Abstract
Bien Hoa airbase is a known dioxin-contaminated hotspot in Vietnam. The contamination occurred during the Vietnam War at the site where dioxins were transported, stored, sprayed, and spilled in the area. Dioxins, which are cancer inducing substances, may transfer from the soil to food crops and finally to human beings living around the area. Many surveys of dioxins in soil, water, organisms, and human have been carried out in this study area since 2002. In this paper vertical distribution of dioxins in undisturbed soil cores were examined. Twelve soil samples from three drilled cores were collected to analyze dioxin levels according to the standard Japanese analytical method. The results showed that the toxicity equivalency quantity (TEQ) in one soil sample at a depth of 2.6 m reached 3,300 pg-TEQ/g-dw. High TEQs were also observed in the clay layer. This anomaly of dioxin concentrations could be attributed to the affinity of dioxins for the clay layer. The isomer patterns in the soils were different from those in the soil of Hokkaido in that 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD) was the most dominant in the soil sample. This indicates that the dioxins originate from a defoliant Agent Orange disposed at the site after the Vietnam War.
Highlights
Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are known as hydrophobic organic compounds (HOCs) subject to long-range transport via vapour and particle-bound phases (Bergknut et al 2010)
The highest concentrations of 3,300 pg-toxicity equivalency quantity (TEQ)/g-dw and 760 pg-TEQ/g-dw were observed at GL-2.5 m in BH01 and GL-3.5 m in BH02, respectively
Higher concentrations of dioxins were found in the silty clay layer (BH01 and BH02)
Summary
Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are known as hydrophobic organic compounds (HOCs) subject to long-range transport via vapour and particle-bound phases (Bergknut et al 2010). The form of PCDD/Fs almost inexorably stabilized during combustion (Altarawned et al 2009). These compounds are formed by natural combustion processes, such as bushfires and volcanoes, as well as being unintentional byproducts of chemical reactions and incomplete combustion processes involving sources of chlorine and carbon (Rappe et al 1987; Rappe 1996). They are harmful to humans when exposed mostly via the consumption of animal products (Elskens et al 2013).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
