ARS | Publication request: Endosulfan in the atmosphere of South Florida: Transport to Everglades and Biscayne National Parks

Submitted to: Atmospheric Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 4, 2012
Publication Date: April 27, 2012
Repository URL: http://dx.doi.org/10.1016/j.atmosenv.2012.04.010
Citation: Hapeman, C.J., Mcconnell, L.L., Potter, T.L., Harman Fetcho, J.A., Schmidt, W.F., Rice, C., Schaffer, B., Curry, R. 2012. Endosulfan in the atmosphere of South Florida: Transport to Everglades and Biscayne National Parks. Atmospheric Environment. dx.doi.org/10.1016/j.atmosenv.2012.04.010.

Interpretive Summary: The environmental health of the unique and fragile ecosystems of South Florida has been declining. Initially, nutrient inputs from agricultural activities and urban encroachment have been implicated in contributing to the loss of organism diversity. However, the frequent prophylactic application of pesticides is being examined as another possible challenge to these ecosystems. Pesticide release to the atmosphere is enhanced in this region more so than other regions due to the calcareous soils, low-water holding capacity, frequent rainfall and irrigation, high humidity and temperatures, and a transmissive aquifer system. This study examined the fate of the insecticide endosulfan which had previously been identified as presenting a major hazard potential to aquatic organisms in this region. Its use has recently been severely restricted by the U.S. Environmental Protection Agency. Air samples were collected over a five-year period in an agricultural area near Homestead and at Everglades and Biscayne National Parks (NPs). The atmospheric contributions of endosulfan were greater than previously observed in many other regions where endosulfan was measured. The contribution of drift during pesticide application versus volatilization from the fields after application to atmospheric residues was examined using the unique chemistry of endosulfan. Results showed that endosulfan drift was most likely to occur nearest the source and that volatilization was more likely to be important at sites further away from the source. Samples were also monitored for the degradation production endosulfan sulfate. This compound is somewhat resistant to further degradation and is potential toxicity concern. These data will be useful for regulators, extension specialists, and decision-makers in modifying agricultural management practices to protect sensitive ecosystems.

Technical Abstract: Nutrient inputs from urban encroachment and agricultural activities have been implicated in contributing to the environmental health decline and loss of organism diversity of South Florida ecosystems. However, the frequent prophylactic application of pesticides is being examined as another possible challenge to these ecosystems. Pesticide release to the atmosphere is enhanced in this region more so than other regions due to the calcareous soils, low-water holding capacity, frequent rainfall and irrigation, high humidity and temperatures, and a transmissive aquifer system. This study examined the fate of the insecticide endosulfan which had previously been identified as presenting a major hazard potential to aquatic organisms in this region. Air samples were collected over a five-year period at the agricultural community of Homestead, Florida and at Biscayne and Everglades National Parks (NPs) nearby. Mean air concentrations ranged from 17 (19 s.d.) ng/m3 at Homestead and 2.3 (3.6 s.d.) ng/m3 at Everglades NP to 0.52 (0.69 s.d.) ng/m3 at Biscayne NP. Higher concentrations were observed nearest the agricultural fields and during higher agricultural production periods. Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) modeling of dispersions plumes of agricultural field emissions indicated that highest concentrations observed at each site corresponded to the wind direction from the agricultural fields. The ratio of alpha-endosulfan to beta-endosulfan was used to examine the contribution of drift versus volatilization or beta to alpha isomerization followed by volatilization to the overall residue level. Analysis of particulate filters revealed that beta-endosulfan was the predominant isomer and that alpha-endosulfan was overwhelmingly in the gas phase.