| Summary: | BACKGROUND With the wide application of PAEs in plastic greenhouse and plastic film mulching cultivation techniques, the pollution of diethylhexyl phthalate (DEHP) in agricultural soils has become widespread in China. OBJECTIVES To quantitatively reveal the release of DEHP from plastic film and the distribution characteristics of DEHP concentration in mulched soil, red soil and tobacco films in the Yunnan Karst Plateau. METHODS Field experiments were conducted to simulate the mulched soil environment, and the DEHP contents in agricultural film and soil media were determined by Gas Chromatography-Mass Spectrometry. RESULTS The maximum release of DEHP from plastic film cover in undisturbed soil was 13.57mg/kg. The average DEHP (10.83mg/kg) released from plastic film covered with biological inhibitors was slightly higher than that from uncovered soil (10.77mg/kg). The releases of DEHP from plastic film included two stages of slow release and concentrated steep increase. The total release increased with time. DEHP concentrations in undisturbed soil ranged from 0.17 to 3.74mg/kg and those in soil with biological inhibitors ranged from 0.34 to 4.29mg/kg. The DEHP levels were within the detection concentration range of phthalate esters (PAEs) in mulched farmland soil at home and abroad. The contents of DEHP in soils increased first and then decreased with time. CONCLUSIONS DEHP in soil mainly comes from the release of DEHP in plastic film. It is concluded that DEHP does not accumulate in red soils of the Karst Plateau within a short period. Reasonable arrangement of crop mulching can effectively reduce organic pollution in soil.
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