TEMPORAL VARIATION IN GROUNDWATER CHEMISTRY OF UPPER GLACIAL AQUIFER

Groundwater nutrient concentration in the urban areas to some extent can exceed the EPA permissible limit and thus pose a threat to public health. The Upper Glacial Aquifer of Long Island consists of a layer of stratified sediment, which underlies Kings, Queens and Nassau Counties. Previous pumping of water from this aquifer resulted in encroachment of salt water and other contaminants into the aquifer. In an attempt to study hydro-geochemical dynamic, the study aims to investigate temporal variation of physical and chemical properties of groundwater. The study utilizes data gathered in situ through two USGS well (N40^o42′12", W73^o47′36") located in the vicinity of York College, Jamaica, NY at the depth of 50 ft. Results showed the minimal fluctuation in groundwater level with an average hydraulic head of 24.8 ft. Physical parameter including temperature, pH, salinity, conductivity, and ORP (oxidation reduction potential) are 17.7^oC; 6.44; 0.76 ppt; 1293 μS/cm and 108 mV respectively. High level of nitrate (45.7 ± 9.5 ppm) with significant fluctuation compare to low nitrite (1.2 ± 1.0 ppm) and non-detectable ammonia is consistent with positive ORP value. The water is indeed limited by the phosphate and always below the detection limit of chemetrics Vacu-vial colorimetric method. The study also investigated the presence of fecal indicative bacteria in the water to understand the surface water intrusion in the aquifer from the sewage system during the storm.