Distribución de elementos traza en sedimentos de la Laguna de Nador (Marruecos): estudio preliminar

An approach to the distribution of the principal trace elements found in the superficial sediments from Nador (NE Morocco) is shown. Samplings were collected in two seasons campaigns and chemical analyses of the < 2mm fraction of material at 0-5cm and 10-20cm depth were performed by INAA and ICP-OES, determining As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn. The median for each element was used as regional geochemical baseline, and percentiles 90 and 95 were reference values for evaluating the most important anomalies. The confined area located at the NW, Beni Ensar-Atelouane, is the most polluted one (As, Co, Cr and Cu). Also samples near a Fe-mining waste pond present high anomalies for As, Co, Cu, Mn, Pb and Zn. The Nador surroundings are very rich in Pb and Zn, and values recorded at the Bouaroug oued outlet are high for Cu, Zn and Mn. Sporadic Cd anomalies can be found close to the coast between Nador and Selouane, and around Selouane high Cr, Ni and Cd anomalies can be also found. No important anomaly is to be indicated concerning the season influence, and the spatial distribution continues to be very similar. In general no important pollution has been found in the lagoon and most anomalies can be related with anthropic activities.