TOXIC TRACE METAL MOBILITY IN THE TROUT BROOK AT THE WEST HARTFORD LANDFILL, WEST HARTFORD, CONNECTICUT

The Park River is an urban river that flows through greater Hartford, into the Connecticut River, and ultimately into the Long Island Sound. The Trout Brook, a channelized tributary of the south branch of the Park River has a history of toxic trace metal discharges from several metal finishing industries. In addition, the West Hartford landfill, a semi-closed unlined landfill facility, discharges its storm and waste water into the Trout Brook. Sediment samples were collected around the storm water outflow of the landfill on four different dates in the spring and summer of 2010 to determine whether the point source contributes to elevated toxic trace metal concentrations within the sediment of the Trout Brook. Before and after several rain events, samples were collected to observe how the rain events influenced the mobility of sediment and toxic trace metals in the channelized stream. We analyzed for nine metals including cadmium, iron, manganese, lead and zinc using inductively coupled plasma spectrometry (ICP-OES) after a weak acid digestion method that extracted metals adsorbed to silt and clay sized particles (grains < 63µm). Contour maps for each metal were constructed in ESRI ArcGIS 9.3 to map spatial and temporal variations of metal concentrations at different sampling sites before and after the rain events. For all trace metals (except cadmium and lead), there was a statistical increase (p-value < 0.05) in metal concentration after the rain events and a statistical increase (p-value <0.05) in metal concentrations downstream of the outflow suggesting a dynamic sediment bedload during moderate storm events.