The geochemistry of dissolved inorganic carbon in a surficial groundwater aquifer in North Inlet, South Carolina, and the carbon fluxes to the coastal ocean

详细信息    查看全文

• 作者：Cai ; Wei-Jun ; Wang ; Yongchen ; Krest ; James ; Moore ; W.S.
• 刊名：Geochimica et Cosmochimica Acta
• 出版年：2003
• 出版时间：February 15, 2003
• 年：2003
• 卷：67
• 期：4
• 页码：631-639
• 全文大小：309 K

文摘

We report measurements of pH, total dissolved inorganic carbon (DIC), total or titration alkalinity (TAlk), Ca²⁺, Mg²⁺, sulfate, and sulfide data at the seawater-freshwater interface in a shallow groundwater aquifer in North Inlet, South Carolina. These measurements and a diagenetic modeling analysis indicate that the groundwaters at North Inlet are mixtures of seawater and freshwater end-members and are seriously modified by carbon dioxide inputs from organic carbon degradation via SO₄^2− reduction across the entire salinity range and fermentation and CaCO₃ dissolution in the low-salinity region. DIC and TAlk are several times higher than the theoretical dilution line, whereas Ca²⁺ is slightly higher and SO₄^2− is somewhat lower than the dilution line. Partial pressure of CO₂ in the groundwater is extremely high (0.05 to 0.12 atm). These deviations are consistent with theoretical predictions from known diagenetic reactions. Estimated groundwater DIC fluxes to the South Atlantic Bight from either the surficial aquifer (via salt marshes) or the Upper Floridan Aquifer (direct input) are significant when compared to riverine flux in this area.