Diversity, Spatial Distribution, and Potential Risk of Microplastic-like Particles in Arid Farmland Soils: A Case Study of Midong District, Urumqi, China

Recent studies have demonstrated that microplastics (MPs) in soils can alter soil physicochemical properties and microbial community structures, thereby disrupting ecological processes and threatening food security and human health. The occurrence and characteristics of microplastic-like particles (MLPs) were investigated in farmland soils from Midong District, Urumqi, Xinjiang, a representative arid region of China. MLPs were extracted and presumptively identified by microscopic observation. An integrated framework combining diversity indices and the Pollution Load Index (PLI) as screening-level indicators was employed to characterize MLP contamination and its spatial patterns. Spatial heterogeneity and the spatial association between MLP abundance and diversity were evaluated using Empirical Bayesian Kriging and local bivariate Moran’s I. Results indicated that (1) MLP abundance ranged from 500 to 9850 items/kg, with fibers dominating; transparent and black were the predominant colors, and medium-sized particles (100–500 µm) were most abundant. (2) Size and color diversity exceeded shape diversity. Size diversity was significantly higher toward the south, whereas relatively high color diversity was observed in parts of the north, although no significant north–south trend was detected in color diversity. (3) The mean PLI indicated a slight-to-moderate contamination level, although heavily contaminated areas occurred in the southern and central regions. Bivariate spatial autocorrelation revealed a significant positive coupling between MLP abundance and particle diversity (Moran’s I = 0.193, p = 0.001), with two high–high (H–H) clusters in the central-southern region, indicating potential contamination hotspots.