In situ monitoring of chlorothalonil and lambda-cyhalothrin by polyethylene passive samplers under fields and greenhouse conditions

Sampling is a critical step in pesticide atmospheric analysis. Passive sampling offers advantages of inexpensive and convenient air monitoring. Polyethylene films (PE) were used as a passive sampler at multiple heights in greenhouse and agricultural field for 15 days to trap atmospheric chlorothalonil and lambda-cyhalothrin in the months of May and July. Among the two PE film thicknesses (20 and 80 mu m), 20 mu m PE was the most effective at absorbing target pesticides from air and attains equilibrium stage earlier than 80 mu m PE film. After approximately 240 h of PE exposure in greenhouse and fields, chlorothalonil and lambda-cyhalothrin reached an equilibrium stage of partitioning between air and PE. Atmospheric concentrations of chlorothalonil (p < 0.01) and lambda-cyhalothrin (p < 0.001) at 1.5 m height were higher with the concentrations of 1855.59 +/- 243.85 ng/m(3) and 3682.11 +/- 316.71 ng/m(3), respectively, in the month of May as compared to the other three respective heights. The concentrations of chlorothalonil in air at 2 m height (1587.27 +/- 284.19 ng/m(3)) were slightly higher than 0.5 m (1392.28 +/- 205.09 ng/m(3)). Atmospheric concentrations of lambda-cyhalothrin at 2 m (3178.26 +/- 299.29 ng/m(3)) were significantly lower than the other heights (p < 0.05). The greenhouse air concentrations of chlorothalonil and lambda-cyhalothrin in the months of May (1855.59 +/- 243.85 and 3682.11 +/- 316.71 ng/m(3), respectively) and July (1749.33 +/- 378.61 and 3445.08 +/- 390.32 ng/m(3), respectively) were higher than fields. The results indicate the usability of PE films to monitor chlorothalonil and lambda-cyhalothrin and potential other semi-volatile pesticides in agricultural fields.