atmospheric monitoring –student presentation · from 750–4400 cm-1 opinion about advantages and...

||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


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.


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


Concentration of CFC-11 over the years

||Analytical Strategy HS 2019 21.09.19Cedric Wüthrich 5

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.

http://agage.mit.edu/data/agage-data


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, 2010 Zero.

https://ozone.unep.org/treaties/montreal-protocol%2022.09.2019


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



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.



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.


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


Barbados and Zeppelin (1)

Sample VolumeGC-ECD: 4.5 mL

Sample VolumeGC-MS: 2 L


Barbados and Zeppelin (2)

Precision Data for Zeppelin GC-MS is missing Data of Jungfrauchjoch taken


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


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



CCl2F2

120/122/124

-Cl CClF2-Cl

85/87

CF2

50

Base Peak [M-Cl]+



CCl3F

136/138/140/142

-Cl CCl2F-Cl

101/103/105

CClF

66/68

Base Peak [M-Cl]+


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]+



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]+



CCl4

152/154/156/158/160

-Cl CCl3-Cl

117/119/121/123

CCl2

82/84/86

Base Peak [M-Cl]+


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.


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.


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


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

https://eia-international.org/wp-content/uploads/Tip-of-the-Iceberg-CFCs-FINAL.pdf


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)


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

https://www.esrl.noaa.gov/gmd/hats/airborne/ucats.html


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


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?

atmospheric monitoring –student presentation · from 750–4400 cm-1 opinion about advantages and...

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