atmospheric monitoring –student presentation · from 750–4400 cm-1 opinion about advantages and...
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||Analytical Strategy HS 2019
Atmospheric Monitoring – Student Presentation
Presenters: Cedric Wüthrich, Richard Zell
24.09.19Cedric Wüthrich, Richard Zell 1
Corrections after the presentation written in red
||Analytical Strategy HS 2019 24.09.19Cedric Wüthrich, Richard Zell 2
The Family of Chlorofluorocarbons
F
ClClCl
CFC-11
F
ClFCl
CFC-12
F
FFCl
CFC-13
FF
Cl
FClCl
CFC-113
FF
F
ClClCl
FF
Cl
FFCl
CFC-114
CFC-115
1st digit #C-12nd digit # H+1
3rd digit #F
||Analytical Strategy HS 2019 24.09.19Cedric Wüthrich, Richard Zell 3
Uses of Chlorofluorocarbons
Liquids for fridges Blowing agent(e.g. polyurethane)
Propellant for spray-cans
R1 O CHN R2
HN COOO
n
Tuning the ratio of chlorine and fluorine enables control of boiling point
McLean, Br. J. Clin. Pharmac. 1977, 4, 663–666.
||Analytical Strategy HS 2019 24.09.19Cedric Wüthrich, Richard Zell 4
Mechanism of Ozone Depletion
Cl
ClFCl
h!ClFCl + Cl
Cl + O3 ClO O2+
Cl O2+ClO + O
O3 + O 2 O2
Stolarski et al., Can. J. of Chem. 1974, 52, 1610–1615.Whalley et al., Atmos. Chem. Phys. 2010, 10, 1555–1576.
O3h!
O2 + O
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Concentration of CFC-11 over the years
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Concentration of CFC-11 over the years
1980 1985 1990 1995 2000 2005 2010 2015 2020
Oct-2018
120
160
200
240
280
320
CCl 3F
mol
e fr
actio
n (p
pt)
Prel
imin
ary
3
http://agage.mit.edu/
ZeppelinAdrigole/Mace HeadJungfraujochCape Meares/Trinidad HeadRagged PointCape MatatulaCape Grim
(79°N)(52°N / 53°N)
(47°N)(45°N / 41°N)
(13°N)(14°S)(41°S)
Taken from http://agage.mit.edu/data/agage-data 22.09.2019 10:50.
||Analytical Strategy HS 2019 24.09.19Cedric Wüthrich, Richard Zell 6
The Montreal Protocol on Substances that Deplete the Ozone Layer
Signed in 1987 by all UN-member states
Phasing out of CFC’s to protect the ozone layer
CFC regulation in Article 2A
Distinction between developed and non-developed countries
Kigali amendment on replacement chemicals
Taken from https://ozone.unep.org/treaties/montreal-protocol 22.09.2019 11:07.
Non-Article 5(1) Parties Article 5(1) PartiesBase level: Production in
1986.Base level: Average of
production for 1995-1997
January 1, 1992 10 per cent of base level.
July 1, 1999 10 per cent of base level.
January 1, 1996 15 per cent of base level until 28 July 2000 (date of entry into force of the Beijing Adjustments).
January 1, 2010 15 per cent of base level.
New base levelfor basic domesticneeds EffectiveJuly 28, 2000
Annual average production for satisfying basic domestic needs of Article 5(1) Parties for the period 1995 to 1997 inclusive.
July 28, 2000 100 per cent of new base level for satisfying basic domestic needs until end of 2002.
January 1, 2003 80 per cent of new base level.
January 1, 2005 50 per cent of new base level.
January 1, 2007 15 per cent of new base level.
January 1, 2010 Zero.
||Analytical Strategy HS 2019 24.09.19Cedric Wüthrich, Richard Zell 7
Measuring the Atmosphere (1)
Gas Name Chemical Formula Percent VolumeNitrogen N2 78.08%Oxygen O2 20.95%Water H2O 0 to 4%Argon Ar 0.93%Carbon Dioxide CO2 0.0360%Neon Ne 0.0018%Helium He 0.0005%Methane CH4 0.00017%Hydrogen H2 0.00005%Nitrous Oxide N2O 0.00003%Ozone O3 0.000004%
Pidwirny, M. (2006). "Atmospheric Composition". Fundamentals of Physical Geography, 2nd Edition. 22.09.2019 http://www.physicalgeography.net/fundamentals/7a.html
Points to consider:• Huge amount of species• Low concentration, high
impact• Variation over the globe• Dynamic system• Chemical reactivity
Average of constituents of atmosphere up to 25 km (troposphere)Amount of CO2 in the table is not accurate anymore
||Analytical Strategy HS 2019 24.09.19Cedric Wüthrich, Richard Zell 8
Measuring the Atmosphere (2)
ALE: Atmospheric Lifetime Experiment 1978–1981Hewlett Packard 5840A dual channel GC, EC (Electron Capture)-detectorN2O, CCl2F2, CCl3F, CH3CCl3, CCl4
GAGE: Global Atmospheric Gas Experiment 1982–1992Hewlett Packard 5880 three channel GC,EC-, FI (Flame Ionization)-detectorN2O, CCl2F2, CCl3F, CH3CCl3, CCl4, CH4, CCl2FCClF2
Picture found on e-bayPrice (used): 1’795 $
Prinn et al., J. Geophys. Res.: Atmos. 2000, 105, 17751–17792.
||Analytical Strategy HS 2019 24.09.19Cedric Wüthrich, Richard Zell 9
Measuring the Atmosphere (3)
AGAGE: Advanced Global Atmospheric Gas Experiment, since 1993Measurement of long lived trace gasesOceanic and mountainous measurement sites
GC-MS (Medusa system❊)Multiple GC-detectors:Electron capture (EC), flame ionization (FI), mercuric oxide reduction (MR), pulsed discharge (PD)✢
Prinn et al., Earth Syst. Sci. Data 2018, 10, 985–1018.❊ Miller et al., Anal. Chem. 2008, 80, 1536–1545.✢ Forsyth, J. Chromatogr. A 2004, 1050, 63–68.
||Analytical Strategy HS 2019 24.09.19Cedric Wüthrich, Richard Zell 10
Medusa
Miller et al., Anal. Chem. 2008, 80, 1536–1545.
EPC: electronic pressure controlMFC: mass flow controller
For CF4
Phase I: drying,concentrating ontrap 1 (-165°C)
Phase 2: volatile compounds are removed from T1and refocused on T2, moved to MS
Phase 3: remaining substances on T1 are refocused on T2 => MS
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Barbados and Zeppelin (1)
Sample VolumeGC-ECD: 4.5 mL
Sample VolumeGC-MS: 2 L
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Barbados and Zeppelin (2)
Precision Data for Zeppelin GC-MS is missing Data of Jungfrauchjoch taken
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Sample Volume
3𝜎: 99.7%
Barbados GC-MD:Median: 229.22 ppt𝜎 0.08 %95% 229.22 ± 0.37 ppt
1.67 mL99.7% 229.22 ± 0.55 ppt
2.48 mL
Zeppelin GC-MS:Median: 230.04 ppt𝜎 0.2 %95% 230.04 ± 0.92 ppt
1.84 L99.7% 230.04 ± 1.38 ppt
2.76 L
Assumption:1 ppt corresponds to the sample volume
Precision value for Zeppelin asummed from Prinn2018
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MS-Spectra of CFC’s (1)
Atom Nominal Mass Rel. AbundanceH 1 ~1C 12 / 13 0.99 / 0.01F 19 1Cl 35 / 37 0.76 / 0.24
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MS-Spectra of CFC’s (2)
CCl2F2
120/122/124
-Cl CClF2-Cl
85/87
CF2
50
Base Peak [M-Cl]+
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MS-Spectra of CFC’s (3)
CCl3F
136/138/140/142
-Cl CCl2F-Cl
101/103/105
CClF
66/68
Base Peak [M-Cl]+
||Analytical Strategy HS 2019 24.09.19Cedric Wüthrich, Richard Zell 17
MS-Spectra of CFC’s (4)CCl2FCClF2
186/188/190/192
-CClF2 CCl2F-Cl
101/103/105
CClF
66/68
CClF2
85/87
-Cl CF2
50
-CCl2F
66/68
-F
CClF -Cl CF
31
CCl2FCClF2
186/188/190/192
-Cl CCl2FCF2
151/153/155
Base Peak [M-CClF2]+
||Analytical Strategy HS 2019 24.09.19Cedric Wüthrich, Richard Zell 18
MS-Spectra of CFC’s (5)
C2H3Cl3
132/134/136/138
-Cl C2H3Cl2-Cl
97/99/101 62/64
C2H3Cl
-CH3
CCl3
117/119/121/123
-Cl CCl2
82/84/86
Base Peak [M-Cl]+
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MS-Spectra of CFC’s (6)
CCl4
152/154/156/158/160
-Cl CCl3-Cl
117/119/121/123
CCl2
82/84/86
Base Peak [M-Cl]+
||Analytical Strategy HS 2019 24.09.19Cedric Wüthrich, Richard Zell 20
Satellite Measurement with IR-Spectroscopy (1)
Nadir (Troposphere) Limb (Stratosphere)
Two geometries to measure different spheres
Coheur et al., J. Geophys. Res.: Atmos. 2003, 108, 4130.
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Satellite Measurement with IR-Spectroscopy (2)Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS)
Solar Occultation:Transmission measured, ratio with the exoatmospheric measurement
Two detectors enable measurement from 750–4400 cm-1
Opinion about advantages and disadvantages:• Spatial resolution• Instantaneous measurement• Detection of short lived species
• Price• Satellite orbits• Additivity effects of interference biases• Global background concentration contains
artifacts• Precision?Steffen et al., J. Quant. Spec. Rad. Transf. 2019, 106619.
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Satellite Measurement with IR-Spectroscopy (3)
VMR: Volume Mixing Ratio
Steffen et al., J. Quant. Spec. Rad. Transf. 2019, 106619.
12.5–29.5 km altitude, average over whole latitude
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What is happening in China?
Rigby et al., Nature 2019, 569, 546–550.
CFC-11 is still used as foaming agent for polyols by manufacturers, according to EIA (Environmental Investigation Agency)
https://eia-international.org/wp-content/uploads/Tip-of-the-Iceberg-CFCs-FINAL.pdf 22.09.2019
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Measurement
ECD: 0.07% peak height precision, 0.017 ppt over background needed for detection
MS: 0.2% precision, 0.48 ppt over background for detection
CCl3F: 137.36 g/mol 𝜚 = 15 ∗ 10()𝑔𝑚, : 137.36
𝑔𝑚𝑜𝑙
= 1.09 ∗ 10(5𝑚𝑜𝑙𝑚,
𝑛𝑉 =
𝑝𝑅 ∗ 𝑇 ⟹ 𝜚 = 40.36
𝑚𝑜𝑙𝑚,
At source: 𝜒 = 2.70 𝑝𝑝𝑏 At station: 𝜒 = 0. 54 𝑝𝑝𝑞
𝜒ABCDEF = 1.09 ∗ 10(5 GBHGI : 40.36
GBHGI = 2.70 ∗ 10(J 𝜒AKLKMBN =
OPQRSTUV∗WXY
= 5.40 ∗ 10(W)
||Analytical Strategy HS 2019 24.09.19Cedric Wüthrich, Richard Zell 26
Strategy to Measure in China
• Need to find hotspot• Generate “heatmap” of China• In-situ measurement on airplane• Concentrations should be high enough / ECD-detectors are
able to detect ppt
https://www.esrl.noaa.gov/gmd/hats/airborne/ucats.html 23.9.2019.
Advantages over stationary measurements:• Mapping possible• Less reliant on atmospheric models• Spatial resolution
ER-2
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From HCFC-22 to CFC-11
CCl4 + HF100 °C
pressure
SbCl5 CCl3F + CCl4 + CCl2F2
CHCl3 + 2 HFSbCl4F CHClF2 + 2 HCl
Spargo et al., Alkyl Halides in Comprehensive Organic Functional Group Transformations, 1995.
CCl4 + 2 HFSbCl4F CHClF2 + HCl + Cl2
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Is EIA right?
Confirmed uses in July 2018 according to EIAMontzka et al., Nature 2018, 557, 413–417.Rigby et al., Nature 2019, 569, 546–550.
• Sites reported by EIA partially match the concentration map of Rigby et al.
• Emissions unlikely stem mostly from banks / release from old buildings etc.
• The numbers of close stations are low, measurements allow only regions to be determined
• Investigative journalism vs. analysis / wind-models
Point to discuss: What is the possible ideal measurement techniques?
||Analytical Strategy HS 2019 24.09.19Cedric Wüthrich, Richard Zell 29