URBAN IMPACTS SUPERIMPOSED OVER NATURAL GEOCHEMICAL VARIATIONS IN THE SUSQUEHANNA AND CHENANGO RIVERS NEAR BINGHAMTON, NEW YORK

The Binghamton metro area is the largest urban center within the predominantly forested headwaters of the NY region of the Chesapeake Bay watershed. The regional wastewater treatment plant that serves the Binghamton area is undergoing improvements, which provided an opportunity to assess the effects of sewage discharge on trace metal budgets prior to completion of the upgrades. Monthly base flow as well as storm event sampling within the Chenango and Susquehanna Rivers was conducted during 2005 and 2006 for this assessment. Sampling occurred at sites on the Susquehanna River and Chenango River prior to entering the urban area, within the City of Binghamton at the confluence of the two rivers; and approximately 10 km downstream in Vestal, NY (5 km beyond the point of discharge from the waste water treatment plant).

Dissolved and particulate bound fractions were analyzed for major cations (DCP-AES) and anions (IC), as well as trace metals (HR-ICPMS). Major differences in Al, Fe, Mn, REE and Pb partitioning between particle and dissolved phases were found on a seasonal, spatial, and flow condition basis. This variation reflected differences in surficial erosional processes and rates within the Devonian shale bedrock and glacial materials within the watersheds. Base flow conditions indicate distinct differences in the Sr/Ba and Mg/Na at the rural sampling site within the Chenango and Susquehanna Rivers that reflect differences in the proportions of carbonate and shale materials within the two watersheds. Enhanced levels of V, Ni, Mo, Rb and K during low flow conditions at the downstream location best reflect the trace metal signature from the sewage effluent superimposed over the natural geochemical variability in the river system.