title: Persistent organic pollutants associated to water fluxes and sedimentary processes in the Colorado River delta, Baja California, México.
abstract: Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were studied in sediment cores from two distinctive modern channels of the Colorado River (CR) delta. Their abundance and temporal changes are associated with flood-flows from the CR across the USA-Mexico border. The CR channel is directly exposed to river flood-flows while the Hardy River (HR) is a local channel derived mainly from agricultural runoff, geothermal effluents, and treated urban wastewater. Different headwater compositions and degrees of exposure to flood-flows appear to be the factors controlling the composition of persistent organic pollutants (POPs). Enrichment of OCPs (46 ng g(-1) dwt in HR and 4.37 ng g(-1) dwt in CR) occurred during or a few years after flooding. PCB-138 (4.2 ng g(-1)dwt) is enriched in HR suggesting its origin in dielectric oils from the geothermal power plant. PCB-28 (2.1 ng g(-1)dwt) in CR may be related with atmospheric input and/or re-deposition of upstream sediments. In surficial sediments (0-3 cm), only HR exceeds international sediment quality guidelines (4,4'-DDE=8.16 ng g(-1)dwt and ΣDDT=8.34 ng g(-1)dwt).
authors: Facultad de Ciencias Marinas, Universidad Autónoma de Baja California UABC, Km 107 Carretera Tijuana-Ensenada, CP 22860, Ensenada, Baja California, Mexico.
authors: K C
authors: KC
authors: Lugo-Ibarra
authors: L W
authors: LW
authors: Daesslé
authors: J V
authors: JV
authors: Macías-Zamora
authors: N
authors: N
authors: Ramírez-Álvarez
mesh_terms: D002706:Chlordan / Q000032:analysis; D003634:DDT / Q000032:analysis; D003633:Dichlorodiphenyl Dichloroethylene / Q000032:analysis; D004726:Endosulfan / Q000032:analysis; D005618:Fresh Water / Q000737:chemistry; D019015:Geologic Sediments / Q000737:chemistry*; D006843:Hydrocarbons, Chlorinated / Q000032:analysis; D008800:Mexico; D010575:Pesticides / Q000032:analysis*; D011078:Polychlorinated Biphenyls / Q000032:analysis*; D045483:Rivers; D014481:United States; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D006843:Hydrocarbons, Chlorinated; D010575:Pesticides; D014874:Water Pollutants, Chemical; D002706:Chlordan; D003633:Dichlorodiphenyl Dichloroethylene; D003634:DDT; D011078:Polychlorinated Biphenyls; D004726:Endosulfan