[Characteristics, Risk Assessment of Microplastics, and Heavy Metal Pollution in Farmland Soils in the Upper Hanjiang River]

To investigate the pollution of microplastics and heavy metals from farmland soils in the upper Han River, the pollution status and distribution characteristics of pollutants were systematically analyzed. The risk level of pollutants was evaluated using methods such as the potential ecological risk index （RI）. Source apportionment was identified using correlation analysis and cluster analysis. The results showed that ① The abundance of microplastics in farmland soils in the upper Hanjiang River ranged from 360 to 6 300 n·kg^-1, with an average abundance of 2 300.73 n·kg^-1； the shapes were mainly films （50.00%）； and the majority of the particle sizes were less than 0.5 mm （64.31%）. Polymers of microplastics were PP, PE, PA, PET, and PS. SEM analysis revealed that the surface of microplastics was characterized as rough, porous, cracked, and torn. ② Within the ten heavy metals （V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb） that were measured, the average concentrations of heavy metals Cu, Zn, Cd, and Pb were higher than the background values by 1.28, 1.15, 1.91, and 1.34 times, respectively, while the other metals were lower than the background values, and none of the heavy metals exceeded the screening values for pollution risks in the soil environmental quality standard. ③ The study area had moderate microplastic pollution, with a risk level of Ⅱ, and low ecological risk from heavy metal pollution. The compound effect of microplastics and heavy metals needs to be assessed. ④ A significant correlation was observed between microplastics and the content of heavy metals Cr, Ni, As, Cd, and Pb in farmland soils. The sources of pollutants were agricultural-traffic sources, natural-agricultural sources, and natural-industrial sources.