Atmospheric phthalate pollution in plastic agricultural greenhouses in Shaanxi Province, China.

Phthalate pollution in soil and vegetables in plastic agricultural greenhouses has attracted wide concern. Investigating airborne phthalates in this environment can improve understanding of air-soil or air-vegetable phthalate migration. However, studies of phthalates in plastic agricultural greenhouse air are rare. To fill this gap, 25 gas-phase and 23 particle-phase samples were collected from 12 typical plastic greenhouses in Shaanxi. 16 types of phthalates were measured by a gas chromatography-mass spectrometry system (GC-MS) to analyse their pollution features and variations. Results showed that in the air of the plastic greenhouses, the median concentration of the sum of sixteen type phthalates (∑16 phthalates) was 5305 ng m-3, with 5th-95th value of 1214-9616 ng m-3. Phthalates in gas-phase samples were over 100 times higher than the levels in particle-phase samples. Air phthalate concentrations in the plastic greenhouses were higher than those in the control groups (P < 0.05). Air bis (2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) accounted for 66.9% and 29.3% of total ∑16 phthalate concentrations, respectively. Air phthalate concentrations in the plastic greenhouses in winter were 1.1-5.3 times higher than the levels in summer respectively (P < 0.05). Gas-particle partition coefficients (KP) values of DEHP in summer (median of 1.52 × 10-4 m3 μg-1) were higher than KP values of DnBP in summer (0.60 × 10-4 m3 μg-1). Log-transformed KP values of DnBP and DEHP were linear correlated to the reciprocal of air temperatures, respectively (P < 0.05).