Abstract

MARTINS, Marta; FERREIRA, Ana Maria  and  VALE, Carlos. PCB composition in flood material and sediments from the Guadiana River estuary. Cienc. mar [online]. 2005, vol.31, n.1b, pp.285-291. ISSN 0185-3880.

Coarse material and freshly deposited particles transported by the exceptional flood of January 2001 were sampled at eight sites along the Guadiana River and estuarine shorelines. Two months after moderate river flows, we collected 27 surface sediments from the river-estuarine system and one sediment core from the coastal area. The PCB levels in sediments were lower than 1.1 ng g^-1, which is in conformity with the absence of industrial activities in the Guadiana drainage basin. Material transported by the flood contained higher PCB concentrations (0.8-1.8 ng g^-1) than surface sediments (0.1-1.1 ng g^-1), indicating the importance of these events in the transport of PCB to this low-contaminated estuarine system. These differences were not related to organic carbon content. Furthermore, this material is enriched in less chlorinated compounds as usually occurs far away from point sources. The diffuse transport influences the CB composition of sediment deposits on the adjacent coast, as revealed by variations in the depth profiles of the tri-/hexa-chlorinated ratio, organic carbon content and Si/Al ratio.

Keywords : PCB; congeners; sediments; flood material; Guadiana River.

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