IMPACTS OF URBANIZATION ON STREAM BIOGEOCHEMISTRY IN SCHENECTADY COUNTY, NY

Urban streams receive a high pollutant load from residential septic tanks, wastewater effluent, piped storm water drainage, and runoff from parking lots, roads, and fertilized lawns. Urban streams, therefore, have higher concentrations of nutrients and contaminants compared to rural streams. In addition, other activities associated with urbanization, such as stream channel modifications, increased area of impervious surfaces, deforestation of riparian vegetation greatly impacts stream chemistry, morphology, hydrology and ecology. The impact of anthropogenic activities on urban streams calls for a quantification of the stream impairment, in order to monitor and evaluate possible need for restoration. This study strives to quantify the differences between rural and urban stream water biogeochemistry.

A total of 46 sites from 10 different urban and rural were sampled throughout Schenectady County in Upstate New York during the summer of 2016. Water temperature, pH and dissolved oxygen were recorded and ion concentrations, alkalinity, and stable carbon isotopic values of the dissolved inorganic content (DIC) were analyzed. Finally, we analyzed the dried filamentous algae for stable carbon and nitrogen isotopes. Nitrogen isotopic values are indicative of anthropogenic sources of pollution such as sewage leachate, fertilizer runoff, and nearby wastewater treatment plants. Carbon isotopic values of algae should be linked to longer term DIC (growing season of the algae) which is influenced by stream geomorphology, the structure of the surrounding terrestrial ecosystem and productivity, and watershed geology. Based on a preliminary study in this region, we expect to confirm the much higher concentration of ions as well as the higher concentration of organic pollution in urban streams.