Spatial-temporal distribution and potential risk of pesticides in ambient air in the North China Plain

The intensive use of pesticides in the North China Plain (NCP) has resulted in widespread contamination of pesticides in the local atmosphere, posing risks to air quality and human health. However, the occurrence and distribution of atmospheric pesticides in the NCP as well as their risk assessment have not been well investigated. In this study, 300 monthly samples were collected using passive air samplers with polyurethane foam at ten rural sites with different crop systems in Quzhou county, the NCP, from June 2021 to May 2022. The pesticides were quantified using mass-spectrometric techniques. Our results revealed that chlorpyrifos, carbendazim, and atrazine were the most frequently found pesticides in the air samples, with detection frequencies of >= 87 % across the samples. The average concentrations of atmospheric pesticides during spring (7.47 pg m(-3)) and summer (16.05 pg m(-3)) were significantly higher than those during autumn (2.04 pg m(-3)) and winter (1.71 pg m(-3)), attributable to the intensified application of pesticides during the warmer seasons. Additionally, cash crop sites exhibited higher concentrations (10.26 pg m(-3)) of atmospheric pesticides compared to grain crop (5.59 pg m(-3)) and greenhouse sites (3.81 pg m(-3)), primarily due to more frequent pesticides spraying events in cash crop fields. These findings indicate a distinct spatial-temporal distribution pattern of atmospheric pesticides influenced by both seasons and crop systems. Furthermore, the model-based inhalation risk assessment indicates that inhalation exposure to atmospheric pesticides is unlikely to pose a significant public concern.