EVALUATION OF THE IMPACT OF MINING ACTIVITIES AND ENVIRONMENTAL REMEDIATION STRATEGY IN UDEGE-BEKI TOWN, NASARAWA LGA, NASARAWA STATE

Abstract

A study was carried out to evaluate the impact of mining activities in Undege-mbeki town and ascertain the level of contamination arising from tin, columbite and tantalite mining. Soil and crop samples from farmlands in a derelict mine were collected and analysed for heavy metal concentration using Atomic Absorption Spectrophotometer (AAS). Micro elements were determined using flame photometer and the physicochemical properties of the soil were determined for chemical properties using standard method. Results of the physicochemical and metal concentration of the soil samples showed that pH ranged (6.49 - 7.04); electrical conductivity (28.88 - 138.88 μS/cm); organic carbon content (0.95 - 2.07 %); organic matter (1.44 - 3.16 %), nitrogen (0.12 - 0.73 %); phosphorus (2.68 - 3.20 ppm); sodium (3.36 - 4.69 ppm); potassium (2.79 - 5.49 ppm); magnesium (1.82 - 41.99 ppm); exchangeable acidity (0.12 - 0.73 %); exchangeable bases (11.12 - 18.52 %); cation exchange capacity (11.53 - 18.72 %) and base saturation ranged (74.55 - 96.73 %). For soil heavy metals the concentration of Pb ranged from (0.18-0.39 mg/kg); Cr (0.13-0.33 mg/kg); Cd (0.04-0.20 mg/kg); Ni (0.02-0.11 mg/kg); Zn (0.64-0.91 mg/kg) and Sn (3.94-6.59 mg/kg) while the crops heavy metal concentration showed that Pb ranged from (0.32-0.81 mg/kg); Cr (0.14-0.21 mg/kg); Cd (0.04-0.18 mg/kg); Ni (1.02-3.17 mg/kg);  Zn (2.00-10.52 mg/kg) and Sn (2.39-4.91 mg/kg). Pollution assessment of the soil samples using single pollution index/Contamination Factor (CF) and Pollution Load Index (PLI) indicated medium elevation in pollution status in all the soil samples investigated. The significant values of some heavy metals in the crops suggest bio-accumulation due to the uptake of the metals from the soil. The ratio of the metal concentration in the soil to the crops indicated that there is high potential for the transport of heavy metals through the food chain. The levels of Pb, Cu, and Zn were found to be significantly high in both soils and crops when compared to other metals in the entire sampling locations though within the World Health Organization standards of 2 mg/kg, 36mg/kg and Zn 50mg/kg. The result obtained in this study is an indication that continued consumption of crops in the studied area poses severe health risk to the community. The crops cultivated within the mining area are unfit for human consumption and should be discouraged while the use of plant species with ability to bio-accumulate heavy metals should be cultivated as a bioremediation strategy.