Intermediate Species Accounts for more Than a Half of Sulfur Speciation in Mine Waters - A Case Study Revealed using Vis Spectrophotometry and Microwave Plasma Atomic Emission Spectrometry

Abstract

Even though sulfate and sulfide concentrations do not adequately describe the total sulfur pool in mine waters influenced by microbial sulfate reduction, detailed speciation of sulfur and the significance of different sulfur species in mine waters are so far less poorly understood in acid mine drainage research. Therefore, this study offers small-scale research on different sulfur species in mine waters and their relevance in total mass balance of sulfur species. The conventional determination of sulfur species is usually carried out using ion chromatography and involves considerable sample preparation, incl. derivatization of the sulfur species. Therefore, methods for easy, effective, and low-cost spectrophotometric determination of sulfur species other than sulfate and sulfide were tested. Additionally, the cross-reactions of organic sulfur species with the spectrophotometric methods were also investigated. Besides sulfate, thiosulfate, sulfite, and sulfide coexist in real mine waters and are determinable with easy and cheap methods suitable for smaller water laboratories. These methods were applied on real mine waters originating from active and remediated mining sites. The results were evaluated regarding potential sulfur imbalances. Sulfur from sulfate usually represents most of the sulfur pool. Thiosulfate is present in considerable quantities; however, it constitutes yet a minor proportion of the total sulfur and ‘other-than-sulfate’ sulfur. It has become clear that some mine waters contain multiple inorganics and possibly, organic sulfur species that would require more advanced analytical methods.