Spatial and seasonal variations of atmospheric organochlorine pesticides along the plain-mountain transect in central China:regional source vs. long-range transport and air–soil exchange

Polyurethane foam (PUF) disk passive air samplers (PAS) were deployed to measure spatiality and seasonality of atmospheric OCPs in Jianghan Plain (JHP) and Western Hubei Mountain (WHM), to make a preliminary explorative study of the source–sink relationship of organochlorine pesticides (OCPs) and their association with the monsoon. The concentrations of individual OCPs in the JHP were generally higher than those in the WHM. Significantly high levels of DDTs and Endosulfan were found in the spring and summer, HCB was found in autumn and winter, and HCHs displayed uniform distributions. Compared with the levels of 2005, a significant decrease of atmospheric HCHs, DDTs and HCB was observed, whereas an increase in Endosulfan was observed. The air–soil equilibrium status of OCPs suggested that Dajiuhu (DJH) soils are likely to be a sink for OCPs, and JHP soils are acting as the emitter, contaminating the atmosphere at certain monitoring stations. Backward air trajectory analysis demonstrated that the seasonal fluctuation of atmospheric DDTs, HCB and Endosulfan at the DJH site were closely associated with the variations of the East Asian monsoon