We analyzed dissolved nutrient, trace metal and vitamin (B-vitamins and methionine) concentrations in the lower course of the Moulouya River (MR, Morocco) and its estuary. The flow of this African river has changed drastically (a reduction of almost 50 %) in the last 50 years due to the regulation of the river flow through dams and alterations of the course constructed to satisfy population necessities and growing agricultural requirements. Consequently, it has produced a remarkable increase in nitrate concentrations (up to 270 µM) and alteration of N:P ratios within the river, as well as a reduction of overall P and Si efflux to nearby coastal waters. Despite the historical mining activities in the upper MR, concentrations of Pb, Zn and other metals in sediments and waters do not display significant contamination as compared with other Mediterranean rivers, mainly due to the retention by dams of upstream metal contamination. Mean concentrations of dissolved B-vitamins in the river showed lower levels (13 to 55% lower) than those in coastal waters and hence the river does not represent an important B-vitamin source.

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A B S T R A C TThis work aims to study the use of a spiral supported liquid membrane (SLM) to extract lead (Pb) from seawater matrix using the di-(2-ethylhexyl) phosphoric acid (DEHPA) dissolved in kerosene as carrier. In this regard, several physical and chemical parameters which could affect Pb extraction (sample pH, sodium acetate buffer, HNO 3 concentration in stripping solution, masking agent effect, flow rate, filter porosity, and configuration of the SLM cell) were studied. In this sense, the permeability parameter was selected to probe the system efficiency. The optimal preconcentration factor was found to be of 14.2, after 2 h under the following conditions: sample pH equal to 4.7 buffered until a 0.08 M of sodium acetate, DEPHA concentration fixed at 0.21 M and HNO 3 concentration of 0.23 M in stripping solution. Besides, SLM filters were analyzed by electron microscopy after each period of 2 h and several microparticles and other deposits in form of a thin layer were observed in the polymeric support.

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