Jorf Lasfar Research Articles

The impact of industrial pollution on the Jorf Lasfar coastal zone (Morocco, Atlantic Ocean): the mussel as an indicator of metal contamination

Abstract The present study characterizes the effluents of the ‘Maroc Phosphore’ factories III and IV (of Jorf Lasfar coastal zone). The results show that the effluent (Cs/l) is very acid, very phosphate-rich, high in suspended matter and calcium-rich. Hydrological parameters indicate an important content of phosphates, especially in the stations located in the South of Cs/l. Tissues of mussel Mytilus galloprovincialis from the Jorf Lasfar zone present high concentrations of Cd and Cu.

Quality of Moroccan Atlantic coastal waters: water monitoring and mussel watching

The quality of Moroccan Atlantic coastal wasters was monitored from 1993 to 1997 by measuring hydrological parameters (dissolved oxygen, suspended particulate matter, phosphates, and nitrates), and using the mussel Mytilus galloprovincialis as a quantitative bioindicator of cadmium, copper, manganese, and zinc contamination. Mean concentrations of dissolved oxygen and suspended particulate matter were indicative of the effects of urban and industrial discharges of wastewater, particularly at Mohammedia, Casablanca, Mehdiya, Jorf Lasfar and Safi. Stations receiving urban wastewater showed high nitrate concentrations, especially at Mehdiya, Rabat, Mohammedia, Casablanca and El Jadida. Metal concentrations in mussels showed significant variations depending on the station and sampling period. Jorf Lasfar and Safi had the highest mean concentrations for cadmium (8 and 7 μg·g –1 dry weight respectively) and copper (74 and 25 μg·g –1 dry weight). The relation between cadmium concentrations in mussels, and phosphate concentrations in water suggests that the processing of phosphate ores at these two sites is responsible for contamination. Mussels in the Mohammedia–Casablanca sector had the highest zinc concentrations (338–379 μg·g –1 dry weight), followed by those collected at Jorf Lasfar (267 μg·g –1 dry weight), and Sidi Moussa and Safi (290–301 μg·g –1 dry weight). The distribution of manganese concentrations, which were maximal in estuaries (up to 19 μg·g –1 dry weight), was indicative of terrigenous inputs. Seasonal variations in mussel metal concentrations were characterised by winter minima, and apparently related to the physiological cycle of the animal. With the exception of cadmium-contaminated areas, the quality of mussels on the Moroccan Atlantic coast is good with respect to food safety standards.

Phosphate industry discharges and their impact on metal contamination and intertidal macrobenthos: Jorf Lasfar and Safi coastlines (morocco)

At Jorf Lasfar and Safi, on the Moroccan Atlantic coastline, there are chemical industry plants that produce phosphate derivates including phosphoric acid and fertilizers, together with by‐products such as sulphuric acid. The liquid effluents of the plants are discharged directly into the sea. In order to evaluate their impact, we have compared the distribution of intertidal macrobenthos in several locations, along gradients subjected to differing degrees of phosphate industry pollution. The results illustrate how biological diversity and species densities decrease abruptly in the vicinity of these industrial effluents, and also how recovery, as measured by the same parameters, proceeds with distance from the discharge points. Mussels Mytilus galloprovincialis were heavily contaminated by Cu and Cd at both study locations and their shells showed four kinds of deformities, notably at the Jorf Lasfar site, where the effluents were more aggressive (high in metals, low pH).