SEASONAL-VARIATION OF ACID VOLATILE SULFIDE CONCENTRATION IN SEDIMENT CORES FROM 3 NORTHEASTERN MINNESOTA LAKES

Acid volatile sulfide (AVS) is a natural agent in sediments which complexes some cationic metals and thereby influences the toxicity of these metals to benthic organisms. Because of its influence on metal bioavailability, AVS has been proposed as a key normalization phase for the development of sediment quality criteria for metals. However, studies conducted primarily in marine and estuarine systems have shown that AVS concentrations can vary markedly both temporally and with (sediment) depth. In this study, AVS concentrations were measured monthly for 16 mo in several segments of sediment cores from three freshwater lakes: Caribou Lake, Fish Lake and Pike Lake in northeastern Minnesota, USA. The concentrations of AVS in cores from the three lakes varied inversely with sediment depth. AVS concentrations also varied seasonally by as much as two orders of magnitude and were directly correlated with changes in water temperature. The correlation between AVS and temperature likely was related both to changes in primary productivity and sediment microbial activity.