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

Martina Šturm,^1,* Sonja Lojen,¹ Miloš Markič² and Jože Pezdič³

¹ Department of Environmental Sciences, “Jožef Stefan” Institute, 1000 Ljubljana, Slovenia
² Geological Survey of Slovenia, Dimičeva ulica 14, 1000 Ljubljana, Slovenia
³ Department of Geology, Faculty of Natural Sciences and Engineering, 1000 Ljubljana Slovenia
* Corresponding author: E-mail: martina.sturm@ijs.si

Abstract
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 δ³⁴S 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.

Keywords: Coal, sulphur, stable isotopes, lignite