Regional accumulation and ecological risks of typical plastic additives in agricultural soils in China

Phthalates (PAEs) and organophosphate esters (OPEs) have been widely detectable in agricultural soils and pose potential risks to ecosystems. However, their regional variations and the influencing factors in agricultural soils in China remain unclear. To address these issues, we assessed the regional accumulation and combined ecological risks of PAEs and OPEs in agricultural soils across China using the literature data, and then analysed their influencing factors from the perspectives of pollutant property parameters, soil physicochemical properties, meteorological conditions, agricultural activities, and geographical variables using Random Forest models and multi-source spatial data. The results showed that the mean concentration of Σ₆PAEs (1591 ± 1610 ng/g) was generally higher than that of Σ₁₁OPEs (52.6 ± 111 ng/g). Di-(2-ethylhexyl) phthalate (DEHP) (791 ± 902 ng/g) and Σ₅Alkyl-OPEs (29.2 ± 88.9 ng/g) were the dominant compounds. The combined ecological risks of the Σ₆PAEs and Σ₁₁OPEs were the highest in agricultural soils in Eastern China (median risk quotient (RQ): 3.75). PAEs showed high risks (RQ ≥ 1) across China, whereas OPEs exhibited moderate risks (0.1 ≤ RQ < 1) except in the West (RQ < 0.1). The importance of pollutant property parameters for PAE and OPE accumulation in agricultural soils reached 49.9 ± 6.44% and 28.9 ± 2.24%, respectively. The soil physicochemical properties and meteorological parameters contributed higher impacts on the OPEs than on the PAEs, especially the precipitation, which contributed 9.13 ± 0.56% to OPEs. These findings provide scientific support for the ecological risk evaluation and environmental management of plastic additives in agricultural soils.