The rapid accumulation of black carbon (BC) in the environment has posed a serious threat to climate change and ecological security in river basins. Lakes are important accumulation sinks for BC, and microorganisms in lake sediments play a significant and irreplaceable role in maintaining lake ecological security. However, there has been little research on the impact of BC on lake microorganisms, and studies have focused only on bacteria, neglecting the impact on fungi. Moreover, there is a lack of methods to identify areas where BC poses a risk of microbial contamination. This study used Taihu Lake as the study area and explored the spatial distribution characteristics of BC components, bacteria, fungi and other indicators in the sediment. The accumulation of organic carbon in the Taihu Lake sediments, like BC, has been strongly affected by human activities in recent years. The BC, BCchar and organic carbon contents in Taihu Lake sediments were the main factors affecting the diversity and function of bacteria and fungi. There are differences in the response of bacteria and fungi to BC in the sediment of Taihu Lake, among which the BC mainly played a negative role in bacterial diversity and a positive role in fungal diversity. A risk assessment model for BC on microorganisms has been established, and risk areas for bacteria and fungi have been identified, accounting for 52.0% and 4.3% of the total area, respectively. Finally, the spatial clustering characteristics of sediment BC and bacterial and fungal diversity were combined, a comprehensive risk assessment model of the effects of BC on microorganisms was constructed, and the risk areas were accurately identified. The risk areas reached 51.0% of the total area of Taihu Lake, and the ecological security areas reached 31.1%. This study provides scientific and systematic methods and technologies for ensuring the security of river and lake ecosystems and preventing and controlling BC pollution.
Keywords: black carbon; ecological risk; microorganisms; sediment; spatial correlation.
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