Microplastics distribution and impacts on soil microbial communities in alpine area

Clarifying the impacts of microplastics (MPs) on microbial communities real natural soil environments is of great significance for evaluating MPs risks and its control. However, it is remains unclear, especially in the alpine soil. Hence, field sampling combined with density separation, Fourier-transform infrared spectroscopy (FTIR), and high-throughput sequencing were employed to reveal the soil MPs distribution and microbial communities characteristics of 63 soil samples from 7 counties in Lhasa areas. Soil MPs abundances ranged from 16.75 to 1374.75 items/kg, with a mean of 244.65 items/kg. Dominant shapes were films (37.7%) and fragments (34.2%), mainly < 500 μm (78.9%) in size, black (66.5%) and green (21.5%) in color, and composed of Polyethylene (PE, 34.9%) and Polypropylene (PP, 28.6%). Soil physicochemical factors (BD, pH, and SOC) and environmental factors (elevation, radiation, and temperature) respectively influenced MPs migration and fragmentation. Proteobacteria (10.12%∼65.06%), Actinobacteriota (4.67%∼57.01%) and Ascomycota (5.29%∼95.19%), Basidiomycota (0.32%∼80.13%) accounted for the highest proportion at the phylum level of soil bacteria and fungi communities. Environmental factors (temperature and radiation) and soil properties (SOC and TN) drive the spatial variability of soil microbial community composition. MPs abundance mainly influences the composition of fungi communities, with 70.83% of fungi taxa significant correlations. Increased abundance of < 500 μm MPs significantly decreased the relative abundance of sensitive microbial (Kribbella and Coprinus). The increase of the MPs abundance significantly increased the relative abundance of tolerant microbial (Sulfurifustis, Papiliotrema, and Cladosporium). These findings elucidate MPs distribution and impacts on soil microbial communities in alpine areas.