Massive microplastics are deposited in the coastal zone. Tire particles (TPs) are an important microplastic source, but little is known about how TPs affect the microbial community composition and function in coastal sediments and the role leachable additives play in TP toxicity. Here, a microcosm experiment was performed using coastal sediments amended with different doses of TPs and with their leachable additives to investigate their effects on the sediment microbial community composition and function. Environmentally relevant concentrations of TPs can change the microbial community structure, decrease community diversity, and inhibit nutrient cycling processes, including carbon fixation and degradation, nitrification, denitrification, and sulfur cycling in sediments. Notably, the raw TP and leachate treatments showed consistent effects. A variety of additives were found in the pore water of sediment, and they could explain over 90% of the variations of the community structure. Further modeling revealed that leachable additives not only directly influenced community function but also indirectly affected community diversity and function by shifting the community structure. In addition, rare taxa could be crucial mediators of ecological functions of sediment microbial community. Combined, this study provides novel insights into the role of TPs’ leachable additives in affecting sediment microbial community and function.

中文翻译：

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轮胎颗粒的可浸出添加剂解释了沿海沉积物中微生物群落组成和功能的转变

大量微塑料沉积在沿海地区。轮胎颗粒（TPs）是一种重要的微塑料来源，但关于 TPs 如何影响沿海沉积物中的微生物群落组成和功能以及可浸出添加剂在 TP 毒性中的作用知之甚少。在这里，使用不同剂量的 TP 及其可浸出添加剂修正的沿海沉积物进行了一个缩影实验，以研究它们对沉积物微生物群落组成和功能的影响。与环境相关的 TPs 浓度可以改变微生物群落结构，降低群落多样性，并抑制养分循环过程，包括沉积物中的碳固定和降解、硝化、反硝化和硫循环。值得注意的是，原始 TP 和渗滤液处理显示出一致的效果。在沉积物孔隙水中发现了多种添加剂，它们可以解释90%以上的群落结构变化。进一步的建模表明，可浸出添加剂不仅直接影响群落功能，而且通过改变群落结构间接影响群落多样性和功能。此外，稀有类群可能是沉积物微生物群落生态功能的重要介质。结合起来，这项研究为 TP 的可浸出添加剂在影响沉积物微生物群落和功能中的作用提供了新的见解。进一步的建模表明，可浸出添加剂不仅直接影响群落功能，而且通过改变群落结构间接影响群落多样性和功能。此外，稀有类群可能是沉积物微生物群落生态功能的重要介质。结合起来，这项研究为 TP 的可浸出添加剂在影响沉积物微生物群落和功能中的作用提供了新的见解。进一步的建模表明，可浸出添加剂不仅直接影响群落功能，而且通过改变群落结构间接影响群落多样性和功能。此外，稀有类群可能是沉积物微生物群落生态功能的重要介质。结合起来，这项研究为 TP 的可浸出添加剂在影响沉积物微生物群落和功能中的作用提供了新的见解。