Small Scale Changes in Stream and Soil Water Chemistry

Olivia Mak, Vassar College ’10 and Prof. Marianne H. Begemann

Our work addresses the relationship between stream chemistry and soil properties in the Coxing Kill watershed Ulster County, NY. Earlier work in our laboratory has documented a steep longitudinal pH gradient in the Coxing Kill that is accompanied by decreasing aqueous aluminum and increasing ANC and sediment aluminum concentrations. It has also been noted that, in the region where Coxing Kill and Fountain Brook merge, the stream water chemistry of Coxing Kill changes rapidly and is very different from that of Fountain Brook. Our work this summer has focused on understanding the relationship between the in-stream chemistry of Coxing Kill and Fountain Brook and soil water chemistry in the region of their confluence. A preliminary analysis of pH, aluminum, base cation and acid anion concentrations in stream water samples was performed using ICP and IC. Soil water samples and additional stream water samples will be obtained in the fall of 2009 and winter and spring of 2010. The data will elucidate the relationship between stream properties and soil processes in regions where heterogeneous geological characteristics result in dramatic variation in surface water properties.