THE ROLE OF SULFUR-OXIDIZING BACTERIA THIOBACILLUS THIOOXIDANS IN PYRITE WEATHERING

The role of the sulfur-oxidizing bacteria Thiobacillus thiooxidans in pyrite weathering was investigated to clarify the effects of the bacte ria on the dissolution behavior of pyrite and the formation of seconda ry minerals using Raman spectroscopy and powder X-ray diffraction (XRD ) in addition to solution analysis. It was found that T. thiooxidans, when present with the iron-oxidizing bacteria Thiobacillus ferrooxidan s, enhanced the dissolution of Fe and S species from pyrite, whereas T . thiooxidans alone did not oxidize pyrite. Enhancement of the consump tion of elemental sulfur and regeneration of Fe(II) ions were also obs erved with T. thiooxidans together with T. ferrooxidans, while this di d not occur with T. ferrooxidans alone. It may be assumed that the con tribution of T. thiooxidans to the formation of acid mine drainage on a geochemical scale should not be overlooked, though pyrite weathering is predominantly caused by iron-oxidizing activity in T. ferrooxidans . (C) 1998 Elsevier Science B.V.