Heavy metal (cu, fe and zn) pollution in soils: pig waste contribution in the central region of Ghana

Abstract

Pig wastes have been considered a source of heavy metal pollution in soils in communities in the Central Region of Ghana where pig production is a major occupation. The concentration of copper (Cu), iron (Fe) and zinc (Zn) in pig droppings and in soils from five pig waste dumping sites designated as NS, AM, AK, AD and NK and one non-dumping site (control) in the Assin South District were studied. The mean Cu concentration in the droppings varied from 12 mg kg-1 to 46 mg kg-1 and in the order NK>AM>NS>AK>AD. The mean Fe concentration in the droppings also ranged from 551 mg kg-1 to 657 mg kg-1 whilst the Zn concentration ranged from 55 mg kg-1 to 118 mg kg-1 and in the order AD>AM>NS>NK>AK and NS>NK>AM>AK>AD, respectively. The mean concentrations of extractable Cu, Fe and Zn in the soils from all the dumping sites were significantly (P˂0.05) higher than the background value (control). The mean Cu concentration in the soils varied from 49 mg kg-1 to 70 mg kg-1, whilst the Fe varied from 957 mg kg-1 to 1020 mg kg-1 and the Zn varied from 108 mg kg-1 to 204 mg kg-1 and the order of the variations differed from that of the pig droppings. The results of the quantification of the metal contamination in the soils from the dumping sites using geoaccumulation index indicated that at all the sites, the Cu pollution in the soils was moderate, the soils were almost not polluted by Fe and the Zn pollution was light