title: Persistent organic pollutants in sediments from Sai Gon-Dong Nai River basin, Vietnam: levels and temporal trends.
abstract: Surficial sediment samples were collected from Hochiminh City canals, the Sai Gon-Dong Nai River, and its estuary, one of the most predominant industrial areas in Hochiminh City, southern Vietnam, for determination of selected persistent organic pollutants (POPs). Contamination pattern was as follows: PCBs > or = DDTs > HCB > CHLs > HCHs. Concentrations of PCBs and DDTs ranged from 0.50-150 ng/g and 0.15-72 ng/g dry wt, respectively. On the other hand, concentrations of CHLs, HCHs, and HCB were mostly <2 ng/g dry wt. Levels of the all organochlorines (OCs) in Hochiminh City canals were significantly higher than those in the other areas, indicating the urban areas as major pollution sources to the aquatic environment. The contamination pattern was PCBs > DDTs in the city canals but PCBs < DDTs in the downstream and the estuary, suggesting particularly high contamination by PCBs in the city. Examination of DDTs composition and their ratios demonstrated continuous input of this pesticide to the city canals. However, the combination of our data and those from available literature implies a decreasing trend of PCBs and DDTs in the environment. DDTs concentrations have been reduced 50% after approximately 5 years. Composition of CHLs in the sediment from Hochiminh City canals was comparable to those of common technical mixtures, suggesting continuous input of CHLs to the environment. CHLs might be in use for purposes like termite control, wood preservation, and protection of underground cables. Hazard assessment implies high toxic potential of DDTs for sediments from Hochiminh City canals and suggests the need for better management of municipal discharges.
authors.affiliation: Center for Marine Environmental Studies, Ehime University, Matsuyama, Japan.
authors.forename: Nguyen Hung
authors.initials: NH
authors.lastname: Minh
authors.forename: Tu Binh
authors.initials: TB
authors.lastname: Minh
authors.forename: Hisato
authors.initials: H
authors.lastname: Iwata
authors.forename: Natsuko
authors.initials: N
authors.lastname: Kajiwara
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kunisue
authors.forename: Shin
authors.initials: S
authors.lastname: Takahashi
authors.forename: Pham Hung
authors.initials: PH
authors.lastname: Viet
authors.forename: Bui Cach
authors.initials: BC
authors.lastname: Tuyen
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Tanabe
mesh_terms: D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000032:analysis*; D006843:Hydrocarbons, Chlorinated / Q000032:analysis* / Q000592:standards; D012016:Reference Values; D045483:Rivers; D013997:Time Factors; D014744:Vietnam; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000592:standards
chemical_list: D006843:Hydrocarbons, Chlorinated; D014874:Water Pollutants, Chemical