Research and Development Center for Efficient Utilization of Coastal Bioresources, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, PR China; Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao, 266237, PR China; Muping Coastal Environment Research Station, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, PR China.
Research and Development Center for Efficient Utilization of Coastal Bioresources, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, PR China; Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao, 266237, PR China.
Environ Pollut. 2024 Oct 15;359:124591. doi: 10.1016/j.envpol.2024.124591. Epub 2024 Jul 21.
Marine microplastics (MPs) pollution, with rivers as a major source, leads to MPs accumulation in estuarine sediments, which are also nitrogen cycling hotspots. However, the impact of MPs on nitrogen cycling in estuarine sediments has rarely been documented. In this study, we conducted microcosm experiment to investigate the effects of commonly encountered polyethylene (PE) and polystyrene (PS) MPs, with two MPs concentrations (0.3% and 3% wet sediment weight) based on environmental concentration considerations and dose-response effects, on sediment dissolved oxygen (DO) diffusion capacity and microbial communities using microelectrode system and metagenomic analysis respectively. The results indicated that high concentrations of PE-MPs inhibited DO diffusion during the mid-phase of the experiment, an effect that dissipated in the later stages. Metagenomic analysis revealed that MP treatments reduced the relative abundance of dominant microbial colonies in the sediments. The PCoA results demonstrated that MPs altered the microbial community structure, particularly evident under high concentration PE-MPs treatments. Functional analysis related to the nitrogen cycle suggested that PS-MPs promoted the nitrification, denitrification, and DNRA processes, but inhibited the ANRA process, while PE-MPs had an inhibitory effect on the nitrate reduction process and the ANRA process. Additionally, the high concentration of PE-MPs treatment significantly stimulated the abundance of genus (Bacillus) by 34.1% and genes (lip, pnbA) by 100-187.5% associated with plastic degradation, respectively. Overall, in terms of microbial community structure and the abundance of nitrogen cycling functional genes, PE- and PS- MPs exhibit both similarities and differences in their impact on nitrogen cycling. Our findings highlight the complexity of MP effects on nitrogen cycling in estuarine sediments and high concentrations of PE-MP stimulated plastic-degrading genus and genes.
海洋微塑料（MPs）污染主要源自河流，导致 MPs 在河口沉积物中积累，而河口沉积物也是氮循环的热点。然而，MPs 对河口沉积物氮循环的影响却鲜有报道。在本研究中，我们通过微宇宙实验，以环境浓度考虑和剂量-反应效应为基础，采用微电极系统和宏基因组分析分别研究了常见的聚乙烯（PE）和聚苯乙烯（PS）MPs 在两个 MPs 浓度（0.3%和 3%湿沉积物重量）下对沉积物溶解氧（DO）扩散能力和微生物群落的影响。结果表明，高浓度的 PE-MPs 在实验中期抑制了 DO 的扩散，这种效应在后期消散。宏基因组分析显示，MP 处理降低了沉积物中优势微生物群落的相对丰度。PCoA 结果表明，MPs 改变了微生物群落结构，尤其是在高浓度 PE-MPs 处理下更为明显。与氮循环相关的功能分析表明，PS-MPs 促进了硝化、反硝化和 DNRA 过程，但抑制了 ANRA 过程，而 PE-MPs 对硝酸盐还原过程和 ANRA 过程具有抑制作用。此外，高浓度的 PE-MPs 处理分别显著刺激了与塑料降解相关的属（芽孢杆菌）丰度增加了 34.1%和基因（lip、pnbA）增加了 100-187.5%。总体而言，就微生物群落结构和氮循环功能基因的丰度而言，PE 和 PS-MPs 在影响氮循环方面既有相似之处，也有不同之处。我们的研究结果强调了 MPs 对河口沉积物氮循环影响的复杂性，以及高浓度的 PE-MPs 刺激了塑料降解属和基因的增加。
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