[Occurrence Characteristics and Ecological Risk Assessment of Soil Microplastics in Xinxiang Section of Weihe River Basin].

Abstract

To understand the occurrence characteristics of microplastics in the soil of the Xinxiang section of the Weihe River Basin, the soil samples of different soil types and different soil layers were collected, soil microplastics were identified using the Agilent 8700 laser direct infrared （LDIR） chemical imaging system, and the ecological risks of soil microplastics were assessed using the polymer risk index （H） and pollution load index （PLI）. The results showed that the proportions of polyurethane （PU） and polyethylene （PE） were 17.57% and 15.97%, respectively, in the soil of the Xinxiang section of Weihe River Basin； the particle diameter of microplastics mainly ranged from 20 to 100 μm, and the proportions of 20 to 50 μm and 50 to 100 μm were 76.17% and 15.56%, respectively； and the average abundance of microplastics was （4 629±683） n·kg^-1. Significant differences exist in soil microplastic type （P<0.001） and microplastic abundance at different soil depths （P<0.05）. The microplastic particle diameter （P<0.05） at each sampling site and the microplastic abundance at each sampling site decreased with the increase in soil depth. The abundance of PU and PE at sampling sites S7 and S3 was 1 587 n·kg^-1 and 960 n·kg^-1, respectively. The ecological risk of soil microplastics at each sampling site decreased with the increase in soil depth； the ecological risk of soil microplastics at sampling site S7 was at high risk, sampling site S6 was at low risk, and other sampling sites were at medium risk.