Contaminants from a former Croatian coal sludge dictate the structure of microbiota in the estuarine (Rasa Bay) sediment and soil

Croatian super high organic sulfur Rasa coal had been mined for nearly 400 years. The release of hazardous trace elements and toxic organic pollutants into the local environment by coal mining, preparation, and combustion activities has resulted in pollution. In this study, the diversity and composition of microbial communities in estuarine sediment and soil samples as well as community function responses to the pollutants were investigated for the first time. The results showed that following 60 years of natural attenuation, the location is still heavily polluted by polycyclic aromatic hydrocarbons and HTEs. Microbial analyses have shown that high concentrations of PAHs have reduced the diversity and richness of microbial communities at the site. Notably, the microorganisms that can degrade PAHs and sulfur-containing organic compounds may have been enriched as a result of the presence of organic pollutants. This study could provide a basis for the monitoring and restoration of ecosystems impacted by coal mining activities in light of the expected decommission of a large number of coal plants on a global scale in the coming years due to growing global climate change concerns