No abstract

An investigation was carried out into the PAH chemical contamination resulting from the "Erika" tanker fuel spillage of December 1999 along the French coast of the Bay of Biscay. A qualitative and quantitative assessment was conducted of this contamination in water, suspended particulate matter, sediments, and in intertidal molluscs. The chemical composition of PAHs in pre-spill and post-spill samples was determined and used to distinguish the "Erika's" fuel as the source of PAHs in the coastal environment of the Bay of Biscay. Changes in concentrations of PAHs were also assessed. The GC-MS analysis made it possible to identify and quantify parent unsubstituted PAHs, alkyl-substituted PAHs (C-PAH) and sulfur heterocycle unsubstituted and alkyl substituted compounds (SPAH and C-SPAH). The results of this study demonstrated that heavily oil-contaminated shorelines, including beaches, rocky coasts as well as sandy sediments apparently became reservoirs of spilled fuel and these continued to contaminate seawater, suspended particulate matter and mussels with PAHs. These conclusions were borne out by the following observations: (1) the pattern changes in PAH composition after the "Erika" oil spill were consistent in all contaminated compartments (water, suspended particulate matter SPM, intertidal sediments and molluscs), (2) the compositional patterns of PAHs after the "Erika" oil spill in contaminated water, SPM, intertidal sediments and molluscs constantly included alkyl-substituted phenanthrenes, pyrenes, chrysenes and sulfur heterocycle compounds in higher relative abundances than those in the pre-spill samples of these compartments, (3) the relative abundances of different suites of PAHs at contaminated sites were similar to those of weathered "Erika" fuel, (4) consistent and visible temporal decline in concentrations for water, SPM and molluscs, (5) the geographical contiguity of the stations with high concentrations of PAHs in molluscs matched the extent of the shoreline contamination by the spilled fuel. The increase in the contamination levels before and after the spill, together with the significant change in the pattern of PAH composition provide evidence of the intense and long-term chemical contamination of the "Erika's" fuel and of the damage to natural marine resources resulting from such contamination by toxic oil components.

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Levels of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were determined in the muscle and liver of European hakes (Merluccius merluccius, L.) from the Mediterranean and Atlantic coasts (France). The liver was always the most contaminated organ by both groups of compounds. Hakes from the Gulf of Lions (Mediterranean) present concentrations of PCBs and PBDEs 1.6 to 13.5 times higher than hakes of a similar size from the Bay of Biscay (Atlantic). Although PCBs present higher levels compared to PBDEs, their concentrations were significantly correlated. The contaminant patterns in hakes were similar in the two studied areas, and were dominated by higher chlorinated PCBs (CB153, 138, 180 and 170), and lower brominated PBDEs congeners (BDE47, 100, 49, and 99). Concentrations globally increase with hake size, and males appear to be more contaminated than females of the equivalent size. However, the compound levels also depend on the physiological status of fish.

Abstract. Important historical informations on the temporal changes of anthropogenic pollution in marine environment can be assessed using sediment analysis. Dating is a crucial prerequisite to reconstruct pollution events, to calculate fluxes, and thus to allow comparison between different sites. This work presents estimates of accumulation rates of sediments in the Bay of Biscay. Fives cores were collected during RIKEAU 2002 cruise on board o/v Thalia in order to study temporal changes in PAH and organohalogens compounds content of sediment. We compare chronostratigraphic estimates on cores derived from the natural radionuclide 210 Pb in excess with estimates from the known times of introduction of the artificial radionuclide 137 Cs to the environment. 210 Pb, 226 Ra and 137 Cs were measured directly by non-destructive gamma spectrometry using a well type γ-detector. Total 210 Pb and 226 Ra activities vary from 30 to 150 mBq g -1 , and 20 to 36 mBq g -1 respectively; 137 Cs presents lower levels (< 5 mBq g -1 ). Profiles of 210 Pb xs in three cores present a well mixed layer, from 2-3 to 10 cm, in the uppermost sediments, followed by an exponential decrease of activities, suitable for the determination of sedimentation rates. Under constant flux and sedimentation rate assumptions, vertical accretion rates derived from 210 Pb xs present a large range from nearly 0.1 cm yr -1 up to almost 0.3 cm yr -1 . Differences are mainly due to relative position of studied cores regarding the muddy patch. Although the moderate level of 137 Cs limits the accuracy of this dating method, profiles of 137 Cs with depth strengthen mean rates derived from 210 Pb xs data. The implication of this dating on pollutant inputs in sediments of the Bay of Biscay is briefly discussed.