title: PCBs and HCHs in a salt-marsh sediment record from South-Central Chile: use of tsunami signatures and 137Cs fallout as temporal markers.
abstract: This paper documents the occurrence of polychlorinated biphenyl (PCB) and hexachlorocyclohexane (HCH) deposition inferred from a sedimentary record exposed in a salt-marsh trench in South-Central Chile. Sediments were carefully collected every 1 cm from the trench wall. The samples were analyzed for PCBs, HCHs, 137Cs, organic carbon and grain size. The 137Cs fallout and the sedimentary signature left by the 1960 Chilean tsunami were used as temporal markers to estimate the stratigraphic chronology and the sedimentation rates. PCBs were quantified by gas chromatography with electron capture detection (GC-ECD), and positive samples were confirmed by gas chromatography and mass spectrometry detection (GC-MS). Based on these results, PCBs and HCHs deposition over the last 40 years was estimated. No PCBs were detected below the tsunami signature. Total concentrations ranged from undetectable (ND) to 32 ng/g d.w. for PCBs and from undetectable (ND) to 1.29 ng/g d.w. for HCHs. The highest PCB concentrations were found in the upper 7 cm of the core. Even though PCBs were banned in 1982 as electrical fluids in Chile, total estimated PCB fluxes have increased approximately 20 times during the last 40 years: from undetectable values to 102.6 ng/cm2/year, reflecting that PCBs are still in use and being released into the environment.
authors.affiliation: Aquatic Systems Research Unit, EULA-Chile Center, Environmental Sciences Center, University of Concepción, Barrio Universitario S/N, P.O. Box 160-C, Concepción, Chile. ricbarra@udec.cl
authors.forename: Ricardo
authors.initials: R
authors.lastname: Barra
authors.forename: Marco
authors.initials: M
authors.lastname: Cisternas
authors.forename: Claudia
authors.initials: C
authors.lastname: Suarez
authors.forename: Alberto
authors.initials: A
authors.lastname: Araneda
authors.forename: Osvaldo
authors.initials: O
authors.lastname: Piñones
authors.forename: Peter
authors.initials: P
authors.lastname: Popp
mesh_terms: D002244:Carbon / Q000032:analysis; D002588:Cesium Radioisotopes / Q000032:analysis; D002677:Chile; D008401:Gas Chromatography-Mass Spectrometry; D019015:Geologic Sediments / Q000032:analysis*; D001556:Hexachlorocyclohexane / Q000032:analysis*; D011078:Polychlorinated Biphenyls / Q000032:analysis*; D013997:Time Factors; D014872:Water Movements
chemical_list: D002588:Cesium Radioisotopes; D001556:Hexachlorocyclohexane; D002244:Carbon; D011078:Polychlorinated Biphenyls