Publication details
APPLICATION OF ORGANIC MATTER MICROSCOPY IN ENVIRONMENTAL STUDIES
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| Year of publication | 2019 |
| Type | Conference abstract |
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| Description | In areas of former or ongoing coal mining, stream and lake sediments contain organic matter not only of recent biological origin, but also fossil or anthropogenically emitted material such as coal, char coal and fly ash. In such areas, it is useful to distinguish the biogenic from the anthropogenic origin of the organic matter in the stream sediments. Thus, the main aim of this study is to microscopically characterize organic matter in the assessed stream flow section and to distinguish the prevailing source of organic matter. Ten coal and six dust samples representing the Bílina open-pit lignite mine and 10 stream sediments from the Bílina River were evaluated. The samples were characterized regarding maceral composition and huminite reflectance. The classification of organic matter used for stream sediments differs from coal and dust. There, organic matter was classified as either recent, fossil or carbonized organic matter. This evaluation method helped to distinguish the prevailing organic matter type and thus determine the river sediment potential to sorb toxic metals. Measurements on dust and stream sediments were carried out statistically by evaluating all particles (huminite, inertinite, recent, fossil and carbonized particles) within the measured area (250x190 micrometers) of 81 random images, covering the whole area of the polished sections. In addition, organic geochemical analysis was applied contemporarily. All samples were subjected to the determination of total organic carbon (TOC) and total inorganic carbon (TIC). Standard sample preparation (ASE extraction, fractionation, sulfur removal) was followed by GC-MS analyses in order to evaluate the selected set of polyaromatic hydrocarbons. The results from maceral analysis prove that the dominant maceral groups in coal and dust samples are huminite and liptinite. The dust samples are mostly composed by coaly particles from lignite mining whereas the composition of organic matter in stream sediments is very variable. The upper part of the stream flow section is industrially unaffected with the predominance of the recent organic matter, while the number of particles of the fossil and carbonized character started to increase further downstream.The random reflectance values of huminite in coal range between 0.29and 0.34% HRrcorresponding to low-rank lignite that is intensely mined in the study area. The random reflectance of particles in dust and stream sediments range between 0.33 and 1.09% Rr. Indicative PAH ratiosmake it possible to distinguish dominant pyrogenic and petrogenicderived organic matter. But when evaluating the maceral composition, it is also possible to distinguish biological and coal-derived material and thus more precisely distinguish potential emission sourcesin heavily contaminated areas. |