Interference between di(2-ethylhexyl) phthalate and heavy metals (Cd and Cu) in a Mollisol during aging and mobilization

• Published in: The Science of the total environment Vol. 836; p. 155635
• Main Authors: Huang, Fuxin, Guan, Rui, Wang, Jingyi, Wang, Lei, Zhang, Ying, Wang, Shiyu, Qu, Jianhua, Dong, Maofeng, Rong, Shaowen
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 25.08.2022
• Subjects: adsorbents; clay; Combined pollution; environment; environmental assessment; fractionation; half life; Heavy metals; Leaching; molecular dynamics; Molecular dynamics simulation; Mollisols; montmorillonite; nonpoint source pollution; Phthalates; Pollutant aging; rain; soil pollution; soil water; surface area; Pollutant aging; Combined pollution; Molecular dynamics simulation; Leaching; Phthalates; Heavy metals
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.155635

Diffuse pollution of the soil by phthalates and heavy metals causes numerous concerns. Their respective fates when coexisting require further investigation. In this study, di(2–ethylhexyl) phthalate (DEHP) and Cd/Cu were used as subjects, focusing on their behavior in Mollisols under combined pollution based on their concentration, fractionation, and leaching. The results indicated that when the two pollutants coexist, the dissipation rate of DEHP in the soil decreased, and its half-life was extended from 30.81 to 40.53 (Cd) and 35.40 d (Cu). DEHP altered the distribution of Cd and Cu in the soil, and this effect persisted after most of the DEHP had degraded. Leaching tests showed that the interaction of DEHP with Cd and Cu hindered leaching during the first rainfall event, but as DEHP degraded and Cd/Cu stabilized, the trapped pollutants were gradually released in subsequent rainfall events. Additionally, to investigate the partitioning of pollutants between soil water and solid surfaces, a diffusion model of DEHP and metal ions on the surface of montmorillonite (high specific surface area adsorbents abundant in soils) was built using molecular dynamics simulations. Simulations revealed their density distribution on the clay surface increased synergistically, whereas their diffusion was antagonistic. This study provides basic data and theoretical support concerning the ecological risk assessment of combined phthalate and heavy metals pollution in soil. [Display omitted] •Combined transformation effects of Cd/Cu and DEHP were studied for the first time.•DEHP altered Cd/Cu fractionation in Mollisols during the aging process.•Cd/Cu reduced the degradation rate of DEHP.•DEHP delayed the leaching of Cd/Cu during periods of repeated rainfall.•Influence of pollutant mobilization examined by combining experiments and simulation.