Thiosulfate, Polythionates, and Rhodanese Activity in Lakes Erie and Ontario Sediments

The concentrations of thiosulfate (10-20 μ g· g dry wt-1) and polythionates (10-70 μ g· g-1) in Lake Ontario sediments are much higher than those (0-20 and 5-40 μ g· g-1) in the more reduced Lake Erie sediments. The distribution of these labile compounds is considered in relation to the forms of sulfur and sulfur bacteria in the different basins of Lake Erie and the importance of microenvironments in the formation of thiosulfate and polythionates is emphasized. The high concentrations in Lake Ontario suggest that once formed, the thiosulfate can persist for a long time in sediments with limited amounts of oxygen. The correlation between rhodanese activity and thiosulfate plus polythionates suggests that rhodanese may catalyze some of the processes responsible for the generation and extinction of these sulfur compounds in lake sediments.