Concentration, distribution, and mode of occurrence of mercury in Bulgarian high-sulphur coals

Irena Kostova, James C. Hower, Denitsa Apostolova, Qiang Wei

Research output: Contribution to journalConference articlepeer-review

2 Scopus citations


The goal of this study is to determine the mercury content, distribution, and modes of occurrence in high-sulphur coals from the Maritza-West, Maritza-East, and Stanyantsi basins in Bulgaria. The investigation is based on 51 samples representing the whole coal beds. The average concentration of Hg for all studied samples is 0.34 ppm and the values vary from 0.07 to 1.20 ppm; the average is 6.8-times higher than the Hg value in the upper continental crust and 3.4-times higher than the average values for world coals. The highest average Hg concentration (0.57 ppm) was found in the Maritza-West samples, followed by the Maritza-East (0.30 ppm), and the Stanyantsi (0.15 ppm) lignite. These data correspond with the sulphur content, i.e, the highest-Hg lignite has the highest S content. A weak positive correlation between Hg and the total and sulphide S and a negative correlation between Hg and the organic S content for the Maritza-West lignite were observed. It is suggested that the Hg is predominantly incorporated in pyrite, which is present in high amount in these coals. The tendency in the distribution of Hg and S forms for the Maritza-East and Stanyantsi basins shows that Hg may be closely connected with S-bearing organic compounds, especially for the Maritza-East lignite. Consequently, the main part of Hg in the high-S coals from the Maritza-East and Stanyantsi basins is closely connected with organic sulphur complexes and may be with inorganic matter other than sulphide minerals. The data determined from this study partially confirms the results for other high-S world coals reported earlier. For the typical high-S Maritza-West lignite it may be suggested that there is a strong connection between Hg and pyrite and especially with epigenetic pyrite infilling the coal veins and cleats, while for high-S Maritza-East and Stanyantsi lignite the Hg is predominantly incorporated in organic matter and especially in sulphur-bearing organic compounds.

Original languageEnglish
Article number012043
JournalIOP Conference Series: Earth and Environmental Science
Issue number1
StatePublished - Dec 15 2020
Event6th World Multidisciplinary Earth Sciences Symposium, WMESS 2020 - Prague, Czech Republic
Duration: Sep 7 2020Sep 11 2020

Bibliographical note

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© 2020 Institute of Physics Publishing. All rights reserved.

ASJC Scopus subject areas

  • General Environmental Science
  • General Earth and Planetary Sciences


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