Stable Hydrogen and Oxygen Isotope Composition of Waters from Mine Tailings in Different Climatic Environments
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- 作者：Jorge E. Spangenberg ; Bernhard Dold ; Marie-Louise Vogt ; Hans-Rudolf Pfeifer
- 刊名：Environmental Science & Technology
- 出版年：2007
- 出版时间：March 15, 2007
- 年：2007
- 卷：41
- 期：6
- 页码：1870 - 1876
- 全文大小：395K
- 年卷期：v.41,no.6(March 15, 2007)
- ISSN：1520-5851
文摘
The stable isotope composition of waters (
2H, 18O) canbe used as a natural tracer of hydrologic processes insystems affected by acid mine drainage. We investigatedthe 2H and 18O values of pore waters from four oxidizingsulfidic mine tailings impoundments in different climaticregions of Chile (Piuquenes at La Andina with Alpine climate,Cauquenes and Carén at El Teniente with Mediterraneanclimate, and Talabre at the Chuquicamata deposit withhyperarid climate). No clear relationship was found betweenaltitude and isotopic composition. The observed displacementof the tailings pore waters from the local meteoricwater line toward higher 18O values (by ~ +2” 18Orelative to 2H) is partly due to water-rock interactionprocesses, including hydration and O-isotope exchange withsulfates and Fe(III) oxyhydroxides produced by pyriteoxidation. In most tailings, from the saturated zone towardthe surface, isotopically different zones can be distinguished.Zone I is characterized by an upward depletion of 2Hand 18O in the pore waters from the saturated zone andthe lowermost vadose zone, due to ascending diffusedisotopically light water triggered by the constant loss ofwater vapor by evaporation at the surface. In zone II, thecapillary flow of a mix of vapor and liquid water causesan evaporative isotopic enrichment in 2H and 18O. At the topof the tailings in dry climate a zone III between thecapillary zone and the surface contains isotopically lightdiffused and atmospheric water vapor. In temperate climates,the upper part of the profile is affected by recent rainfalland zone III may not differ isotopically from zone II.
2H, 18O) canbe used as a natural tracer of hydrologic processes insystems affected by acid mine drainage. We investigatedthe 2H and 18O values of pore waters from four oxidizingsulfidic mine tailings impoundments in different climaticregions of Chile (Piuquenes at La Andina with Alpine climate,Cauquenes and Carén at El Teniente with Mediterraneanclimate, and Talabre at the Chuquicamata deposit withhyperarid climate). No clear relationship was found betweenaltitude and isotopic composition. The observed displacementof the tailings pore waters from the local meteoricwater line toward higher 18O values (by ~ +2” 18Orelative to 2H) is partly due to water-rock interactionprocesses, including hydration and O-isotope exchange withsulfates and Fe(III) oxyhydroxides produced by pyriteoxidation. In most tailings, from the saturated zone towardthe surface, isotopically different zones can be distinguished.Zone I is characterized by an upward depletion of 2Hand 18O in the pore waters from the saturated zone andthe lowermost vadose zone, due to ascending diffusedisotopically light water triggered by the constant loss ofwater vapor by evaporation at the surface. In zone II, thecapillary flow of a mix of vapor and liquid water causesan evaporative isotopic enrichment in 2H and 18O. At the topof the tailings in dry climate a zone III between thecapillary zone and the surface contains isotopically lightdiffused and atmospheric water vapor. In temperate climates,the upper part of the profile is affected by recent rainfalland zone III may not differ isotopically from zone II.