| Summary |
Sixteen wells in southeastern North Carolina were sampled and analyzed for Ca²⁺, Mg²⁺, Na⁺, K⁺, Fe, Cf, S0₄²̄, SiO₂, HCO₃(B-, O₂, NO₃̄, NO₂̄, P0₄(B3-, NH₄(B+, F, HS', TDS, pH, and Eh in order to characterize the major element chemistry of groundwater in the Castle Hayne Aquifer System. These data along with data collected by Sutton and Woods in the northern coastal plain were used to delineate regional chemical trends and to elucidate the major geochemical processes affecting water chemistry. Geochemical modeling programs, contour maps of ion concentrations, and Piper diagrams were used to analyze the chemical data. Waters from wells in the Lower Castle Hayne Aquifer and the northeasternmost wells in the Upper Castle Hayne Aquifer are all alkali and chloride rich and appear to be dominated by mixing with saline formation water. Waters from northwestern and southwestern wells of the Upper Castle Hayne Aquifer are calcium and bicarbonate rich due to dissolution of carbonate minerals in the aquifer. This water is also affected by dissolution of soil salts. Cation exchange appears to be a major geochemical process throughout the CHAS. Data from this investigation can be used by municipalities, fish farmers, and private citizens to better plan and develop water supplies in the North Carolina coastal plain. |
