INVENTORY ANALYSIS AND TRANSPORT OF LEGACY METALS IN RIVER AND MILLPOND SEDIMENTS: AN EXAMPLE FROM THE NEPONSET RIVER WATERSHED, MASSACHUSETTS

Recognized as the second industrialized watershed in the United States, the Neponset River Watershed has a complex history of metal loading from both point sources and non-point sources. In collaboration with the Neponset Watershed Association (NepRWA), this study links targeted industrial history with geochemically distinct sub-regions in the watershed. We evaluate the fate and transport of toxic metals by combining complete bulk and trace element characterization of sediment cores, analyses of surface samples using x-ray fluorescence (XRF) and analyses of loss on ignition procedures with historical land use, native knowledge, and multivariable statistics. Using an interdisciplinary approach can provide a means for linking recorded industrial outputs to integrated metal concentrations as a function of depth. The relationship between metal inventories in both sediments and suspended matter may reveal the mechanism by which suites of metals are alternatively sequestered or transported out of point-source dominated systems. This mechanistic understanding of metal concentration across environmental matrices will be crucial for predicting the effects of remobilized contaminants on downstream ecosystems as a result of dam removal. Future work will thus be focused on quantifying the extent of metal mobilization by examining metal concentrations on and within submerged vegetation in the Neponset Reservoir.