PCDD/Fs in sediments of Central Vietnam coastal lagoons: in search of TCDD.
Samples from nine Central Vietnam coastal lagoons, together with three soils and sediments collected in two freshwater reservoirs of the Thua Thien-Hué province, were analysed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Total concentrations are low, from 192 to 2912 pg g(-1) and depth profiles in Tam Giang-Cau Hai (TG-CH) sediment cores show only minor changes over time in PCDD/F input and composition. Octachloro dibenzo-p-dioxin (OCDD) is the prevailing congener (approximately 90%), indicating combustion as the main PCDD/F source to these coastal systems, whereas natural formation might be partly responsible for the presence at depth. 2,3,7,8-Tetrachloro dibenzo-p-dioxin (TCDD), largely sprayed together with Agent Orange over the study areas during the war (1961-1971), is absent or very low. This result supports the hypothesis of strong degradation soon after spraying. Multivariate statistical analyses account for the presence of local, short-range sources as observed in the northern part of the TG-CH lagoon.
University Ca' Foscari, Dorsoduro 2137, 30123 Venice, Italy.
Rossano
R
Piazza
Silvia
S
Giuliani
Luca Giorgio
LG
Bellucci
Cristian
C
Mugnai
Nguyen Huu
NH
Cu
Dang Hoai
DH
Nhon
Marco
M
Vecchiato
Stefania
S
Romano
Mauro
M
Frignani
D001572:Benzofurans / Q000032:analysis*; D004784:Environmental Monitoring; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis*; D011108:Polymers / Q000032:analysis*; D012623:Seawater / Q000737:chemistry; D012987:Soil / Q000737:chemistry; D014744:Vietnam; D014874:Water Pollutants, Chemical / Q000032:analysis*
D001572:Benzofurans; D000072317:Polychlorinated Dibenzodioxins; D011108:Polymers; D012987:Soil; D014874:Water Pollutants, Chemical; C016068:polychlorodibenzofuran