Occurrence, distribution, and characteristics of microplastics in agricultural soil around a solid waste treatment center in southeast China

Purpose In recent years, microplastic (MP) contamination has raised enormous concern. However, data on the influence of solid waste treatment systems on MP pollution around agricultural soil are lacking. This study investigated the distribution and characteristics of MPs in agricultural soil surrounding a solid waste treatment center in southeastern China. Materials and methods Fifty-seven agricultural topsoil samples around the solid waste treatment center were collected. The samples were pretreated by drying, flotation separation using NaCl solution, and digestion by H2O2. The abundance and morphological characteristics of MPs were determined by a microscope, followed by Raman spectroscopy analysis identified polymer types and SEM-EDS analysis observed surface morphology and the type of metals accumulated on the MPs. Results and discussion Soil MPs' abundance ranged from 280 to 2360 items/kg, while a higher abundance of MPs was distributed in the downwind area. The <1-mm MPs were dominant, and white fragment MPs were widely found. Polyethylene (52.86%) and polypropylene (27.14%) were the most common Moreover, SEM-EDS images illustrated that MPs were significantly weathered and showed the uneven distribution of metal(loid) elements on the surface, implying that MPs may migrate as heavy metal vectors to threaten agroecosystem safety. Conclusions This study reveals the distribution and characteristics of MPs in agricultural soil surrounding a solid waste treatment center in southeastern China, as well as the potential source of soil MPs, and provides systematic data for further research on MP pollution in agricultural soil.