|
Hydrological hazards |
Institute of Geological Sciences, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK (e-mail: ear6shb{at}earth.leeds.ac.uk)
Isotopic compositions of sulphate (
18O and
34S) have been analysed in groundwaters from a karst aquifer in Xingwen, China to assess their use as indigenous tracers of different pollutant sulphate sources. Sulphate
18O is highly effective at distinguishing sulphate from atmospheric acid rain sources (higher
18O values) from sulphate produced by aqueous pyrite oxidation (natural or acid mine drainage), which always has lower
18O. The range of sulphate
34S produced by aqueous oxidation of different pyrite sources is sufficiently wide to enable different natural and pollutant sulphate sources to be distinguished. Despite the fact that streams containing processing fines and pyrite mine drainage both derive sulphate from oxidation of ore materials, there is still a clear distinction in their sulphate
34S. A combination of sulphur and oxygen isotopic measurements is thus highly effective at discriminating between all the sulphate sources to the karst aquifer and this indigenous tracer provides a powerful tool for assessing the impact of acid mine drainage on karst groundwater.