Bioaccumulation potential of heavy metals in leaves of Amaranthus hybridus L.) and Telfaria occidentalis Hook. f. from selected vegetable farms within Akure metropolis

Anthropogenic activities and indiscriminate waste disposal constitutes a threat to the environment. The bioaccumulation potential of copper (Cu), zinc (Zn), lead (Pb), Manganese (Mn) and Cadmium (Cd) were investigated in two leafy vegetables; Amaranthus hybridus L (Green Amaranth) and Telfaria occidentalis Hook. f. (Fluted Pumpkin) and in the soil of selected vegetable farms within Akure metropolis, Ondo State, Nigeria. This is with the aim of determining the concentration of heavy metals in these leafy vegetables and in their corresponding soil and also to determine their safety levels relative to the tolerable limits recommended for heavy metals by World Health Organization (WHO) and Food Agricultural Organization (FAO). Vegetable and soil samples were collected randomly from selected sampling sites, prepared and digested according to standard protocols recommended by the American Public Health Association. The concentrations of heavy metals present in the vegetable and soil samples were determined using Atomic Absorption Spectrophotometer (AAS). Findings from this study revealed that the concentration of Cu, Zn, Mn and Cd in both Fluted Pumpkin and Green Amaranth were below the permissible limit recommended by WHO/FAO. The concentration of Pb in Amaranthus hybridus L. and Telfaria occidentalis Hook. f. sampled from the markets are 0.390-0.400 mg/kg respectively while their concentration in vegetables sampled from farms are 0.000-0.600 mg/kg and 0.000-0.590 mg/kg respectively. Hence, the concentration of Pb. In both vegetable species sampled from selected markets and vegetable farms were above the threshold of 0.300 mg/kg recommended by WHO/FAO. However, the concentrations of heavy metals in the soil of vegetable farms were below the standard limits recommended by WHO/FAO and National Environmental Standard and Regulation Enforcement Agency (NESREA).