Distribution of microplastics and microorganisms and their relationship in high-salinity soil

Irrigation is one of the main methods used to increase crop yield in saline soils. However, microplastics (MPs) occur in saline soil due complex irrigation water sources and agricultural operations, and these may affect the soil microbial population structure. We selected soil from the Inner Mongolia section of the Hetao Irrigation District as the research object to determine the microplastic (MP) pollution status and microbial population structure and to explore the relationship between them. The results showed that (1) MPs were mainly polyethylene terephthalate (white and blue), with particle sizes mainly < 0.5 mm, and concentrations ranging from 100 to 480 n/kg, increasing and then decreasing from east to west, with the highest concentration of MPs detected in the soil near drain 5. (2) The bacterial and archaeal population structures in the soil were less diverse and more evenly distributed than fungi, which showed a non-uniform distribution in terms of both species and relative abundance. (3) Salt-tolerant and MPs-degrading bacteria were distributed within the soil, and the distribution of these species may be related to long-term high salinity and high MP abundance stress. The results of this study provide a scientific basis for the management of soil MPs.