Assessment of the Effects of Urbanization on Water Quality along a New England Stream

Dudiac, Tatyana

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Assessment of the Effects of Urbanization on Water Quality along a New England Stream

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Abstract. Urbanization has a significant impact on water quality. Urban drainage systems and impervious surfaces accelerate the delivery of pollutants from land areas in watersheds to streams and rivers. The harmful pollutants include sodium and chloride associated with the application of road salts during the winter, metals and oils associated with vehicles and impervious surface. The goal of this project was to access impacts of urbanization on River Meadow Brook and validate a chloride assessment tool. The first phase of this research was a part of a chloride study sponsored by the Massachusetts Department of Environmental Protection (MassDEP). The second phase of the projects included flow and water quality monitoring. The first phase of the project involved the development of a linear regression equation to validate a chloride assessment tool that MassDEP had developed and implemented based on historical data. River Meadow Brook, a Massachusetts stream that flows from a non-urban, rural area with relatively low pollutant concentrations to highly urbanized area in Lowell, MA, was chosen for that purpose because of the area’s large concentration of roadways and highways and historically high concentrations of chloride. Water samples and continuous conductivity data were collected for a 7-month period. Using 24 grab samples analyzed at the United States Environmental Protection Agency (USEPA) laboratory in Chelmsford, MA, the model was validated with 99.37% confidence using a linear regression equation. Therefore, the relationship between conductivity and chloride was validated. Calculated chloride was used to identify chloride violations of ambient water quality standards in River Meadow Brook. In addition to MassDEP study, the relationship between the percent of imperviousness and various trace metals, anions and total suspended solids was developed to show impacts of urbanization on the stream. The research approach included collection of both water samples and flows to calculate daily pollutant loads. Water monitoring included grab samples and unattended continuous conductivity with a 30-minute recording intervals. Discharge monitoring included collection of flows in River Meadow Brook using a brad- crested dam and the area- velocity technique. A wide variety of cations from a sampling of 5 sites along River Meadow Brook were analyzed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Cl, sulfate and nitrate were analyzed using the Dionex ICS-2100 Ion Chromatography System. Laboratory results of water quality parameters showed that pollutants associated with impervious surface increase as the stream flows from its headwaters to downstream. The result from the Pearson correlation analysis revealed that sodium, chloride, potassium, vanadium, nickel, copper, arsenic, TSs and pH had a positive relationship with imperviousness while DO and nitrate had negative relationship. The combination of laboratory and field analysis helped to assess the impacts of urbanization and checked against ambient water quality standards.

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