The origin of high sulfate concentrations in a coastal plain aquifer, Long Island, New York

Ion-exchange batch experiments were run on Cretaceous (Magothy aquifer) clay cores from a nearshore borehole and an inland borehole on Long Island, NY, to determine the origin of high SO42- concentrations in ground water. Desorption batch tests indicate that the amounts of SO 42- released from the core samples are much greater (980-4700 ??g/g of sediment) than the concentrations in ground-water samples. The locally high SO42- concentrations in pore water extracted from cores are consistent with the overall increase in SO 42- concentrations in ground water along Magothy flow paths. Results of the sorption batch tests indicate that SO42- sorption onto clay is small but significant (40-120 ??g/g of sediment) in the low-pH (