Isotope Geochemistry, Hydrochemistry, And Mineralogy Of A River Affected By Acid Mine Drainage In A Mining Area, South China

The Hengshi River is a classic example of an acid mine drainage (AMD)-affected river located in the Dabaoshan mining area in southern China. This work utilized stable isotopes (delta S-34 and delta O-18) and hydrochemical data of surface water samples as well as the mineralogical composition of sediment samples to evaluate the processes that affect the sulfate content in water of the Hengshi River. High concentrations of heavy metals (e.g. Fe: >347.78 mg L-1; Zn: >96.48 mg L-1) in the mud impoundment and relatively stable S isotope values (delta S-34: -1.53%(0) similar to -0.88%(0)) in the upper stream suggested that most of the sulfates were derived from sulfide oxidation. Dilution and mineralization could decrease SO42- concentration, but had no significant influence on the isotope composition of SO42 . However, delta S-34 and delta O-18 increased with the decrease of SO42- concentration, accompanied by the elevation of pH and adequate organic matter being available, suggesting that bacterial (dissimilatory) sulfate reduction played an important role in the transformation of sulfate downstream. The methods used in this study can also be used in other natural systems. Furthermore, it is important to understand the causes of environmental pollution and to help environmental remediation.