The Impact of Galena Mining in North-Eastern Nigeria on Nearby Food Crops

Aims: To investigate and evaluate trace elements concentration in soils and bioaccumulation on food crops grown on agricultural fields around galena mine area, Wukari, north eastern Nigeria.

Study Design: The studied area is situated in the northwestern part of Wukari Local Government Area of Taraba State, North-East Nigeria. The hydrology of the area is conducive for the cultivation of crops and fresh water for fishing. The soils and food crops samples were collected in the month of May, 2018.

Methodology: Edible parts of plants such as leaf, stem and seed were collected from Soybeans (Glycine max), Guinea corn (Sorghum bicolor), Millet (Penniselum typhoides), Spinach (Amaranthus) and Tomato (Lycosipinus esculentum). A 1.00 g of the finely ground soil samples were digested with 10 mL of aqua regia (a mixture of 1:3 HNO3/HCl v/v) at 70°C on hot plate for 3 hours in a fume hood and 1.00 g of each sieved plant samples were digested with 10 mL mixture of HNO3: HCIO4 in the ratio 5:1 at 90°C for 30 minutes in a fume cupboard.

Results: The concentrations (µg/g DW) of the trace elements in soil are in the order Mn > Fe > Se > Pb > Cr > Cu > Al > As. The bio-accumulation of trace elements in all food crops were in the range: Se (0.250 – 20.88 µg/g DW), Al (0.250 – 0.980 µg/g DW), As (0.070 – 0.620 µg/g DW) and Pb (0.020 – 0.090 µg/g DW). Cr, Cu, Pb, Mn concentrations in food crops were above FAO/WHO permissible limits of 2.30, 40.0, 0.30, 500 µg/g DW respectively.

Conclusion: The Health Risk Index of As, Cr and Fe in spinach and Guinea corn were > 1. The study revealed that food crops grown on farmlands around mining areas are not safe for consumption.