Local and regional sources of organochlorine pesticides in a rural zone in central Chile

There is a lack of knowledge about exposure to airborne organochlorinated pesticides (OCPs), especially for people living near agricultural zones in developing countries. This study is the first one to measure spatiotemporal variation of airborne OCPs within a major agriculture area in Central Chile. Polyurethane foam passive air samplers (PUF-PAS) were deployed in five sites in the town of Molina (35°7′S, 71°17′W) and another one in the nearby town of Lontué (35°3′S, 71°17′W). Samplers were deployed from August 2016 to January 2018, in 8 periods lasting 2–3 months each. The measured concentrations in air (pg m⁻³) as geometric mean were α-HCH: 0.59, γ-HCH: 3.8, o,p'-DDT: 1.3, p,p'-DDT: 2.0, o,p'-DDE: 0.52, p,p'-DDE: 5.5, o,p'-DDD: 0.26, p,p'-DDD: 0.64, PeCB: 29.1 and HCB: 14.5. The highest concentrations were measured in the warmer months and negative correlations (p < 0.05) between the log of the concentrations and the inverse of ambient temperature were found, suggesting soil volatilization as the main release process. The exceptions were o,p'-DDE, p,p'-DDE and HCB. In the case of HCB, waste burning was a likely source. Most OCP concentrations showed significant spatial heterogeneity (p < 0.05), suggesting local source contributions are dominant; the exceptions are α-HCH and PeCB (p > 0.05) whose concentrations depend on regional sources. Backward wind trajectories obtained using NOAA's HYSPLIT identified air masses coming from the south and southwest when ambient concentrations are highest; these regional sources contribute to all ambient OCP concentrations.