Agricultural activity in the South Florida region occurs in close proximity to both urban and  natural areas like Biscayne and Everglades National Parks. One possible transport mechanism for pesticides into these sensitive ecosystems is release to the atmosphere after application. The process is enhanced in this region due to the calcareous soils, frequent rainfall, and high humidity and temperatures. Endosulfan is a widely-used pesticide with high toxicity to aquatic organisms. Air samples were collected over a five-year period (2001 to 2006) at a site within the agricultural community of Homestead, Florida and at sites located in Biscayne and Everglades National Parks (NPs). Mean gas-phase air concentrations of a-endosulfan were 17 � 19 ng m-3 at Homestead, 2.3 � 3.6 ng m-3 at Everglades NP, and 0.52 � 0.69 ng m-3 at Biscayne NP. Examination of spatial and temporal trends indicated that endosulfan emissions from agricultural areas around Homestead influenced air concentration observations at the NP sites. Results of an intensive sampling campaign during the larger study indicated the highest total endosulfan concentrations at the NP sites were observed on days when air parcels were predicted to move from Homestead agricultural area towards the sampling locations. The a-endosulfan fraction (a/(a+�)) was used to examine the contribution of pesticide drift versus volatilization to the overall residue level. The median a-fraction observed during periods of high agricultural activity at Homestead and Everglades NP was 0.84 and 0.88, respectively, and during periods of low agricultural activity the median at Homestead was 0.86, indicating contributions from drift. The median a-fraction at Everglades NP was 1.0 during periods of low agricultural activity, while Biscayne NP was 1.0 year round indicating air concentrations are primarily influenced by regional volatilization.

Examining the fate and transport of a- and �-endosulfan in the atmosphere of South Florida

246th National Meeting (2013)

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