Environmental persistence of 2,3,7,8-tetrachlorodibenzo-p-dioxin in soil around Hardstand 7 at Eglin Air Force Base, Florida

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doi: 10.1065/jss2004.07.106
Authors:Vasquez, Astrid P.; Regens, James L.; Gunter, James T.
Author Affiliations:Primary:
Weston Solutions, Oklahoma City, OK, United States
University of Oklahoma, United States
Volume Title:Journal of Soils and Sediments
Source:Journal of Soils and Sediments, 4(3), p.151-156. Publisher: Ecomed Publishers, Landsberg, Federal Republic of Germany. ISSN: 1439-0108
Publication Date:2004
Note:In English. 22 refs.; illus., incl. geol. sketch map
Summary:Background and Goal. A number of global events have generated intense scientific scrutiny and public concern of polychlorinated dibenzo-p-dioxins (dioxin). Dioxins have been associated with a range of adverse health effects. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is recognized as among the most dangerous of the dioxin compounds, and was a contaminant found in one of the herbicides used for vegetation control during the Vietnam conflict: Agent Orange. As a result of purging spray systems and leaking drums of Agent Orange concentrate, TCDD contamination occurred in the soils surrounding Hardstand 7 at Eglin Air Force Base, Florida. This research uses a multimedia model to estimate the TCDD concentrations in surface soil around Hardstand 7 for a 70-year time interval beginning with observed surface soil concentrations 1984. Methods, Hardstand 7 is a nearly 40-m circular concrete and asphalt aircraft parking area. The hardstand was used as a staging area for spraying equipment used to disseminate herbicide in a test area called C-52A within EAFB. Concentrated herbicide was also stored in 208-L barrels for use with the equipment, and later, for disposal. In 1984, a field investigation characterized the extent of TCDD contamination in surface soils around Hardstand 7 using a radial sampling protocol. The 1984 observed concentrations and locations was used in a multimedia model, CalTOX, as an initial source term concentrations and locations to estimate expected concentrations during the subsequent 70-years. Results. The results indicate that more than 94% of the TCDD observed in surface soils 1984 will remain after a 70-year period. Access restrictions and remediation activities at the site eliminate bar verification of the CalTOX estimates. Conclusions. TCDD is highly persistent in the soil medium and natural attenuation may not produce a significant decrease in soil concentrations. Recommendation. Active remediation actions may be required to prevent exposure to TCDD contamination surface soils. Verifying CalTox concentration estimates an important step that should be performed, however, the model provides an easy to use tool to estimate TCDD surface soil contamination at herbicide storage or dispersion staging sites.
Subjects:Chemical composition; Chemical reactions; Concentration; Degradation; Dioxins; Environmental effects; Herbicides; Organic compounds; Pesticides; Pollutants; Pollution; Soils; Atlantic Ocean; Florida; Gulf of Mexico; North Atlantic; Okaloosa County Florida; United States; CalTOX; Elgin Air Force Base
Coordinates:N302500 N310000 W0862500 W0865000
Record ID:2005069824
Copyright Information:GeoRef, Copyright 2018 American Geosciences Institute.
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