Humic Acid Distribution Factors in the Sergeyevsky Brown Coal Deposit

Abstract

Humic acids are unevenly distributed throughout the Sergeyevsky coal deposit. This is due to the variety of sources of humic material and the different conditions under which coal accumulates. The upper coal seam contains a high concentration of allochthonous humic acids, which were formed under oxidative conditions from terrestrial biomaterial that was introduced into the area. Humic acids with autochthonous origins are present in coal in minimal concentrations, as they are derived from aquatic vegetation that grew in the area where the coal formed. An intermediate group of humic acids has a mixed origin and was formed under conditions with varying facies, where physical factors played a dominant role. The anaerobic environment of the lower part of the deposit promotes the development of processes that reduce the concentration of humic acids by dehydrating, decarboxylating, and demethylating them. The presented factual material on the geochemical aspects of humic acid accumulation is consistent with palynological data on the distribution of biologically predestined plants in the Sergeyevsky brown coal deposit.