Soil Quality Assessment in Mining and Non-Mining Sites of Edo North, Edo State: Implications for Environmental Conservation

Abstract

Mining activities in Ikpeshi, Edo North, present a major environmental challenge with implications for soil health and agricultural sustainability. The study investigated the concentrations of heavy metals, physicochemical parameters, and enzyme activities in soils around Ikpeshi mining sites in Akoko Edo LGA and Iyamho in Etsako West, Edo State, Nigeria. Soil samples (0–20 cm) were analyzed using Atomic Absorption Spectroscopy (AAS) and standard laboratory procedures. The tested null hypothesis that says there is a negative
correlation between heavy metal concentration and soil biological activity. The soil quality assessment revealed significant differences between sites. Ikpeshi soils exhibited a lower pH (5.68), reduced organic matter (2.89%), and diminished cation exchange capacity (8.80 meq/100g) compared to Iyamho soils. Enzyme activities, including urease, dehydrogenase, and amylases, were markedly suppressed in Ikpeshi, indicating impaired microbial functioning. Heavy metal analysis showed extreme contamination in Ikpeshi soils, with elevated
levels of Cd (11.32 mg/kg), Ni (14.00 mg/kg), Cr (13.10 mg/kg), Pb (8.80 mg/kg), and Hg (11.40 mg/kg), far exceeding background levels in Iyamho. The results revealed that the mean metal content in the two soil samples was ordered as: Fe > Co > Ni > Cr > Cd > Hg > Pb > Cu > Mn > Zn > As. This research provides an integrated soil quality assessment quantitatively linking physicochemical degradation, heavy metal contamination, and suppressed enzymatic activity with the broader risks of reduced fertility, food insecurity, and ecological vulnerability in a mining context.