LSCE visit introduction, PTRMS and OH reactivity pdf

Visit at the LSCE

• Presentations

– Overview of the LSCE and the CAE Team

– The PTR-MS

– The OH reactivity

• Workshop on PTR-MS and OH reactivity (2 groups:

20min+20min)

• Visit at the SIRTA Station (2 groups/20 min each)

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Climate and Environment Sciences Laboratory

5 axes of research

• Dynamics and climate archives:

• Climate modeling, biogeochemical cycles and their interactions

• Transfers and Tracers in the Environment

• Atmospheric composition and surface fluxes

+ Interactions Human-Climate-Environment

300 people, including 150 permanent

2

Air q

ua

lityC

lima

teM

arin

e

Bio

ge

och

em

istry

Photochemistry, aging,

deposition

Experimental Atmospheric Chemistry (CAE) Team

Characterization of reactive gases (VOC) and aerosols

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Permanent Researchers: B. Bonsang, V. Gros, J. Sciare, C. Boissard , F:Dulac

Engineers: R.Sarda-Estève, N.Bonnaire, D.Baisnee

PhD students: J-E. Petit, A. Baudic, A-C. Genard, Nora Zannoni, Cerise Kalogridis

Post-Doc: V. Crenn

CAE TeamIntensive Measurement campaigns & Long-term Observations

Urban RuralRemote

PARIS city center/MEGAPOLI

PARIS tunnel-ring road

Ile-de-France/ACTRIS

Oak Forest in

South France

Crete and Corsica

ChArMeX

Amsterdam island

ANR CANOPEE/

ChArMeX

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The Mediterranean region

ChArMEx: Chemistry-Aerosol Mediterranean Experiment

Ozone levels in the tropospheric column- Summer 2000-satellite GOME (Dobson Unit)

• Almost enclosed sea surrounded by very urbanized

littorals

• Emissions and reactivity of BVOCs enhanced due to

high temperatures and sunny conditions :

• Models predicts ozone increases in the future

• Interest for the SOA production

• Region Sensible to climatic change (IPCC, 2007)

ChArMEx aim: scientific assessment of the present and future

state of the atmospheric environment and of its impacts in the

Mediterranean basin

Target: particulate and gaseous tropospheric trace species

Measurements sites:

• Oak Observatory of Haute Provence (FRANCE) –2012/2014:

• Finokalia (Crete-GREECE)- FAME 2011

• Cap Corse (France)- CHARMEX 2013

Study the photooxidation of BVOCs and its impact on ozone

production

• (Malta, Sardignia..)

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Volatile Organic Compounds

6

VOC measurements

by Proton-Transfer Reaction Mass Spectrometer (PTR-MS)

• Online technique for measuring VOC concentrations

• Developed at the University of Innsbruck

(Hansel et al., Int. J. Mass Spectrom., 1995; Lindinger et al., Int. J. Mass Spectrom.,

1998)

• Commercial quadrupole and time-of-flight instruments

• Very sensitive ( few pptv)

• Measure in real time (>100 ms)

• No sample preparation

• Measure sequentially a wide range of VOCs (1-512 amu)

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PTR-QMS Operation

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PTR-QMS Operation

H2O

The Ion Source:

• Soft Ionization: formation of H3O+

• Very low impurity content< 1% (mainly O2+): No need for mass filter

• High intensity (about 40 M counts)

1:

HC

2:

DS

First Chamber: hollow cathode

� +��� → ��� + � + 2�

� +��� → �� + �� + 2�

� +��� → �� + �� + 2�

� +��� → ���� + 2�

Second Chamber: short source drift region

��� +��� → ���

� + ��

�� +��� → ���

� + �

�� +��� → ���

� + �

��� +�� → �� + �

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PTR-QMS Operation

[ - VOC ]

Proton affinity < H2O

N2

O2

H2O.H+ + Ar � NO REACTION

CO2

CH4

Proton affinity > H2O

C3H6 � C3H6 H+

C6H6 � C3H6 H+

H2O.H+ + CH3OH � CH3OH H+

CH3CN � C3H6 H+

VOCs

The Reaction chamber (or drift tube):

Low fragmentation, No buffer gas needed

Pdrift=2.2 mbar, Udrift=600V

[ + VOC]

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PTR-QMS Operation

H+ VOC

Quadrupole

• Vacuum chamber: reduces collisions

between ions and molecules

• Analyte ions are mass selected (m/z

RH+)

• Sequential detection depending on the

voltage applied on the parallel rods

• Mass resolution : 1 amu

• No distinction between

isomers/isobares

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PTR-QMS Operation

ION DETECTOR: Secondary Electron Multiplier + ion counting system

• I(H3O+) and I(MH+) measured in counts per second (CPS):

proportional to the respective densities of these ions

H+ VOC

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PTR-QMS Operation

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PTR-QMS data process overview

Raw signal (cps) ���� Concentration (ppb)

• Normalization to the number of primary ions (decrease with time)

• m/z 19: H3O+ (about 40 M counts)� saturation of SEM

• m/z 21: H318O+ (about 2.104 counts), with (m/z 19)/(m/z21) = 500

• Normalization to water cluster formation in the drift tube (dependent on

Humidity)

• m/z 37: (H2O) H3O+

• Substraction of the instrumental background (measured using a scrubber)

• Calibration

[��]���= 10�� � ���

� ��(����)!"#$

%/'�(∗*++�%/',-* fi

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PTR-MS Application

BVOC emission rates at the branch-scale

Concentration of BVOCs

Flux measurements (Disjunct Eddy covariance)

Total OH reactivity measurements

C.Kalogridis et al., 2014 ACPD

A-C.Genard et al., in prep

Zannoni et al., in prep

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VOC Flux measurements by PTR-MS

The eddy covariance technique:

Same principle but enable the use of:

• Relatively slow response instruments in single-compound measurements

• Fast response instruments in multi-compound measurements (e.g) PTR-MS

First measurements by Karl et al. (Atmos. Chem. Phys., 2002)

The disjunct eddy covariance technique:

High frequency

analyzers!

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PTR-MS and Disjunct Eddy covariance

Lower frequency for VOC measurements by PTR-MS:

• 100-500 ms/mass minimum

• Multi-compound sequential measurements:

a few seconds for one cycle

1000

800

600

400

200

0

PT

R-M

S r

m/z

69

raw

sig

na

l [cp

s]

706050403020100seconds

-1.4

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

vertica

l win

d sp

ee

d [m

/s]

Isoprene measurements (ci) High frequency vertical wind measurements (wi)

High frequency of Wind velocity measurements (10–20 Hz).

Resulting in a disjunct concentration time series!

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18

Total OH reactivity measurements with

the Comparative Reactivity Method

(CRM)

Nora Zannoni

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Contents

• Introduction

- The total OH reactivity

- The Comparative Reactivity Method (CRM)

- Experimental set up

• Exemples of

- Measured OH reactivity with CRM

- Measured vs. Calculated

-Missing Reactivity

• Outlook

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OH role in the atmosphere

• OH sources: O3, HO2+O3, HO2+NO

• OH Sinks? (atmospheric composition? K

rate?)

Total OH reactivity

Total loss rate of OH radicals due to the

presence of reactive compounds in the

atmosphere

Calculated reactivity

Measured ReactivityMissing reactivity?

∙OHCH4

CO

NO2

?

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Measuring the Total OH reactivity:

The Comparative Reactivity Method (CRM)(Sinha et al., 2008)

• Glass reactor + PTR-MS

• OH produced in situ

• Pyrrole (m/z 68) reference compound

• Competition between pyrrole and ambient reactive compounds

Pyrrole + zero air

Hg lamp N2 dry pump

To PTR-MS

14 cm

3 cm

20x103

18

16

14

12

10

8

6

pyrr

ole

conc

entr

atio

n (c

ps)

1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM 6:00 PMTime

1)31(

)23(CKp

CC

CCRair ⋅⋅

−−=

C0 Lamp on

C1Wet N2 in

C2ambient air in

C3

Pyrrole + ambient air

N2 wet

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Experimental set up

CRM scheme used in ChArMEx, 2013Bubbling N2

4way valve

N2 Pyrrole Propane Zero air

GCU

4-way

valve4way

valve

MFC MFC MFC MFC

3 way

valve

pump

pump

Glass

reactor

PTR-MS

MFC

Ambient air

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Project name/

where

Type of

environment

Investigated OH

reactivity range (s-1)

LOD of

CRM (s-1)

Reference

GABRIEL

(Suriname)

Tropical forest 28-72 6 Sinha et al.,

2008

Mainz Urban 6±3-18±4 6 Sinha et al.,

2008

BFORM

(Hyttiala,

Finland)

Boreal forest 3.5-60 3.5 Sinha et al.,

2010

CABINEX (USA) Boreal forest Up to 1000 15 Kim et al., 2011

HUMPPA-COPEC

(Hyttiala,

Finland)

Boreal forest 3-76 3-4 Noelscher et al.,

2012

DOMINO (El

Arenosillo,

Spain)

Rural site 3.5-84 3.5 Sinha et al.,

2012

MEGAPOLI

(Paris, France)

Urban Up to 130 3.5 Dolgouroky et

al., 2012

Germany Boreal forest

(Norwey spruce)

4-15 3-4 Noelscher et al.,

2013

Previous studies with the CRM

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First field deployment of our set upCARBOSOR 2013: Cape Corsica monitoring station (42.97°N, 9.38°E, alt 533 m)

6 km2.5 km

Courtesy of J.Sciare

24/06/13

Installation

and tests

01/07/13 08/07/13 13/07/13 16/07/13 05/08/13

Intercomparison with CRM MD

Plant experimentMeasurement campaign

Total measured OH reactivity [s-1] from 16/07/2013- 05/08/2013

20

15

10

5Tot

al O

H r

eact

ivity

(s-

1)

16/07/2013 21/07/2013 26/07/2013 31/07/2013 05/08/2013

hourly avg OH reactivity OH reactivity

• Measurements from 16/07/2013- to 5/08/2013 � 3 weeks of data

• A data point every 10 minutes

• 2 major gaps: humidity problem, atmospheric conditions

• avg value of 5.5 s-1, up to 20 s-1

• LOD of the system≈ 2.5 s-1

• Uncertainty of CRM ≈ 20% (k rate, flow fluctuations in MFCs, instrumental error, pyrrole

standard) 25

preliminary results

26

Compound K (cm3/mol*s) Compound K

(cm3/mol*s)

Compound K (cm3/mol*s)

isoprene 1.00E-10 ethane 2.41E-13 Hexane 5.20E-12

2-methyl-2-butene 8.72E-11 b-pinene 7.81E-11 2,2,3-trimethylbutane 3.81E-12

1,3-butadiene 6.66E-11 a-pinene 5.33E-11 Isooctane 3.34E-12

T2-butene 6.37E-11 styrene 5.30E-11 Benzene 1.28E-12

T2-pentene 5.71E-11 hexene 3.70E-11 NO2 7.51E-11

C2-pentene 5.71E-11 m-xylene 2.45E-11 NO 3.30E-11

C2-butene 5.60E-11 p-xylene 1.52E-11 HCHO 9.38E-12

isobutene 5.18E-11 tridecane 1.51E-11 CO 1.49E-13

3-methyl-1-butene 3.17E-11 o-xylene 1.47E-11 CH4 6.28E-15

1-butene 3.11E-11 dodecane 1.32E-11 Methanol 9.00E-13

1-pentene 2.74E-11 undecane 1.23E-11 Acetonitrile 2.20E-14

propene 2.60E-11 nonane 9.70E-12 acetaldehyde 1.50E-11

ethylene 8.51E-12 octane 8.11E-12 formic acid 4.50E-13

1-butyne 7.27E-12 ethylbenzene 7.51E-12 Acetone 1.80E-13

pentane 3.84E-12 cyclohexane 6.97E-12 acetic acid 8.00E-13

n-butane 2.36E-12 2-methylhexane 6.69E-12 MVK+ MACR 3.00E-11

2,2-dimethylbutane 2.23E-12 2,3,4-trimethylpentane 6.50E-12 MGLYOX 1.72E-11

isobutane 2.14E-12 2,3-dimethylpentane 6.46E-12 MEK 1.20E-12

propane 1.09E-12 toluene 6.16E-12 propionic acid 1.20E-12

2,2-dimethylpropane 8.40E-13 2,4-dimethylpentane 5.48E-12 EVK 3.60E-11

acetylene 7.79E-13 2-methylpentane 5.20E-12 Butiric acid 1.79E-12

Nopinone 1.43E-11

Pinonaldehyde 4.00E-11

GC-FID, MD

NOx analyser, LAMP

Hantzsch, LSCE

Picarro, LSCE PTR-TOF-MS, MD

Measured vs calculated OH reactivity (s-1) from 16/07/2013- 05/08/2013

16

14

12

10

8

6

4

2

Tota

l OH

reac

tivity

(s-1

)

16/07/2013 21/07/2013 26/07/2013 31/07/2013 05/08/2013

Calculated Measured

27

preliminary results

28

Missing OH reactivity in-depth: unknown

known

20

15

10

5Tot

al O

H r

eact

ivity

(s-

1)

16/07/2013 21/07/2013 26/07/2013 31/07/2013 05/08/2013

hourly avg OH reactivity OH reactivity

32%

68%

52% 48%

26%

74% 44%

56%

36%

64%

average all campaign

50% 50%

preliminary results

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Outlook• We are not able to know precisely the atmospheric composition and the

kinetics of many reactions is still unknown (discrepancies between studies and

data missing)…

• …total OH reactivity measurements give information on the total loading of

reactants in the atmosphere

• Comparative Reactivity method employs a glass reactor and a PTR-MS: many

applications so far but still some technical optimization needed!

• We can calculate the OH reactivity of the measured gases and compare this

value with the measured one: we have the missing reactivity;

• Investigations on the missing reactivity helps to understand the chemical

processes

Thank you for your attention!

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Thank you for your attention!

Acknowledgments:

MD: Sebastien Dusanter, Stephane Sauvage, Nadine Locoge, Thierry Leonardis, Vincent Michoud;

LSCE: Cerise Kalogridis, Cyril Vuillemin, Francois Dulac, Eric Hamonou;

LAMP: Aurelie Colomb, Jean Marc Pichon