Metal Transport within a Small Urbanized Watershed

Abstract

Hydrograph separation techniques are used to interpret metals (Fe, Cr, Cu, and metalloid As) data within the Aberjona River watershed, a highly urbanized watershed located near Boston. Results indicate that streamflow can be separated into three separate components: quick storm flow, slow storm flow, and long-term baseflow. Quick storm flows presumably activate highly mobile sources of sediment from outside the river and result in large increases in concentrations during storm events. Slow storm flows and long-term baseflows are characterized by low and relatively constant suspended-sediment concentrations. Variability of metal transport can be explained by assigning a dissolved-metal concentration to each streamflow component and a particulate-metal concentration to each suspended-sediment component. The net concentration of dissolved and particulate metals observed in the river is a result of mixing the components. Differences between subbasins can be addressed by postulating that the concentration of metals associated with streamflow and suspended-sediment components from each subbasin were different.