Spectrophotometric Determination of Heavy Metals Levels in Ethiopian Cement and Soils Around the Cement Factories

Abstract

The current boom in construction sector of the country has aroused scientific concern about the safety of construction workers who regularly work with cement. The aim of this study was to determine the levels of selected heavy metals (Cr, Pb, Cd, Cu and Ni) in branded cement samples (Mugher, Dangote, Capital, and Derba) and soils around the Mugher cement factory. The level of the selected heavy metals in cement and soil samples were analyzed by Flame Atomic Absorption Spectroscopy. The detected range of metal concentrations (mg/kg dry mass) in different cement sample were Cu (0.131 ± 0.021-0.302 ± 0.004), Cd (0.02 ± 0.008-0.023 ± 0.008), Pb (0.187 ± 0.042- 0.353 ± 0.016), Cr (0.185 ± 0.017 - 0.765 ± 0.017), Ni (0.233 ± 0.002 - 0.906 ± 0.290) in ppm. Among the tested heavy metals Ni was found in highest concentration and it was in Capital cement sample. The heavy metal levels in the studied samples not comply with international standards. The detected range of the heavy metals in soil samples collected at different distances from the target cement factory were Cr (7.317 ± 0.501 - 25.558 ± 0.055), Cu (1.269 ± 0.003 - 45.317 ± 0.014), Pb (0.45 ± 0.0433 - 9.867 ± 0.011), Cd (0.492 ± 0.076 to 2.442 ± 0.063), Ni (13.383 ± 0.638 - 49.958 ± 0.0205) in subsoil and that of layer soil sample were Cr (1.292 ± 0.052 to 24.141 ± 0.476), Pb (0.058 ± 0.039 - 6.942 ± 0.284), Cu (0.537 ± 0.003 - 32.725 ± 0.083), Cd ( 0.108 ± 0.072 to 0.883 ± 0.014), Ni (11.183 ± 0.341-49.517 ± 0.892) in mg/kg. The measured physicochemical parameters in soil sample ranged pH (7.393 ± 0.061 - 8.483 ± 0.014), Electrical Conductivity (0.613 ± 0.005 -2.918 ± 0.072) mS /cm. The level of heavy metals in soil samples was found to increases as sampling distance from the factory decreases. This study indicates that all of the metals are concentrated on the surface soil, and decreased in the lower part of the soil, this due to reflect heavy metal’s mobility and physical properties of soil and its alkaline pH values.

Keyword: Cement, FAAS, Heavy metals, physicochemical parameters