Mohamed Maanan

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.

Source Contributions to Heavy Metal Fluxes into the Loukous Estuary (Moroccan Atlantic Coast)

Abstract KALLOUL, S.; HAMID, W.; MAANAN, M.; ROBIN, M.; SAYOUTY, E. H., and ZOURARAH, B., 2012. Source contributions to heavy metal fluxes into the Loukous estuary (Moroccan Atlantic Coast). Aluminum, iron, mercury, lead, copper, cadmium, chromium, zinc, manganese, and nickel concentrations were determined in surface and core sediment samples collected in the Loukous estuary (Atlantic Coast, Morocco) to evaluate their levels and spatial distribution. For various metals, the enrichment factor was calculated as a criterion to assess whether their concentrations represented contamination levels or could be considered background levels. Analytical results were processed using Geographical Information System software to show areas of metal accumulation. Using multivariate statistical analysis, the possibility of distinguishing the sampling stations in relation to their geographical position was evaluated. The radiolead (210Pb) and cesium 137 (137Cs) profiles in sediment core retrieved from the Loukous estuary were used to study the temporal variations in sedimentation rate and to reconstruct historical trends of heavy metal input and the effects of human activities. The results show that the distribution of metals in the Loukous estuary is principally influenced by industrial and urban wastes located mostly in the northern coastal area. Marine currents are additional factors influencing metal accumulation in sediments.

Heavy metal and polycyclic aromatic hydrocarbons in Ebrié lagoon sediments, Côte d'Ivoire

Surface sediments throughout Ebrié lagoon, Côte d’Ivoire were collected in 2001 and analyzed for their heavy metal and polycyclic aromatic hydrocarbons (PAH) contaminant content. Geochemical maps of heavy metals (Cd, Cu, Zn, Fe, and Mn) in the surface sediment were produced based on geographical information system (GIS) technology. Heavy metals and PAH were detected at high concentration and provide evidence for several anthropogenic inputs to the lagoon. A significant spatial relationship was found for Fe, Zn, and Cu in the sediment using a GIS-based analysis, suggesting that these metal contaminants in the sediments of the Biétri bay had common sources.

Environmental risk assessment of the Moroccan Atlantic continental shelf: The role of the industrial and urban area

The present research presents the first large-scale analysis of heavy metal assessment in the Moroccan Atlantic shelf. This work provides scientific basis for future studies on environmental research and fills the gap in knowledge on the worldwide continental platforms. Metal distributions identified three different zones, mainly influenced by industrial and urban sewer (northern areas), agriculture runoffs (central zone), and estuarine discharges (southern areas), respectively. In the north part of the shelf, metal enrichments are observed near industrial and urban sewer mouths (Casablanca and Mohammedia cities). In the south and central areas, the probable absence of human impact on sediments is attributed to effective trapping in the estuary (Oum Er Rbia) and coastal zones, as well as dilution with less contaminated sediments and shelf sediments and removal with fine fractions due to estuary discharges.

Using Fuzzy Analytic Hierarchy Process multi-criteria and automatic computation to analyse coastal vulnerability:

This paper presents an integrated method to assess the vulnerability of coastal risks by applying the Fuzzy Analytic Hierarchy Process (FAHP) and spatial analysis techniques with a geographic information system (GIS). The coast of Mohammedia, located in Morocco, was chosen as the study site to implement and validate the proposed framework by applying a GIS-FAHP-based methodology. Coastal risk vulnerability mapping reflects multi-parametric causative factors such as sea level rise, significan twave height, tidal range, shoreline evolution, elevation, geomorphology and distance to an urban area. The results show that the coastline of Mohammedia is characterised by low, moderate and high levels of vulnerability to coastal risk. The high vulnerability areas are situated in the east at Monica and Sablettes beaches. This technical approach helps decision-makers to find optimal strategies and to minimise coastal risks. In comparison with other assessment methods, this approach involves rapid data processing and provides an improved means of sustainable and multi-objective coastal management.

Assess the human and environmental vulnerability for coastal hazard by using a multi-criteria decision analysis

ABSTRACT This study provides an integrated approach using geographical information system (GIS) based on a multi-criteria approach (MCDA) to assess coastal vulnerability, resulting from human activity, population density, erosion, and climate change-induced sea level rise. A coastal vulnerability index (CVI) for erosion and floods was calculated and mapped (∼24 km in length; ∼400 m in width, and 11.47 km2 in surface) for the lagoon barrier of Nador located on the Mediterranean coast of Morocco. Results suggest that 54% (∼13 km) of the shoreline is moderately vulnerable, while 42% (∼10 km) is highly vulnerable and only 4% (1 km) present a low vulnerability. The vulnerability map of the socio-economic activities indicates that most wetlands and forest areas 83% (∼31 ha) and 50% (∼440 ha) respectively, present low vulnerability. 52% percent of artificial areas (∼23 ha), 73% of agricultural land (∼128 ha), and 41% of natural areas (∼363 ha) present moderate vulnerability. However, the level of vulnerability of the remaining artificial and agricultural areas classifies from high to very high. The north-western sector was classified as the most vulnerable area, characterized by an erosion (−0.6 m/yr to −1.20 m/yr) for 70% of this area, while the south-eastern part shows a low to moderate vulnerability marked by an erosion (−0.1 m/yr to −1m/yr) for 40% of this area. Coastal vulnerability maps have potential as decision tools to prepare and respond to sea level rise, and identify exposed coastal zones, as such contributing to national climate action and disaster risk reduction sustainable development goals (goals 13 and 11, respectively).

Origin and potential ecological risk assessment of trace elements in the watershed topsoil and coastal sediment of the Oualidia lagoon, Morocco

ABSTRACT The Oualidia lagoon provides important ecosystem services, such as fishing, aquaculture, tourism and high biological and ecological productivity. Many indices have been developed to evaluate environmental risks and to estimate the anthropogenic contribution of potentially toxic elements (PTE) in surficial sediments. The results show that the concentrations of the PTE found in surface sediments due to the anthropogenic activities in the area (urban effluents, aquaculture and agricultural areas) are significantly higher than those from the local background and sediment quality guidelines (SQGs). The potential ecological and biological risk index present satisfactory results. However, the sites near to the areas where anthropogenic activities are developed present 49% probability of toxicity, while the rest of the lagoon, present 9% to 21% probability of toxicity and low potential ecological risk, except for Hg where the risk was considered to be considerable. The PTE are mainly originated from the anthropogenic activities; nevertheless, anthropogenic contributions represent up to 69% of the total sediment of content, but it depends on the PTE: Cd (16%), Ni (38%), Zn (41%), Cr (43%), Cu (56%), Hg (68%), Pb (69%). Compared with the Sub-basin soils, the PTE are higher than 80%, hence the sub-basin feeds the lagoon by these elements (PTE).

Polychaete diversity and assemblage structure in the Oualidia Lagoon, Moroccan Atlantic coast

The polychaete assemblages inhabiting the coastal waters of the Oualidia lagoon were studied during winter 2013 and summer 2013. Taxonomic composition and diversity were determined at 43 sample sites. Among the 13 species of polychaetes recorded, 10 were newly reported for Oualidia lagoon. Hediste diversicolor and Capitella sp. were the most abundant taxa in both seasons. Temperature and salinity were higher, and chl-a and OM were lower, in summer than in winter. The structure of the polychaete assemblages was characterized by forming three main clusters, either based on sampling stations or on polychaete species. These clusters were organized according to a downstream gradient, with the stations having fine sediments and a H. diversicolor assemblage in the inner lagoon being replaced by stations with medium grain-sized sediment and a Capitella sp. assemblage in the mid-lagoon, which were in turn replaced by stations having sandy sediments and assemblages dominated by Glycera alba (winter) and P. africana (summer) in the areas closer to the lagoon inlets. The shift was, in fact, from a classical, brackish, lacunar assemblage to two different, temporal aspects of a marine assemblage (close to the inlets), with a transition assemblage in between. This corresponded with a typically paralic spatial structure whose main descriptors responded to a confinement gradient. Despite the absence of a river, the organization of the polychaete assemblages closely resembled that of an estuarine system, with the tidal regime playing a major driving role.

Chronology of Holocene storm events along the European Atlantic coast: New data from the Island of Yeu, France

This paper reviews the reconstruction of European Atlantic storm events with the contribution of a new stormy reconstruction in its central part. Three marsh environments on the island of Yeu were chosen to identify disturbing storm events from the Mid- to Late Holocene with vibracore sampling, radiocarbon dating and sedimentary analysis. Nine probable intervals of high energy deposition in these low-transport-activity environments are estimated: 600–500, near 1590, 2100–1950, 2850–2350, 3500–3270, 5400–5370, 6650–6510, near 7000 and between 7670 and 7470 calibrated years before present (cal y BP). By comparison with sedimentological paleostorm studies, we confirm six European Atlantic storm events estimated at near 600–300, 1700–1100, 2900–2500, 3500–3300, 5500–5100 and 7700–7100 cal y BP, corresponding to worldwide Holocene cooling climatic periods. A comparison with other storminess reviews of worldwide main stormy coasts shows that Holocene storms can increase during global cooling periods in the northern hemisphere.