Abstract：
The continuous accumulation of microplastics in agricultural soils may affect the natural attenuation of oxygen-containing polycyclic aromatic hydrocarbons (OPAHs). The effects of low-density polyethylene (LDPE) microplastics with the spiking proportion of 1 % and 0.01 % in soils on the natural attenuation of OPAHs were investigated via soil microcosm experiments. The relation between the response of bacterial communities and OPAHs dissipation was also explored. The initial content of OPAHs in the soil was 34.6 mg·kg-1. The dissipation of OPAHs in the soil on day 14 was inhibited by LDPE. The contents of OPAHs in LDPE groups were higher than that in the control by 0.9-1.6 mg·kg-1, and the inhibition degree increased with the proportion of LDPE. The contents of OPAHs were not significantly different among groups on day 28, indicating that the inhibitory effect of LDPE disappeared. LDPE did not change the composition of the dominant taxa in the OPAHs-contaminated soil community but influenced the relative abundances of some dominant taxa. LDPE increased the relative abundance of Proteobacteria and Actinobacteria at the phylum level and decreased that of Bacillus and increased those of Micromonospora, Sphingomonas, and Nitrospira (potential degrading bacteria of LDPE and endogenous substances) at the genus level, all four of which were the main genera dominating intergroup community differences. LDPE changed the α and β diversity of bacterial communities, but the extents were not significant. LDPE affected the function of the bacterial community, reducing the total abundance of PAHs-degrading genes and some degrading enzymes, inhibiting the growth of PAHs-degrading bacteria and thus interfering with the natural decay of OPAHs.
摘要：
微塑料在农业土壤中的持续积累可能会影响含氧多环芳烃（OPAHs）的自然衰减。通过土壤微观实验研究了加标比例为1％和0.01％的低密度聚乙烯（LDPE）微塑料对OPAHs自然衰减的影响。还探讨了细菌群落响应与OPAHs消散之间的关系。土壤中OPAHs的初始含量为34.6mg·kg-1。LDPE抑制了14天土壤中OPAHs的消散。LDPE组的OPAHs含量比对照组高0.9~1.6mg·kg-1,且抑制程度随LDPE比例的增加而增加。在第28天，OPAHs的含量在各组之间没有显着差异，表明LDPE的抑制作用消失了。LDPE并未改变受OPAHs污染的土壤群落中优势类群的组成，但影响了某些优势类群的相对丰度。LDPE在门水平上增加了变形杆菌和放线菌的相对丰度，降低了芽孢杆菌的相对丰度，增加了微单孢菌的相对丰度，鞘氨醇单胞菌,和Nitrospira（LDPE和内源性物质的潜在降解细菌）在属水平，所有这四个都是主要的属，主导了群体间的群落差异。LDPE改变了细菌群落的α和β多样性，但程度并不显著。LDPE影响细菌群落的功能，减少PAHs降解基因和一些降解酶的总丰度，抑制PAHs降解细菌的生长，从而干扰OPAHs的自然衰变。
