Determination of Concentration and Carbon Isotopic Composition of Dissolved Methane in Sediments and Nearshore Waters

1995 ◽  
Vol 67 (2) ◽  
pp. 405-411 ◽  
Author(s):  
Brian N. Popp ◽  
Francis J. Sansone ◽  
Terri M. Rust ◽  
Dawn A. Merritt
Keyword(s):  
Isotopic Composition ◽  
Carbon Isotopic Composition ◽  
Dissolved Methane ◽  
Carbon Isotopic

scholarly journals A high volume sampling system for isotope determination of volatile halocarbons and hydrocarbons

2011 ◽  
Vol 4 (10) ◽  
pp. 2073-2086 ◽  
Author(s):  
E. Bahlmann ◽  
I. Weinberg ◽  
R. Seifert ◽  
C. Tubbesing ◽  
W. Michaelis
Keyword(s):  
Isotopic Composition ◽  
Carbon Isotopic Composition ◽  
High Volume ◽  
Isotope Ratios ◽  
Urban Site ◽  
Sampling System ◽  
Mixing Ratios ◽  
Carbon Isotopic ◽  
Promising Tool

Abstract. The isotopic composition of volatile organic compounds (VOCs) can provide valuable information on their sources and fate not deducible from mixing ratios alone. In particular the reported carbon stable isotope ratios of chloromethane and bromomethane from different sources cover a δ13C-range of almost 100‰ making isotope ratios a very promising tool for studying the biogeochemistry of these compounds. So far, the determination of the isotopic composition of C1 and C2 halocarbons others than chloromethane is hampered by their low mixing ratios. In order to determine the carbon isotopic composition of C1 and C2 halocarbons with mixing ratios as low as 1 pptv (i) a field suitable cryogenic high volume sampling system and (ii) a chromatographic set up for processing these samples have been developed and validated. The sampling system was tested at two different sampling sites, an urban and a coastal location in Northern Germany. The average δ13C-values for bromomethane at the urban site were −42.9 ± 1.1‰ and agreed well with previously published results. But at the coastal site bromomethane was substantially enriched in 13C by almost 10‰. Less pronounced differences were observed for chlorodifluoromethane, 1,1,1-trichloroethane and chloromethane. We suggest that these differences are related to the turnover of these compounds in ocean surface waters. Furthermore we report first carbon isotope ratios for iodomethane (−40.4‰ to −79.8‰), bromoform (−13.8‰ to 22.9‰), and other halocarbons.

scholarly journals A high volume sampling system for isotope determination of volatile halocarbons and hydrocarbons

2011 ◽  
Vol 4 (2) ◽  
pp. 2161-2188 ◽  
Author(s):  
E. Bahlmann ◽  
I. Weinberg ◽  
R. Seifert ◽  
C. Tubbesing ◽  
W. Michaelis
Keyword(s):  
Isotopic Composition ◽  
Carbon Isotopic Composition ◽  
High Volume ◽  
Isotope Ratios ◽  
Urban Site ◽  
Sampling System ◽  
Mixing Ratios ◽  
Carbon Isotopic ◽  
Promising Tool

Abstract. The isotopic composition of volatile organic compounds (VOCs) can provide valuable information on their sources and fate not deducible from mixing ratios alone. In particular the reported carbon stable isotope ratios of chloromethane and bromomethane from different sources cover a δ13C-range of almost 100‰ making isotope ratios a very promising tool for studying the biogeochemistry of these compounds. So far, the determination of the isotopic composition of C1 and C2 halocarbons others than chloromethane is hampered by their low mixing ratios. In order to determine the carbon isotopic composition of C1 and C2 halocarbons with mixing ratios as low as 1 pptv (i) a field suitable cryogenic high volume sampling system and (ii) a chromatographic set up for processing these samples have been developed and validated. The sampling system was tested at two different sampling sites, an urban and a coastal location in Northern Germany. The average δ13C-values for bromomethane at the urban site were −42.9±1.1‰ and agreed well with previously published results. But at the coastal site bromomethane was substantially enriched in 13C by almost 10‰. Less pronounced differences were observed for chlorodifluoromethane, 1,1,1-trichloroethane and chloromethane. We suggest that these differences are related to the turnover of these compounds in ocean surface waters. Furthermore we report first carbon isotope ratios for iodomethane (−53.6‰), bromoform (−13.5‰) and other halocarbons.

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