Speciation and Isotopic Composition of Sulphur in Low-rank Coals from Four Slovenian Coal Seams

The abundance, distribution and isotopic composition of sulphur in low-rank coals from four Slovenian coal seams are presented. Samples were characterised as medium (1–3 wt%) or as high sulphur coals (>3 wt%), with the majority of sulphur occurring in the organic form. The isotopic composition of sulphur in coals in Slovenia was determined for the first time. It was found that S34S varies between different coal seams, as well as between different lithotypes inside particular coal seams. This can be explained by different SO4 2– and Fe2+ availability and microbial activity inside the coal forming basin.