NITROGEN DYNAMICS IN PRECIPITATION, SOIL MOISTURE, AND GROUNDWATER IN A SMALL WATERSHED

This is a study that focuses on the differences in nitrate concentrations in water samples from the upper Canacadea watershed in Alfred NY. Located in Allegany County, NY, this small watershed incorporates both urban and rural land use areas. We are using stable nitrogen isotope analysis, capillary zone electrophoresis, and ion chromatography to study the nitrogen speciation and nitrogen isotope fractionation in samples of rain water, soil moisture, groundwater and stream water in order to determine the sources and fate of dissolved nitrogen species in the watershed.

Samples have been collected over the past two years of incoming precipitation, soil moisture, ground water, and stream water. Subsurface samples are collected with lysimeters placed at different depths and from ground water wells, also sampling a variety of depths. The samples have been analyzed for a variety of analytes, including nitrate. Additionally, stable isotopes, hydrogen isotopes and tritium concentrations have been determined for some of the samples. The oxygen isotopic data plot very close to the meteoric water line for all samples. Sources of nitrate into the watershed include acid precipitation and agricultural runoff. Our analyses show that nitrate concentrations increase slightly as the water travels through the upper soil levels and then decrease as you go deeper into the subsurface, indicating that nitrate is being transformed and/or consumed by biota, probably by denitrification