EVALUATION DE LA CONTAMINATION DES SOLS PAR LES ELEMENTS TRACES METALLIQUES DANS LES ZONES URBAINES ET PERIURBAINES DE LA VILLE DE NIAMEY (NIGER)

Abstract

This study is part of a research program on chemical contaminants in urban areas, and focuses on the determination of trace metals in soils of the Niamey. For this purpose, soil samples were collected from 10 urban sites and theirs metals concentrations (As, Cd, Cr, Cu, Ni, Pb and Zn) were determined by inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion. The results show that metals concentrations in soils differ depending on the element analyzed and the site. They range from 1.36 to 13.70 mg/kg for As, 0.23 to 1.79 mg/kg for Cd, from 2.36 to 19.13 mg/kg for Co, 26.26 to 71.11 mg/kg for Cr, 8.24 to 228.30 mg/kg for Cu, 8.67 to 50, 71mg /kg for Ni, 8.91 to 779.91 mg/kg for Pb and 61.51 to 12,220 mg/kg for Zn. Detection, in Niamey urban soils, of the metals as Cd, Cu, Ni, Pb and Zn that have adverse effects on human health at concentrations above the permitted limits is a concern about their transfer into the food chain. The results of this study should enable the Niamey authorities to take measures for the risks prevention, by regulating the crops types depending on the soil contamination level, or prohibiting prior to remediation, the use for agricultural land whose metals concentrations exceed regulatory thresholds.