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table aquifer and form carbonic acid (HZC03) as described by the following reactions. • <br />COZ(9) + HZO ~ C03_Z + 2H+ <br />-Z + <br />C03 + 2H -~ HZC03 <br />In the presence of carbonic acid and water, the following dissolution reactions should <br />occur: <br />+Z <br />CaC03 + HZC03 ~ Ca + p HC03 (calcite dissolution) <br />+2 +y <br />CaMg(C03)Z + 2HZ C03-~ Ca + Mg + 4HC03 (dolomite dissolution) <br />CaFe(C03)Z + 2HZC03 -~ Ca+Z + Fe+Z + 4HC03 (ankerite dissolution) <br />CaSO4.ZHZ0(s)~ Ca+Z + SO4-Z + 2 HZO (gypsum dissolution) <br />Typical dissociation reactions would include the following. <br />H CO ~ HCO + H <br />2 3 3Z + <br />HCO r CO + H <br />3 3 <br />H SO -~ SO -Z + 2H+ <br />2 4 4 <br />Oxidation reactions with reduced sulfur species and organic matter would create sulfuric • <br />acid and carbonic acid. These acids would then contribute to the dissolution of sulfur <br />and carbonate minerals. The reactions are described by the following chemical equations. <br />4FeSZ + 1502 + 14HZ0 4Fe(OH)3 + g504_Z + 16H+ (pyrite oxidation) <br />+ -2 <br />2H + SO4 - HZSO4 (formation of sulfuric acid) <br />2CaC03 + HZSO4 -~2Ca+Z + 2HC03 + SO4 Z (sulfuric acid dissolution of calcite) <br />+Z +y -p <br />CaMg(C03)Z + HZSO -~ Ca + Mg + SO4 +ZHC03 (sulfuric acid dissolution of <br />dolomite) <br />CHZO + OZ~ COZ + HZO (oxidation of organic matter) <br />Cation exchange capacities (CEC) are strongly correlated to particle sizes. Thus, the <br />clay minerals are the focus rather than the bulk of lattice spacing, charge deficiencies <br />per unit cell, and the ions available at the exchange sites. Grim (1968) presented ranges <br />of CE Os for the major clay mineral groups. Posed on Grim, the CEC ranges for the clay <br />minerals identified at the Seneca Mine are presented below. <br />Clay Mineral CEC (meq/100 gm) <br />Kaolinite 3-15 <br />I llite 10-40 <br />Smectite 80-150 <br />Chlorite 10-40 <br />• <br />30 <br />