Microplastic characteristics and microplastic-heavy metal synergistic contamination in agricultural soil under different cultivation modes in Chengdu, China.

Microplastics have significant implications for global ecosystems. The microplastic distribution, types, sources, and quantified microplastic-heavy metal synergistic pollution in agricultural soil in Chengdu, China were analyzed. The microplastics were detected in all soil samples collected from 103 sites, with concentrations ranging from 1333 to 15067 particle kg−1. The abundance of microplastics in grassland (12,667 ± 3394 particle kg−1) was more than twice higher than that in open field, vegetable field, orchard, and woodland. The main morphological types of microplastics included fibers, films, and granules (all "3-Dimensional" microplastics), with the colors red, blue, and transparent. Granular and fiber microplastics were predominantly in particles < 500 mm, while film microplastics were uniformly distributed at all sizes. The plastic compositions were mainly polypropylene and polyethylene plastics, accounting for 20.73% and 27.90% of the soil microplastic, respectively. Agricultural plastic applications and irrigation water were the sources of soil microplastics. The concentration of Cd, Cr, and Cu in the microplastics was strongly correlated with the corresponding concentration in the soils (p < 0.01), and the microplastic-heavy metal synergistic pollution might deteriorate the soil environment. The results of soil TOC measurements were influenced by microplastics in the soil. The results provide important data for the characteristics of microplastics in the agroecosystem. [Display omitted] • Microplastics are widespread in agricultural fields in Chengdu, China. • The highest MPs abundance is in grassland among the five cultivation modes. • The main sources of soil MPs are varied among different cultivation modes. • Cd, Cr, and Cu content in soil and in microplastics are positively correlated. • Microplastics may influence the results of soil TOC measurements. [ABSTRACT FROM AUTHOR]