Evaluation of soil quality and heavy metals in Manihot esculenta and Musa paradisiaca grown on reclaimed mined lands in the Bogoso/Prestea area, Ghana

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The study was conducted at Golden Star Bogoso/Prestea Ltd. catchment to evaluate soil quality and heavy metals in cassava and plantain grown on reclaimed mined lands. Soil and crop samples were collected from four reclaimed sites of ages 1, 5, 12 and 15 years and two reference sites. The samples were analysed for physico-chemical parameters (pH, conductivity, organic matter, organic carbon, nitrate, phosphate, sulphate, chloride, exchangeable bases) and heavy metals (Cu, Zn, As, Cd, Pb, and Hg) using standard methods. It was observed that age of reclamation significantly influenced chloride, conductivity, exchangeable base, nitrate and soil pH. Sulphate was highest (23.6 mg/kg) in the 5 year site and least (5.5 mg/kg) in the 12 year site. Conductivity and chloride were observed to be lowest (95.0 μS/cm and 3.9 mg/kg) in the 1 year site while the reference site recorded the highest of (333.3 μS/cm and 10.3 mg/kg) respectively. Exchangeable bases ranged from 18.8 - 1.6 meq/100g for the 12 year and 1 year site respectively. The older reclaimed sites both recorded the highest pH of 7.3. Arsenic content ranged from 5.1 - 21.4 mg/kg for the 12 and 15 year sites respectively. The reference site registered the highest cadmium of 3.5 mg/kg, while copper ranged from 53.7 – 83.9 mg/kg for the sites. Zinc and manganese levels of 331.7 mg/kg and 256.5 mg/kg were highest in the 12 year and 15 year sites respectively. Heavy metals in crops were within maximum WHO/FAO permissible threshold except iron (24.5-25.8 mg/kg). Arsenic, cadmium, lead and mercury were not detected.
A thesis submitted to the Department of Environmental Science, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements of Master of Science degree in Environmental Science.