GROUNDWATER QUALITY ASSESSMENT OF THE PINEY POINT AQUIFER IN THE VIRGINIA COASTAL PLAIN

Groundwater quality of Piney Point aquifer in the Virginia Coastal Plain is assessed in terms of anion concentrations and leaching experiment is conducted to acquire an understanding of the release mechanisms of anions from the solid phases of the aquifer under varying pH conditions. Present study reveals that in low pH conditions, fluoride concentrations in ground water relates to phosphorous content of sediments. Release of chloride is also comparatively high in low pH condition. Sulfate concentrations in leachate were found to be directly associated with the sediment characteristics. Comparatively higher concentration of nitrate is observed in the sediments of Piney Point formation. The occurrence of higher concentration of nitrate in a confined aquifer require further investigation, but it appears that dissolution of total inorganic carbon (TIC) due to pH changes increases the concentration of total organic carbon (TOC) and probably have a greater effect on nitrogen chemistry in the confined aquifer sediments. Concentrations of anions are higher in leachate than in groundwater samples collected from Piney Point aquifer. Additionally, sulfate concentrations in leaching experiments exceeded their Secondary Drinking Water Standards (SMCL) of EPA for nearly every sample. The nitrate concentrations were close to their Maximum Contamination Level (MCL) of EPA in the underlaying Nanjemoy sediments and nitrate levels will need to be carefully monitored.

Present study initiated an idea how the increased water exploitation may affect the groundwater quality of the Piney Point aquifer in Virginia Coastal Plain.