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

Croatian Rasa coal had been mined for nearly 400 years. The release of hazardous trace elements (HTEs) and toxic organic pollutants (TOPs) 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. Samples were collected from an estuarine site (north Adriatic Sea) that had been contaminated by coal sludge (wastewater from coal washing). The results showed that following 60 years of natural attenuation, the location is still heavily polluted by polycyclic aromatic hydrocarbons (PAHs) and HTEs. Microbial analyses have shown that high concentrations of PAHs have reduced the diversity and richness of microbial communities at the site. PICRUSt analysis also suggests that the native communities in this area contain microbes capable of degradation of PAHs and sulfur-containing organic compounds. Notably, the microorganisms that can degrade these substances may have been enriched as a result of the presence of organic pollutants. The results of this study revealed an adverse, long-term impact of coal waste pollution on the microbial community structure and function in the brackish aquatic ecosystem. 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.

克罗地亚拉萨地区的煤炭开采历史已近400年。煤炭开采、洗选与燃烧活动向当地环境释放了有害微量元素（HTEs）与有毒有机污染物（TOPs），由此造成了环境污染。本研究首次针对河口沉积物与土壤样本中的微生物群落多样性、组成结构，以及群落功能对污染物的响应展开了调查。研究样本采自一处受煤泥（洗煤废水）污染的河口区域（亚得里亚海北部）。结果显示，尽管经历了60年的自然衰减，该区域仍受到多环芳烃（PAHs）与有害微量元素的严重污染。微生物分析表明，高浓度的多环芳烃已降低了该区域微生物群落的多样性与丰富度。PICRUSt分析进一步显示，该区域的土著微生物群落中存在能够降解多环芳烃与含硫有机化合物的微生物。值得注意的是，这类可降解此类污染物的微生物或因有机污染物的存在而得到了富集。本研究结果揭示了煤矿废物污染对咸淡水水生生态系统微生物群落结构与功能产生的长期负面影响。鉴于全球气候变化议题愈发受到重视，未来数年全球范围内将有大量燃煤电厂退役，本研究可为煤矿开采活动影响生态系统的监测与修复工作提供理论支撑。