Istituto di Scienze Marine     
Ruiz-Fernandez ,. C. A., Sprovieri M., Piazza R., Frignani M., Sanchez-Cabeza J., Feo M. L., Bellucci L. G., Vecchiato M., Perez-Bernal H. L., Paez-Osuna F. Pb-210-derived history of PAH and PCB accumulation in sediments of a tropical inner lagoon (Las Matas, Gulf of Mexico) near a major oil refinery. In: Geochimica et Cosmochimica Acta, vol. 82 pp. 136 - 153. PERGAMON-ELSEVIER SCIENCE LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND, 2012.
Concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were measured in a sediment core from the tropical freshwater inner lagoon of Las Matas, near the petroleum industrial area of Minatitlan-Coatzacoalcos, in the Gulf of Mexico. A Pb-210-derived chronology was used to reconstruct the historical PAH and PCB accumulation in the site during one century (1906-2005). Both geochemical and sedimentological data indicated that a major change occurred in 1947 +/- 4, including a shift to coarser sediments and a significant decrease of Al, Li, Fe, organic C and total N contents. This was likely due to the changes in hydrology caused by the confinement of Las Matas Lagoon due to the construction of the Trans-Isthmus road in 1946. PAHs in these samples show relatively low concentrations (259-1176 ng g(-1)), and the congener relative abundances indicate the influence of pyrogenic (petroleum combustion) sources. Total PCB concentrations in the sediments ranged from 24 to 77 ng g(-1), and are composed by low chlorinated PCBs, with 3-and 4-CB as the prevalent species (51-65% and 29-40%, respectively). PAHs and PCBs were detected at depths corresponding to the early 1900s, when Minatitlan refinery started operations, although their time evolution appears to be influenced by different accumulation processes. The PCB background is most likely produced by the combustion of natural organic matter, and an industrial contribution can be recognized when normalizing with OC contents. We concluded that atmospheric deposition is the most significant source of PAHs and PCBs for this water body. This study also provided evidence of the alteration of the wetlands surrounding this industrial area due to urbanization; the fragmentation and alteration of Las Matas Lagoon hydrology contributes to the gradual loss of the wetlands in the zone. (C) 2011 Elsevier Ltd. All rights reserved.
DOI: 10.1016/j.gca.2011.02.041

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