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

Highlights: • We studied 16 types of phthalates in plastic greenhouse (PG) air. • Phthalates in gas-phase samples were over 100 times of those in particle-phase. • The sum of DEHP and DnBP was over 90% of total Σ₁₆ phthalates in air of PGs. • Phthalates in PG air in winter were 1.0–6.7 times higher than those in summer. • Log K_P values of air DEHP and DnBP were linear correlated to 1/T (P < 0.05). 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 (K_P) values of DEHP in summer (median of 1.52 × 10⁻⁴ m³ μg⁻¹) were higher than K_P values of DnBP in summer (0.60 × 10⁻⁴ m³ μg⁻¹). Log-transformed K_P values of DnBP and DEHP were linear correlated to the reciprocal of air temperatures, respectively (P < 0.05).