Reduction effects of solar radiation, mechanical tension, and soil burial on phthalate esters concentrations in plastic film and soils.

Phthalate esters (PAEs) are potentially dangerous chemicals in plastic film mulched fields; however, few studies have investigated how to reduce their concentrations in plastic film and soil. In this study, the effects of solar radiation, mechanical tension, and soil burial on PAEs concentrations in polyethylene (PE) film and degradable film were investigated, and the half-lives of di-n-butyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) in soil also studied. PAEs concentrations in polyethylene films were about twice those in the degradable films; however, PAEs concentrations in all experimental films were similar after 1-year of field exposure. Mechanical tension had no effect on the PAEs concentrations of polyethylene films, but increased the detected concentrations of PAEs in degradable films by 34%-120%. After 4-years of burial, the PAEs concentrations in films decreased by 79.2%-98.0%, and mechanical tension promoted the reductions. However, there was little difference in PAEs concentrations between the buried soils with and without films, indicating the released PAEs reduced quickly in soil. Also, the half-lives of DBP and DEHP were 2.4-4.6 days and 18.5-41.4 days, respectively. Overall, the results presented herein provide reasonable approaches to reduce the concentrations of PAEs in plastic films and soils.