Institute of Ecosystem Studies

2008 BES Annual Meeting Presentation and Poster Abstracts

Stream chemistry of forested headwater watersheds along the Binghamton-to-Catskill urban-rural gradient
Zhu, Weixing
Co-Authors: Nichole Hantsch and Weixing Zhu
Abstract: Increases in urbanization are changing ecosystems in the immediate urban surroundings as well as those downwind through processes such as atmospheric deposition. Watersheds have been widely used to study such large-scale environmental changes. The Binghamton Urban-to-Rural Gradient project in New York includes an urban center surrounded by several forested watersheds. The exurban area extends through Broome and Delaware Counties to the edge of the rural Catskill Preserve. We sampled 25 headwater streams along this urban-rural forested watershed gradient (total west to east distance of 120 km) starting from 2005 to 2006. Stream waters were analyzed for ammonium (NH4+), nitrate (NO3-), soluble reactive phosphorus (SRP), and chloride (Cl-). Conductivity, pH, and temperature were measured in situ. Ammonium concentrations were under 0.1 mg N/l in nearly all streams. Nitrate concentrations were higher, averaging 0.317 mg/l in urban sites, 0.160 mg/l in exurban sites, and 0.244 mg/l in rural sites. DON, Cl-, and SRP concentrations all declined along this urban-to-rural watershed gradient, with DON concentrations averaging 0.288, 0.268, and 0.197 mg N/l in urban, exurban, and rural watersheds respectively. Chloride concentrations decreased from summer 2005 to winter 2005, but increased again in spring 2006. Spring runoffs washing de-icing salt from the roads could have contributed to such seasonal variation. Stream pH averaged 7.4 in urban sites and 7.0 in rural locations, while conductivity averaged 201 ÁS in urban vs. 54 ÁS in rural streams. These data showed that urban centers could have a large impact on the headwater watersheds in their immediate neighborhood and those hundreds kilometers away, and affecting a suite of stream chemistry.