Acid-volatile sulfide (AVS) in a seasonally anoxic mesotrophic lake: Seasonal and spatial changes in sediment AVS

Acid-volatile sulfide (AVS) is an operational definition for the sulfides removed from sediment by cold acid extraction. It has been proposed that this fraction could be used as an indicator of divalent metal toxicity (e.g., Cd, Ni, Hg), as it increases the metal-binding capacity of sediments and hence renders metals unavailable to biota. Before AVS can be used as a predictive tool in freshwater systems, we must develop a better understanding of the impact of seasonal turnover events on its geochemistry. An in-depth study of spatial and temporal variation in AVS concentrations in a seasonally anoxic mesotrophic lake is presented. Comparisons are made to AVS in other lakes, with reference to its utilization as a sediment toxicity parameter. Results indicate that AVS increases during anoxic periods and that lake morphology is important due to sediment focusing. Seasonal variations in AVS concentration were observed that may change the potential toxicity of metals in freshwater sediments.