Biogenic brominated and iodinated organic compounds in ponds on the McMurdo Ice Shelf, Antarctica

• Published in: Antarctic Science
• Main Authors: Schall, Christian, Heumann, Klaus Gustav, Mora, Stephen De, Lee, Peter A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1996
• Subjects: Geology; Ecology, Evolution, Behavior and Systematics; Oceanography; McMurdo Ice Shelf; Two Ponds; Antarc*; Antarctic Science; Antarctica; Ice Shelf
• Online Access: http://dx.doi.org/10.1017/s0954102096000089; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102096000089

During January 1994 seven meltwater ponds on the McMurdo Ice Shelf were investigated for their content of biogenic iodinated and brominated volatile hydrocarbons. An efficient purge and trap system in combination with a powerful gas chromatographic separation and an electron capture detector achieved detection limits of 0.02–0.4 ng 1 −1 , depending on the different substances. The following compounds could be identified and quantified: CH 3I , CH 2 I 2 , CH 2 C1I, CHBr 3 , CH 2 Br 2 , BrCH 2 CH 2 Br, CHBr 2 Cl, and CHBrCl 2 . This is the first time that 1,2–dibromoethane has been detected as a biogenic substance in the environment. In contrast to many other aquatic systems, where CH 3 I is found to be the most volatile iodine compound, CH 2 I 2 showed the highest concentration in all ponds falling in the range of 5–20 ng 1 −1 . In three of seven ponds investigated, CH 2 CII was the second abundant iodinated substance. CHBr 3 usually exhibited concentrations in the range of 2.5–8.6 ng 1 −1 . BrCH 2 CH 2 Br, previously not observed as a biogenic compound, was found to have concentrations similar to those of bromoform and even exceeded the bromoform content in two ponds and the CH 2 Br 2 content in all ponds. Whether cyanobacteria, the dominant organisms in the ponds, are responsible for this distribution pattern must be clarified by further investigations.