Assessment of Contaminated Soil with Some Heavy Metals in Selected Auto Repair Shops in Katsina North Western, Nigeria

Anthropogenic activities of humans lead to heavy metals toxicity into the soils. Auto mechanic workshops are one of the major sources of increase in heavy metal concentration in soils in Katsina North western Nigeria. Katsina is located on latitude 12o59'N and longitude 7o36'E and it's the capital city of Katsina state Nigeria. Five selected auto repair shops which include; Garejin Tsohuwar Tasha (TT), Albarkar Motors-Garage (AM), Garejin Abdulhadi (GA), Garejin Bebeji (GB) and Garejin KofarDurbi (GK) were considered for this study. Heavy metals in the soil samples at 0-15cm and 15-30cm depths were subjected to sequential extraction to ascertain the bioavailability of the metals in the soils. The percentage bioavailability of metals in the experimental sites at 0-15cm were; (GB- Cd-23.08%, Pb-38.48%, Cu-33.49%, Zn-44.15%, Cr-23.1%), (GK-Cd-57.38%, Pb 65.49%, Cu-71.59%, Zn-41.75%, Cr-57.02%), (TT-Cd 28.30%, Pb 31.70%, Cu26.93%, Zn-64.47%, Cr-27.24%), (AM-Cd 36.59%, Pb-47.67%, Cu-25.45%, Zn-54.26%, Cr-21.39%), (GA-Cd 58.43%,Pb 24.00%, Cu-12.17%, Zn-67.13% Cr-18.02%), while the percentage bioavailability at 15-30cm depth were (GB- Cd 10.53%, Pb 23.96%, Cu-76.51%, Zn-26.53%, Cr 52.23%), (GKi - Cd 44.44%, Pb 23.19%, Cu 5.54% ,Zn 25.35%,Cr-59.80%), (TT-Cd 80.0%, Pb 34.97%, Cu31.79%, Zn 5.19%, Cr 50.24%),(AM-Cd 26.67%, Pb 39.74%, Cu 13.88%, Zn 2.45%, Cr 25.90%) and (GA-Cd 81.82%, Pb 88.69%, Cu-25.00%, Zn 5.23%, Cr 17.52%). The high level of concentration of the heavy metals in the soils from the five experimental sites were slightly higher than from the control sites and higher than the recommended limits given by European Commission and World Health Organization.