Accumulation of Toxic Metals in Soils of Different Sections of Mechanic Village Abakaliki, Nigeria and Their Health Implications

Abstract

Composite samples of soil were collected between June 2013 and May 2014 from different sections of mechanic village Abakaliki such as mechanic, welder, electrician and panel beater workshop. A control sample was collected from a farm near the mechanic village about 500 m away. Orion 920A pH meter and X-ray Fluorescence spectrophotometer were used to determine the pH and different concentrations of metal in the soil. In addition, Walkley and Black method was used to determine the percentage of organic matter while Hydrometer method was used to determine the percentage of sand, silt, and clay in the soil samples. The results showed average pH of 6.2±0.82 and metal concentration (in mg/Kg) ranged from (0.12±0.2 – 84.41±6.4) for As; (6.41±0.2 – 116.02±12..2) for Cd; (8.12±1.2 – 80.72±12.2) for Co (764.32±112.4 – 444.14±16.14) for Cu; (1.14±0.12 – 6.18±0.18) for Cr; (1212.8±24.1 – 525.12±44.2) for Fe; (822.0±72 – 620.18±66.2) for Mn; (82.4±8.0 – 228±8.6) for Ni;  (268.12±46.8 – 664.62±52) for Pb and (788.24±84.2 – 1420±142) for Zn. Percentage (%) of organic matter, sand, silt, and clay respectively were of the range 1.12±3.4 – 1.68±3.4;  54±22 – 58.12; 9.31±0.92 – 18.8±1.22 and 26.48±2.81 – 32.18±3.22. The concentrations of the investigated heavy metals were higher in the top soil than in the sub soil and this suggest that source of pollution was anthropogenic. Elevated concentrations of  Ni > Pb > Cd > As above the US-EPA Regulatory Limits in that order were observed in the samples collected from, while variations in the heavy metal levels were generally observed between and within groups. Regular monitoring of heavy metal in the soil is expedient for safety of environment and human health.