摘要
      在环境行为研究中，土壤中比微塑料大的塑料总是被忽视。被塑料污染的土壤只包括在整个土壤系统的“土层”中，可以称为塑料污染层（PCL），并且始终缺乏基于PCL的整个土壤系统中完整的塑料污染风险评估。在本研究中，研究了超大尺寸微塑料（OMPs）及其PCL对多西环素和细菌/噬菌体抗生素抗性基因（ARGs）在施肥条件下在完整土壤系统中迁移和残留规律的影响。结果表明，OMP在短时间内显著提高了PCL中土壤DOX的残留浓度（最高DOX浓度为133.12μg/kg）；此外，纤维OMP在56天后仍然可以显著降低DOX的降解。PCL还增强了DOX从PCL向深层土壤的迁移和残留DOX。尽管DOX暴露大大增加了潜在ARG宿主细菌的总丰度，但DOX和OMP的组合对细菌ARG总丰度的贡献比例最高（34.18%）。此外，OMP增加了噬菌体ARG的绝对丰度，OMP甚至在没有DOX暴露的情况下增强了深部土壤中的噬菌体ARG迁移和残留丰度。本研究首先强调了OMP及其PCL在施肥过程中的双重风险，OMP的形状也可能导致风险的差异。
Abstract
Plastics that are larger than microplastics (MPs) in soil are always ignored in studies of environmental behavior. The soil contaminated by plastic is only included in the “soil layer” of the entire soil system, which could be called the plastic contamination layer (PCL), and a complete plastic contamination risk evaluation in the entire soil system based on the PCL is always lacking. In the present study, oversized microplastics (OMPs) and their PCL effects on the migration and residual regularity of doxycycline and bacteria/phage antibiotic resistance genes (ARGs) in complete soil systems under manuring conditions were investigated. The results showed that the OMPs greatly increased the soil DOX residual concentration in the PCL (the highest DOX concentration was 133.12 μg/kg) in a short time; moreover, the fiber OMPs could still significantly decrease DOX degradation after 56 days. The PCL also enhanced DOX migration and residual DOX from the PCL to the deeper soil. Although DOX exposure greatly increased the total abundance of potential ARG host bacteria, the combination of DOX and OMP had the highest bacterial ARG total abundance contribution proportion (34.18%). In addition, OMPs increased the absolute abundance of phage ARGs, and OMPs even enhanced phage ARG migration and residual abundance in deep soil without DOX exposure. The present study first highlights the double risks of OMPs and their PCLs during manuring, and the shape of OMPs could also cause a difference in the risks.

https://www.sciencedirect.com/science/article/abs/pii/S1385894722029370