Microplastic pollution in cultivated soil has received increasing attention recently. There may be more serious microplastic abundance but little research has been done in cultivated soil in plateau areas. To survey the pollution characteristics of microplastics in inland cultivated soil, 100 soil samples collected from 10 counties of Yunnan Province were investigated through density separation and microscopic examination. The research results showed that microplastic abundance was in the range of 0.9 × 103 to 40.8 × 103 particles (kg Ds)-1 with average abundance of 9.8 × 103 particles (kg Ds)-1. Moreover, compared with other studies on sediments, it was found that microplastic abundance in inland soil was one order of magnitude higher than that in offshore sediments. The use of plastic mulch and its long-term residue in cultivated soil was an important reason for microplastic pollution. In this survey, various morphologies of microplastics existed, including fragment (78.3%), transparent/translucency (49.7%), and micro-size microplastics (< 500 μm) (89.3%). And the microplastic morphologies occurred in different degrees of aging phenomenon under the influence of the environment factors such as ultraviolet radiation. The findings provided the pollution status of microplastics in cultivated soil, and more attention should be paid to inland soil microplastic pollution. Grapical abstract.
Keywords: Cultivated soil; Microplastic contamination; Microplastic morphology; Mulch; Spatial distribution.