Sulfur chemistry and microbiological fractionation of sulfur isotopes in a saline Antarctic lake

Abstract

Data on temperature, water chemistry and abundance of bacteria in Ace Lake, Antarctica, are presented. In particular, the S chemistry and microbiological fractionation of S isotopes are discussed in relation to the possible development of the lake and the climatic history of the lake catchment. The lake is covered by ice for 9 mo. each year and has a maximum depth of 23 m. A layer of water at a 10-m depth contains colloidal S and is situated between a well-oxygenated mixolimnion and an anoxic monimolimnion. In the monimolimnion, H2S concentrations rapidly increase with depth and SO42- decreases to below the limit of detection near the bottom. High .delta.34S values (up to +67.permill.) were encountered in sulfate from the lake and mean .delta.34S values of sulfate plus sulfide were similar at all depths measured.