Characteristics and Risk Assessment of Microplastics in Farmland Soil in Kashgar, Xinjiang

Abstract

This study investigates the characteristics and pollution risks associated with microplastic contamination in farmland soil within Kashgar  City. Soil samples were collected from corn fields, cotton fields, greenhouses constructed in 2012, and greenhouses built in 2022, specifically from a depth of 0-30 cm. The saturated NaCl solution density separation method was employed alongside micro-Fourier transform infrared spectroscopy to extract and analyze microplastics present in the soil samples. The analysis focused on the abundance, color, morphological characteristics, particle size distribution, and types of components of microplastics found in the farmland soil of Kashgar City. Subsequently, the PLIn model was utilized to conduct a pollution risk assessment of microplastics, clarifying the associated risk levels. This research aims to elucidate the occurrence and migration characteristics of microplastics in the soil environment, thereby providing a scientific basis for the management of soil microplastics. The findings indicate that: (1) Microplastics in the farmland soil exhibit various forms, predominantly film-like and fibrous (>60%); their color is primarily transparent (>50%); and most particles are less than 200 μm in size, with polyethylene (PE) being the predominant material. (2) The microplastic pollution load index for cornfields in Kashgar City indicates mild pollution, categorized as level I, while the cotton field and greenhouse soils exhibit moderate pollution, reaching level II. Overall, the degree of microplastic pollution in the farmland of Kashgar City is assessed as moderate, corresponding to risk level II.