Measurements of CHFCl2 in background tropospheric air

Penkett, S. A.; Prosser, N. J. D.; Rasmussen, R. A.; Khalil, M. A. K.

doi:10.1038/286793a0

Cited by 18 publications

(10 citation statements)

References 7 publications

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“…Sci. USA 78 (1981) 5935 (24,26) and by Rasmussen (27,34 (27,34). The corresponding world average should be near the 101 pptv average for these two locations.…”

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confidence: 99%

Tropospheric concentrations of methylchloroform, CH ₃ CCl ₃ , in January 1978 and estimates of the atmospheric residence times for hydrohalocarbons

Makide

Rowland

1981

Proc. Natl. Acad. Sci. U.S.A.

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The ground level tropospheric concentrations of CH3CCI3 were measured from 55°N to 53S during the time period around Jan. 1, 1978. The northern temperate zone concentration ofCH3CC13 averaged 94.6 ± 4.0 x 10'z by volume. The southern temperate zone concentration averaged 65.2 ± 1.3 x 10-12, for a worldwide average of 80 x 1012 by volume. The ratio of concentrations between the two zones is 1.45 ± 0.07. The observed CH3CCI3 concentrations correspond to 0.52 ± 0.05 times the atmospheric release to that date, corresponding to an atmospheric residence time of 6.9 ± 1.2 yr. The atmospheric residence times for 22 other hydrohalocarbon molecules were estimated in comparison to that of CH3CC13 through the relative rates of reaction with OH radicals.The primary chemical process that can decompose saturated hydrochlorocarbon molecules in the troposphere is reaction with OH radical as in Eq. 1 (1-14, §).OH + RH-H2O+R [1] However, quantitative evaluation of the actual rate of removal of RH from the real atmosphere by this reaction cannot yet be made directly because of the lack of sufficient worldwide data on the concentrations of OH radicals in time and space. Methylchloroform, CH3CC13, has been released into the atmosphere in recent years in reasonably accurately known megaton quantities, chiefly as a consequence of its use as a metal degreasing agent and in other industrial applications (15-17). Measurements of its present atmospheric concentration in comparison with the known total release to date offers opportunities for estimates of (i) the atmospheric lifetime of CH3CC13 and (ii) by analogy, the atmospheric lifetimes of other molecules containing C-H bonds subject to OH attack. Such measurements also can serve less successfully as a basis for (iii) crude estimates of the worldwide average OH concentrations in the troposphere, on the reasonable assumption that the only important tropospheric removal process for CH3CC13 is reaction 2.OH + CH3CC13 --H20 + C2H2C13 [2] Tropospheric removal processes for chlorine-containing molecules such as CH3CC13 have another important aspect, for destruction ofthese molecules in the stratosphere releases atomic chlorine, which can then participate in CIO. chain catalytic destruction of stratospheric ozone by reactions 3 and 4.C1+ 03 CIO + 02 [3] Saturated perhalo chlorofluorocarbon molecules (e.g., CC13F, CC12F2) have long atmospheric residence times (>30 yr) and are known to penetrate into the midstratosphere, where they are decomposed by solar UV radiation with the release ofatomic chlorine (1-3, 5, 9-13, §). Consequently, the use ofCC13F and CCl2F2 as propellent gases in aerosol sprays has been restricted by emission regulations in the United States and several other countries, and further regulation has been discussed on a worldwide basis (15).The potential for removal of stratospheric ozone by groundlevel injection ofCH3CC13 or by other hydrochlorocarbon molecules is dependent upon the fraction of such compounds that survives long enough in the troposphere for eventual di...

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“…Sci. USA 78 (1981) 5935 (24,26) and by Rasmussen (27,34 (27,34). The corresponding world average should be near the 101 pptv average for these two locations.…”

mentioning

confidence: 99%

Tropospheric concentrations of methylchloroform, CH ₃ CCl ₃ , in January 1978 and estimates of the atmospheric residence times for hydrohalocarbons

Makide

Rowland

1981

Proc. Natl. Acad. Sci. U.S.A.

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“…The various peaks from F12, MeCl, The Harwell instrument is used to make measurements of many substances including sulphur compounds, hydrocarbons, halocarbons, etc; its capabilities can be shown with reference to the fluorocarbon 21 situation referred to earlier. 53 Figure 11 shows a chromatogram at m/e 67 on a 9 ft OV101 column. The small peak at 2 min 54 sec comes from F21 at a level of approximately 2.7 pptv.…”

Section: Chromatographic Techniquesmentioning

confidence: 99%

The application of analytical techniques to the understanding of chemical processes occurring in the atmosphere†

Penkett¹

1981

Toxicological & Environmental Chemistry

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The science of atmospheric chemistry has expanded enormously over the last decade. In the stratosphere it has become apparent that small traces of a number of gases can perturb the earth's ozone layer. In the troposphere it is now realised that a general oxidation process is occurring which involves several free radicals and a large number of stable gaseous molecules containing the elements H, C, N, O, S, P, F, Cl, Br and I. In areas close to centres of large population this leads to the phenomenon of photochemical smog and in more remote areas it leads to excess acidity in rainwater.In order to gain information on these problems and understand the underlying causes, many new analytical techniques have been developed. These are based mostly on chemiluminescence, laser spectroscopy, gas chromatography and mass spectrometry. Some examples of the application of these techniques will be given with emphasis placed on the role of GC/MS (gas chromatography combined with mass spectrometry).

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“…Some experimental evidence was reported suggesting that F-ll may be destroyed on suspended atmospheric particles producing F-21 (3,4). F-21 is removed relatively rapidly (lifetime ^2 years) from the troposphere by reacting with hydroxyl (OH) radicals (5). Since very little F-21 is produced in industrial processes, its tropospheric background concentration could be used to estimate the possible significance of this removal mechanism of F-ll.…”

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“…Since very little F-21 is produced in industrial processes, its tropospheric background concentration could be used to estimate the possible significance of this removal mechanism of F-ll. Calculations show that if the average concentration of F-21 in the troposphere is ^6 pptv, and most of it is due to the conversion of F-ll to F-21, then this tropospheric mechanism could remove as much as F-ll from the atmosphere as the stratospheric removal, thus making it a significant component of the fluorocarbon-ozone cycle (5).…”

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Interlaboratory comparison, preparation, and stability of dichlorofluoromethane samples and standards

Rasmussen¹,

Khalil²,

Crescentini³

et al. 1983

Anal. Chem.

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Measurements of CHFCl2 in background tropospheric air

Cited by 18 publications

References 7 publications

Tropospheric concentrations of methylchloroform, CH ₃ CCl ₃ , in January 1978 and estimates of the atmospheric residence times for hydrohalocarbons

Tropospheric concentrations of methylchloroform, CH ₃ CCl ₃ , in January 1978 and estimates of the atmospheric residence times for hydrohalocarbons

The application of analytical techniques to the understanding of chemical processes occurring in the atmosphere†

Interlaboratory comparison, preparation, and stability of dichlorofluoromethane samples and standards

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Measurements of CHFCl2 in background tropospheric air

Cited by 18 publications

References 7 publications

Tropospheric concentrations of methylchloroform, CH 3 CCl 3 , in January 1978 and estimates of the atmospheric residence times for hydrohalocarbons

Tropospheric concentrations of methylchloroform, CH 3 CCl 3 , in January 1978 and estimates of the atmospheric residence times for hydrohalocarbons

The application of analytical techniques to the understanding of chemical processes occurring in the atmosphere†

Interlaboratory comparison, preparation, and stability of dichlorofluoromethane samples and standards

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Tropospheric concentrations of methylchloroform, CH ₃ CCl ₃ , in January 1978 and estimates of the atmospheric residence times for hydrohalocarbons

Tropospheric concentrations of methylchloroform, CH ₃ CCl ₃ , in January 1978 and estimates of the atmospheric residence times for hydrohalocarbons