Composition of Organic Matter in Dump Materials from East Maritsa Coal Basin (Bulgaria)

Abstract

One sample (Sm. 1) from dump site “Iztok” (composed of coal particles and black clayey materials) and one sample (Sm. 2) from dump site “Starosselets” (gray laminated clayey materials from coal interlayer) were studied. Total organic carbon (TOC) content was determined by modified Turin's method аnd organic matter composition was determined by the method of Kononova-Belchikova. Bitumens were prepared by subsequent chloroform and ethanol-benzene (1: 1, v: v) extractions.
Fulvic-humic апа humuc-fulvic type of organic matter was observed. Humic acids in both samples are mainly (over 50%) “free” оr R2O3 bounded which is а precondition of formation оf more labile аnd mobile substances humus substances in the for formation in the surface environment and for low compaction capacity. The content of unextractable organic carbon is very low, which indicates that most of the organic substances are bound unstably with mineral part of the sample.
In the soluble organic matter of both samples studied neutral structures prevail, asphaltenes being the most prominent, аnd resins аrе presented in lower extent. The neutral oils content is the lowest. The elevated resins’ percentage in the dump materials is probably a result of thermal autooxidation processes. In the materials from “Iztok” dump the content of aromatic structures is higher. The relative preponderance of short- and mid-chain alkanes in clay materials (dump “Staroselets”) could Ье related to the proceeded destruction of the long chain alkanes under the catalytic action of the clay minerals. The higher relative content of n-alkanes in the range of nC23-nC29 in the dump materials is аn indication for terrestrial vegetation presence during initial organic matter formation