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Hydrology and Biogeochemistry of Three Alpine Proglacial Environments Resulting From Recent Glacier Retreat BRUCKNER, Monica Z.¹*, Skidmore, Mark L.¹, and Bond, Jeff²
¹Department of Earth Sciences, Montana State University, Bozeman, MT, 59717, ²Yukon Geological Survey, Whitehorse, YT, Canada *[email protected]
OVERVIEW AND SIGNIFICANCE
SITE DESCRIPTION
CARBON AND ION DYNAMICS AND BIOTA
Beginning ofdischarge data
LO
ELS
Air Temperature vs. Area-Normalized Discharge
-2
0
2
4
6
8
10
12
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un
30-J
un
10-J
ul
20-J
ul
30-J
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9-A
ug
Date
Air
Tem
pera
ture
(ºC
)
0
0.2
0.4
0.6
0.8
1.0
Beginning ofdischarge data (UWL)
Lake Primary Productivity
0
1
2
3
4
20-J
un
30-J
un
10-J
ul
20-J
ul
30-J
ul
9-Au
g
Date
Prim
ary
Prod
uctio
n (μ
g C
L-1d-1
)
Dissolved Organic Carbon
0
0.2
0.4
0.6
0.8
DOC
(ppm
)
Bacterial Cell Count
0.0E+00
4.0E+03
8.0E+03
1.2E+04
Num
ber o
f Cel
ls (m
l-1)
HYDROLOGY AND WEATHER
Calcium
0
100
200
300
Bicarbonate
0
40
80
120
160
1-Ju
l
6-Ju
l
11-J
ul
16-J
ul
21-J
ul
26-J
ul
31-J
ul
5-Au
g
10-A
ug
Date
Conc
entra
tion
(μeq
L-1)
Sulfate
0
20
40
60
80
Nitrate
0
2
4
6
8Climate-induced deglaciation is occurring worldwide - what is the consequence of this retreat in high alpine headwater catchments with regard to the formation of different proglacial environments?
Headwater catchments are crucial to examining the effects of climate change and deglaciation as they are the first in a chain of variables that affect downstream chemistry and hydrology.
High alpine environments, especially those in remote areas, are excellent indicators for climate change, as they are sensitive environments and few anthropogenic factors directly affect them.
This study compares the hydrology, biology, and hydrochemistry for three adjacentand unique outlet streams draining a small glacier in a remote, high alpine catchment in south-central Yukon Territories, Canada. One stream flows directly from the glacier,a second stream has a longer flow path from its source with high degree of contact with the medial moraine, and a third stream drains a proglacial lake.
The three proglacial environments have similar bedrock geology, weather, and sourcewaters for the contributing areas, which provides an ideal environment for the comparison of hydrology, biology, and carbon and nutrient dynamics for these distinct headwater systems.
[NO3-] higher in ELS than LO and UWL for
most of season, possibly due to microbial utilization in the lake (LO) and withinsnowpack (UWL).
Ca2+ and bicarbonate are the dominant ionsin the catchment.
[SO42-], [Ca2+], & [bicarbonate] increase in
UWL on 1 Aug. & 10 Aug., possibly due to increased supply of reactive sediments from medial moraine.
I II III
Three periods in the DOC record: I: DOC utilized until depletion II: DOC depleted III: Rebound in DOC
Decline in lake productivity 24 June-10 July at 0.5-1.5 m depth possibly due to photoinhibition from high solar irradiance1.
Bacterial cells increase in LO & decrease in ELS, potentially indicating a viable and growing population of biota in the lake.
SUMMARY
Conc
entra
tion
(μeq
L-1)
Conc
entra
tion
(μeq
L-1)
Conc
entra
tion
(μeq
L-1)
WATER TEMPERATURE
The presence of a lake in the catchment results in water storage which increases meltwater temperatures by 0.5-1°C, which may promote biotic growth within lake and LO; increasing bacterial biomass in LO and lower [NO3
-] than the ELS potentially indicate a viable microbial community forming in the lake as the field season progresses.
The UWL has greater access to & thus transports medial morainal sediments leading to high [SSC]and greater sediment export, whereas a portion of SSC & POC are deposited in the lake before beingexported via the LO.
Primary productivity rates in the young Wheaton proglacial lake are consistent with those in an older oligotrophic high Arctic lake in Svalbard2 and 15 sub-Arctic lakes in northern Sweden3.
References Cited: 1Vinebrooke, R.D., Leavi�, P.R. (1996) Effects of ultraviolet radiation on periphyton in an alpine lake. Limnology and Oceanography: v. 41, pp. 1035-1040.2Laybourn-Parry, J. and Marshall, W.A. (2003) Photosynthesis, mixotrophy, and microbial plankton dynamics in two high Arctic lakes during summer. Polar Biology: v. 26, pp. 517-524. 3Karlsson, J., Honsson, A., and Jansson, M. (2005) Productivity of high-latitude lakes: climate effect inferred from altitude gradient. Global Change Biology: v. 11, pp. 710-715.
Acknowledgements: Research funding provided by Yukon Geological Survey, Montana State University, VP Research, and American Alpine Club. Thanks to Galena Ackerman, Sco� Montross, & Shawn McGlynn from Montana State University and Jeff Bond, Carrie Labonte, Amber Church, and Erin from the Yukon Geological Survey, for all their help in making this project a success. Thanks also to Dr. Julia Foght, Dr. Martin Sharp, & Joel Barker from University of Alberta for advise, laboratory time, and equipment loan. Thank you to USGS Boulder Carbon laboratory for laboratory space, time and equipment. Thanks to Al VonFinster, Yukon Fisheries, for the boat loan, and to Karl Birkeland, USFS, for datalogger & temperature sensor loan. Thanks also to Delmar (helicopter pilot) for his humor and field transportation.
Air temperature (ºC)ELS discharge (m3 s-1)LO discharge (m3 s-1)UWL stream discharge (m3 s-1)Snow-ice transitionMajor precipitation eventOvercast day(s)Clear day(s)
L1: Lake surface ; L2: 1.5 m Lake depth ; L3: 5.0 m Lake depth ; LO: Lake Outlet ; ELS: East Lobe Stream ; UWL: Upper West Lobe Stream
Photo 4: Snow (a) to ice (b) transition on lower lake lobe results in a decrease in albedo on the ice surface.
Photo 2: The east lobeterminates directly intothe ELS proglacial stream.
Photo 1: (A) Sept. 1995 aerial photo of the Wheaton Glacier catchment with drainage areas delineated & streams outlined. Stream gauging stations (dots) for the (B) East Lobe Stream (ELS), (C) Upper West Lobe (UWL), & (D) Lake Outlet (LO) are shown. The air temperature monitoring station (E) was set up ~10 m N of the LO gauging station. Rebar pole height is ~1.5 m(B, C, D, E).
Air temperature affects discharge with 0-3 hr. lag time; lag may be affected by albedo.
UWL discharge is more flashy than ELS and LO discharge.
Mean water temperatures were: 1.4°C, σ = 0.6 in the LO, 0.3°C, σ = 0.2 in the ELS, and 0.4°C, σ = 0.3 in the UWL.
LO water temperature fluctuates the most, possibly due to 2 inputs: Meltwater flowing in direct current from glacier to LO Meltwater that has been warmed in lake prior to exiting via LO.
Water Temperature
0
0.5
1.0
1.5
2.0
2.5
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un
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un
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ul
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ug
Date
Tem
pera
ture
(°C
)
LOELSUWL
SUSPENDED SEDIMENT CONCENTRATIONSuspended Sediment
0
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l
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l
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ul
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31-J
ul
5-A
ug
10-A
ug
Date
Sedi
men
t (m
g L-1
) (La
ke, L
O, a
nd E
LS)
0
5000
10000
15000
20000
Sedi
men
t (m
g L-1
) (U
WL)
L1L2L3LOELSUWL
[Suspended sediment] (SSC) in UWLis an order of magnitudehigher than the LO and ELS.
Some suspended sediment is deposited in the lake before beingexported via the LO stream.
SSC is not directly related todischarge in the ELS, LO, or UWL.
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•
•
•
•
•
•
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•
•
Dis
char
ge (m
3 s-1km
-2)
Strong Winds
•
•
•
•
•
•
Photo 3: The west lobe terminates into a proglacial lake, which is drained via the LO stream.
••
•
a) Lake lobe, 19 July
b) Lake lobe, 29 July
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B C D E
Stream Confluence
LO
Camp UWL
ELS
Lake
230 m N
A
WhitehorseStudy Site
UWL Drainage Area1.3 km2
(0.8 km2 glacier ice)
ELS Drainage Area1.9 km2
(1.1 km2 glacier ice)
LO Drainage Area
0.6 km2
(0.4 km2 glacier ice)
••
•
GC41A-0099
Particulate Organic Carbon
0
20
40
60
80
POC
(mg
L-1)
