[Distribution and Influencing Factors of Microplastics in Cultivated Soil in Northeastern Qinghai-Xizang Plateau].

To investigate the distribution and influencing factors of microplastics in cultivated soil of the Qinghai-Xizang Plateau， 95 cultivated soil samples from the eastern Qinghai and Gannan regions were analyzed by density separation， metallographic microscopy， and Fourier transform infrared spectroscopy. The results showed that the abundance of microplastics in the surface layer （0-20 cm） soil of the northeastern Qinghai-Xizang Plateau was 68-3 668 n·kg-1， and the average abundance of microplastics in the eastern Qinghai and Gannan regions was （1 296±779） n·kg-1 and （1 421±624） n·kg-1， respectively. The shapes of microplastics were mainly films （35%） and fragments （31%）， the size was mainly concentrated between 15 μm and 500 μm （54%）， the main color was brown （61%） and transparent （17%）， and the polymer types were mainly polyethylene （45%） and polypropylene （31%）. The abundance of microplastics was positively correlated with soil organic carbon， but it was negatively correlated with soil bulk density. Higher temperature promoted the fragmentation of microplastics， while strong wind and precipitation reduced microplastic pollution to a certain extent. The tertiary industry （especially tourism） and cities were important sources of microplastics with small size （< 500 μm）.