Concentration, enrichment and distribution of heavy metals in surface sediments of the Tangier Bay, Morocco

Abstract

SUMMARY: The distribution, enrichment, and accumulation of heavy metals in the surface sediments of the Tangier Bay, Morocco, were investigated. Surface sediment samples from eleven locations in the Bay of Tangier were collected in 2007 and characterized for grain size, organic matter and metal content (e.g. Fe, Mn, Cr, Cu, Ni, Pb, Zn and Cd). The evaluation of the heavy metal contamination status of the bay showed minor enrichment by the enrichment factors (EF) calculation, corroborated by the metal pollution index (MPI). The results of a Pearson correlation showed high positive correlations among organic carbon and most metals (0.788<r<0.939) and cluster analysis grouped the stations inside the harbour (stations 1, 10 and 9) and in the vicinity of the principal rivers in the bay (stations 3 and 11), which showed the highest concentrations of metal content. The main sources of contamination are domestic and industrial effluents, which arise due to the lack of sewage treatment. However, these areas could not be classified as polluted when the data were compared with sediment quality guidelines (USEPA, 1997).Keywords: metals, contamination, sediments, Tangier Bay, enrichment factors, Tangier Harbour, Morocco. RESUMEN: Concentración, enriquecimiento y distribución de metales pesados en sedimentos de la bahía de Tánger, Marruecos. -Se ha investigado la distribución y acumulación de metales pesados en sedimentos superficiales de la bahía de Tánger, Marruecos. Se tomaron 11 muestras de sedimentos superficiales ubicadas en la bahía de Tánger durante el año 2007 y se analizaron los metales (Fe, Mn, Cr, Cu, Ni, Pb, Zn y Cd), materia orgánica y distribución granulométrica. El estado de contaminación por metales de la bahía, se evaluó mediante el cálculo del factor de enriquecimiento (EF) y en general mostró bajo enriquecimiento, corroborado por el uso del índice de polución metálica (MPI). Los resultados de la correlación de Pearson presentaron una correlación significativa importante entre el carbono orgánico y la mayoría de los metales (0.788<r<0.939). El análisis clúster agrupó las estaciones dentro del puerto (estaciones 1, 10 y 9) y en las proximidades de los ríos que desembocan en la bahía (estaciones 3 y 11), que mostraron la mayor concentración del contenido de metales. Las principales fuentes de contaminación fueron los efluentes domésticos e industriales, como consecuencia del escaso tratamiento de estos vertidos. Sin embargo, esta zona no puede ser clasificada como contaminada al comparar los datos con las normas de calidad de sedimentos (USEPA, 1997).Palabras clave: metales, contaminación, sedimentos, bahía de Tánger, factor de enriquecimiento, puerto de Tánger,

Bioindication of Beetles and Spiders for the Ecotoxicological Study of the Impact of Heavy Metals and their Interaction with Detoxification Enzymes

“…It may be arranged as follows: heavy industries >medium industries >light industries. This arrangement may be due to the mass accumulation of heavy metals and nearness to effluents as explained by some earlier workers (Rodríguez-Barroso, Benhamou, et al 2010).…”

Enrichment and Distribution of Elements Concentration in Sediment of Sungai Balok, Pahang

“…The enrichment factor (EF) is a tool that can be used to determine the enrichment of heavy metals concentration in order to evaluate the possible sources of these metals either from natural or anthropogenic sources [26]. The enrichment factor measured was used Fe as the natural background value [28]. The element mostly used in enrichment factor for sediment normalization is Al because of its characteristics such as high natural concentration, minimal anthropogenic contamination, it is a structural element of clays, and the proportions of metal in the crust are constant [22].…”