Metal Pollution Assessment of Surface Sediments Along a New Gas Pipeline in the Niger Delta (Nigeria) |
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Authors: | Gianpiero Adami Igino Cabras Sergio Predonzani Pierluigi Barbieri Edoardo Reisenhofer |
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Institution: | (1) Department of Chemical Sciences, University of Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy;(2) Laboratory of Marine Biology, Via A. Piccard 54, Santa Croce, 34010 Trieste, Italy |
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Abstract: | Chromium, nickel, copper, zinc and cadmium were determined in sediments of the Niger Delta (Nigeria) in order to discriminate
between natural metal sources and anthropogenic ones. Surface sediments were collected at seven sites along a new gas pipeline
near Port Harcourt, between the New Calabar River and the Bonny River towards Bonny town. Chemical characterisation is obtained
by hydrofluoric–nitric acid digestion procedure, providing the ‘total’ (‘residual’) metal contents. Information about the
anthropogenic metal fraction was obtained by cold diluted hydrochloric acid extraction procedure. This ‘labile’ acid soluble
fraction of metals, perhaps due to relatively recent inputs in the sediments, constitutes the fraction more likely to be available
to marine organisms, and furnishes a first evaluation of the possible toxicity of sediments of this sensitive ecosystem. Zinc
appears to be the most available of all the heavy metals: its ‘labile’ fraction attains 40–50% of the ‘total’ zinc in sediment.
Sites near Port Harcourt city are the most contaminated. All the examined metals are one order of magnitude below the respective
values proposed as a limit for toxicity and are comparable with those observed by other authors in similar Niger Delta areas.
Some anomalous data found near Port Harcourt city suggest that zinc and cadmium are the metals that require further monitoring.
Their anthropogenic source could be derived from urban and industrial sewage. |
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Keywords: | Niger Delta Nigeria Pollution Sediment Metals Gas pipeline |
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