Paul Fattal

A long-term record of land use change impacts on sediments in Oualidia lagoon, Morocco

An integrated approach, involving land use patterns and heavy metal contents of the surficial and cored sediment, was proposed to detect the characteristic spatial and temporal scale of point and non-point source human disturbances on the Oualidia lagoon in Morocco. Identification and description of the temporal and spatial distributions of the main contamination sources of heavy metals are analyzed using statistics and GIS methods. The results show that surficial sediments are highly enriched in heavy metals compared to their preindustrial background levels. Land-use types affected lagoon sediment pollution in different ways: 1) agricultural areas had the highest potential for sediment contamination by heavy metals, particularly Pb, Cu and Hg, 2) Ni and Cr are the main pollutants originating from urban sewage and 3) oyster farming and traditional land uses such as salt flats, pastures showed low levels of others metals. The enrichment factors (normalized by Al) obtained from the sediment cores indicated that the lagoon is (strongly/moderately) polluted by all metals which were attributed to agricultural activities and wastewater discharges from urbanized areas.

Coastal Vulnerability to Oil Spill Pollution: the Case of Noirmoutier Island (France)

Abstract Over the last 30 years, oil spills have contributed significantly to coastal and marine pollution, causing disturbance of the coastal environment. This recurrent hazard has increasingly been taken into account through prevention plans in Coastal Zones Integrated Management. Numerous studies have attempted to analyse the effects of oil pollution, in particular to identify those areas that are the most vulnerable. Although several studies have considered both environmental and socioeconomic issues, most of them have focused only on environmental vulnerability. The aim of our research is to formalise an alternative approach to map global vulnerability, using both environmental and socioeconomic factors. This article describes and discusses the methodology used to identify the critical variables required to assess coastal vulnerability to oil spills. The first part introduces previous research and identifies the parameters that have been used to map this type of vulnerability. The study area is presented in the second part of the paper. The third part presents the method we used to compute a spatialised vulnerability index that is based on a multicriteria analysis including both environmental and socioeconomic parameters. The final part of this paper describes and discusses the results of the implementation of this method on Noirmoutier Island located off the west coast of France. The resulting synthetic mapping for risk monitoring, carried out using a geographical information system, seems to be a relevant and useful complementary tool to improve the management of oil spill crises.

Dynamics of spilled oil natural transformation on the sea coasts in different geographical conditions.

The paper is devoted to the comparative analysis of results of long-term field observations carried out on geographically different sea coasts contaminated by spilled fuel oil. Such investigations are of particular interest as they make it possible to assess the rates of oil pollution natural transformation as well as their correlation with principal geographical factors such as climatic and hydrological conditions, coast exposure and geomorphology, sediment types, intensity of biogeochemical cycles. For these purposes, the authors have chosen three zones where the accidental oil spills occurred in the last years: on the north-western coast of France (tanker “Erika” accident in December 1999; accident at an oil refinery in the Loire River Estuary in March 2008), on the north-western coast of Spain (tanker “Prestige” accident in November 2002) and in the Strait of Kerch (tanker “Volgoneft-139” accident in November 2007). The duration of long-term observations ranged from 5 to 13 years. The present investigation included visual assessment and sampling of oil slicks and sediment cores. The analysis of samples were carried out with the use of thin layer and column chromatography, optical and gravimetric methods making possible to determine separately the sum of saturated, mono- and di-aromatic hydrocarbons (HC), the sum of polycyclic aromatic hydrocarbons (PAH) and the sum of asphaltic components (AC) as well as the presence of hydrocarbons of contemporary biological origin. The obtained results show that even 10 to 13 years after the oil spills their weathered traces are still present in the coastal zone, especially in its upper part. In the course of time an exponential diminution in the oil pollution level and the ratio between hydrocarbons and asphaltic components (HC/AC) was revealed. In the studied cases, the half-periods of fuel oil natural transformation varied from 1 to 5 years. The highest activity of the self-cleaning process was observed for small fuel oil traces on the rocky substrate exposed to the influence of fresh air, solar radiation, storm waves and surf action. On the Strait of Kerch coasts influenced by shallow, slightly salted and highly bio-productive waters of the Sea of Azov the spilled fuel oil tends to disappear more rapidly than on French and Spanish coasts washed by the Atlantic Ocean.