Distribution and Characteristics of Microplastics in Agricultural Soils around Gehu Lake, China.

Agricultural soil is subject to the serious contamination of microplastics (MPs) derived from the intensive agricultural activities. The representative sites under different farming practices (mulching, greenhouse, or traditional plantation) were selected, with soil samples collected from shallow (0–5 cm) and deep (5–10 cm) layers. Results showed that the distribution of MPs varied greatly with sites, with the abundance ranging from 373 ± 236 to 7 888 ± 1 797 items kg⁻¹. Meanwhile, MPs in deep soil appeared to have higher abundance and smaller size compared to those in shallow layer, indicating the vertical transport of MPs especially the small ones. Overall, MPs with the size of < 1 mm, the shapes of fragment and fiber, and the colors of black, white, and transparent, individually played the most contribution. Furthermore, laser direct infrared spectroscopy (LDIR) and micro-Fourier transform infrared spectroscopy (µ-FTIR) were applied for identification of MPs, and 20 polymer types were identified. Among them, polyethylene terephthalate and polypropylene were the primary types. The distribution of MPs revealed that facility agriculture application (such as mulching and greenhouse) led to more serious MP pollution in farmland, while the diverse characteristics of MPs inferred multiple sources other than agricultural plastic film/net. The surface morphology and elemental composition of typical MPs were characterized, showing polymer-special weathering features and multiple chemical pollutants (such as Ti, Br, and Cu) on MPs. This work provided a comprehensive insight into MP pollution in agricultural soil, thus, to better understand MP potential environmental risk to soil system. [ABSTRACT FROM AUTHOR]