ANION AND CATION DYNAMICS IN A PARTIALLY DEVELOPED WATERSHED

This is a study that focuses on the differences in anion and cation concentrations in water, soil, and aquifer material samples from the upper Canacadea watershed in Alfred NY. Located in Allegany County, this small watershed incorporates both urban and rural land use areas. The geology of the area is characterized by an upper soil layer (3ft thick) that is underlain by an unconfined aquifer (dirty glacial outwash 17ft thick). The unconfined aquifer is underlain by 8 feet of glaciolacustrine clay. The glaciolacustrine clay serves as a confining unit for the lower aquifer (silty glacial outwash). In our laboratories, we have analyzed the samples (both water and geologic samples) using a variety of standard techniques, including atomic absorption spectrophotometry, ion chromatography, and x-ray diffraction. Water samples have been collected over the past two years of incoming precipitation (four sites), soil moisture from two depths (four sites), groundwater from three depths, and stream samples from two sites. The geologic material was collected from three sites at varying depths.

The changes in water chemistry are providing information about processes in the subsurface. Tritium analysis shows the lower aquifer is at least fifty years older than the lower aquifer, but no data indicates total isolation of water chemistry. Our analyses show nitrate concentrations increase slightly as the water travels through the upper soil levels and decrease with greater depth. Spring and summer sulfate levels show trends opposite that of nitrate. During fall and early winter months, sulfate increases in the upper soil layer then decreases in the deeper levels of the soil until dramatic increases are observed as depth increases. Bulk soil chemistry and mineralogy are uniform with depth. No mineralogical sources of sulfate or nitrate have been identified in the soil or aquifer material; therefore ion concentrations with depth undoubtedly reflect differences in biologic activity with depth. Changes in cation concentrations in soil moisture and groundwater with depth indicate cation exchange processes are occurring in the soil zone and possibly the upper aquifer.