Aspects of the biogeochemistry of sulphur in glacial melt water ponds on the McMurdo Ice Shelf, Antarctica

The distribution of dimethylsulphide (DMS), together with the precursor dimethylsulphonio-propionate (DMSP) and the oxidation product dimethylsulphoxide (DMSO), was measured in melt waters on the McMurdo Ice Shelf in the immediate vicinity of Bratina Island. Conductivity in these sulphate dominated...

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Bibliographic Details
Published in:Antarctic Science
Main Authors: De Mora, S.J., Lee, P.A., Grout, A., Schall, C., Heumann, K.G.
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 1996
Subjects:
Geology
Ecology, Evolution, Behavior and Systematics
Oceanography
McMurdo Ice Shelf
Bratina Island
Antarc*
Antarctic Science
Antarctica
Ice Shelf
Online Access:http://dx.doi.org/10.1017/s0954102096000041
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102096000041
Description
Summary:The distribution of dimethylsulphide (DMS), together with the precursor dimethylsulphonio-propionate (DMSP) and the oxidation product dimethylsulphoxide (DMSO), was measured in melt waters on the McMurdo Ice Shelf in the immediate vicinity of Bratina Island. Conductivity in these sulphate dominated ponds was extremely variable, ranging from 0.106–52.3 mS cm −1 . Similarly, chlorophyll a concentrations in the pond waters (1–150 μg 1 −1 ) and mats (1.4–33 μg cm −2 ) differed considerably. The biomass was dominated by benthic felts of phototrophic cyanobacteria, which might act as a source of biogenic sulphur compounds in the ponds. The mean (and ranges) of concentrations of dissolved sulphur compounds (nmol 1 −1 ) were: CS 2 0.16 (<0.04–1.29); DMSP d 0.6 (<0.07–8.4); DMS 3.5 (<0.07–183); DMSO 27.9 (15.5–184.5). Very high concentrations of DMSO were ubiquitous in the ponds in the ice-cored moraine region of the ice shelf, with dissolved concentrations having been 1–2 orders of magnitude greater than those of DMS or DMSP d . It is difficult to ascribe the formation of DMSO solely to the conventionally accepted pathways of DMS oxidation by either bacterial activity or photochemical reactions. A direct biosynthetic production from phytoplankton or bacteria might be involved which means that DMSO in aquatic environments could act as a significant source of DMS rather than as a sink as generally supposed.

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