[Advances in Research of the Effects and Mechanisms of Polyethylene Microplastics on Soil Nitrogen Transformation]

In the agricultural lands of China, polyethylene is the main component of microplastics （MPs）, with characteristics such as small size, wide distribution, easy accumulation, and difficult degradation. Therefore, it may have an impact on the elemental cycling process of the soil. On the basis of reviewing the key literatures in the past few years, this study systematically analyzed and summarized the key factors and processes of the polyethylene microplastics （PE-MPs） affecting soil nitrogen transformation. On the one hand, PE-MPs directly affected the activities of microorganisms and key enzymes related to soil nitrogen transformation by enriching microorganisms, selecting colonized microbial populations, and releasing additives. On the other hand, PE-MPs had indirect impacts on the activities of microorganisms and key enzymes related to soil nitrogen transformation by affecting soil physicochemical properties of soil and changing the microenvironment for microbial growth. Moreover, phthalates, an important additive of the MPs, may be the key factor affecting soil nitrogen transformation in the short-term. Finally, we posed key scientific issues that should be further studied in order to provide scientific support for nitrogen nutrition regulation and ecological risk assessment of soils contaminated by PE-MPs.