Influence of the oceanographic conditions during spring 2003 on the transport of the Prestige tanker fuel oil to the Galician coast

Efficient tools for marine operational forecast and oil spill tracking

Ocean forecasting and oil spill modelling and tracking are complex activities requiring specialised institutions. In this work we present a lighter solution based on the Operational Ocean Forecast Python Engine (OOFε) and the oil spill model General NOAA Operational Modelling Environment (GNOME). These two are robust relocatable and simple to implement and maintain. Implementations of the operational engine in three different regions with distinct oceanic systems, using the ocean model Regional Ocean Modelling System (ROMS), are described, namely the Galician region, the southeastern Brazilian waters and the Texas-Louisiana shelf. GNOME was able to simulate the fate of the Prestige oil spill (Galicia) and compared well with observations of the Krimsk accident (Texas). Scenarios of hypothetical spills in Campos Basin (Brazil) are illustrated, evidencing the sensitiveness to the dynamical system. OOFε and GNOME are proved to be valuable, efficient and low cost tools and can be seen as an intermediate stage towards more complex operational implementations of ocean forecasting and oil spill modelling strategies.

Supercritical fluid extraction of polycyclic aromatic hydrocarbons from seaweed samples before and after the prestige oil spill

Samples of seaweed which are used for human consumption were collected along the Galician coast (NW Spain), in order to determine the level of contamination from polycyclic aromatic hydrocarbons, by supercritical fluid extraction and liquid chromatographic analysis. No detection was made of benzo[a]pyrene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[ghi]perylene and dibenzo[ah]anthracene. PAHs were found and quantified in only two samples. The PAHs found were the following: anthracene, chrysene, fluoranthene, fluorene and pyrene. The levels found were below maximum limits established by the Spanish Food Safety authority (<200 mg/kg dry weight). Here we show that no relevant effects were detected in terms of PAHs contamination in seaweed.

Fingerprinting petroleum hydrocarbons in plankton and surface sediments during the spring and early summer blooms in the Galician coast (NW Spain) after the Prestige oil spill

Plankton samples (20-350 microm and >350 microm) collected at three transects along the Galician coast (NW Spain) were analysed for individual aliphatic and aromatic hydrocarbons by GC-MS. Sample collection was performed in April-July 2003, after the Prestige oil spill (November 2002), to determine whether the hydrocarbons released into the water column as a consequence of the spill were accumulated by the planktonic communities during the subsequent spring and early summer blooms. Surface sediments were also collected to assess the presence of the spilled oil, removed from the water column by downward particle transport. Plankton concentrations of PAHs (Sigma14 parent components) were in the range of 25-898 ng g(-1)dw, the highest values being close to coastal urban areas. However, the individual distributions were highly dominated by alkyl naphthalenes and phenanthrenes, paralleling those in the water dissolved fraction. The detailed study of petrogenic molecular markers (e.g. steranes and triterpanes, and methyl phenanthrenes and dibenzothiophenes) showed the occurrence of background petrogenic pollution but not related with the Prestige oil, with the possible exception of the station off Costa da Morte in May 2003, heavily oiled after the accident. The dominant northerly wind conditions during the spring and early summer 2003, which prevented the arrival of fresh oil spilled from the wreck, together with the heavy nature of the fuel oil, which was barely dispersed in seawater, and the large variability of planktonic cycles, could be the factors hiding the acute accumulation of the spilled hydrocarbons. Then, with the above exception, the concentrations of PAHs found in the collected samples, mostly deriving from chronic pollution, can be considered as the reference values for the region.

Spatial and temporal trends of petroleum hydrocarbons in wild mussels from the Galician coast (NW Spain) affected by the Prestige oil spill

Polycyclic aromatic hydrocarbons (PAHs) were determined in tissues of wild mussels (Mytilus galloprovincialis) from the Galicia coast (NW Spain) in order to assess the extent of the environmental impact caused by the Prestige oil spill (November 13, 2002). Three sampling campaigns were carried out in February, June and November 2003 at 24 stations along the Galicia coast, from La Guardia (Pontevedra) to Ribadeo (Lugo). The spatial distribution of PAHs found in the first sampling period, clearly revealed the central area (Costa da Morte) as the most affected by the oil spill. In these stations, concentrations up to 7780 microg/kg dw of the sum of 13 parent PAHs were found 2-3 months after the spill. Molecular parameters within the aliphatic and aromatic fractions confirmed the presence of the Prestige oil in these samples. The levels markedly decreased at most of the stations in the second sampling and recovered to levels found before the spill in November 2003, 1 year after the accident (29-279 microg/kg dw, av. 133+/-83 microg/kg dw). However, a certain increase was observed in some sites which could be related to the remobilization of oil residues from still unclean intertidal spots or sediments due to the winter marine weather conditions.

The BEEP Stavanger Workshop: Mesocosm exposures

Within the BEEP project (Biological Effects of Environmental Pollution in Marine Ecosystems) the Work Package 1 was addressed to the development of new and more sensitive biomarkers of exposure in several sentinel organisms. Within this framework, common mesocosm exposures of organic pollutants relevant for marine ecosystems were conducted in the facilities of Akvamiljø a/s (Stavanger, Norway). In the first experiment, Atlantic cod (Gadus morhua), turbot (Scophthalmus maximus) and shore crab (Carcinus maenas) were exposed to nonylphenol, North Sea crude oil and a combination of crude oil and alkylated phenols. Mussels (Mytilus edulis) were exposed to North Sea crude oil and a combination of crude oil, alkylated phenols and PAHs. In the second experiment, Atlantic cod, turbot, mussel and spider crab (Hyas araneus) were exposed to the plasticizers bisphenol A and diallyl phatalate and the brominated flame retardant BDE-47. The main purpose of the present study was to provide the 30 participating Institutes with samples which had been exposed to defined contaminant concentrations in a controlled laboratory exposure for 3 weeks. This paper describes the mesocosm experimental design, the transplantation and treatment of the organisms, and the contaminant exposures.

Oceanographic conditions in North and Northwest Iberia and their influence on the Prestige oil spill

Oceanographic conditions at the time of the Prestige oil spill (November 2002) and following months are analyzed based on a set of hydrographic cruises. The ship sank off one of the flanks of the Galician Bank, an offshore seamount, and a major oil spill drifted to the N and NW Iberian coast mainly driven by dominant winds. Coastal circulation was characterized by freshwater plumes and the poleward slope current, and could have affected the fate of the oil spill and influenced stranding places. Seasonal evolution of oceanographic conditions in this particular year is compared with the long-term average and reveals specific features that need to be taken into account in studies of the impact of the oil spill on populations. Spring conditions commenced earlier than other years in the Southern Bay of Biscay, contrastingly in western Iberia. The lack of subsurface intrusion of subtropical waters suggests a low intense penetration of the poleward current in Spanish Biscay slopes. In western Iberia, the slope poleward current observed in late autumn weakens and is exported off slope during upwelling pulses in the spring, with no strong intrusion of the poleward current on the slope at the time of the spring bloom. A description of current velocities near the wreck on the Galician Bank is obtained after the analysis of a mooring line.