor was indicated by methane concentrations
increasing with water depth. The deep basins in the central Baltic Sea showed the strongest methane enrich-
ments in stagnant anoxic water bodies, with a pronounced decrease towards the pelagic redox-cline and only
slightly elevated surface water concentrations. In general, the low-salinity basins in the northern part of the
Baltic Sea were characterized by lower water column methane concentrations and with surface water saturation
values close to the atmospheric equilibrium (Fig. 19).
1 for further details see: see Jensen, J.B., and o. Bennike (2009) Geological setting as background for methane distribution in Holo-
cene mud deposits, Arhus Bay, Denmark. Continental Shelf Research, 29(5-6), 775-784
Fig. 16. Seismic profile of Aarhus Bay sediment showing the Hol-ocene mud layer (56º N 6.81’, 10º E 24.71’ to 56º N 6.64’, 10º E 25.21’). The top of the free gas layer (= free gas depth, FGD) is shown by the upper dashed line. Below the FGD the presence of free gas in the Holocene mud results in acoustic blanking and concealment of underlying sediments. The base of the mud layer in the gassy sediments is extrapolated from the slope in the non–gassy sediments (lower dashed line). The sampling stations and penetration depth of the gravity cores are indicated.
21
Fig. 17. CH4 and SO4
2- profiles along the transect shown on Fig. 16. Stations M21 – M26 are in the gas-free area with M26 at the transition and M27 – M30 are in the gassy sediment area. The gray line represents the position of the SMT (defined at equi-molar concentrations of CH4 and SO4
2-, i.e. [CH4] = [SO42-].
Fig. 18. Factors leading to increased CH4 production along the transect relative to station M24 (the first station with quantifiable CH4 production (see Fig. 16 and Fig. 17) based on integration of mineralization rates determined from sulfate reduction rates. The upward shift of the sul-fate-methane transition is contributing much more to the total methane production than is the thickening of the Holocene mud layer.
22
Fig. 19. Oxygen (b) and methane (c) concentration along two transects across the Baltic Sea sampled in summer 2008. Hydrogen sulfide was converted into negative oxygen equivalents. The insertion in a1 displays the location of the two transects (note red and green color code), insertion a2 shows the bathymetry of the Baltic Sea and the location of the main basins (K, Kattegat; BS, Belt Sea; AB, Arkona Basin; BB, Bornholm Basin; WGB, Western Gotland Basin; EGB, Eastern Gotland Basin; A, Åland Sea; BOS, Bothnian Sea; BOB, Bothnian Bay; GF, Gulf of Finland). The extension of the individual basins is also indicated at the top of the oxygen section. The data obtained from the red (station 3075 to 3041) and green transect (station 3005to 3095) are displayed on the left and right side in Figure 1bc, with the stations labeled at the top of Figure 1b for better orientation. Modified from Schmale et al. (20102).
Based on the comprehensive analysis represented in this basin-wide data set, more detailed investigations of the
water column were performed. The strong link between enhanced methane concentrations and oxygen defi-
ciency was demonstrated by vertical profiles from fixed locations at stations with frequent oxic/anoxic shifts of
the bottom water sampled various times (Fig. 20). The mechanism of this fast buildup of a dissolved methane
pool in the water column is still under investigation, and demonstrates the sensitivity of the methane cycle to
changes in ventilation and to the extent of hypoxic and anoxic areas in the Baltic Sea.
1.4.4 Continuous measurement of surface methane concentrations – ships of opportunity
Within the framework of Baltic Gas, the partner IOW developed and operated a system which allows the contin-
uous measurement of methane and carbon dioxide concentrations in surface waters autonomously using ships
of opportunity (Fig. 21; Deliverable 4.2). The analytical setup consists of a methane and carbon dioxide analyzer
based on off-axis integrated cavity output spectroscopy (ICOS) coupled to an established equilibrator setup.
2 Schmale, O, J. Schneider v. Deimling., W. Gülzow, G. Nausch, J. Waniek, G. Rehder (2010) The distribution of methane in the water
column of the Baltic Sea. Geophysical Research Letters, 37, L12604,
23
Fig. 20. Methane concentrations (dots) and hydrographic parameters at a station in the central Bornholm Basin in De-cember 2009 (left), and August 2010 (right, with high resolution sampling of the lower 5m). Note jump in methane scale. Bottom waters were characterized by inflow of oxygenated waters at the bottom in December and anoxic conditions in summer, in conjunction with an increase of dissolved methane concentrations from 20 to 80 nM over this period of time.
Fig. 21. Schematic of a system for the contin-uous measurement of CH4 and pCO2 in sur-face waters using off-axis ICOS. The system is installed on the ferry Finnmaid run by Finn-lines.
24
The analyzer used a highly specific infrared band laser with a set of strongly reflective mirrors to obtain an effec-
tive laser path length of several kilometers. This allowed us to detect methane and carbon dioxide with high
precision (better 0.1%) and frequency. The system was installed in November 2009 on the cargo ship Finnmaid
(Finnlines) that commutes regularly in the Baltic Sea between Travemünde (Germany), Gdynia (Poland) and Hel-
sinki (Finnland).
Figure 22 shows the first complete year of opera-
tion (2010), with more than 300 days of operation,
allowing hitherto unrivaled insights into the spatio-
temporal development of sea-air disequilibria and
fluxes for methane in a marginal sea, and the analy-
sis and identification of the controlling parameters.
Surface methane saturations with general minimum
values from December to February and maximum
values during August till September showed great
seasonal differences in shallow regions like the
Mecklenburger Bight (103-507%) compared to
deeper regions like the Gotland Basin (96-161%).
Parameters influencing methane supersaturation
and emission to the atmosphere, like temperature,
wind and mixed layer depth, as well as processes,
like upwelling, mixing of the water column, and
sedimentary methane emissions, were investigated.
Highest methane fluxes were observed during the autumn and winter period. The annual interaction of stratifi-
cation and mixed layer depth was found to be a key parameter for methane fluxes in deeper regions like Gulf of
Finland or Bornholm Basis. Methane fluxes from shallow regions like the Mecklenburger Bight are controlled by
sedimentary production and consumption of methane, wind events and the temperature induced change of the
solubility of methane in the surface water.
1.4.5 The role of the inshore and littoral region for methane emissions from the Baltic Sea
Investigations of the inshore coastal fluxes from the sediment and to the atmosphere focused primarily on the
southern Stockholm archipelago with the eutrophied Himmerfjärden (Deliverable 4.2). In addition to water col-
umn methane concentration measurements, air measurements and floating methane-gas flux chambers (for the
first time Lagrangian) were deployed in the coastal regions of Swedish Baltic waters. From 2009 to 2011, an as-
semblage of 69 chambers was used for direct flux measurements between 0.5 m and 75 meter depth.
Sea-to-air fluxes determined at water depths from 3 to 75 m in June 2011 and October 2011 ranged from 0.01 to
0.12 mmol CH4 m-2
d-1
with an average of 0.06 ± 0.007 mmol CH4 m-2
d-1
(Fig. 23). Methane fluxes decreased
slightly with water depth. The highest flux was obtained from additional 24-hour measurements at the edge of
densely vegetated shore areas in only 0.5 meter water depth. Here the fluxes were as high as 0.57 mmol m-2
d-1
.
Bubble shield experiments at four shallow sites in depths less than 5 meters were conducted to separate diffu-
sive and bubble fluxes. These experiments indicated that between 30% and 84% of the total flux could be at-
tributed to bubbles. Inshore measurements in the eutrophic inner Himmerfjärden revealed clear methane sur-
face maxima, which are likely due to discharge of methane from a local sewage treatment. These concentrations
Fig. 22. Methane surface concentrations between Lübeck and Helsinki in 2010 along all transects passing close to the west of east of the Island of Gotland color-coded for each individual month.
25
Fig. 23. Sea-to-air methane fluxes (mmol m-2 d-1) at three localities Himmerfjärden, Hållsviken, and Tvären, respectively in the southern Stockholm archipelago. Chamber derived measurement were performed in June and October 2011.
were significantly higher than concentrations measured in bottom waters over a whole summer-fall measuring
campaign and suggest that a significant part of the methane in this area is not derived from benthic emissions,
but of sewage origin.
Of particular interest was the finding that the efficiency of methane oxidation above the deep anoxic basins of
the archipelago sea was very high. The deep water in these basins had methane concentrations as high as 644
nM, but more than 98% of this methane was oxidized at the chemocline and in the oxic water column above
resulting in very low emissions to the atmosphere.
Based on our data, we conclude that the inshore zone has methane emissions that are an order of magnitude
higher than in the open waters of the Baltic Sea. Of these emissions, the littoral zone with water depths less than
8 meters emits a significant part of methane in the form of bubbles. Since the littoral area is the most critically
affected zone by nutrient runoff and groundwater discharge, future work must concentrate on the littoral to
improve our predictions for future methane emissions.
Tvären transect
0.00
0.02
0.04
0.06
0.08
0.10
0.12
Tväre
n 1
Tväre
n 2
Tväre
n 3
Tväre
n 4
Tväre
n 5
Tväre
n 6M
etha
ne fl
ux (
mm
ol/m
2 /d)
Oct-11Jun-11
Hållsviken transect
0.00
0.03
0.06
0.09
0.12
0.15
Hållsviken1
Hållsviken2
Hållsviken3
B1Met
hane
flux
(m
mol
/m2 /d
)
Oct-11Jun-11
Himmerfjärden transect
0.00
0.02
0.04
0.06
0.08
0.10
0.12
H6
SIVAB H5
Frinsö H4 H3 H2M
etha
ne fl
ux (
mm
ol/m
2 /d)
Oct-11Jun-11
Himmerfjärden
Hållsviken
Tvären
Tvären transect
0.00
0.02
0.04
0.06
0.08
0.10
0.12
Tväre
n 1
Tväre
n 2
Tväre
n 3
Tväre
n 4
Tväre
n 5
Tväre
n 6M
etha
ne fl
ux (
mm
ol/m
2 /d)
Oct-11Jun-11
Hållsviken transect
0.00
0.03
0.06
0.09
0.12
0.15
Hållsviken1
Hållsviken2
Hållsviken3
B1Met
hane
flux
(m
mol
/m2 /d
)
Oct-11Jun-11
Himmerfjärden transect
0.00
0.02
0.04
0.06
0.08
0.10
0.12
H6
SIVAB H5
Frinsö H4 H3 H2M
etha
ne fl
ux (
mm
ol/m
2 /d)
Oct-11Jun-11
Himmerfjärden transect
0.00
0.02
0.04
0.06
0.08
0.10
0.12
H6
SIVAB H5
Frinsö H4 H3 H2M
etha
ne fl
ux (
mm
ol/m
2 /d)
Oct-11Jun-11
Himmerfjärden
Hållsviken
Tvären
26
1.5 Modelling methane dynamics in the Baltic Sea
Shallow seismic data were important basic information for locating free methane in the Baltic Sea sediments. In
combination with physical/chemical parameters measured in sediment cores – in particular methane and sulfate
– BALTIC GAS scientists at Utrecht University (NL) established models which were able to couple a large array of
user-defined geochemical reactions to transport processes which affected aqueous and/or solid species. The
modeling performed for BALTIC GAS was based on the Biogeochemical Reaction Network Simulator (BRNS) de-
veloped by Regnier and co-workers and made available to the public through the BALTIC GAS homepage at
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp5-deliverable-1/ (see also Deliverable 5.1). Here,
the user can access the model and define which chemical species, reactions, transport processes, and spatio-
temporal domain is to be used. Although the model can be adapted to variable boundary conditions, grids, and
highly-complex reaction equations, these features require additional manipulation of the model code which can
be performed by the scientists involved in the project. Several examples of sediment modeling for the dynamics
of organic matter, sulfate and methane are shown below.
1.5.1 Climate-related effects on past and future methane dynamics
A transient reactive-transport model (Deliverable 5.1) was developed to study the evolution of the benthic me-
thane and sulfur cycles at the millennial and centennial timescales. The overarching goal of the research was (1)
to reconstruct the evolution of methane turnover rates as a result of long-term changes in climate conditions
over glacial-interglacial cycles (Holocene period, 104 year timescale) and (2) to predict whether future climate-
dependent changes in temperature and ventilation of the Baltic Sea, combined with continued organic carbon
loading, could enhance methane gas production and release from the seabed (Deliverable 5.2).
1.5.1.1 Hindcasting methane dynamics during the Holocene period
The model was used to track the development of the methane geochemistry following the deposition and deg-
radation of organic rich sediments. This process was initiated 8,000 years ago when the Baltic Sea changed from
a freshwater system to a brackish system due to the rising sea level and a connection to the North Sea (the Litto-
rina Sea stage of the Baltic Sea). By simulating the sedimentary history of the methane cycle since its inception,
the required timescales for the development of a methanogenic zone and for free gas formation in Baltic Sea
sediments was reconstructed. Figure 24 shows the benthic biogeochemical dynamics near the center of the Ar-
Fig. 24. Development in particulate organic carbon (POC, i.e organic matter deposition; brown line), sulfate (SO4
2-; blue line), dissolved methane (CH4(aq); red line), and free methane gas (gray shaded curve) in Baltic Sea sediment (Arcona Basin) starting 8,000 years before present (BP) when the environment gradually turned brackish. The maximum depth penetration of POC (vertical brown line) equals the thickness of the Holocene mud layer. An example from the Arkona Basin modelled by use of a reactive transport model coupling solid-aqueous-gas dynamics.
27
kona Basin as an example. Simulations revealed that sulfate diffusion and sulfate-reduction controlled the fate
of organic matter during the first 3 kyr of the Littorina Sea stage. Thereafter, organic carbon degradation ex-
ceeded the rate at which sulfate was transported to the deeper sediment layers and methanogenesis occurred.
Almost concomitantly, anaerobic oxidation of methane began to consume the sulfate diffusing down from above
the methanogenic zone and also the residual sulfate pool within the glacial sediment below the muddy layer.
Consequently, the sulfate-methane transition shoaled upwards towards the sediment-water interface. A further
3 kyr until 1.6 kyr BP were required for the dissolved methane to reach the in situ solubility limit and form free
methane gas. Over the last 2 kyrs, the gas volume fraction increased to reach a contemporary concentration of
about 5 % by volume. Repeating such simulations at selected locations in the basin has also allowed to delineate
the zones where aqueous and gaseous methane are present and to construct a basin-scale methane budget.
1.5.1.2 Forecasting the impact of climate change on methane gas inventories
A reactive-transport model, which accounts for the effect of climate change on the productivity, bottom-water
temperature and salinity of the Baltic Sea, has been applied to forecast the evolution of the seafloor methane
gas inventory (Fig. 25). Full transient simulations were performed for the period 2010-2110, using boundary
conditions extracted from a 3-dimensional ecosystem model of the Baltic Sea3 forced by a regional dataset of
greenhouse gas emissions (IPCC scenario A1B).
The results obtained for the Arhus Bay transect
reveal that the temperature rise of circa 1.8 de-
grees predicted for the period 2010-2100 could
trigger a significant increase in gaseous methane
inventory, move the gas front closer to the
ment-water interface and lead to the formation of
gas at stations where there currently is none (sta-
tion M26). Similar results have been obtained in
shallow sediments of the Bothnian Bay, where gas
production is enhanced by the combined effects
of temperature and decrease in bottom-water
sulfate induced by the freshening of Baltic Sea.
Altogether, these factors could favor methane
release from the seabed, although this remains
essentially unknown. In the example below from
Aarhus Bay, model results reveal that if gas mi-
grates upwards through the sediment, most (if not
all) of this gaseous methane is concurrently re-
dissolved and oxidized during transit towards the
sediment-water interface. This gas movement
should theoretically occur if the gas pressure ex-
ceeds the pore throat entry pressure but is not
sufficiently high to fracture the sediment. No gas
fractures were observed in the sediment, and
neither was gas escape into the water column. The
exact mechanisms of gas advection and dissolu-
3 Neumann, T. (2010) Journal of Marine Systems, 81, 213-24
Fig. 25. Concentration profiles of sulfate, methane and methane gas at 4 stations in Aarhus Bay with increasing mud thickness denoted by the horizontal line (see also Fig. 16 and 17). The stations are approximately 50 m apart. The sulfate-methane transition is indicated by the gray shaded band. The top panels represent the present day (steady state) situation, and the lower panels are those where the model is run for 100 yr imposing a +0.018 oC yr-1 change in temperature in the bottom water.
28
tion remain uncertain and prediction of how gas migration will respond to future environmental and climate
changes (e.g. through the onset of sediment fracturing) remains similarly uncertain (Deliveable 3.2). Sensitivity
studies show that the methane flux (aqueous + gaseous) to the water column forecasted for the year 2100 is
highly dependent to the controlling processes, with high advection rates and/or slow dissolution rates promot-
ing the propensity for methane escape (results not shown). The model results represent the first data-
supported predictions of future methane fluxes in the Baltic Sea. Yet, further research in this area is essential for
a more accurate forecasting of the role of Baltic Sea sediments to green-house gas emission and thereby to cli-
mate-induced warming.
1.5.2 Environmental controls on gaseous methane production in the Baltic Sea (an example from Aarhus Bay)
The methane dynamics in the Baltic Sea are closely related to the deposition and build–up of an organic–rich
marine mud layer which began around 8 kyr ago as a result of rising sea level and brackish-water inundation of
the Baltic Sea that we know of today. This Holocene mud overlays organic–poor silty sediments deposited under
freshwater of glacial origin. Because of the uneven topography at the upper fringe of the freshwater sediment,
the thickness of the overlying marine mud deposits is often highly variable. Numerous seismic observations
throughout the Baltic Sea reveal that the formation of methane gas only occurs once a critical mud thickness is
surpassed. As an example, a seismic profile from Aarhus Bay at the entrance to the Baltic Sea is shown in Fig. 16
and illustrates that the appearance of free methane gas in this case occurs where the mud layer exceeds about
10 m. Yet, this depth is not fixed, but varies over Aarhus Bay and over the Baltic Sea in general. Reactive-
transport modeling was applied to (1) identify the main controls of methanogenesis and gas formation in the
seabed and (2) derive a mechanistic explanation for the abrupt appearance of gas when a critical mud thickness
is reached. The study area covered a mud lens in Aarhus Bay (Denmark), sampled for concentrations and rates at
7 stations along a transect characterized by increasingly thicker Holocene mud (Fig. 16).
Numerical simulations show that the main trigger for gas formation is the bulk sediment accumulation rate asso-
ciated with increasing mud thickness. High accumulation rates dilute the organic material deposited on the sea
floor with inorganic material and lead to a more rapid burial of reactive organic matter down into the methano-
genic zone, with resulting higher rates of methano-
genesis as well as gas production. This is illustrated
in Fig. 25 (upper panel), where the sedimentation
rate increases from 110 cm kyr-1
at station M25 to
152 cm kyr-1
at station M28 and where gas forms
when the mud thickness becomes larger than ̴10
m (station M27). The model captures also the posi-
tion of the gas layer, the so called Free Gas Depth
(FGD) corresponding to the uppermost depth
where gas first occurs, by allowing methane gas to
advect upwards through the sediment. If the gas
did not move but instead remained in situ, a hypo-
thetical simulation from site M29 shows that the
FGD would not rise above 850 cm and the simulat-
ed sulfate penetration depth would be about one
meter deeper than observed (Fig. 26a,b). Gas ad-
vection is accompanied by gas dissolution in the
Fig. 26. Simulated (curves) and measured (symbols) pore water concentrations and free gas volumes at station M29 (see Fig. 17). (a) Without allowing for gas advection through the sediment, (b) with gas advection, (c) δ13C isotopic distributions of dissolved inorganic carbon without gas advection and (d) δ13C isotopic distributions of dis-solved inorganic carbon with gas advection. The gray band indicates the sulfate-methane transition zone (SMTZ) pre-dicted by the model.
29
zone of Anaerobic Oxidation of Methane (AOM). Since this process consumes dissolved methane and is the
prime cause for bringing the methane concentration down below saturation, AOM can be likened to a geochem-
ical barrier for gas escape. Modeling of stable carbon isotope distributions support further the hypothesis that
methane gas advection and dissolution occur in the AOM zone (Fig. 26d). Without this mechanism, the AOM
rates would be significantly lower and would lead to simulated δ13
C isotopic distributions that were significantly
heavier (less negative) than the measured values (Fig. 26c). The suite of data and model results are nevertheless
consistent with the idea that all the methane transported by diffusion and gas migration is ultimately consumed
by AOM, and consequently only minor or no methane currently escapes to the ocean–atmosphere (Deliverable
5.3).
1.5.3 Regionalization and budgeting of methane cycle In sediments of the Baltic Sea high concentrations of methane (CH4) were observed by biogeochemical as well as
geophysical investigations. Biogeochemical investigations were based on sediment and pore water sampling at
selected sites and subsequent chemical and microbiological analyses. This provided detailed information about
the production and fate of biogenic methane, generated by microbially mediated processes, as well as the po-
tential release of this greenhouse gas into the water column. Geophysical methods like shallow seismic surveys
provided new information about the spatial distribution of free gas (methane gas bubbles) in sediments.
Data derived by biogeochemical or geophysical studies provided very detailed information for selected sites as
well as along survey lines. Nevertheless, the spatial coverage of these studies was – due to the time consuming
and costly techniques – rather sparse. For considerations of large scale spatial patterns and budgets, a combina-
tion of elaborate, site specific measurements with geophysical data on forcing factors which are available with
sufficient spatial coverage, are required. This supports the computation of methane budgets as well as identifi-
cation of regions where high or low methane concentrations are expected.
For spatial modeling, forcing factors like the accumulation rate of particulate organic matter (POC), the POC-
content, bottom water concentrations of e.g. sulfate and oxygen, bathymetry, slope, morphological units, bot-
tom water temperature, and current speed as well as indicators for methane formation like pockmarks were
considered. All data were projected and combined applying the Lambert azimuthal equal-area projection and
using similar grid size. By statistical analysis we compared the former mentioned parameters for regions where
free gas was observed with regions in the surrounding where free gas was not observed (Fig. 27). The spatial
modeling was applied for the different sub-regions of the Baltic Sea. For each region, a set of factors was derived
that are likely to contribute to the formation of free gas. These factors were iteratively improved and applied to
compute predictive maps about the spatial distribution and the total area of free gas in sediments of the Baltic
Sea (Fig. 28).
30
Fig. 27. (A) Locations in the Baltic Sea where free gas were observed in surface sediments (red polygons). For spatial analysis POC (i.e. particulate organic carbon) accumulation rates (B) or oxygen concentrations in bottom water (C) were considered as forcing factors. From statistical analysis of forcing factors related to the formation of free gas in surface sediments weighting coefficients were derived.
31
1.6 Deliverables
WP1.1: BALTIC GAS web-page
www.balticgas.au.dk (Bo Barker Jørgensen, Henrik Fossing)
WP1.2: Scientific reports (Y1, Y2, final)
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp1-deliverable-no-2-scientific- reports/
(Bo Barker Jørgensen, Henrik Fossing)
WP1.3: BALTIC GAS Workshops and meetings (reports)
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp1-deliverable-no-3-baltic-gas-workshops-and-
meetings-reports/ (Bo Barker Jørgensen, Henrik Fossing)
WP1.4: Submission of data to a common database
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp1-deliverable-no-4-submission-of-data-to-a-
common-database/ (Bo Barker Jørgensen, Henrik Fossing)
Fig. 28. Spatial distributing of free gas (modeled) in Baltic Sea (except Gulf of Bothnia and Finland) showing the proba-bility to find free gas in surface sediments. The prediction is based on analyses of parameters like particulate organic carbon (POC) accumulation, O2 and SO4
2- concentration in bottom water as well sediment type, observed within known free gas areas. The data set was factorized to obtain a prediction for the occurrence of free gas areas within the Baltic Sea. This procedure was optimized by comparison of the similarity of the spatial distribution of known free gas and predicted free gas areas. Based on this comparison predicted probability levels of gas occurrence (low, medium-low, medium, high) were assigned.
32
WP1.5: Research cruises
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp1-deliverable-no-5-research-cruises/
(Bo Barker Jørgensen, Henrik Fossing)
WP2.1: GIS-map of mined data
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp2-deliverable-no-1-gis-map-of-mined-data/ (Jørn B.
Jensen, Bo Barker Jørgensen)
WP2.2: GIS-map of methane flux and distribution in sediments
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp2-deliverable-no-2-gis-map-of-methane-flux-and-
distribution-in-sediments/ (Michael Schlüter, Torben Gentz, Roi Martinez, Jørn B. Jensen, Laura Lapham)
WP2.3: GIS-map of hot-spots of present and future CH4-emission
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp2-deliverable-no-3-gis-map-of-hot-spots-of-
present-and-future-ch4-emmission/ (Michael Schlüter, Torben Gentz, Roi Martinez)
WP3.1: Mapping of shallow gas and physical characterisation of gas-bearing sediments
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp3-deliverable-no-1-mapping-of-shallow-gas-and-
physical-characterisation-of-gas-bearing-sediments/ (Jørn B. Jensen, Rudolf Endler)
WP3.2: Identification of zones of potential weakness
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp3-deliverable-no-2-identification-of-zones-of-
potential-weakness/ (Gregor Rehder, B.B. Jørgensen)
WP3.3: Detection and monitoring of methane ebullition
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp3-deliverable-no-3-detection-and-monitoring-of-
methane-ebullition/ (Jens Schneider v. Deimling, Wanda Gülzow, Marina Ulyanova, Zygmunt Klusek, Gregor
Rehder)
WP4.1: Methane distributions and breakdown
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp4-deliverable-no-1-methane-distributions-and-
breakdown/ (Timothy G. Ferdelman, Volker Brüchert, Sabine Flury, Henrik Fossing, Bo Barker Jørgensen, Laura
Lapham, Nikolay Pimenov, Maja Reinholdsson, Nguyen M. Thang)
WP4.2: Methane emission through sediment-water and sea-air interfaces
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp4-deliverable-no-2-methane-emission-through-
sediment-water-and-sea-air-interfaces/ (Volker Brüchert, Timothy G. Ferdelman, Henrik Fossing, Wanda Gülzow,
Laura Lapham, Gregor Rehder, Nguyen Thanh Manh, Jens Schneider von Deimling, Torben Gentz, Michael
Schlüter)
WP4.3: Holocene evolution of the Baltic Sea ecosystem
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp4-deliverable-no-3-holocene-evolution-of-the-
baltic-sea-ecosystem/ (Daniel Conley, Maja Reinholdsson, Conny Lenz, Lovisa Zillén)
WP4.4: Submitted MS on: Sulphur and methane biogeochemistry
Flury, S., A.W. Dale, H. Røy, H. Fossing, J.B. Jensen, B.B. Jørgensen (submitted) Methane fluxes and shallow gas
formation controlled by Holocene mud thickness in Baltic Sea sediments. Geochimica et Cosmochimica Acta
WP5.1: Transport/ reaction models reg. methane and sulphur dynamics
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp5-deliverable-1/ (José Mogollón and Pierre Reg-
nier)
33
WP5.2: Predictive model and climate change scenarios
http://balticgas.au.dk/balticgasaudk/project/deliverables/wp5-deliverable-no-2-predictive-model-and-climate-
change-scenarios/ (Pierre Regnier and Andy Dale)
WP5.3: Submitted MS on: Integration gas, acoustics and biogeochemistry
Dale, A.W., S. Flury, P. Regnier, H. Røy, H. Fossing, B.B. Jørgensen (submitted) Coupling between methanogene-
sis, anaerobic oxidation of methane and δ13C distributions in gassy sediments from the Baltic Sea (Aarhus Bay).
Geochimica et Cosmochimica Acta
2. Further research and exploitation of the results
2.1. Further research
BALTIC GAS has generated a large and high-quality dataset for the distribution and dynamics of methane, proba-
bly the most comprehensive methane dataset for any marginal sea. This has been possible through the acquisi-
tion of new data during the many research cruises and through the mining of existing data. The information was
compiled in GIS maps that provide geographical overviews and information on the parameters controlling me-
thane accumulation and turnover. Such GIS maps are based on our current understanding of statistical and
causal relationships between sediment properties, water quality, and microbial processes. The GIS maps should
be considered as dynamic, however, and will be improved as further data become available or as the algorithms
for the calculation of derived properties are adjusted.
Researchers of the BALTIC GAS project have combined seismo-acoustic mapping of gas distribution and sedi-
mentology with biogeochemical point analyses. An important verification and quality control of the developed
GIS maps is therefore a further targeted core sampling and analysis to check the properties predicted by the GIS
algorithms. Key areas for such verification include the Bornholm Basin in which the latest interpretation phase
has shown that it is possible to map late Holocene subunits like the Medieval Warm Period and the Little Ice Age.
Future research would be able to focus on such Holocene time intervals and investigate methane production
and flux in these intervals.
Due to the limited capacity of BALTIC GAS, the project focused on the main sedimentary basins in the Baltic Sea
where most methane is supposedly generated. The coastal zone is, however, much more dynamic and is also
much more sensitive to local effects such as sewage outlets (e.g. Himmerfjärden) or river outlets (e.g. Bay of
Gdansk). Our data from the Swedish archipelago indicate that the coastal zone methane emission to the atmos-
phere may be ten-fold higher than in the central Baltic Sea where most studies were done. Information on the
source strength of the coastal zone for the overall emission of methane is therefore needed in order to develop
a methane budget for the entire Baltic Sea. In this respect data are largely lacking for the Bothnian Gulf (i.e.
Bothnian Sea and Bay) and in the Gulf of Finland compared to the southern part of the Baltic Sea. Future moni-
toring of methane requires the installation of more ship-based and coast-based continuous measurement sys-
tems to extend areal and temporal coverage.
As a part of BALTIC GAS we searched for point sources of gas ebullition and for sediment structures (pockmarks)
as indicators for such ebullition. The project reached the conclusion that pockmark areas are rather few and that
34
the continuous outgassing from such point sources is negligible in the overall methane budget. The project was,
however, not able to monitor potential large scale and diffuse outgassing that may take place during extreme
weather conditions such as low water level or storms, particularly at more shallow waters where also waves
might induce a pumping effect on the seabed. There are undocumented observations that such transient out-
gassing indeed takes place in some areas of the Baltic Sea where gas bubbles have accumulated at shallow depth
in the seabed. The temporal dynamics of methane cycling are therefore important. These may in the future be
monitored by measuring buoys that are positioned in strategic areas and are equipped with the instrumentation
for continuous methane analysis.
BALTIC GAS focused on only one of the important natural green-house gases, methane. Other trace gases, such
as nitrous oxide or dimethyl sulfide, may also be important and are known to be emitted in particular from the
coastal zone. Future Baltic Sea research should include this highly dynamic zone which presumably constitutes a
belt of high natural green-house gas emission all around the Baltic Sea.
Finally, we have not addressed which influence dredging, trawling or construction activity has on the biogeo-
chemistry of Baltic Sea sediments and their ecosystems. How much of the Baltic Sea seafloor is turned over and
what does this mean for the Baltic Sea are critical questions in the Anthropocene.
2.2. Exploitation of the results
With the end of the BALTIC GAS project the scientific exploitation of the results is by far not ended. A vast
amount of new acoustic data has been gathered, and though the processing has been mostly finalized within the
project’s time frame, data interpretation is by far not complete. Currently, at the end of the project, analysis of,
e.g. the multi-frequency data set of the Bornholm basin will continue with the aim to quantify the free gas oc-
currence in this area. The new methodological approach uses low frequency multibeam backscatter data able to
penetrate the seafloor down to 10 m and very precisely define the depth of the ‘acoustic gas front’ within this
range. This approach to map the 3-D distribution of free gas in shallow sediments has enormous potential as a
tool for seafloor monitoring prior to offshore constructions, i.e. wind farms or pipelines.
Two other new and promising seismo-acoustic techniques were developed during BALTIC GAS and demonstrat-
ed major scientific progress in quantification of gas distribution and gas volume in marine sediments. For the
first time, BALTIC GAS scientists were able to quantify the volume of free gas in marine sediments by monitoring
methane gas bubble resonance with a Parasound sediment echo-sounder at 4.2, 18.5 and 42.8 kHz. By use of a
new algorithm the signal was transformed to a gas volume of 0.1 – 2% in the Bornholm Basin test area. Further-
more, the technique enabled for the first time the mapping of the lower boundary of gas and thereby opened
the possibility to determine the total quantity of gas in the entire sediment column.
A novel application of a multibeam swath mapping system for sediment visualization was developed to detect
and quantify gas bubbles rising from the seabed. A new cross-correlation technique similar to that used in parti-
cle imaging velocimetry has yielded impressive results with respect to unambiguous bubble detection and re-
mote bubble rise velocimetry and thus presents a new tool for future mapping of gas ebullition through the
water column.
35
The pore water and solid phase data collected in the muddy regions of the Baltic Sea will serve a baseline for
sediment biogeochemistry in the Baltic. These chemical data have been used and will continue to be used to
constrain the reservoirs of dissolved methane and hydrogen sulfide in Baltic Sea sediments. The mapped depths
of the sulfate-methane transition will serve to identify areas where free methane gas and associated high con-
centrations of reactive hydrogen sulfide exist near the surface. For the purposes of planning human activities,
e.g. the placement of structures, dredging, and/or fishing, at or near the seafloor, these maps and distributions
will serve to identify zones where gas may be problematic (e.g. due to sulfide corrosion).
The comprehensive database compiled for methane and other geochemical key parameters in the Baltic Sea
provides highly valuable environmental information for this sensitive ecosystem. The data have been submitted
to the database, PANGAEA, which refers to the World Data Center for Marine Environmental Sciences, hosted
and maintained at the Alfred Wegener Institute for Marine and Polar Sciences. The valuable data are thereby
secured for public access and are open to targeted data search by all scientists and environmental authorities. A
moratorium on new and still unpublished data has, in agreement with the participating scientists, been limited
to two years after the end of BALTIC GAS.
The webpage of BALTIC GAS (www.balticgas.net) will be maintained and continue to provide extensive and edu-
cational information on the principles of methane cycling and the past and future methane dynamics in the Bal-
tic Sea. Similarly, compiled data in the form of GIS maps will be available through this webpage. Finally, the
webpage links to a reactive-transport model which was developed by the University of Utrecht and which is
available for external users to model their scientific data.
The BALTIC GAS project has had an important component of basic science. Among the primary objectives has
been to understand the controls on the modern methane cycle and potential hotspots of methane emission. The
project reached important milestones towards these objectives and can now present realistic forecasts of me-
thane production and accumulation under different scenarios of climate change and eutrophication. The main
results of these achievements will become available to the public in the form of publications in the international
scientific literature and through popular articles and press information.
Last but not least, BALTIC GAS successfully promoted the collaboration among scientists from different Baltic
countries and from different disciplines, in particular with key expertise in geophysics and biogeochemistry. The
project also trained many students and young scientists in these fields. The joint efforts allow interdisciplinary
approaches for the interpretation and interpolation of biogeochemical measurements by using geophysical
maps. In this respect, the network of scientists established within the project is a sustainable achievement,
which will result in continued collaboration and joint proposals far beyond the finalization of BALTIC GAS.
36
3. Work package overview
WP 1: Project management, coordination and dissemination (reported by Henrik Fossing, National Environmental Research and Bo Barker Jørgensen, Center for Geomicrobiology, both at Aarhus University, Denmark)
Task 1.1: Management and dissemination 1.1.1: Coordination scientific Reports 1.1.2: Organizing Workshops or Meetings 1.1.3: Establishment of project home-page
Task 1.2: Submission of data to a common database
Task 1.3: Research cruises 1.3.1: Identification of target sites 1.3.2: GIS based maps of target areas 1.3.3: Organizing two weeks cruises
Task 1.4: Ph.D-training program
Deliverables due within this reporting period:
1.2 Scientific reports (Y1, Y2, final)
1.3 BALTIC GAS Workshops and meetings (reports)
1.4 Submission of data to a common database
1.5 Research cruises
Task 1.1: Management and dissemination
The coordinators have discussed the outcome of BALTIC GAS with all WP-leaders, Principal Scientists and Task
Responsibles and express that
− all WPs and Tasks have been accomplished according to original research and financial plan,
− no adaptation of the research plan and schedule of deliverables was done during the project.
During the third project year two BALTIC GAS-workshop were organized, the first in cooperation with the hosting
institution: Shirshov Institute of Oceanology, Atlantic Branch, Russian Academy of Sciences, Kaliningrad-region,
Russia (February 23-24) – the second organized by the coordinators at Department of Biological Sciences, Aarhus
University (November 1-3). Meeting reports with agenda and minutes from these workshops are accessible from
the BALTIC GAS home-page (http://balticgas.au.dk/).
Task 1.2: Submission of data to a common database
BALTIC GAS scientists have uploaded data of primarily biogeochemical nature to the PANGAEA database
(http://pangaea.de) rather than SeaDataNet in compliance with the BONUS Steering Committee. Importantly, by
using PANGAEA we ensure that not only metadata but also the original data are stored and maintained on the
long term in an open database. To ensure a reproducible format in all data sets delivered to the data base and
thus facilitate data delivery to PANGAEA a ‘data manger’ (Henrik Fossing, Aarhus University) was appointed. The
data manger receives, coordinates, and keeps track of the delivery of data from the Baltic Gas scientific commu-
nity to PANGAEA. These data are easily accessible from the PANGAEA-data base by an ‘advanced search’ for
project: BALTIC GAS. However, data from analyses not presently accomplished and data not having passed the
final ‘quality control’ will be added the PANGAEA data bases when ready.
Task 1.3: Research cruises
Two research cruises with BALTIC GAS participation have been performed during 2011 both organized by BALTIC
GAS institutions:
37
− RV Limanda (June 10 - 16) Field study campaign to Himmerfjärden. BALTIC GAS-cruise. Chief Scientist:
Volker Brüchert, Department of Geology and Geochemistry, Stockholm University, Sweden. 5 partici-
pants/ 2 BALTIC GAS institutions
− RV Limanda (October 20 - 21) Field study campaign to Himmerfjärden. BALTIC GAS-cruise. Chief Scien-
tist: Volker Brüchert, Department of Geology and Geochemistry, Stockholm University, Sweden. 2 par-
ticipants/ 1 BALTIC GAS institution
A brief summary of the two research cruises incl. published cruise reports are available at the BALTIC GAS
webpage http://balticgas.au.dk/balticgasaudk/project/workingareasandcruises/. Here you also find the cruise
reports from the 13 other cruises to the Baltic Sea performed during BALTIC GAS (see also Table 2 in Executive
Summary and The Y1 and Y2 BALTIC GAS scientific Reports (Deliverable 1.2) for further details.
Task 1.4: Ph.D-training program
A total of 7 PhD and 2 Master students received the major part of their educational training during BALTIC GAS
of which one students graduated during 2011 and the rest will give in the thesis/ dissertation during the next
two years. Educational activities comprised i.a. participation in workshops and research cruises where the stu-
dents depending on their educational field took part in seismo-acoustic imaging, sediment coring and sampling,
chemical analyses, biogeochemical process analyses, and modeling. For further details see 5. Educational activi-
ties below).
Additionally in 2010 a training BONUS-course Seismo-acoustic Imaging of Sedimentary and Gas-related Features
in the Baltic Sea organized by University of Bremen and University of Szczecin took place in the Malkocin Confer-
ence Center of the University of Szczecin (Poland) and on board M/V Nawigator XXI between15-27 July, 2010
(see The Y2 BALTIC GAS scientific Report and ‘cruise report,
http://balticgas.au.dk/balticgasaudk/workshopsandcourses/ further details).
WP 2: Data mining and GIS-mapping (reported by Jørn Bo Jensen, Geological Survey of Denmark and Greenland, Denmark)
Task 2.1: Data mining 2.1.1: Searching Baltic Sea methane data in national data-bases 2.1.2: Compiling data in a common database
Task 2.2: GIS-mapping 2.2.1: Mapping of mined data 2.2.2: Mapping of methane flux and distribution in sediments 2.2.3: Mapping of hot-spots of present and future CH4-emission
Deliverables due within this reporting period:
2.1 GIS-map of mined data
2.2 GIS-map of methane flux and distribution in sediments
2.3 GIS-map of hot-spots of present and future CH4-emission
Task 2.1: Data mining
Data mining was a two phase process starting with search of mainly seismic data within and outside the project
partners, as well as additional alternative data types, such as organic contents in samples, sediment distribution
maps and maps of Holocene sediment thickness. The collected project seismic data and archive data were com-
piled in a common database and the seismic data has been interpreted in a seismic workstation.
38
2.1.1 Searching Baltic Sea methane data in national data-bases
Data mining was done within and outside the project partners (i.e. BALTIC GAS institutions) and was as such
divided into two categories.
Data mining within the project partners included, besides the already mapped areas (Metrol project gas map-
ping (Laier and Jensen 2007)4) in the Danish sector, data from IOW’s and RAS’s archives. IOW data included in
the first step the Mecklenburg Bay, Arkona Basin and Bornholm Basin and in these areas no additional data from
‘outside’ was required, but data collected during the BALTIC GAS project was included as well. Additional data
from the IOW-archive covered parts of the Polish Stolpe Forchannel and Gdansk Bay as well as data from the
Gotland Deep. The Russian sector offshore Kaliningrad was covered by archive data from RAS and the methane
distribution in this region was mapped by RAS as well.
Data mining from outside the project partners was more difficult than expected. An inquiry among Baltic State
geological surveys revealed that search for seismic data and subsequently preparing and handing over these
data to BALTIC GAS comprise a workload that most geological surveys were not able to handle without addition-
al resources. These institutions were asked to estimate their costs for data handling but replies were unfortu-
nately lacking. Most promising was the responds from Swedish and Finnish institutions whereas seismic data
from the Polish Geological Survey was dropped as explained below.
The Swedish Geological Survey (SGU) was visited in May 2010 by TA Jørn Bo Jensen and SGU showed interest in
the project. SGU has like the rest of the Baltic Sea surveys no tradition of mapping the distribution of methane
gas in the seabed, but BALTIC GAS has been provided with detailed maps of Holocene clay distribution and sam-
pling positions containing free gas. This has been key data in estimation of the Baltic Sea methane distribution.
Tom Flodén, retired from The University of Stockholm, holds an extensive and scientific valuable database of
seismic data from the central Baltic Sea. Tom Flodén offered to share his data with BALTIC GAS and for a minor
cost he prepared his data for transfer to BALTIC GAS and mapped the methane distribution in the Baltic Sea
seabed in the offshore region between Gotland and Estonia.
The Geological Survey of Finland (GSF) has been addressed as a Bonus partner (i.e. Inflow) and has replied posi-
tive. Like SGU, GSF has not mapped methane in the seabed but Baltic Gas participated in the RV Aranda, April
21-28, 2009 cruise and was provided with available seismic data from the cruise.
The Polish Geological Survey (PGS) has been contacted in writing and asked for information about distribution of
methane in the Polish sector seabed. The official answer from PSG was that they could not supply information
free of charge. This implied that Baltic Gas would have to pay for interpreting the archived Polish data and sub-
sequent transfer to the project. However it was concluded that ‘mining‘ methane data from PSG would not con-
tribute significantly to the Baltic Gas database compared to data form the Polish seabed already available within
the Baltic Gas group (IOW archive data).
4 Laier, T. and J.B. Jensen (2007) Shallow gas depth-contour map of the Skagerrak-western Baltic Sea region. Geo-Mar Lett 27:127–
141.
39
In addition to the search in national databases a literature search was carried out in order to collect published
information on gas distribution in local areas, as example environmental studies in the Stockholm archipelago
and the Szczecin Lagoon, as well as scientific papers dealing with seismic studies and geochemical parameters.
Of special interest are GIS map compilation results from the EU BALANCE project (http://www.balance-eu.org)
that indicates the distribution of Holocene clay in relation to morphology types like valleys and basins. These
data has been provided from the GEUS GIS database.
2.1.2 Compiling data in a common database
Methane distribution data collected during Baltic Gas and ‘mined’ from the project partners were compiled at
GEUS, as basis for GIS-mapping carried out by AWI. The data base holds methane distribution data sampled by
Russian, German and Danish institutions and primarily covering the Baltic Sea sectors of these countries. The
collected seismic data has been loaded on a seismic workstation, the distribution of free gas has been digitised
and the data has been exported to GIS map presentation. Alternative information has likewise been geo-coded
and GIS maps have been compiled. The GIS themes are basic information for the GIS map compilations in WP 2
task 2.2.
Task 2.2: GIS-mapping
2.2.1: Mapping of mined data
GIS-mapping of mined data focused on the collection of basic map themes from the Baltic Sea like bathymetry,
economic zones, bottom water chemistry as well as the spatial distribution of pockmarks. In addition we inte-
grated data into the GeoInformation-System ArcGIS (ESRI) about sedimentology, seafloor properties like slope
angles or bottom water currents, as well as – from a process oriented and descriptive perspective – data sets
directly related to the presence or the formation of methane in surface sediments. The later includes free gas
areas observed by seismic surveys, known pockmark sites as well as gas flares released form the accumulation
rates of particulate organic matter were compiled and integrated into the GIS. The entire set of different param-
eters, geodata compiled within Task 2.1 as well as maps were georeferenced to a common map projection
(Equal Area Projections like the Albers projection), suitable for calculations of mass budgets.
2.2.2: Mapping of methane flux and distribution in sediments
For mapping of methane fluxes as well as the distribution of free gas in surface sediments the data derived with-
in Task 2.1, data measured by the BALTIC GAS partners during research cruises, information derived from seismic
lines as well as geochemical data derived from literature recherché were considered.
For aquatic environments like the Baltic Sea, the transition from the degradation of organic matter by microbial
mediated processes driven by agents like oxygen, nitrate or sulfate to the formation of methane by fermentation
is indicated by the sulfate-methane-transition-zone (SMTZ). Within the SMTZ the pore water concentration of
sulfate is entirely consumed by degradation of organic matter and re-oxidation of methane. Production of me-
thane is starting below the SMTZ. In the close vicinity to the SMTZ concentration gradients of sulfate and me-
thane are steep and well defined. From the perspective of biogeochemical analysis and sampling techniques, the
depth of the SMTZ can be well defined by pore water studies, whereas measurement of methane fluxes from
sediments into the water column or atmosphere are much more demanding. Therefore, the sediment depth of
the SMTZ provides a robust – in terms analytical accuracy and data availability- proxy for identification of regions
at the seafloor of the Baltic Sea where high or low methane production as well as fluxes of CH4 into the water
column are expected. For example, low SMTZ depths, suggesting high CH4 concentrations and fluxes into the
SMTZ, are mainly observed within mud sediment located in basins and valleys. In these regions the median value
40
of the SMTZ is about 0.2 m. For muddy sediments located in plains, a much wider range (0.2 to 2.2 m) and a
median depths of the SMTZ of about 0.6 m were derived.
Deliverable 2.2.3: Mapping of hot-spots of present and future CH4-emission
Regions where free gas within surface sediments or specific features like pockmarks or gas flares are observed
are hot-spots for present as and future methane emissions. Based on data derived in Task 2.1 and Task 2.2 as
well as contributions by the BalticGas partners, we integrated free gas region, pockmarks sites and sites where
gas flares were reported into the GIS.
Worldwide hot spots for methane formation and fluxes are observed. For examples, this includes (1) pockmarks
(morphological depression at the seafloor) where high methane concentrations were often detected, (2) gas
flares, where methane gas bubbles are released from the seabed, (3) shallow gas regions, where gas bubbles are
detected in close vicinity to the sediment-water interface as well as (4) chemo-autotrophic communities nour-
ished by upward fluxes of e.g. methane. Such hot spots are related to geological as well as environmental condi-
tions, favorable for formation of biogenic methane or the transport of thermogenic methane, produced within
deeper strata and transported along conduits to the sediment surface.
In close cooperation with the partners of the BALTIC GAS project, we compiled data about the spatial distribu-
tion of such hot spots for methane fluxes and integrated these information into the Geo-Information-System.
Especially in the western part of the Baltic Sea pockmarks and free gas areas were observed. In the eastern part
of the Baltic Sea pockmarks were detected in Gdansk Bay or the Gulf of Finland. For some of these sites, there
seems to be indications for thermogenic sources for methane. The GIS maps considering hot spots of methane
fluxes are intended to be applied by the BALTIC GAS partners as well as for the modeling of methane distribution
and fluxes.
WP 3: Gas and seismo-acoustic mapping (reported by Gregor Rehder, Baltic Sea Research Institute Warnemünde, Germany)
Task 3.1: Mapping and quantification of shallow gas by seismo-acoustic techniques
Task 3.2 Physical characterization of gas-bearing sediments
Task 3.3: Assessment of sites of sediment weakness for recent and future gas ebullition using multidiciplinary seismo-acoustic and sediment property data
Task 3.4: Detection and monitoring of gas bubble propagation through the water column and into the atmosphere in key regions of the Baltic
Deliverables due within this reporting period.
3.1 Mapping of shallow gas and physical characterisation of gas - bearing sediments
3.2 Identification of zones of potential weakness under the external forcing of climate change and eu-
trophication for future political and hazard prevention measures
3.3 Detection and monitoring of methane ebullition
A suite of new data has been gathered by scientific cruises organized by BALTIC GAS or with contribution from
partners of the BALTIC GAS consortium over the course of the project, involving both new acoustic (Task 3.1) as
well as sediment-physical data (Task 3.2). Additionally, existing knowledge on gas ebuillition in the Baltic was
compiled from literature and and scientific exchange with partners working in the Baltic, and extended by acous-
tic investigations seeking for gas emanating from the seafloor (Task 3.4).
41
Task 3.1: Mapping and quantification of shallow gas by seismo-acoustic techniques
Valuable seismic data (backed up with three gravity cores) were sampled in the Gulf of Finland and northern part
of Gotland deep during the Aranda-cruise (April 22-25, 2009). Also the annual student cruise of Bremen Universi-
ty with RV Alkor (cruise Al347 October 8 –18, 2009) in Mecklenburg Bay and Prorer Wiek (east of Rügen) was of
major relevance to the scientific scope of BALTIC GAS. Here, new multi-frequency seismoacoustic data were
collected for the mapping of gas in the shallow sediments by use of high-frequency seismic sources (i.e. airgun
and boomer) and an echo sounder system. Two cruises with RV Oceania were carried out as part of the collabo-
rative project BALTIC GAS from 20-27 February, 2009, and 05-15 November, 2009, respectively. Objectives of
these efforts were to collect acoustic (seismic) data in the areas with potential presence of shallow gas sedi-
ments, active gas seeping, and pockmarks. The near-bottom water column and seafloor was surveyed with hy-
dro-acoustic methods working in a broad frequency range. A sediment coring program took place during the
cruise in November. The cruise focused on the EEZ of Poland, including the fault system near the Smoldzino
Fault, the inner Gulf of Gdansk between Gdynia and Hel, and the Vistula River mouth. Acoustic data acquisition
included chirp data, 360 kHz multibeam data, and a dual frequency side scan sonar as well as other methods
During RV Poseidon cruise 392 (November 28 – December 17, 2009) seismo-acoustic data, long gravity cores as
well as undisturbed upper sedimentary cores, and hydrographic data in combination with dissolved methane
data from the water column were collected in the Mecklenburg Bay, Arkona Basin, Bornholm Basin and Gotland
Deep. The sampling program focused on gradients from gas underlain to gas-poor sediments along sections, and
to investigate the water column methane inventory along these sections. The hydrographic work also aimed for
across-basin sections of the methane distribution in a winter situation. The combination of older and new hy-
droacoustic data will help to assess the persistence of the shallow gas accumulations in Holocene sediments.
Single beam echosounder data (38, 200 kHz) in the Russian sector of the Baltic Sea, as well as in an area in Swe-
dish waters north of Gdansk Bay, were gathered during RV Professor Shtokman cruise 103 from June 20-27,
2010, and enabled a refinement of the areal extend of sediments underlain by shallow gas (~300 km2) and host-
ing pockmark structures (~1,7 km2) in the Russian sector.
The largest field expedition of the BALTIC GAS project, RV Maria S. Merian cruise MSM 16/1, covering nearly all
major basins (Arkona Basin, Bornholm Basin, Gotland Basin, Bothnian Bay and Bothnian Sea) took place from
July 30 to August 22. Acoustic data gathered comprise swath bathymetry data, multibeam backscatter data,
multi frequency single beam data (5-100 kHz), Parasound data as well as high frequency seismic data. The sedi-
ment acoustic work using the 5-100 kHz signal was focused in the western Baltic (Mecklenburg Bay, Arkona Ba-
sin and Bornholm Basin) on shallow gas hot spots, and reconnaissance surveys and detailed studies at new dis-
covered shallow gas hot spots were performed in the eastern Gotland Basin and northern Baltic Sea. Here, Para-
sound data were gathered simultaneously along all acoustic profiles. Extensive seismic data acquisition was fo-
cused on the known gassy part of the Bornholm Basin, as well as the Piltene depression west of the Gulf of Riga.
For seismic data acquisition two streamers in three different configurations were used in order to collect data
with high resolution and large offsets, necessary for precise imaging and quantification of shallow gas. In addi-
tion, a new method for spatial mapping of shallow gas using low frequency multibeam sonar backscatter signals
was demonstrated. The sediment acoustic records were used to select stations for water column and sediment
work during the cruise and the simultaneous recording of various systems will allow intercomparison of the re-
sponse of the different systems to the occurrence of shallow gas.
42
The annual student cruise of University of Bremen, R/V Alkor Al363, took place October 4 – 15, 2010, collecting
new multi-frequency seismo-acoustic data with the goal of completing the existing data sets imaging shallow gas
in the sediments. High spatial resolution surveys were carried out in the Mecklenburg Bay and the Arkona Basin.
Data were collected using high-frequency seismic sources (airgun, boomer), fan sweep bathymetric equipment,
and the echosounder system of the ship. Seismic lines were run along previous coring stations (from cruises
Gunnar Thorson Western Baltic 2004; Poseidon 392, 2009) where methane measurements were carried out on
samples from gravity cores, in order to investigate the geological controls on gas production. In addition, two
interesting pockmark areas in the Bay of Mecklenburg and in the Arkona Basin were surveyed in denser grids.
Fieldwork continued in 2011. A short cruise was fulfilled onboard a fishing vessel in August 25-26, in the Russian
sector of the south-eastern Baltic. Single beam echosounder (38, 200 kHz) was used for detailed study of the
pockmarks location area on the eastern slope of the Gdansk Deep as well as for the on-way bottom sediments
survey (total 137 nm).Two additional research cruises serving BalticGas took place on R/V Oceania from March
15 – 24 and September 18 – 28. Investigations were focused primarily in the Gdansk Basin, with special attention
on the Gdansk Deep pockmark area and the inner Gulf of Gdansk. The acoustic survey was extended to Slupsk
Bank/Slupsk Furrow area. The 12 kHz and CW/Chirp echosounders were mainly used to detect gas occurrence in
this regions (hydro-acoustic transect of sea bottom and water column). To confirm acoustical observations geo-
chemical sampling was performed (undisturbed upper sedimentary cores). Based on gathered information it was
possible to designate gas saturated sediments area including gas pocket areas and to determine the location of
gas pockmarks. Also, it was possible to observe gas outflows from one of the pockmarks east of Hel Peninsula,
where supplementary observations by 70,120 and 200 kHz echosounders have been performed.
The student cruise of University of Bremen in 2011 has been accomplished between 6-16 October on board R/V
Alkor (Al382) with focus on multi-frequency seismo-acoustic surveying. For the purpose of investigating the shal-
low gas content in the muddy areas of the Bay of Mecklenburg and East of Rügen, the existing seismo-acoustic
data were complemented with new profiles. High frequency sources (airgun, boomer), the ship’s multi-
frequency sediment echosounder, side scan sonar and multibeam echosounder were used.
Apart from these new data acquisition campaigns, major effort in 2011 was on the processing, compilation, and
interpretation of the data gathered over the course of the project. Multichannel seismic data collected on the
cruise MSM 16/1 in the Bornholm Basin, Gotland Deep, Bothnian Sea and Bothnian Bay, and on some of the
annual student cruises in the Bay of Mecklenburg and in the Arkona Basin were processed at the University of
Bremen during 2011. For the purpose of stratigraphical and structural interpretation, processing of seismic pro-
files followed a conventional data processing flow with special emphasis on the velocity analysis. Parasound
sediment echosounder data recorded at three frequencies were loaded into an interpretation software along
with the seismic profiles. In order to quantify the shallow gas content in the sediment, seismic attributes were
analyzed in detail.
The seismic data collected during the Baltic Gas project has been loaded on a seismic workstation and combined
with seismic archive data collected under WP2. The seismic dataset has been interpreted and combined with
additional seabed data information to present a GIS map of gas distribution in the Baltic Sea.
Task 3.2: Physical characterization of gas-bearing sediments
This task is mainly based on the extremely successful coring program performed during the expeditions POS 392
and MSM 16/1 (see Task 3.1). The full core MSCL-loggings of all cores intended for physical property analyses are
finished. The split core logging, core description, subsampling and selected sedimentological analyses were final-
43
ized in 2011. Core by core the data were compiled, calibrated, and processed. The data are used for geo acoustic
models and the interpretation of the seismo-acoustic records. At IOW, the physical properties and geoacoustic
data provide input to the development of a geoacoustic model based on the BIOT/STOLL theory for gas free and
gas charged sediments. Further questions investigated based on the physical properties data in combination
with the acoustics are the influence of gas bubble on the acoustic properties and on the strength of the muddy
sediments, the latter also contributing to Deliverable 3.2.
Task 3.3: Assessment of sites of sediment weakness for recent and future gas ebullition using multidiciplinary
seismo-acoustic and sediment property data
This task is an end-deliverable of the project and was based on the mapping of shallow gas occurrences and sites
of current methane ebullition. During brainstorming sessions at various of the semiannual Baltic Gas meetings, it
was discussed to use the model efforts within the project to further constrain future zones of weakness based
on diagenetic models using external forcing parameters mimicking projected changes (i.e. eutrophication, warm-
ing etc.), which has been further addressed for the assessment of future scenarios as treated in Deliverable 5.2.
The general limited risk of strong gas ebullition from the shallow methanogenic sediment in the Baltic is docu-
mented in Deliverable 3.3.
Task 3.4: Detection and monitoring of gas bubble propagation through the water column and into the atmos-
phere in key regions of the Baltic
During RV Poseidon cruise 392, a prototype of a water column imaging (WCI) multibeam system (50 kHz, ELAC)
was used for the first time to monitor free gas bubbles in the water column. It was possible to demonstrate the
potential to visualize seep-related gas release occurring during deployment of instruments on the seafloor. This
part of the program is a major technological breakthrough in the framework of Task 3.4, and the respective pro-
totype dataset was also used for the development of an automated gas bubble detection algorithm for WCI da-
ta.
However, continuous observation of the acoustic signals in the water column as well as compilation of existing
observations have so far led to the picture that gas ebullition is of minor importance in the Baltic Sea (except for
the Kattegat), as is the occurrence of pockmarks hinting to potential gas ebullition (with only one structure
found in the Mecklenburg Bay, one in the Arkona, Basin, known groundwater structures in the Eckernförder Bay,
and the exception of the Pockmark area in the Russian sector). This is in accordance with the general observa-
tion of a strong gradient in methane concentration across the pycnocline, which would be “blurred” by vertical
ascent of bubbles. Based on the work performed within Baltic Gas, it can be argued that the low pressure shal-
low gas accumulations do not drive methane ebullition, that the few indications of gas seepage point to episodic
emission and a strong seasonal bias (i.e. bottom water temperature), and are expected to strongly react to wind-
driven water level changes. These considerations are compiled in Deliverable report 3.3.
WP 4: Biogeochemistry (reported by Timothy Ferdelman, Max Planck Institute for Marine Microbiology, Germany)
Task 4.1: Methane distribution and geochemical in situ gradients 4.1.1: Sulfur biogeochemistry 4.1.2: Methane biogeochemistry
Task 4.2: Gas emission across sediment-water and sea-air interface 4.2.1: Methane flux and ebullition measurements 4.2.2: Hydrogen sulphide flux
44
4.2.3: Water column methane and ferry box surface methane measurements
Task 4.3: Methane and key biogeochemical processes 4.3.1: Quantify production and breakdown of methane 4.3.2: Analyze controls on relevant key geochemical processes 4.3.3. CH4 and H2S oxidation coupled to water column oxygen consumption
Task 4.4: Holocene evolution of the Baltic Sea ecosystem
Deliverables due within this reporting period.
4.1. Methane distributions and breakdown
4.2. Methane emission through sediment-water and sea-air interfaces
4.3. Holocene evolution of the Baltic Sea ecosystem
4.4. Submitted MS on: Sulphur and methane biogeochemistry
Task 4.1: Methane distribution and geochemical in situ gradients
The first two years of the project were, to a large extent, dedicated to obtaining high quality, high resolution
down-core geochemical data related to methane and sulfur biogeochemistry. The following regions were identi-
fied as important sampling and study regions:
• Gulf of Bothnia (i.e. Bothnian Bay and Sea)
• Vyborg/Gulf of Finland
• Himmerfjärden
• Gotland Deep
• Stolpe Fore Delta, Mid-Baltic
• Kaliningrad Sector
• Gdansk Basin
• Bornholm Basin
• Arkona Basin
• Mecklenburg Bay
• Aarhus Bay
A number of sampling campaigns were undertaken to evaluate the methane and sulfur biogeochemistry in Baltic
Sea sediments:
• An expedition to Himmerfjärden (Askö Marine Lab, Sweeden) where scientists and students from three
BALTIC GAS Institutes participated in a field campaign to obtain cores from the Himmelfjärden, an an-
thropogenically impacted fjord in the north-central basin of the Baltic Sea. The principal goals were to
obtain baseline porewater, gas, and solid phase sediment data for the Baltic Gas project, as well as to
obtain samples for experimentation and flux measurements. In addition, this expedition provided the in-
itial training for 2 BALTIC GAS doctoral students in pore water sampling.
• The aforementioned doctoral students joined the R/V Aranda Expediton with BONUS HYPER scientists
on a coring expedition throughout the entire length of the Baltic Sea.
• A BALTIC GAS biogeochemist was invited to participate on the F/S Merian cruise M12-4a project with
partners from 4 different BONUS projects participated: INFLOW, BALTIC-C, AMBER, and BALTIC GAS.
Stations for BALTIC GAS activities targeted the Gotland Deep, Aland Sea, Bothnian Bay and Bothnian
Bight, as there have been no published data on the distribution, depth, and abundance of methane in
sediments from the oligotrophic, low-salinity northern Baltic Sea.
• Employing a unique, converted ferry boat, the Susanne A, as a sampling platform, a high resolution, bio-
geochemical sampling transect was completed along a gas-rich seismic line in Aarhus Bay.
45
• The Bay of Gdansk was targeted for high resolution sediment porewater methane and sulfate profiling
and experimentation during the BALTIC GAS R/V Oceana expedition in November 2009 by scientists
from three BALTIC GAS institutes.
• During the course of a three week expedition in December on the R/V Poseidon, BALTIC GAS scientists
from 4 institutes collected high resolution pore water samples for methane and chemistry analyses
along seismic transects in Mecklenburger Bay, Arkona Basin, Bornholm Basin, and the Stolpe Foredelta.
• A return expedition to Himmerfjärden (Askö Marine Lab, Sweeden) in June where scientists and stu-
dents participated in a field campaign to obtain cores from the Himmelfjärden, an anthropogenic im-
pacted fjord in the north-central basin of the Baltic Sea.
• Extensive sampling of Aarhus Bay was performed during the Arhus Bay Cruise (ABC2010) using the Su-
sanne A in April. Long gravity cores were taken for further geochemical work-up
• The sampling highlight of the year was the major two-leg expedition onboard the German research ves-
sel R/V Maria S. Merian in over 3.5 weeks in August of 2010. Surface multi-core and deep gravity cores
were obtained from the southern, central and into the northern Baltic reaches. Extensive gas, pore wa-
ter, solid phase sampling and radiotracer experimentation on the retrieved cores was performed.
The Baltic Gas project focused extensively on acquiring a large data set of sulfate and methane distributions in
Baltic Sea sediments. The dominant experimental/field approach to the problem was to study the connection
between the seismic signals observed in the sediment (i.e. seismic picture) and ‘in situ’ concentration profiles of
methane, sulfate and other pore water constituents. Thus, targeted sediment sampling was performed based on
seismic signals along transects reaching from sediments with deep or no ‘methane-reflection’ of the seismic
signal (i.e. non-gaseous sediment) to sediments with methane saturation (and thus a sharp reflection, i.e. gase-
ous sediment) in the (surface) sediments. In addition to sulfate and methane, corresponding chemical species
such as δ13
CH4, density/porosity, CN-content, and pore water (i.e. SO42-
, Cl-, H2S, Fe
2+, PO4
3-, DIC, metals, and
nutrients), and 210
Pb were often also measured.
Generally, analyses of the pore water data suggest that in the diffusive systems of the southern Baltic the thick-
ness (accumulation rate of organic rich sediment) of the Holocene mud layer is a controlling variable for the flux
of methane. Deeper layers are not a source of methane. High resolution porewater sampling and analyses from
both the R/V Poseidon 2009 expedition and the R/V MS Merian expedition to Bornholm Basin reveal a deep flux
of methane into the underlying clay sediments. In the northern, low salinity reaches of the Baltic, the methane-
sulfate interface is within a few tens of centimetres of the sediment-water interface. Finally, the first map of
sedimentary dissolve methane fluxes from deep sediments to the surface sediment has been produced based on
data collected from Baltic Gas and data mining .
Task 4.2: Gas emission across sediment-water and sea-air interface
4.2.1.1 Methane flux and ebullition measurements
For the near-shore coastal flux quantification, two field areas were selected: The southern Stockholm archipela-
go with the case study area Himmerfjärden and the archipelago off Västervik in southern Sweden. Floating, La-
grangian, methane-gas flux chambers were deployed in the littoral regions of Swedish Baltic waters. In 2009, an
assemblage of 38 chambers was distributed for 24 hour-flux measurements from very-shallow 0.5 m water
depth to 8 m water depth.
In 2010, additional 15 chambers were deployed near Hornsudde, Västervik to compare inshore fluxes within the
eutrophic southern Stockholm archipelago with fluxes in this less populated coastal area to the south. Finally, in
46
2011, 15 more stations were selected along the eutrophication gradient of the Himmerfjärden and in neighbour-
ing bights including selected stations surrounding the SYVAB sewage treatment plant in order to assess the ef-
fect of treated sewage discharge for methane concentrations and fluxes to the atmosphere and to determine
onshore-offshore trends in methane fluxes.
These measurements were conducted in the early summer and fall. The combined data suggest that the littoral
regions of the Baltic Sea have been underrepresented in estimates of fluxes of methane gas from the water col-
umn to the atmosphere. Very shallow water fluxes ranged from 5 to 553 µmol m-2
d-1
in the very shallow water
environments. In coastal waters between 10 m and 75 m depth, fluxes varied between 11 and 168 µmol m-2
d-1
.
There was no significant relationship between methane and fluxes and water depth. The highest fluxes, howev-
er, were measured in very shallow water (0.5 m depth), where it is likely that bubble emission significantly con-
tributed to the total flux. A comparison with fluxes calculated from surface methane concentrations determined
with ICOS-water equilibration system (4.2.3) shows that the inshore fluxes exceed the offshore fluxes by more
than an order of magnitude.
4.2.1.2 Benthic fluxes
A large data set of benthic flux measurements was assembled from the various research cruises in 2009 and
2010. The temporal variability in benthic fluxes was assessed in the Himmerfjärden area, where spring and late
summer data were acquired in June and September 2010 and compared to early spring data acquired at the
same stations in May 2009. Benthic fluxes and fluxes to the sediment surface were calculated from porewater
concentrations obtained directly after collecting sediment cores in order to avoid gas loss. The measurements
and calculations indicated a high variability in benthic fluxes ranging from near zero to 3625 µmol m-2
d-1
. The
highest fluxes were determined in the inshore areas and suggest an important ebullition component.
4.2.2: Hydrogen sulphide fluxes
Porewater concentrations of hydrogen sulphide fluxes were determined on RV Aranda, Merian, Poseidon, and
Limanda cruises. These data are fitted in reactive transport pore water fitting models to calculate fluxes of hy-
drogen sulphide to the sediment surface. Of particular relevance was to establish potential correlations between
methane and hydrogen sulphide fluxes. At present, only part of the available pore water sulphide data were
analyzed to calculate hydrogen sulphide fluxes. In these instances, the presence of Fe-oxyhydroxide near the
sediment surface effectively eliminated the hydrogen sulphide flux to the water column decoupling transport of
hydrogen sulphide and methane. Further analysis of the remaining pore water data will continue.
4.2.3: Water column methane and ferry box surface methane measurements
To obtain a synoptic view of the temporal and spatial in surface methane concentrations sea-air fluxes of me-
thane, a CH4-CO2-H2O analyzer was installed in November 2009 on the cargo ship M/S Finnmaid (Finnlines),
which commutes regularly between Travemünde (Germany) and Helsinki (Finland). The analytical setup consists
of a methane carbon dioxide-analyzer based on off-axis integrated cavity output spectroscopy (ICOS) analyzer
coupled to an established water-air equilibrator setup. With this system, methane concentration time series in
the surface water were obtained in two- to three-day intervals for the western and central Baltic. In addition
water column methane distributions were determined on the December 2009 RV Poseidon expedition. These
provided a detailed picture of the early winter depth distribution of methane, which support the synoptic distri-
butions of methane obtained from the ferry box IR spectrosopy measurements. On the RV Maria S. Merian ex-
pedition M16-1, the methane distribution in the water column was assessed, revealing amongst other findings a
drastic increase in bottom water methane concentration between the post bloom summer situation and the
47
situation in the winter of 2009, in connection to the occurrence of a benthic nepheloid layer. Very low post-
bloom surface pCO2 values and distinct patterns of surface methane concentrations obtained from the surface
survey using ICOS pointed to local sources.
A 2nd system was built for shipboard work on research vessels and was successfully used to monitor the gas
concentrations along the ship track during RV Maria S. Merian expedition 16-1b in August 2010. The highest
methane fluxes were found during the autumn and winter period. The annual interaction of stratification and
mixed layer depth was found to be a key parameter for methane fluxes in deeper regions like Gulf of Finland or
Bornholm Basis. Methane fluxes from shallow regions like the Mecklenburger Bight are controlled by sedimen-
tary production and consumption of methane, wind events and the temperature induced change of the solubili-
ty of methane in the surface water.
Task 4.3: Methane and key biogeochemical processes
Two years of the project were dedicated to the successful completion of several major cruises to the Baltic Sea,
and to gather all known geochemical data from the Baltic. The purpose of these cruises was to determine the
distribution of shallow gas in sediments, quantify the production and breakdown of methane, and analyze con-
trols on relevant key geochemical processes. A number of scientific results were gained during these two years:
• During the 2009 Poseiden cruise, long (10 meter) sediment cores were collected from Bornholm Basin
and measured for methane concentrations, along with many other geochemical parameters. Methane
concentrations first showed the typical increase with sediment depth but then decreased again with
depth, indicating downward diffusion (sink) of methane into Baltic Ice Lake sediments. Although, the
sink for the methane in these iron- and manganese-oxide rich sediments is not clear. Radiotracer exper-
iments (started on R/V MS Merian expedition) to elucidate mechanisms of the methane oxidation in
these deep sediments are underway.
• Using powerful acoustical techniques, the distribution of shallow gas in Baltic sediments can be deter-
mined. These techniques are mainly shipboard operations and quicker than traditional sediment coring.
On the 2010 Merian cruise, we used parasound techniques to find shallow gas deposits in the Arkona
Basin. The acoustic signals of gas were groundtruthed with sediment coring to confirm these results.
Such techniques can be used in the future to search for shallow gas.
• To analyze controls on methane accumulation on sediments, we used a two-tiered approach. First,
seismic lines were gathered, and then, sediment coring stations chosen based on these lines. For exam-
ple, a transect was carried out in the northern Gotland Basin. Along this line, the seismic reflections
showed areas with gas accumulations, thick layers of Holocene sediments, and thin layers of such sedi-
ments. Results showed that methane concentrations were high where acoustic anomalies suggested
shallow gas, and low where no gas was pictured.
• In the Bothnian Bay, a seafloor gas flare was imaged in the water column. Upon coring the sediments
below this flare, sediment pore-water methane concentrations were quite high, reaching near satura-
tion at in situ temperatures and pressures. Although this does not prove the existence of the flare, it
supports that a flare was possibly sourced in the sediments.
• One key goal of BALTIC GAS was to analyze a number of key controls on the geochemical distribution of
methane. To do this, we compared the flux of methane out of sediments to bottom water temperature,
bottom water salinity, water depth, carbon content and organic carbon quality. No correlations were
found with physical processes, such as salinity, temperature, or water depth. However, the collective
48
data over the entire Baltic as well as a very detailed study along a transect of increasing mud thickness
in Aarhus Bay, revealed that the quality as well as the amount of organic matter buried in the sediment
play a crucial role in gas formation and its accumulation
• Experiments combined with stable isotope measurements from samples taken in Aarhus Bay suggest
that the sulfur cycle may be active in the methane oxidation process below the sulfate-methane transi-
tion zone. Solid phase analyses combined with sulfur isotope analyses suggest that a major sink for re-
duced sulfur in the Baltic Sea appears to be organically-bound sulfur
• Methanogenesis experiments in the highly organic rich sediments of Himmerfjärden demonstrate that
the highest rates of methane production (principally through bicarbonate reduction) are occurring just
below the sulfate-methane transition zone. In Himmerfjärden, where sulfate penetration depths are
very shallow this leads to a steep gradient of methane towards the surface sediments .
• Key controls on the methane flux out of sediments were also analyzed on a local level at Himmerfjärden,
Sweden. The estuary has very high sedimentation and organic carbon accumulation rates compared to
open Baltic sediment (0.65 cm/a in the outer compared to 0.91 cm/a in the inner part of the estuary.
These rates correlate well with the organic carbon accumulation rates and the calculated diffusive fluxes
of methane to the sediment surface indicating that the amount of deposited organic matter is a key
driver for methane fluxes.
• Sedimentation rates were calculated from sediment cores collected during the Merian cruise August
2010. Rates were 0.3, 0.2, and 0.1 cm/yr for sites in the Gotland Basin, the Bothnian Sea, and Bothnian
Bay, respectively. Such data will be input into a larger database that was published in Geo-Marine Let-
ters, 2010 by Leipe and colleagues, and will be used in the GIS work of the Baltic Gas project.
• Carbon stable isotopes of dissolved methane from the 2010 Merian and 2009 Poseidon cruises were
measured. A unique signature of methane production was found in the very surface layers of the cores,
a sediment depth not typically known to produce methane due to the high concentrations of sulfate.
Task 4.4: Holocene evolution of the Baltic Sea ecosystem
The overall goal of the task was describe the Holocene evolution of the Baltic Sea ecosystem. To achieve this
goal, we participated in a number of different sampling campaigns throughout the 3 years of the BALTIC GAS
project utilizing important infrastructures from different countries around the Baltic Sea. We collected 33 long
sediment gravity cores with accompanying surface cores. Briefly, cores were split into two sections, described
for sediment characteristics and photographed. A number of analyses were preformed, especially different
methodologies for dating sediments using 14C and lead concentrations/stable istopes, and mineral magnetic
measurements.
A one-day workshop was held in Warnemünde (September 2009) to introduce the scientists in the BALTIC GAS
project to problems associated with evaluating Holocene evolution of the Baltic Sea. Alternate dating methods,
for instance the use of lead isotopes (lead pollution history) have led to a refined age-model for reconstructing
Baltic Sea sedimentation and basin development.
A precise determination of reservoir ages is one of the most problematic parts of establishing an accurate chro-
nology of sedimentation in the Baltic Sea. Reservoir ages in the Baltic Sea vary due both to changes in salinity,
e.g. due to salt water input from the Kattegat, and due to older carbon entering the Baltic Sea from freshwater
sources. Recent work has established that reservoir ages have decrease through the last 8,000 years of Baltic Sea
history (Lougheed et al., Submitted). In our project we attempted to obtain adequate numbers of foraminifera,
49
although we were unsuccessful. We, therefore, are using reservoir dates determined by (Lougheed et al., Sub-
mitted). In addition, we successfully applied a methodology new to the Baltic Sea regarding the use of lead con-
centration profiles and isotopes (Zillén et al., Accepted) to better determine time markers for the last 1000 years
of Baltic Sea history.
The mineral magnetic measurements provided a unique signature for laminations. When the Baltic Sea is hypox-
ic with laminations present, the magnetic susceptibility of the sediments greatly increased. We have investigated
the ferromagnetic properties of these materials including magnetic separation of mineral particles from bulk
sediments. The preliminary conclusion is that the material is likely magnetite magnetosomes made by magnoto-
tactic bateria.
Further, we have contributed to a paper on the topic of the evolution of the Baltic Sea ecosystem through time
(Andrén et al., 2011) and our sediments studies have improved our understanding of changes in the Baltic Sea
ecosystem through time.
WP 5: Modelling and data integration (reported by Pierre Regnier, Department of Earth Sciences, Utrecht University, The Netherlands)
Task 5.1: Modelling methane and sulfur dynamics 5.1.1: transport-reaction models 5.1.2: Predictive models (i.e. climate change scenarios)
Task 5.2: GIS-modelling
Task 5.3: Integrating gas, acoustics and biogeochemistry
Deliverables due within this reporting period.
5.1. Transport/ reaction models reg. methane and sulphur dynamics
5.2. Predictive model and climate change scenarios
5.3 Submitted MS on: Integration gas, acoustics and biogeochemistry
Task 5.1: Modelling methane and sulphur dynamics
5.1.1: Reaction-transport models
We have developed a detailed model for the coupling of the benthic methane and sulphur cycles. This reactive-
transport model (RTM) includes methane gas formation, migration and dissolution in marine sediments
(Mogollon et al., 2011)5. It has been validated against field data (organic carbon content and sedimentation
rates, aqueous ammonium, dissolved inorganic carbon, sulphate and methane profiles, sulphate reduction rates,
depth of free gas) collected by the partners of the project in several gassy areas of the Baltic Sea. The RTM oper-
ates both under steady-state and transient conditions (seasonal and secular variations).
The model has been applied to unravel the methane cycle in Arkona Basin (south-western Baltic Sea). The model
was used to quantify the changes in production and consumption of aqueous and gaseous methane over the last
8000 yrs as a result of the marine transgression in the Baltic Sea (Mogollon et al., 2011)6. The relationships be-
5 Mogollon, J.M., A. Dale, I. L’Heureux, and P. Regnier, P. (2011) Seasonal controls on methane gas and anaerobic oxidation of me-
thane in shallow marine sediments. Journal of Geophysical Research. 116, G03031, doi:10.1029/2010JG001592. 6 Mogollon, J.M., Dale, A., Fossing H. and Regnier, P. (2011b) Timescales for the development of methanogenesis and free gas layers
in recently-deposited sediments of Arkona Basin (Baltic Sea).Biogeosciences Discuss., 8, 7623–7669.
50
tween the thickness of organic rich-muds, methanogenesis and methane gas production has been investigated.
A similar modelling study has been conducted in the gassy sediments of Aarhus Bay (together with dr. Dale, IFM-
GEOMAR, DE) where high resolution profiles of concentrations and rates have recently been measured by Baltic
Gas partners. Here, the focus is on how the flux and reactivity of organic matter controls the formation and
depth of gassy layers, as determined by high resolution seismic images. Numerical simulations show that the
main trigger for gas formation is the bulk sediment accumulation rate associated with increasing mud thickness.
High accumulation rates dilute the organic material deposited on the sea floor with inorganic material, yet lead
to a more rapid burial of reactive organic matter fractions to the methanic zone and higher rates of methano-
genesis as well as gas production. Modeling of stable carbon isotope distributions provides further constrains on
the coupled methane and sulfur cycles and reveals that methane gas advection towards the sediment-interface
is very likely. Nevertheless, all our model results show that anaerobic oxidation of methane (AOM) acts as a very
efficient subsurface barrier against aqueous and gaseous methane escape into the overlying water column. The
work carried out in the framework of Baltic-gas has been integrated in a broader framework and summarized in
a review paper (Regnier et al., 2011)7
The modelling tools have also been used to establish basin-scale budgets of methane production and consump-
tion in the Baltic Sea. First, a link between the thickness of the organic rich mud and the amount of aqueous and
gaseous methane being produced was established. Next, using the mud thickness (and sedimentation rate) as a
master variable for the simulations, spatial extrapolation was conducted and a basin-scale budget was estab-
lished. This approach was corroborated for the Arkona Basin, using the extensive seismic surveys carried out in
this area. Based on the model results, we have also developed a prognostic indicator for methane fluxes based
on the depth of methane gas and the methane solubility concentration. This indicator has been used in combi-
nation with GIS tools to establish first-order regional estimates of methane production in the Belt seas and Ore-
sund (Denmark).
5.1.2: Predictive models (including climate change scenarios)
The RTM developed for Arhus Bay sediments has been extended to simulate the effects of eutrophication and
climate at the centennial timescale. The model can account for changes in bottom-water sulphate due to fresh-
ening of the Baltic, changes in organic matter flux triggered by variations in productivity and variations in bot-
tom-water temperatures. The model was applied at different locations in the Baltic Sea to forecast the increase
in methane gas inventories triggered by climate change in the Baltic Sea region. Full transient simulations were
performed for the period 2010-2110, using the boundary forcing’s extracted from a 3D ecosystem model of the
Baltic Sea (Neumann 2010)8. The latter was constrained using a regional data set for greenhouse gas emission
(scenario A1B), which allows to predict changes in temperature, freshwater inflows, sea-ice cover and productiv-
ity over the entire Baltic Sea with a horizontal resolution of 18 km.
Two shallow benthic areas were considered: a transect in Arhus Bay, where temperature rise could be significant
(circa 1.8 degrees for the period 2010-2110) and the Bothnian Bay, were the combined effects of freshening and
warming (circa – 1.5 PSU and + 2.2 degrees) could trigger a significant increase in gaseous methane production.
The site selection will be complemented in the near future by an investigation of a sediment core from the
Bornholm Basin, where methane gas formation occurs at significantly greater water depth. Results reveal that
7 Regnier P., Arndt, S., Dale, A.W., LaRowe, D.E., Mogollon, J. and Van Cappellen, P. (2011). Quantitative analysis of anaerobic oxi-
dation of methane (AOM) in marine sediments: A modeling perspective. Earth Science Reviews. 106, 105-130. 8 T. Neumann, Climate-change effects on the Baltic Sea ecosystem: A model study, Journal of Marine Systems 81 (2010) 213–224
51
the gas inventory in the sediments and the areal coverage of the gassy zones could increase significantly (depth
integrated gas content higher by up to a factor of 5 in some areas). The position of the gas front could also be
significantly shallower than today. Because of the large uncertainties in gas ascent and dissolution rates, includ-
ing their response to changes in environmental conditions, the capacity of the sedimentary methane gas to es-
cape to the atmosphere remains nevertheless uncertain.
Task 5.2: GIS- Modelling
The compilation of data about the occurrence of free gas in surface sediments, chemical composition of pore
waters, bottom water chemistry, sediment distribution, accumulation rates of particulate organic matter (POC)
as well as observations of pockmarks derived in WP 2 (Data mining and GIS-mapping), allows the spatial analysis
of factors favorable for the formation of methane in sediments of the Baltic Sea.
Complementary to process oriented modeling by numerical Reaction-Transport-Modeling we applied a statistical
approach using different GIS techniques supporting spatial modeling. For this purpose former mentioned data
sets were converted to raster data using a similar grid size and map projection. For spatial budgets and analysis
we applied a Lambert azimuthal equal-area projection. By GIS techniques like overlay, we selected for areas
where free gas is observed the values for POC accumulation rates, water depth, seafloor morphology etc. More
than 10 different parameters were considered by the GIS modeling of the spatial distribution of the occurrence
of free gas.
For each parameter the data selected from free gas areas were compared with data in the surrounding (e.g. sub-
basins of the Baltic proper) where no free gas appears. Based on this approach and applying statistical means we
derived a factorization of parameters which are likely to contribute to the formation of free gas. The factoriza-
tion, which was iteratively improved, was used to compute predictive maps about the spatial distribution and
the total area of free gas in sediments of the Baltic Sea.
The derived maps were cross validated by extracting data from the full data set and computing a new estimate
based on reduced set as well as by consideration of seismic lines. The later allows identifying false positive cases,
where free gas is predicted but not detected by seismic investigations. As a step towards an even improved GIS
modeling, the reliability of the spatial distribution of parameters like mass accumulation rates will be considered
to identify regions with a higher/lower statistical confidence of prediction.
Task 5.3: Integrating gas, acoustics and biogeochemistry
Among the main goals of BALTIC GAS were the quantification and mapping of methane fluxes in the Baltic sea-
bed. This was previously done by taking several-meter deep sediment cores in which the depth distribution of
methane was analyzed. The capacity for such coring during research cruises was very limited, however, consider-
ing the number of cores needed to make regional extrapolations or even draw maps of methane fluxes. Since
areas of high methane accumulation and turnover are particularly important as potential sources of methane
ebullition such hot-spots were among the primary targets for the project.
In many areas of the Baltic Sea methane production leads to free gas formation in the subsurface seabed. The
gas bubbles are highly visible in seismo-acoustic transects using appropriate instruments and the top of the bub-
ble zone can be easily recorded and mapped. In BALTIC GAS we used the distribution and depth of the bubbles
as a proxy for high methane fluxes. Fig. 5.1 shows the rationale for this approach by which the methane flux was
calculated according to the following equation:
52
Flux (CH4) = -(Φ/∆Ztotal) (Ds(SO42-
) [SO42-
]sw + Ds(CH4) [CH4]bubble) Eq. 5.1
where the symbols (and their source) are:
∆Ztotal = ∆ZSO4 + ∆ZCH4 = depth of onset of bubbles (from acoustics)
[SO42-
]sw = sulfate concentration (from seawater salinity)
[CH4]bubble = methane saturation concentration at onset of bubbles (from water depth)
Ds(SO42-
) = diffusion coefficient of sulphate (from literature)
Ds(CH4) = diffusion coefficient of methane (from literature)
Φ = porosity (from sedimentology)
As seen from Eq. 5.1, the depth of onset of
bubbles can be used for the calculation of
methane fluxes, provided that a number of
parameters are known. Those parameters
are, however, all easy to measure and map,
e.g. salinity, water depth plus bubble depth
below the sediment surface, diffusion coef-
ficients of sulfate and methane at the am-
bient bottom water temperature, and sed-
iment porosity.
During joint cruises of geophysicists and
geochemists the strategy was to use initial
seismo-acoustic mapping to guide the sub-
sequent targeted coring of sediment.
Thereby, it was possible to obtain multiple
combined data sets of methane profiles
and gas depth to calibrate the algorithm
and to test it in different regions, water
depths and geological settings in the Baltic
Sea. The approach proved highly successful
and is the basis for the hot-spot maps of
methane fluxes that are now available for a
number of areas in the Baltic Sea. It is also
the basis for models that explain the rela-
tionship between methane gas accumulation and the thickness of organic-rich Holocene mud. Finally, it is used
in the forecasting models that predict the future development and areal extent of gassy sediments in the Baltic
Sea.
Fig. 5.1. Conceptual model used for the calculation of methane
fluxes based on the depth of gas bubbles. In reality, the model used
was a more complex and realistic reactive-transport model, but this
figure may serve as a simplified illustration of the principles.
53
4. BALTIC GAS Science team
Group photo from the final BALTIC GAS Workshop, held in Aarhus, Denmark, November 1-3, 2011
Center for Geomicrobiology, Department of Biociences, Aarhus University, Denmark
Bo Barker Jørgensen ([email protected]) coordinator, WP1-leader
Britta Gribsholt
Sabine Flury
Hans Røy
Irene Harder Tarpgaard
Laura Lapham
Camilla Nissen Toftdal
Department of Biociences, Aarhus University, Denmark9
Henrik Fossing ([email protected]) Principal scientist, assisting coordinator and WP1-leader
Geological Survey of Denmark and Greenland, Copenhagen, Denmark
Jørn Bo Jensen ([email protected]) Principal scientist, WP2-leader
Zyad Al-Hamdani
Lars Georg Rödel
Department of Earth Sciences, University of Bremen, Germany
Volkhard Spiess ([email protected]) Principal Scientist
Hanno Keil
Noemi Fekete
Tilmann Schwenk
Zsuzsanna Toth
Marius Raab
9 Formerly named National Environmental Research Institute, University of Aarhus, Denmark
54
Max Planck Institute for Marine Microbiology, Bremen, Germany
Timothy Ferdelman ([email protected]) Principal scientist, WP4-leader
Michael Formolo
Thang Manh Nguyen
Natascha Riedinger
Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
Michael Schlüter ([email protected]) Principal scientist
Ellen Damm
Sabine Kasten
Torben Gentz
Michiel Rutgers van der Loeff
Kerstin Jerosch
Baltic Sea Research Institute Warnemünde, Germany
Gregor Rehder ([email protected]) Principal scientist, WP3-leader
Rudolf Endler
Thomas Leipe
Wanda Gülzow
Jens Schneider v Deimling
Oliver Schmale
Sascha Plewe
Institute of Oceanology, Polish Academy of Science, Gdansk, Poland
Klusek Zygmunt ([email protected]) Principal scientist
Piotr Majewski
Winogradsky Institute of Microbiology, Russian Academy of Sciences, Moscow, Russia
Nikolay Pimenov ([email protected]) Principal scientist
Timur Kanapatsky
Vadim Sivkov10
Marina Ulyanova10
Dmitry Dorokhov10
Department of Geological Sciences11
, Stockholm University, Sweden
Volker Brüchert ([email protected]) Principal scientist
David Bastviken12
Patrick Crill
Livija Ginters
10 Russian Academy of Sciences, Shirshov Institute of Oceanology, Atlantic Branch, Kaliningrad, Russia 11 formerly named Department of Geology and Geochemistry 12 Department Water and Environmental Studies, Lindköping University, Sweden
55
Department of Geology, Lund University, Sweden
Daniel Conley ([email protected]) Principal scientist
Maja Reinholdsson
Svante Björck
Department of Earth Sciences, Utrecht University, The Netherlands
Regnier Pierre13
([email protected]) Principal scientist, WP5-leader
Philippe van Cappellen14
José Mogollon15
Andy Dale16
5. Educational activities
A total of 7 PhD and 2 Master students received part of their educational training during BALTIC GAS of which
two students graduated during 2011 and the rest will give in their thesis/ dissertation during the next two years.
Name Institution Graduation
Ph.D students
Thang Manh Nguyen
Max Planck Institute for Marine Microbiology
Bremen, Germany
Jan 2009 – Dec 2011 Nov 2012
Maja Reinholdsson Department of Geology
Lund University, Sweden
Feb 2009 – Dec 2011 Sep 2013
Piotr Majewski Institute of Oceanology
Polish Academy of Science Gdansk, Poland
Jan 2009 – Dec 2011 2013
Wanda Gülzow Baltic Sea Research Institute Warnemünde
Germany
Jan 2009 – Dec 2011 Jun 2012
José Mogollón Department of Earth Sciences
Utrecht University, The Netherlands
Mar 2010 – Feb 2011 May 2011
Zsuzsanna Toth Department of Earth Sciences
University of Bremen, Germany
Sep 2009 – Dec 2011 Dec 2012
Torben Gentz Alfred Wegener Institute for Polar and Ma-
rine Research, Bremerhaven, Germany
Jul 2009 – Dec 2011 Sep 2012
Master students
Stine Thomas Baltic Sea Research Institute Warnemünde
Germany
Oct 2010 – Jun 2011 Jun 2011
Livija Ginters Department of Geological Sciences Stock-
holm University, Sweden
May 2010– Oct 2010 Feb 2012
BALTIC GAS educational activities comprised students’ participation in workshops, research cruises, meetings
and conferences and at a training course: Seismo-acoustic Imaging of Sedimentary and Gas-related Features in
the Baltic Sea, the latter funded by The EEIG Steering Committee.
Now at
13Dept. Earth & Environmental Sciences Université Libre de Bruxelles, Belgium
14Canada Excellence Research Chair in Ecohydrology, University of Waterloo, Ontario, Canada
15Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
16 Dept. Marine Biogeochemistry, IMF-Geomar, Kiel, Germany
56
BALTIC GAS workshops (Table 1; 1. Executive Summary) had all Ph.D. and Master students participating with
presentation of their research projects, engaged discussions, and evaluations of BALTIC GAS results in general.
At BALTIC GAS research cruises PhD-students were trained how to handle heavy sampling gear for water and
sediment sampling, seismo-acoustic imaging of the sea floor, onboard good laboratory praxis, recording a cruise
logbook, and participation at onboard scientists meetings comprising research presentations, scientific discus-
sions, general cruise logistics etc. Cruises with PhD-participation comprised (see also Table Y2; 1. Executive
Summary)
• 2 Ph.D.: RV Oceania, Feb. 20 – 27, 2009
• 2 Ph.D.: RV Limanda, May 12 – 17, 2009
• 2 Ph.D.: RV Aranda, Jun. 4 – 17, 2009
• 1 Ph.D.: RV Susanne A, Oct. 6, 2009
• 4 Ph.D.: RV Oceania, Nov. 5 – 16, 2009
• 1 Ph.D.: RV Poseidon, Nov. 27 – Dec 17, 2009
• 2 Ph.D.: RV Susanne A, May 4, 2010
• 9 Ph.D.: RV Merian, Jul. 31 – Aug. 21, 2010
• 2 Ph.D.: RV Limanda, Jun. 10 – 14, 2010
• 2 Ph.D.: RV Limanda, Jun. 10-16, 2011
Additionally a cruise planning workshop reg. RV Maria S. Merian cruise MSM 16/1 was offered at Stockholm
University and Askö Field Station Laboratory (Sweden), June 6 – 7, 2010 where a total of 7 PhD-students were
introduced to and actively participated in planning of this major research cruise.
Meetings and conferences (see 7. Meetings and conferences) were important fora for Ph.D.-students to present
their research, to network and improve their scientific career. Thus, in BALTIC GAS the principal scientists gave
highest priorities to Ph.D.-students to participate in such events with oral and/or poster presentations:
• 1 Ph.D.: Association of Hungarian Geophysicists, Mátrafüred, Hungary, 26-27 March 2010, Hungary, 26-
27 March 2010
• 1 Ph.D.: EGU General Assembly, Vienna, May 2-7 2010
• 1 Ph.D.: 10th
International Conference on Gas in Marine Sediments, Listvyanka, Lake Baikal, Russia, 6-12
September 2010
• 1 Ph.D.: AGU, San Francisco, USA. December 13-17 2010
• 1 Ph.D.: EGU General Assembly, Vienna, 3-9 April 2011
• 1 Ph.D.: Bremen PhD days in Marine Sciences 2011, University of Bremen, Bremen, Germany, 13-14
April 2011
• 5 Ph.D.: 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, August 22-26 2011
• 1 Ph.D.: 2nd Young Scientist Excellence Cluster Conference on Marine and Climate Research, Bremen,
Germany, 4-5 October 2011
The training course in Seismo-acoustic Imaging of Sedimentary and Gas-related Features in the Baltic Sea was
organized by University of Bremen, Germany, and University of Szczecin, Poland, took place in the Malkocin
57
Conference Center of the University of Szczecin (Poland) and on board the Polish M/V Nawigator XXI during 15-
27 July, 2010.
Altogether 20 students participated of which 6 students came from the University of Szczecin (Poland) and 14
students were active in the BONUS-projects: Baltic Gas, Inflow and Hyper comprising the „BONUS-institutions:
Institute of Oceanology of the Polish Academy of Sciences (Poland), P.P. Shirshov Institute of Oceanology of the
Russian Academy of Sciences (Kaliningrad, Russia), and University of Bremen (Germany).
During the three-day preparatory course the marine geology of the Baltic Sea was presented by an invited lec-
ture (Jan Harff, IOW/US), and the relevant instruments and survey methods of acoustic surface and sub-surface
imagery were introduced to both geophysicist and non-geophysicist participants. Discussions about cruise plan-
ning strategies aimed to acquaint participants with considerations leading to flexibility and successful decisions
in scientific cruise management. The seagoing expedition on RV Nawigator XXI was carried out in the Polish wa-
ters of the Baltic Sea. Seis-mic and side scan sonar data were collected in the Pomeranian Bay, eastern Bornholm
Deep and offshore Wladyslawowo during the cruise. During these days, participants gathered experience in
equipment handling, data acquisition, processing of seismo-acoustic data, and using preliminary interpretations
to aid cruise planning. The expedition was followed by a two-day post-cruise evaluation workshop. Results were
evaluated, put in scientific context, and collected in a preliminary cruise report. Cruise participants presented
selected topics in short lectures, highlighting different aspects of new data from the perspective of regional ge-
ology. Main scientific results include indications of shallow gas found south of Bornholm, and the mapping of a
basement fault zone in the eastern study area.
The course convinced us that a mixture of theory and practice taught in groups produces fruitful discussions
between young scientists and enthusiasm as well as knowledge about the selected topic.
6. Stakeholder events and other related activities
6.1 Stakeholder and scientific committees
BALTIC GAS scientists 31 times during the program period served as members or observers in stakeholder and
scientific committees and once in consultations carried out by the European Commission (see Statistics for the
performance assessment of the Programme).
2009 - Stakeholder and scientific committees
1. Conley, Daniel (Lund University) SCANBALT Forum, Kalmar, Sweden, 9 September 2009
2. Ferdelman, Timothy (Max Planck Institute, Bremen) 13th Meeting of the IODP Science Steering and
Evaluation Panel. Melbourne, Australia, 16-18 November 2009
3. Jørgensen, Bo Barker (Center for Geomicrobiology, Aarhus University) Scientific Advisory Board, Alfred
Wegener Institute for Marine and Polar Research, Bremerhaven, Germany, 2-day Meeting in Bremerha-
ven 2009
4. Jørgensen, Bo Barker (Center for Geomicrobiology, Aarhus University) Scientific Advisory Board, Faculty
of Biology, University of Vienna, Austria, 2-day Meeting in Vienna 2009
58
5. Jørgensen, Bo Barker (Center for Geomicrobiology, Aarhus University) Scientific Planning Committee for
IODP Drilling Proposal in Baltic Sea, 1-day Magellan Workshop on IODP Drilling Project 2009
6. Pimenov, Nikolay (Winogradsky Institute of Microbiology, Moskow) Steering committee for the Interna-
tional Workshop “Geological and bio(geo)chemical processes at cold seeps – Challenges in recent and
ancient systems. Varna, Bulgaria, 28-30 September 2009
7. Regnier, Pierre (Utrecht University) Foreign advisory committee member: MERMEX (Marine Ecosystems
Response in the Mediterranean Experiment) project consortiumCNRS, CEREGE, Europole de l’Arbois, Aix
en provence,France, 22-23 September 2009
8. Regnier, Pierre (Utrecht University) Invited scientific expert. 1st scientific meeting on the chemical Evo-
lution of Lake Kivu. Royal Museum for Central Africa. Tervuren, Belgium, 19 January 2009
9. Regnier, Pierre (Utrecht University) Steering committee member. KAUST-GRP Center in Developmen-
tSOWACOR (Saudi Arabia). Utrecht, The Netherlands, 18-19 May 2009
2010 - Stakeholder and scientific committees
1. Conley, Daniel (Lund University) HELCOM Ministers meeting, Parliment, Stockholm, Sweden, 25 August
2010
2. Conley, Daniel (Lund University) IVL Swedish Environmental Research Institute, The Swedish Royal Insti-
tute of Technology, Stockholm Sweden (followed by a interview on Swedish Radio), 2 September 2010
3. Jørgensen, Bo Barker (Center for Geomicrobiology, Aarhus University) EU Coordinated Action "Deep Sea
and Sub-Seafloor Frontiers", Member of Steering Committee, Kick-off meeting, Brussels, 1 day 2010
4. Jørgensen, Bo Barker (Center for Geomicrobiology, Aarhus University) Scientific Advisory Board, Alfred
Wegener Institute for Marine and Polar Research, Bremerhaven, Germany, 2-day Meeting in Bremerha-
ven 2010
5. Jørgensen, Bo Barker (Center for Geomicrobiology, Aarhus University) Scientific Advisory Board, Faculty
of Biology, University of Vienna, Austria, 2-day Meeting in Vienna 2010
6. Pimenov, Nikolay (Winogradsky Institute of Microbiology, Moskow) Scientific steering comities of 10th
International Conference on Gas in Marine Sediments. Limnological Institute SB RAS (Listvyanka Lake
Baikal), 06-12 September, 2010
7. Regnier, Pierre (Utrecht University) Invited scientific Expert. ICES meeting on ‘How Models help us to
understand Climate Change Evolution and Impacts in the Regional Oceans (WKMCCEI)’. Brussels, Bel-
gium, 12–14 January 2010
8. Regnier, Pierre (Utrecht University) Foreign advisory committee member: MERMEX (Marine Ecosystems
Response in the Mediterranean Experiment) project consortium CNRS. World Trade Center Marseille,
France, 8-9 July 2010,
9. Regnier, Pierre (Utrecht University) Advisory committee member: Advanced modeling and research on
eutrophication (AMORE III), Belgian Science Policy. Brussels, Belgium, 6 October 2010.
10. Regnier, Pierre (Utrecht University) Invited scientific expert. High-level workshop on living in a low-
carbon society. Atomium Culture, the permanent platform for European Excellence. Brussels, Belgium,
18-19 November 2010
11. Rehder, Gregor (Baltic Sea Research Institute Warnemünde) Member of the organizing scientific com-
mittee of The National Academy of Science/ Humbolt Foundation (German American Frontiers of Sci-
ence/ Kavli Conference) October 2010
59
12. Sivkov, Vadim (Shirshov Institute of Oceanology, Atlantic Branch, Kaliningrad) Scientific steering com-
mittee member of International symposium ”Mining and processing of the amber in Sambia”, Kalinin-
grad. 12-14 May 2010
13. Sivkov, Vadim (Shirshov Institute of Oceanology, Atlantic Branch, Kaliningrad) Scientific steering com-
mittee member of International Conference ”Multiphase systems: the World ocean, environment, hu-
man, society, technologies”, Shirshov Institute of Oceanology, onboard R/V Academik Sergey Vavilov, 7-
14 June 2010
2011 - Stakeholder and scientific committees
1. Brüchert, Volker (Stockholm University) Swedish Nuclear Waste and Management Company (SKB) Origin
of methane in groundwater discharge near sites of long-term nuclear waste disposal in Sweden 2011
2. Ferdelman, Timothy (Max Planck Institute, Bremen) served as a steering committee member on the EU
FP7 Deep Sea and Sub-seafloor Frontier Coordinated Action. He was also a member of the IODP Proposal
Evaluation Panel 2011
3. Ferdelman, Timothy (Max Planck Institute, Bremen) also served on the PhD committee of BONUS doc-
toral student Zsusanna Toth, which met twice in 2011
4. Fossing, Henrik (Inst. Bioscience, Aarhus University) BONUS Forum 2011, Gdansk, Poland, 24 October
2011
5. Fossing, Henrik (Inst. Bioscience, Aarhus University) 13th Baltic Development Forum Summit and Euro-
pean Commision’s 2nd
Annual Forum on the Strategy for the Baltic Sea Region, Gdansk, Poland, 24-26
October 2011
6. Klusek, Zygmunt (Institute of Oceanology, Polish Academy of Science, Gdansk) Scientific Committee, 8th
EAA International Symposium on Hydroacoustics - XXVIII Symposium on Hydroacoustics, Jurata, Poland,
17-20 May 2011
7. Regnier, Pierre (Utrecht University) Committee member. Section Earth and Life Sciences (ALW), Dutch
Science Foundation (NWO). 1 day meeting, 2011
8. Regnier, Pierre (Utrecht University / Université Libre de Bruxelles) Committee member. Section Sciences
Exactes et Naturelle. Fonds National de la Recherche Scientifique (National Research Fund for Scientific
Research – FNRS). Belgium. 1 day meeting 2011
9. Sivkov, Vadim (Shirshov Institute of Oceanology, Atlantic Branch, Kaliningrad) Scientific steering com-
mittee member of International Conferense (School) on marine geology, Moscow, 14-18 November
2011
2011 - contribution to consultations carried out by the European Commission
1. Regnier, Pierre (Utrecht University / Université Libre de Bruxelles) The Baltic Gas project. Bonus + high-
lights to the European community. Brussels, Belgium. 8 November 2011.
6.1 Other related activities
The Danish Crown Prince Frederik and his wife, Crown Princess Mary, visited The Leibniz-Institute for Baltic Sea
Research, Warnemünde (IOW) on September 28, 2010. The Danish Ambassador in Germany and rep-
resentatives from Germany and Denmark at ministerial level participated in the visit. On this special occasion a
booklet on Danish-German research collaborations in marine sciences was published by the Royal Danish Em-
60
bassy, with preface written by Denmark's Minister for Science, Technology and Innovation. The booklet specifi-
cally mentions collaboration within the BONUS project BALTIC GAS.
The Maria S. Merian cruise MSM 16/1 (July 31 – August 21, 2010) was presented to the public through weekly
reports, blogs and press releases and received significant public interest. Also, a small group of visitors was wel-
comed on board the research vessel for a 12 hour cruise through the Kiel Canal (German: Nord-Ostsee-Kanal) by
the end of the cruise.
7. Meetings and conferences
Brüchert, V., D. Bastviken, L. Ginters. Sediment-water and sea-air fluxes of methane along a salinity and eutroph-
ication gradient in the coastal Baltic Sea. Fall Meeting American Geophysical Union, San Francisco, Decem-
ber 5-9, 2011
Brüchert, V., L. Ginters, D. Bastviken, T. M. Nguyen, T. G. Ferdelman. Methane dynamics in Himmerfjärden, Baltic
Sea. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, August 22-26 2011
Brüchert, V., L. Ginters, D. Bastviken, T. M. Nguyen, T. G. Ferdelman. Methane dynamics in Himmerfjärden, Baltic
Sea. Visions of the Sea Conference 2011. The Swedish Society for Marine Sciences. Royal Swedish Academy
of Sciences, Stockholm, November 21-23 2011
Brüchert, V., T. Nguyen, A. Deutschmann, M.E. Boettcher, T.G. Ferdelman. Bacterial sulfate reduction and meth-
anogenesis in oligotrophic sediments of the northern Baltic. European Geoscience Union, EGU 2010, Vienna,
2-7 May 2010
Conley, D.J. Effect of hypoxia on nutrient biogeochemistry in the Baltic Sea. 2011 ASLO Aquatic Sciences Meeting,
San Juan, Puerto Rico, USA, 13-18 February 2011
Conley, D.J. Hypoxia in the Baltic Sea. Nereis Park Conference, Kristineberg, Sweden, 29-31 August 2011
Conley, D.J. Time series of oxygen concentrations in the Baltic Sea. Coastal and Estuarine Research Federation
Meeting, Daytona Beach, FL, USA, 6-10 November 2011
Endler, R., J. Wunderlich, J. Schneider von Deimling, S. Erdmann. Acoustic imaging of shallow gas in Baltic Sea
sediments. Int. Conf. HYDRO 2010, Warnemünde, 2-5 November 2010
Flury, S., H. Fossing, H. Røy, M. Lever, B. Gribsholt and B. B. Jørgensen. Enhanced methane fluxes in gassy sedi-
ments - a paradox? 10th International Conference on Gas in Marine Sediments, Listvyanka, Lake Baikal,
Russia, 6-12 September 2010
Flury, S., H. Fossing, H. Røy, J.B. Jensen, A. Dale, B.B. Jørgensen. Geochemical dynamics along a transect of gas-
free and gas charged sediments – A detailed study in Aarhus Bay. 8th Baltic Sea Science Congress, Skt. Pe-
tersburg, Russia, 22-26 August 2011
Fossing, H., T.G. Ferdelman, L. Lapham, S. Flury, B.B. Jørgensen, J.B. Jensen, R. Endler, J. Mogollon. Methane
concentrations along a transect crossing an area with free methane gas (Bornholm Basin, Baltic Sea). 8th
Baltic Sea Science Congress, Skt. Petersburg, Russia, 22-26 August 2011
Gentz, T., M. Schlüter. Underwater cryotrap - membrane inlet system (CT-MIS) for improved in situ analysis of
gases by mass spectrometry. 8th Harsh-Environment Mass Spectrometry Workshop, St. Petersburg, USA,
19-22 September 2011
Gentz, T., M. Schlüter, R. Martinez. Identification of the regional distribution of gassy sediments in the Baltic Sea
by application of Geo-Information-Systems. Bonus Annual Conference 2010, Vilnius, 19-21 January 2010
61
Gülzow, W., G. Rehder, J. Schneider v. Deimling, T. Seifert. Seasonal and spatial distribution of methane in the
surface water of the Baltic Sea. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, August 22-26 2011
Gülzow, W., G. Rehder, B. Schneider, J. Schneider v. Deimling, B. Sadkowiak. Continuous measurement of me-
thane and carbon dioxide concentrations in surface waters based on off-axis integrated cavity output spec-
troscopy Fall Meeting American Geophysical Union, San Francisco, USA. December 13-17 2010
Gülzow, W., G. Rehder, B. Schneider, J. Schneider von Deimling, B. Sadkowiak. A new method for continuous
measurement of methane and carbon dioxide in surface waters of the Baltic Sea using off-axis integrated
cavity output spectroscopy (ICOS). Geophysical Research Abstracts Vol.12, EGU 2010-2913, EGU General As-
sembly, Vienna, May 2-7 2010
Jakobs, G., O. Schmale, M. Blumenberg, G. Rehder. Indications for microbially mediated methane oxidation in the
water column of the central Baltic Sea (Gotland Deep and Landsort Deep). 8th Baltic Sea Science Congress,
Skt. Petersburg, Russia, August 22-26 2011
Jensen J.B. 2010. Major tectonic control of near bottom current sedimentation and methane distribution in the
Bornholm basin, South-Western Baltic Sea. The 10th International Marine Geological Conference ”The Baltic
Sea Geology - 10”, St.Petersburg, Russia, 24-28 August 2010
Jørgensen, B.B. Havbundens metanproduktion – fra Østersøen til verdenshavet. Dansk Havforskermøde, 28 Janu-
ary 2009
Jørgensen, B.B. The dynamic methane cycle in marine sediments. University of Cardiff, 5 May 2009
Jørgensen, B.B., T.G. Ferdelman, S. Flury, H. Fossing, L. Holmkvist, L. Lapham. Controls on methane formation in
Baltic Sea sediments. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, August 22-26 2011
Jørgensen, B.B., S. Flury, H. Fossing, L. Holmkvist, J.B. Jensen, R.J. Parkes and the BALTIC GAS team. 2010. BALTIC
GAS: Dynamic methane fluxes in the seabed. 10th International Conference on Gas in Marine Sediments,
Listvyanka, Lake Baikal, Russia, 6-12 September 2010
Jørgensen, B.B., H. Fossing and the BALTIC GAS team. BALTIC GAS: The dynamic methane fluxes in the seabed.
Bonus Annual Conference 2010, Vilnius, 19-21 January 2010
Jørgensen, B.B. A cryptic sulfur cycle driven by iron in the methane zone of marine sediment (Aarhus Bay, Den-
mark). EGU General Assembly, Vienna, Austria, 5-7 April 2011
Klusek, Z., P. Majewski. Acoustics methods used in shallow gassy sediments: detection and classification in the
Baltic Sea PEEZ. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, 22-26 August, 2011
Klusek, K., P. Majewski. Acoustics detection and classification of shallow gas in sediments in the Gulf of Gdansk.
58th Open Seminar on Acoustics joint with 2nd Polish-German Structured Conference on Acoustics, Jurata,
Poland, 13-16 September 2011
Lapham, L., S. Flury, H. Fossing, V. Brüchert, T. Ferdelman, N.M. Thang, L. Ginters, B.B. Jørgensen. Using stable
carbon isotope ratios of CH4 and CO2 to follow the production and consumption of CH4 along the south to
north salinity gradient in the Baltic Sea. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, 22-26 Au-
gust 2011
Mogollón, J.M., A. Dale, P. Regnier. Modeling the Holocene methane cycle in Arkona Basin sediments. 10th Inter-
national Conference on Gas in Marine Sediments, Listvyanka, Lake Baikal, Russia, 6-12 September 2010
Mogollón, J.M., A. Dale, P. Regnier. Methane cycling in the Baltic Sea: Hindcast modeling at the 10 kyr timescale.
Workshop on uncertainties of scenario simulations, Norrköpping, Sweden, 14 October 2010
Mogollón, J.M., A.W. Dale, P. Regnier, M. Schlüter. Methane oxidation rates in gassy areas across the North Sea,
Baltic Sea transition. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia 22-26 August 2011
62
Pimenov, N.V., T.A. Kanapatsky, P.A. Sigalevich, A.G. Grigoriev, V.A. Zhamoida. Microbial processes of carbon and
sulfur cycling in the Holocene sediments of the Vyborg Bay (Finland Gulf, Baltic Sea). 8th Baltic Sea Science
Congress, Skt. Petersburg, Russia, 22-26 August 2010
Pimenov, N.V., T.A. Kanapatsky, P.A. Sigalevich, A.G. Grigoriev, V.A. Zhamoida. Microbially mediated methane
and sulfur cycling in gas-bearing sediments of the Vyborg Bay (Finland Gulf, Baltic Sea). 10th International
Conference on Gas in Marine Sediments, Listvyanka, Lake Baikal, Russia, 6-12 September 2010
Regnier, P. (invited) Marine methane flux and climate change: From biosphere to geosphere. ICES workshop on
models and regional climate change, Brussels, Belgium, January 2010
Regnier, P. (invited) Modeling biosphere-geosphere interactions: CO2, CH4 and the global seafloor carbon cycle.
Introductory Lecture. Belgian Geological Society Annual Meeting, Leuven, Belgium, February 2010
Regnier, P. Continental and marine sources and sinks of methane in the context of climate change. Theme leader
working group 3. Workshop ‘Exploring Knowledge gaps along the gobal carbon route’. Rochefort, Belgium,
October 4-7 2011
Regnier, P., P. Friedlingstein, F.J. Ciais, F. Mackenzie, M. Thullner, P. Van Cappellen. Exploring Knowledge gaps
along the global carbon route: A hitchhiker’s guide for a boundless cycle. Plenary presentation/ Plenary lec-
ture. Royal Academy of Sciences. Brussels, Belgium, October 4 2011
Rehder, G., H. Fossing, L. Lapham, R. Endler, V. Spiess, V. Bruchert, T. Nguyen, W. Gülzow, J. Schneider von
Deimling, D. Conley, B. Jørgensen. Methane fluxes and their controlling processes in the Baltic Sea. Fall
Meeting American Geophysical Union, San Francisco, USA. December 13-17 2010
Rehder, G., L. Lapham, H. Fossing, W. Gülzow, J. Schneider von Deimling, R. Endler, V. Spiess, J.B. Jensen, V.
Bruechert, T. Ferdelmann, O. Schmale, J. Virtasalo, D. Conley, T. Neumann, T. Leipe, S. Flury, Z. Toth, B.B.
Jørgensen, and the MSM 16/1shipboard scientific party. Shallow gas occurrences, methane fluxes and their
controlling processes in the Baltic. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, 22-26 August
2011
Schneider v. Deimling, J. Gas Mapping using Multibeam Mapping Sonar. Int. Conf. HYDRO 2010, Warnemünde,
2-5 November 2010
Schneider v. Deimling, J., W. Weinrebe, D. Bürk, Z.Thot, R. Endler, H. Fossing, V. Spiess, G. Rehder. Subbottom
mapping of shallow gas using medium to low frequency multibeam sounders. Fall Meeting American Geo-
physical Union, San Francisco, USA. December 13-17 2010
Sivkov, V., D. Dorokhov, T. Kanapatsky, N. Pimenov. Gas-Bearing Sediments of the South-eastern Baltic Sea:
Acoustical and Gas-Geochemical Investigation. 8th Baltic Sea Science Congress, Skt. Petersburg, Russia, 22-
26 August 2011
Thang, N.M., V. Brüchert, M. Fomolo, G. Wegener, M. Reinholdsson, L. Ginters, B.B. Jørgensen, T.G. Ferdelman.
Biogeochemistry of methane and sulfate in Himmerfjärden estuary sediment, Sweden. EGU General Assem-
bly, Vienna, 3-9 April 2011
Thang, N.M., M. Formolo, S. Flury, B.B. Jørgensen, T.G. Ferdelman. Biogeochemistry of sulfur in Gdansk Bay sed-
iments (Baltic Sea). EGU General Assembly, Vienna, 3-9 April 2011
Tóth, Z., N. Allroggen, V. Spiess. Geoacoustic characterization of and estimation of the shallow gas content in
Baltic Sea sediments. 8th Baltic Sea Science Congress, St. Petersburg, Russia, 22-26 August 2011
Tóth, Z., N. Allroggen, V. Spiess (2011) Geoacoustic properties of shallow gas accumulations in Baltic Sea sedi-
ments – which can be used for quantification? 2nd Young Scientist Excellence Cluster Conference on Marine
and Climate Research, Bremen, Germany, 4-5 October 2011
63
Tóth, Z., J. Schneider von Deimling ,V. Spiess. Distribution of shallow gas accumulations in the sediments of the
Mecklenburg Bay, Baltic Sea; based on multi-frequency seismo-acoustic mapping. Mátrafüred, Hungary, 26-
27 March 2010
Tóth, Z:, V. Spiess. Geoacoustic characterization of shallow gas accumulations in marine sediments. Bremen PhD
days in Marine Sciences 2011, University of Bremen, Bremen, Germany, 13-14 April 2011
Tóth, Z., V. Spiess. Multi-frequency seismo-acoustic imaging of shallow free gas in the southwestern part of the
Baltic Sea. 10th International Conference on Gas in Marine Sediments, Listvyanka, Lake Baikal, Russia, 6-12
September 2010
Ulyanova M., D. Dorokhov (in Russian) Gas-bearing sediments distribution in Gdansk Deep, the Baltic Sea. In: Sea
and ocean geology: Materials of XVIII International scientific Conference (School) on marine geology. Vol. II,
p. 102-104, 16-18 November 2009
Ulyanova M., T. Kanapackiy (in Russian) Methane fluxes in sediments of the Gdansk Basin, the Baltic Sea. In: Sea
and ocean geology: Materials of XVIII International scientific Conference (School) on marine geology, p.116-
117, 16-18 November 2009
Ulyanova, M., T. Kanapatsky, D. Dorokhov, V. Sivkov, N. Pimenov (2011) Gas-Bearing Sediments of the South-
eastern Baltic Sea: Acoustical and Gas-Geochemical Investigation. In: Book of Abstracts of 8th Baltic Sea
Science Congress, p 113
Ulyanova, M., V. Sivkov, D. Dorokhov. (2010) Gas-bearing sediments distribution in the Baltic Sea based on
acoustical data. 10th International Conference on Gas in Marine Sediments, Listvyanka, Lake Baikal, Russia,
6-12 September 2010
Ulyanova, M., V. Sivkov, D. Dorokhov, T. Kanapatsky, N. Pimenov (2011) Gas-bearing sediments of the south-
eastern Baltic Sea: acoustical and gasgeochemical investigation, 8th Baltic Sea Science Congress, Skt. Pe-
tersburg, Russia, 22-26 August, 2011
8. Peer reviewed scientific papers
Gülzow, W., G. Rehder, B. Schneider, J. Schneider v. Deimling, B. Sadkowiak (2011) A new method for continuous
measurement of methane and carbon dioxide in surface waters using off-axis integrated cavity output spec-
troscopy (ICOS): An example from the Baltic Sea. Limnology Oceanography Methods, 9, p 168-174
Majewski, P. Z. Klusek (2011) Expressions of shallow gas in the Gdansk Basin. Zeszyty Naukowe Akademii
Marynarki Wojennej, ISSN 0860-889X, vol. 51, No 4
Mogollón, J.M., A.W. Dale, I. L’Heureux, P. Regnier (2011) Impact of seasonal temperature and pressure changes
on methane gas production, dissolution, and transport in unfractured sediments marine sediments. Journal
of Geophysical Research, 116, G03031, 17 pp
Mogollón, J.M., A.W. Dale, H. Fossing, P. Regnier (2011) Timescales for the development of methanogenesis and
free gas layers in recently-deposited sediments of Arkona Basin (Baltic Sea). Biogeosciences Discussions, 8, p
7623-7699
Pimenov N.V., M.O. Ulyanova, T.A. Kanapatsky, E.F. Veslopolova, P.A. Sigalevich, V.V. Sivkov (2010) Microbially
mediated methane and sulfur cycling in pockmark sediments of the Gdansk Basin, Baltic Sea. Geo-Marine
Letters, 30, p 439-448
Regnier, P., S. Arndt, A.W. Dale, D.E. LaRowe, J. Mogollon, P Van Cappellen, P (2011) Advances in the biogeo-
chemical modeling of the marine methane cycle. Earth Science Reviews 106, p 105-130
64
Schmale, O, J. Schneider v. Deimling., W. Gülzow, G. Nausch, J. Waniek, G. Rehder (2010) The distribution of
methane in the water column of the Baltic Sea. Geophysical Research Letters, 37, L12604,
Schneider von Deimling, J., C. Papenberg (2011) Technical Note: Detection of gas bubble leakage via correlation
of water column multibeam images, Ocean Science Discussions, 8, p 1757-1775
Schneider von Deimling, J., G. Rehder, D.F. McGinnnis, J. Greinert, P. Linke (2011) Quantification of seep-related
methane gas emissions at Tommeliten, North Sea. Continental Shelf Research, 31, p 867-878
Steckbauer, A., C.M. Duarte, J. Carstensen, R. Vaquer-Sunyer, D.J. Conley (2011). Ecosystem impacts of hypoxia:
thresholds of hypoxia and pathways to recovery. Environmental Research Letters, 6, 025003, 12pp
9. Submitted scientific papers
Dale, A.W., S. Flury, P. Regnier, H. Røy, H. Fossing, B.B. Jørgensen (submitted) Coupling between methanogene-
sis, anaerobic oxidation of methane and δ13C distributions in gassy sediments from the Baltic Sea (Aarhus
Bay). Geochimica et Cosmochimica Acta
Flury, S., A.W. Dale, H. Røy, H. Fossing, J.B. Jensen, B.B. Jørgensen (submitted) Methane fluxes and shallow gas
formation controlled by Holocene mud thickness in Baltic Sea sediments. Geochimica et Cosmochimica Acta
Gentz, T., M. Schlüter (submitted) Underwater cryotrap - membrane inlet system (CT-MIS) for improved in situ
analysis of gases. Limnology Oceanography Methods
Gülzow, W., G. Rehder, B. Schneider, J. Schneider v. Deimling, B. Sadkowiak (submitted) A new method for con-
tinuous measurement of 1 methane and carbon dioxide in surface waters of the Baltic Sea using off-axis in-
tegrated cavity output spectroscopy (ICOS). Limnology Oceanography Methods
Pimenov, N.V., T. A. Kanapatskii, P.A. Sigalevich, I.I. Rusanov, E.F. Veslopolova, A.G. Grigorev, V.A. Zhamoida (in
pres; 2012) Sulfate Reduction, Methanogenesis, and Methane Oxidation in the Holocene Sediments of the
Vyborg Bay, Baltic Sea. Microbiolog, 81
10. Statistics for the performance assessment of the Programme
BALTIC GAS principal scientists used the BONUS EPSS - Electronic Proposal Submission System to report Statistics
and research infrastructures:
Statistics for the performance assessment of the Programme
1 Number of times your project has contributed to consultations carried out by European Commis-
sion. (Provide more information in annual and final reports) 1
2 Number of times the scientists working in your Project have served as members or observers in
stakeholder and scientific committees. (Provide more information in annual and final reports) 31
3 Number of times the effort of your Project has resulted in modifications made to relevant policy
documents and action plans (in particular, Baltic Sea Action Plan). (Provide more information in
annual and final reports)
0
4 Number of times the effort of your Project has resulted in modifications made to relevant policy
documents and action plans (in particular, Baltic Sea Action Plan). (Provide more information in
annual and final reports)
0
5 Number of persons (above) and working days (below) spent by foreign scientists on research ves-
sels participating in the cruises arranged by your Project
51
301
65
6 Number of persons (above) and working days (below) spent by foreign scientists using other major
facilities involved in your Project
14
36
7 Number of popular science papers produced by your Project 3
8 Number of interviews to media given by members of your Project's consortium 29
9 Number of multi-media products and TV episodes produced by your Project with dissemination
purpose 5
10 Number of other dissemination products produced by your Project 10
11 Number of times your Project team has issued a recommendation how to improve general public's
comprehension and priorities regarding the Baltic Sea 3
12 Number of times your project has contributed to dissemination products/events addressed to
general public concerning coupling between marine environmental quality and human health and
well-being
9
13 Number of datasets your project has delivered to the common metadata base of the Programme 87
14 Number of scientists that attended international workshops, WG meetings, conferences, intercali-
bration exercises etc. paid by BONUS+ 135
15 Number of PhD courses (above) organized by your Project and persons participating (below) 6
49
16 Number of modifications made to current PhD course programmes that resulted from the work of
your Project 7
17 Number of student visits (persons above, visit days below) from your Project to other BONUS pro-
jects
9
80
Significant research infrastructures jointly used by the Project consortium
1. Description: Askö Marine Research Station (Stockholm University) incl. RV Limada
Purpose: Himmerfjärden: Sediment and water column + laboratory experiments. 12-18.6, 09-
15.8, 06-12.9, 2010
Amount of use: 6 days cruise days / 12 laboratory days
In-kind contribution: 3,300 EUR
2. Description: Askö Marine Research Station (Stockholm University) incl. RV Limanda
Purpose: Himmerfjärden: Sediment and water column incl. laboratory experiments. 12-17.5,
2009
Amount of use: 2 days cruise days / 4 laboratory days
In-kind contribution: 1,100 EUR
3. Description: RV Alkor Atlas fansweep multibeam EK60 echosounder multichannel streamer boomer
GI gun magnetometer heat flow probe data acquisition equipment
Purpose: Mecklenburg and Arkona Bays: mapping and quantification of gas in sediment and
water column
Amount of use: 7 days
In-kind contribution: 100,000 EUR
4. Description: RV Alkor Atlas fansweep multibeam EK60 echosounder multichannel streamer boomer
GI gun magnetometer heat flow probe data acquisition equipment
Purpose: Mecklenburg and Arkona Bays: mapping and quantification of gas in sediment and
water column
66
Amount of use: 10 days
In-kind contribution: 140,000 EUR
5. Description: RV Ladoga
Purpose: Finland Gulf (Vyborg Bay): Crater-like structures and gas-saturated sediments. 30.06-
03.07.2009
Amount of use: 4 days, 6 scientists
In-kind contribution: 5,500 EUR
6. Description: RV Maria S Merian Cruise 16/1
Purpose: Western Baltic Sea, Gulf of Bothnia: CH4 distribution in sediments and water column.
31.7-21.8, 2010
Amount of use: 24 days, 23 scientists
In-kind contribution: 528,000 EUR
7. Description: RV Nawigator XXI geophysical data acquisition systems shallow water multichannel
streamer GI gun side scan sonar
Purpose: Western Baltic: Mapping and quantification of gas in sediment and water column. 15-
27.7, 2010
Amount of use: 7 days
In-kind contribution: 35,000 EUR
8. Description: RV Oceania Chirp echo sounder 'nonlinear acoustic' echo sounder
Purpose: Gulf of Gdansk: gas-saturated sediments. 08-13.4, 2010
Amount of use: 6 days, 5 scientist,
In-kind contribution: 18,000 EUR
9. Description: RV Oceania Chirp echo sounder 'nonlinear acoustic' echo sounder
Purpose: Southern Baltic: gas-saturated sediments and gaseous structures (e.g. pockmarks). 17-
30.4 2010
Amount of use: 2 days allocated for 2 BALTIC GAS scientists
In-kind contribution: 6,000 EUR
10. Description: RV Poseidon (cruise 392)
Purpose: Baltic Sea: shallow gas and methane distribution in sediments and water column.
27.11.-17.12, 2009
Amount of use: 19 days, 11 scientists
In-kind contribution: 180,000 EUR
11. Description: RV Professor Shtockmann
Purpose: Russian Sector of Gdansk Basin and Gotland Deep: Gas-saturated deposits. 20-
27.06.2010
Amount of use: 8 days, 25 scientists
67
In-kind contribution: 30,000 EUR
12. Description: RV Safira Chirp echo sounder 'nonlinear acoustic' echo sounder
Purpose: Gulf of Gdansk: Gas-saturated sediments. 16-19.10, 2010
Amount of use: 1 day allocated for 1 BALTIC GAS scientist
In-kind contribution: 500 EUR
13. Description: RV Shelf
Purpose: Russian sector of Gdansk Basin: Pockmarks and gas-bearing sediments. 04-10.09, 2009
Amount of use: 7 days, 9 scientists
In-kind contribution: 10,000 EUR
14. Description: RV Susanne A
Purpose: Sediment sampling Aarhus Bay. 04.5, 2010
Amount of use: 1 day, 5 scientists
In-kind contribution: 10,000 EUR
15. Description: RV Susanne A
Purpose: Sediment sampling Aarhus Bay. 5.10, 2009
Amount of use: 1 day, 5 scientists
In-kind contribution: 10,000 EUR