Environmental Burden of Heavy Metal Contamination Levels in Soil from Sewage Irrigation Area of Geriyo Catchment, Nigeria

Abstract

The heavy metal concentration levels and contamination/pollution index of agricultural soils taken from 0 – 30 cm depth from site I and II of sewage irrigation area and from a control site of Geriyo catchment in Adamawa State, Nigeria was determined using atomic absorption spectrophotometer standard method. The mean concentration levels of trace and heavy metals (Fe, Zn, Mn, Cu, Cd, Cr and Pb) at site I are 89.90 mg/kg for Fe, 74.39 mg/kg for Zn, 12.79 mg/kg for Mn, 15.09 mg/kg for Cu, 9.86 mg/kg for Cd, 11.2 mg/kg for Cr and 7.18 mg/kg for Pb, while at site II, the concentrations levels of  294.7 mg/kg for Fe, 310.2 mg/kg for Zn, 131.9 mg/kg for Mn, 254.8 mg/kg for Cu, 240.2 mg/kg for Cd, 199.6 mg/kg for Cr and 159.2 mg/kg for Pb were observed. The concentration levels of trace and heavy metals of site II soil is significantly higher than site I and the control site with values of (Cu, Cd, Cr and Pb) mostly above the maximum permissible heavy metal concentration levels in soil set out by EU, UK and USA. The contamination/pollution index assessment of the soils revealed that the soils belong to slight pollution to excessive heavy metal pollution soil category with the potentials of negative effect on plants and ground water reserve contamination. Leaching and liming of the soil to reduce the level of metals is recommended in the context of very high land competition for sustainable agricultural productivity.

Keywords: Sewage irrigation, heavy metal, pollution index, soil, Geriyo catchment