A COMPARISON OF THE MAJOR ION CHEMISTRY OF TWO MAINE WATERSHEDS, PLEASANT RIVER (BETHEL, ME) AND STETSON BROOK (LEWISTON, ME)

This study compares the major ion water chemistry (Ca²⁺, Mg⁺, Na⁺, K⁺, HCO₃^-, SO₄^2-, Cl^-) and nutrient levels of two watersheds in Maine. Water chemistry is largely determined by rock weathering, and can be severely altered by humans in many ways including through inputs of road salt, detergents and fertilizers. The Pleasant River watershed near Bethel, ME is over 87% forested with less than 2% developed land. The Stetson Brook watershed in Lewiston, ME is 56% forested with over 24% developed land. Ca²⁺, Na⁺, HCO₃^-, and Cl^- were the most abundant ions in both watersheds. There were higher concentrations of all major ions and increased levels of nutrients (NH₄⁺, NO₃^-, PO₄^3-) in the Stetson Brook watershed relative to the Pleasant River watershed. Of particular interest is the fact that Ca²⁺ and Na⁺ are the dominant cations in both watersheds, and concentrations of these ions in the Stetson Brook are approximately 5x greater than in the Pleasant River. The differences in these major ion concentrations can likely be attributed to anthropogenic impacts because of the differences in land use between the two watersheds.