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(38-33) Metallic content and toxicity in the sediments of Algeciras Bay (Spain). Morillo, José*,1, Usero, José1, 1 Universidad de Sevilla, Sevilla, Spain ABSTRACT- Algeciras Bay is located in the province of Cadiz in the most western part of the Mediterranean coast. In this bay there are large amounts of pollutant waste, most of which comes from large cities (Algeciras, La Linea de la Concepcion and Gibraltar) and their industrial area, one of the biggest in Andalusia. In this study 13 sediment samples were taken in Algeciras Bay and were analysed for the content of 9 metals (Cr, Ni, Mn, Cu, Cd, Pb, As, Hg y Zn); the toxicity was also determined. To determine the toxicity, a new toxicity test method placing the luminescent bacteria Photobacterium phosphoreum in direct contact with the sediments was used. Suspensions of sediments in water were tested in direct contact with the luminescent bacteria followed by separation of sediment particles from the bacteria prior to light intensity measurements. The results showed that there are high correlation coefficients among the toxicity levels and the amount of metal of the sediments. The greatest amounts of toxicity and contamination by metals were obtained in the northern part of the bay, where most of the area's industry is concentrated. This is where the highest concentrations of Cr, Ni, Pb and Zn are found. Also noteworthy is the sample taken from the area where the sewage from the city of Algeciras empties into the bay, which shows maximum Cu and As content and very high toxicity. Key words: sediment, metal pollution, toxicity |
