SEDIMENT QUALITY OF THE SCHUYLKILL RIVER: A COOPERATIVE USGS, PWD, AND WCU STUDY

The Schuylkill River drains 2,000 sq. mi. of Southeastern Pennsylvania, is a drinking water source for more than one million people, and is an industrial and recreational resource for the region. Unfortunately, past practices introduced coal, polychlorinated biphenyls (PCBs), and pesticides to sediments of the Schuylkill River. In spring 2006 the United States Geological Survey (USGS) and Philadelphia Water Department (PWD) collected 18 sediment cores from Black Rock Dam near Phoenixville and the Fairmount Dam in Philadelphia with a USGS hovercraft that was equipped with a hydraulic press and Virbra core unit. Core sediments were analyzed for PCBs and pesticides (DDT, DDE, DDD) using the USGS gas chromatographic method. Sediment age was determined through radiometric analysis for Cs-137. Students from West Chester University described the cores using the USDA and USCS soil classification systems as part of an outreach project conducted during a soils course taught in the Department of Geology and Astronomy. WCU Students also analyzed sediments for metals and coal using WCU's Quanta Environmental Scanning Electron Microscope (ESEM).

Preliminary results from the core analyses indicate a strong anthropogenic control over river sediments and a widespread distribution of coal in the lower basin. Sediment descriptions and ESEM analysis of selected cores identified fine- to coarse-grained sands of crushed coal in horizons up to one meter thick. Anthracite mines located in the headwater region of the basin are the probable source of the coal, which was likely transported via fluvial and anthropogenic processes. The 2006 study found that PCB and pesticide concentrations were generally higher at Fairmount Dam, with maximum PCB and DDT concentrations of 255 and 25µg/kg, respectively. An earlier study conducted by Yorke (1985) reported higher concentrations of PCBs and pesticides at the upstream Black Rock location. A comparison of these studies suggests that contaminated sediments migrated downstream since the 1980s and are now present at the sediment surface at Fairmount Dam. Future research will be necessary to assess the ecological and human health risk posed by contaminated river sediments and to develop best management practices for the Schuylkill River.