Influence of Landfill Leachate Microenvironment on the Occurrence of Microplastics: Toc Changes are the Main Driving Factor

Abstract

Factors such as inorganic salts, heavy metals and organics in landfill leachate can affect the environmental behavior and transport properties of microplastics. However, the influence of microenvironment on the behavioral effects of microplastics in landfill leachate is still limited. In this study, the abundance characteristics of microplastics in leachate from 15 landfills in the North China Plain were investigated. The results showed that the abundance of microplastics in the leachate in this region was 712.0 items/L, which was mainly composed of small particle size and long fibrous microplastics. Using models such as structural equations, the relationship between leachate physicochemical factors and microplastic accumulation patterns was explored. Among them, TOC had the strongest driving effect on 50-100 μm microplastics. And it had different effects on different microplastics: it promoted the degradation of PET, while it inhibited the degradation of PVC, FVMQ and PSU. The ridge regression model indicated that the interaction of landfill age with Cr and the interaction of redox potential with Cr were the key factors influencing the behavioral characteristics of microplastics in leachate. These results are intended to provide a scientific basis for the treatment of waste leachate and the control of emerging pollutants.

Keywords: Landfill leachate, Microplastics, heavy metals, Physical and chemical factors, Ridge regression