Characterizing Geochemical Reactions in Unsaturated Mine Waste-Rock Piles Using Gaseous O2, CO2, 12CO2, and 13CO2
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- 作者：Tyler K. Birkham ; M. Jim Hendry ; L. I. Wassenaar ; Carl A. Mendoza ; and Eung Seok Lee
- 刊名：Environmental Science & Technology
- 出版年：2003
- 出版时间：February 1, 2003
- 年：2003
- 卷：37
- 期：3
- 页码：496 - 501
- 全文大小：150K
- 年卷期：v.37,no.3(February 1, 2003)
- ISSN：1520-5851
文摘
In situ determinations of geochemical reaction rates inmine waste-rock piles remain a challenge. Depth-profilesof field O2 and CO2 pore-gas concentrations, 
13CCO2values, and moisture contents were used to characterizeand quantify geochemical reaction rates in two waste-rockpiles at the Key Lake Uranium Mine in northernSaskatchewan, Canada. Traditionally, the presence of O2concentrations less than atmospheric in waste-rock pileshas been attributed to mineral oxidation. This studyshowed that the interpretation of O2 and CO2 concentrationprofiles alone could not be used to identify the depths ofdominant geochemical reactions in the piles and could leadto erroneous estimates of reaction rates. Modeling ofthe 13CCO2 depth profiles clearly showed that the gasconcentration profiles present in the piles were the resultof the oxidation of organic matter present below thepiles, a mechanism not previously reported in the literature.Based on these findings, the rates of reactions in theorganic zone were determined. The oxidation of organicmatter at the base of waste-rock piles should be consideredin future mine-waste pore-gas studies, in addition tosulfide oxidation and carbonate buffering.
13CCO2values, and moisture contents were used to characterizeand quantify geochemical reaction rates in two waste-rockpiles at the Key Lake Uranium Mine in northernSaskatchewan, Canada. Traditionally, the presence of O2concentrations less than atmospheric in waste-rock pileshas been attributed to mineral oxidation. This studyshowed that the interpretation of O2 and CO2 concentrationprofiles alone could not be used to identify the depths ofdominant geochemical reactions in the piles and could leadto erroneous estimates of reaction rates. Modeling ofthe 13CCO2 depth profiles clearly showed that the gasconcentration profiles present in the piles were the resultof the oxidation of organic matter present below thepiles, a mechanism not previously reported in the literature.Based on these findings, the rates of reactions in theorganic zone were determined. The oxidation of organicmatter at the base of waste-rock piles should be consideredin future mine-waste pore-gas studies, in addition tosulfide oxidation and carbonate buffering.