REDUCED SULFUR GASES IN SALINE LAKES OF THE VESTFOLD HILLS, ANTARCTICA

A survey of reduced sulfur gases in the lakes of the Vestfold Hills, Antarctica, was undertaken to elucidate the environmental factors affecting the distribution of these compounds. The oxygenated water of all lakes was found to contain low levels of dimethylsulfide (DMS) (0-30 nM) and no other sulfur compounds. The meromictic lakes show considerable variation in the speciation and concentration of the reduced sulfur compounds present in the anoxic bottom water. Meromictic lakes of low salinity (< 80 parts per thousand) possessed anoxylimnia nearly devoid of dimethylsulfide (DMS) but with high concentrations of H2S. In these lakes it appeared that rates of degradation of DMS were as fast as production. Lakes of intermediate salinity (80-185 parts per thousand) had high concentrations of both sulfur species while lakes of salinity greater than 185 parts per thousand had no H2S but high concentrations of DMS. The absence of hydrogen sulfide was attributed to the absence of sulfate-reducing bacteria. The observed DMS concentrations were the result of the balance between the production and degradation of DMS by bacteria. At high salt concentrations either the degradation processes became relatively less efficient or more DMS was produced in response to increased salinity.