Risks of microplastics in different land-use types of soil in a typical petrochemical city in China

Abstract Although microplastic pollution is a global concern, information on the distribution of microplastics in petroleum and petrochemical urban soils is limited. In this study, we investigated the occurrence, ecological risk, and human exposure risk of microplastics in different land-use types of soil in Daqing Administrative region, a prominent petroleum and petrochemical industrial base in China. Stereoscopic microscopy and Fourier transform infrared spectroscopy (µ-FTIR) were used to study the chemical composition and distribution characteristics of microplastics. We found that the abundance of microplastics in Daqing soil ranged from 714.29 to 11122.45 items/kg, with the highest value in educational land and the lowest in parks and green land. The dominant particle size of microplastics was < 1 mm (65.7%), and the shape was mainly fiber (55.1%), with white and black as the predominant colors. The most common polymer types were rayon (RY), polypropylene (PP), and polyethylene (PE). Using the potential ecological risk index (RI) and polymeric risk index (H), we found that all land-use types, except woodland (Level I), were classified into Level V of ecological risk, with the highest risk in industrial land (RI = 14959.85, H = 588.31). The daily exposure of infants to microplastics was much higher than that of adults, with a decreasing trend with age. The average estimated daily intake (EDI) of microplastics in different land-use types followed the decreasing trend of educational land > farmland > industrial land > woodland > residential land > riparian land > parks and green lands. These findings provide valuable data for the pollution and potential risk assessment of microplastics in urban and rural environments, suggesting the importance of taking action to minimize its harmful effects on ecological and human health.