title: Transport and bioaccumulation of polychlorinated dibenzo-p-dioxins and dibenzofurans at the Bien Hoa Agent Orange hotspot in Vietnam.
abstract: The Bien Hoa airbase (south of Vietnam) is known as one of the Agent Orange hotspots which have been seriously contaminated by Agent Orange/dioxin during the Vietnam War. Hundreds of samples including soil, sediment and fish were collected at the Bien Hoa Agent Orange hotspot for assessment of the environmental contamination caused by dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). The toxicity equivalency quotient (TEQ) concentration of PCDD/Fs in soil and sediment varied from 7.6 to 962,000 and 17 to 4860 pg/g dry wt, respectively, implying very high contamination of PCDD/Fs in several areas. PCDD/F levels in fish ranged between 1.8 and 288 pg/g TEQ wet wt and was generally higher than advisory guidelines for food consumption. 2,3,7,8-Tetrachlorinated dibenzo-p-dioxins (2,3,7,8-TCDD) contributed 66-99 % of TEQ for most of the samples, suggesting 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) from Agent Orange as the major source of the contamination. The vertical transport of PCDD/Fs was observed in soil column with high TEQ levels above 1000 pg/g dry wt (Vietnamese limit for necessary remediation activities- TCVN 8183:2009 (2009)) even at a depth of 1.8 m. The vertical transport of PCDD/Fs has probably mainly taken place during the "Ranch Hand" defoliant spray activities due to the leaks and spills of phenoxy herbicides and solvents. The congener patterns suggest that transports of PCDD/Fs by weathering processes have led to their redistribution in the low-land areas. Also, an estimate for the total volume of contaminated soil requiring remediation to meet Vietnamese regulatory limits is provided.
authors.affiliation: Dioxin Laboratory Project, Vietnam Environment Administration (VEA), Nr. 556 Nguyen Van Cu, Long Bien, Hanoi, Vietnam.
authors.forename: Nguyen
authors.initials: N
authors.lastname: Van Thuong
authors.affiliation: Dioxin Laboratory Project, Vietnam Environment Administration (VEA), Nr. 556 Nguyen Van Cu, Long Bien, Hanoi, Vietnam.
authors.forename: Nguyen Xuan
authors.initials: NX
authors.lastname: Hung
authors.affiliation: Dioxin Laboratory Project, Vietnam Environment Administration (VEA), Nr. 556 Nguyen Van Cu, Long Bien, Hanoi, Vietnam.
authors.forename: Nguyen Thi
authors.initials: NT
authors.lastname: Mo
authors.affiliation: Dioxin Laboratory Project, Vietnam Environment Administration (VEA), Nr. 556 Nguyen Van Cu, Long Bien, Hanoi, Vietnam.
authors.forename: Nguyen Manh
authors.initials: NM
authors.lastname: Thang
authors.affiliation: Dioxin Laboratory Project, Vietnam Environment Administration (VEA), Nr. 556 Nguyen Van Cu, Long Bien, Hanoi, Vietnam.
authors.forename: Pham Quang
authors.initials: PQ
authors.lastname: Huy
authors.affiliation: Dioxin Laboratory Project, Vietnam Environment Administration (VEA), Nr. 556 Nguyen Van Cu, Long Bien, Hanoi, Vietnam.
authors.forename: Hoang
authors.initials: H
authors.lastname: Van Binh
authors.affiliation: Dioxin Laboratory Project, Vietnam Environment Administration (VEA), Nr. 556 Nguyen Van Cu, Long Bien, Hanoi, Vietnam.
authors.forename: Vu Duc
authors.initials: VD
authors.lastname: Nam
authors.affiliation: Center for Environmental Monitoring (CEM), Vietnam Environment Administration (VEA), Nr. 556 Nguyen Van Cu, Long Bien, Hanoi, Vietnam.
authors.forename: Nguyen
authors.initials: N
authors.lastname: Van Thuy
authors.affiliation: Dioxin Laboratory Project, Vietnam Environment Administration (VEA), Nr. 556 Nguyen Van Cu, Long Bien, Hanoi, Vietnam.|Office of the National Steering Committee 33, Ministry of Natural Resources and Environment (MONRE), Nr. 83 Nguyen Chi Thanh Street, Dong Da, Hanoi, Vietnam.
authors.forename: Le Ke
authors.initials: le K
authors.lastname: Son
authors.affiliation: Dioxin Laboratory Project, Vietnam Environment Administration (VEA), Nr. 556 Nguyen Van Cu, Long Bien, Hanoi, Vietnam. lab.dioxin@gmail.com.
authors.forename: Nguyen Hung
authors.initials: NH
authors.lastname: Minh
mesh_terms: D015085:2,4,5-Trichlorophenoxyacetic Acid / Q000032:analysis* / Q000493:pharmacokinetics; D015084:2,4-Dichlorophenoxyacetic Acid / Q000032:analysis* / Q000493:pharmacokinetics; D000075182:Agent Orange; D000818:Animals; D001572:Benzofurans / Q000032:analysis* / Q000493:pharmacokinetics; D000072338:Dibenzofurans, Polychlorinated; D004784:Environmental Monitoring / Q000379:methods*; D052918:Environmental Restoration and Remediation; D005399:Fishes / Q000378:metabolism; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis / Q000493:pharmacokinetics; D012989:Soil Pollutants / Q000032:analysis* / Q000493:pharmacokinetics; D014744:Vietnam; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000493:pharmacokinetics
chemical_list: D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D000072317:Polychlorinated Dibenzodioxins; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D015084:2,4-Dichlorophenoxyacetic Acid; D000075182:Agent Orange; D015085:2,4,5-Trichlorophenoxyacetic Acid
keywords: 2,3,7,8-TCDD; 2,4,5-T; Agent Orange; Contaminated site; Dioxin; Fish