2007 BES Annual Meeting Presentation and Poster Abstracts
Water quality in a restored urban stream, Pittsburgh, PA
Co-Authors: Marion Sikora, Daniel J. Bain, Emily M. Elliott Department of Geology & Planetary Science, University of Pittsburgh
Abstract: The Nine Mile Run (NMR) Watershed is the site of the largest aquatic ecosystem restoration in the U.S. The NMR watershed drains a significant portion of east Pittsburgh, emerging from culverts and flowing through Frick Park to the Monongahela River. A visual inspection of the water shows a marked qualitative improvement in the stream quality downstream, however there has been no continuous water quality monitoring and there is little pre-restoration water quality data. We initiated water quality monitoring in summer 2007 to: 1) determine sources of nutrient contamination and; 2) assess the influence of sanitary sewers and combined sewer overflows (CSO) on nutrient dynamics. Low-flow samples were collected bi-weekly in four locations and analyzed for major anion (nitrite, nitrate, sulfate, Br, F, Cl) and cation concentrations (Mg, Ca, Na, K, Sr, Si). Discharge data, nitrate, and fluoride concentrations suggest that connections between sanitary sewers and NMR impact streamwater quantity and quality more than combined sewer overflow (CSO) during low flow. Although nitrogen sources remain ambiguous, nitrate concentration variations suggest in-stream processing or multiple sanitary sewer inputs during low flow. Future work will employ stable isotope compositions of nitrate (d15N, d18O, d17O) to determine how nitrate sources to NMR vary with streamlength and during high and low flow regimes. In addition sampling of high-flow events will be conducted to understand the influence of CSO's on stream function.