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Dissolve Inorganic Carbon (DIC) and Stable Carbon Isotope Evolution in a Tailings Pile

Hendratta Ali and Eliot Atekwana
Boone Pickens School of Geology, Oklahoma State University 105 Noble Research Center, Stillwater, OK 74078

The Old Lead Belt of SE Missouri (USA) was the nation's major source of lead for close to 100 years. As a result mine spoils estimated at more than 254 billion kg are disposed of in more than 6 major tailings piles that cover more than 12 sq km within the Big and Flat River watersheds. Sediments of mine tailings, groundwater below mine spoils, Previous HitsoilNext Hit water, surface water and Previous HitsoilNext Hit gas from tailings were analyzed for physical parameters, major ions and carbon isotope ratios of DIC and carbon dioxide. Surface water was collected from lakes surrounding the tailings, groundwater from wells between 4.6 and 30.5m deep, Previous HitsoilNext Hit water and Previous HitsoilNext Hit gas from lysimeters and gas samplers between 0.5 and 3m. Results show that in ground-, Previous HitsoilNext Hit- and surface water, pH ranged from 6.3 to 8.1, alkalinity from 60 to 513 mg/l and DIC range from 0.6 to 4.9 mM/l for groundwater, 3.4, to 8.5 mM/l for Previous HitsoilNext Hit water, 1.3 mM/l in lake water and 2.7 and 3.3 mM/l at tailings seeps. Previous HitSoilNext Hit carbon dioxide ranged between 0.4 and 21.9 mM C. The isotope ratios of DIC was -9.0 per mil for tailing seeps, -8.4 to -9.3 per mil for lake water, -2.9 to -12.5 for groundwater, -3.5 to -5.8 per mil for Previous HitsoilNext Hit water and -1.4 for tailings sediments. The stable carbon isotope ratio of carbon dioxide from Previous HitsoilNext Hit gas was -11.4 to -16.4 per mil and background Previous HitsoilNext Hit gas (without mine spoils) -22.1 per mil. The results of this study show that mine tailings can generate high DIC in ground and Previous HitsoilNext Hit water that degas as carbon dioxide to the unsaturated Previous HitsoilNext Hit zone. Isotope values intermediate between tailings sediment and background Previous HitsoilNext Hit carbon agree with input of heavier carbon from tailings carbonate into ground, Previous HitsoilTop and surface water DIC.

AAPG Search and Discover Article #90087 © 2008 AAPG/SEG Student Expo, Houston, Texas