Project Summary (1995-2000)

Four major pathways influencing arsenic concentration in Upper Mystic Lake are being examined in this study: transport through and trapping in shallow forebays; initial transport to lake sediments; subsequent and repeated remobilization from lake sediment; and finally, vertical transport to and within the surface waters. Intensive field measurement is used to characterize both the temporal and spatial variability of these processes. Measurement focuses on arsenic speciation (concentration and soluble vs. particulate fraction), particulate suspension/deposition, and the mean and turbulent flow fields. Temporal variations are correlated with meteorological conditions, and in particular to river inflow dynamics, wind stress, internal wave activity and seiching. The specific goal is to produce a conceptual model of the physical, biological and chemical processes active in determining the arsenic distribution in the system. This model provides the predictive capacity needed to develop management principles, based on easily monitored quantities, that could minimize hazardous exposure to humans. The transport processes examined in this study are not specific to arsenic or to this system, but are relevant to any aquatic system with high concentrations of heavy metals. The results of this study should be easily extended to other contaminated sites.