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 sulfur chemistry and microbiological fractionation of sulfur 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 months each year and has a maximum depth of 23 m. A layer of water at a 10‐m depth contains colloidal sulfur and is situated between a well‐oxygenated mixolimnion and an anoxic monimolimnion. In the monimolimnion, H₂S concentrations rapidly increase with depth and SO₄ ^2‐ decreases to below the limit of detection near the bottom. High δ³⁴S values (up to +67‰) were encountered in sulfate from the lake and mean δ³⁴S values of sulfate plus sulfide were similar at all depths measured.