Bioavailability of heavy metal load in soil, groundwater, and food crops manihot esculenta and carica papaya in dumpsite environment

Abstract

The need for consciousness of the impact of heavy metal on crop production and human health risk through policy formulation necessitated the study. Screening of the total heavy metal iron (Fe), nickel (Ni), cadmium (Cd), lead (Pb), chromium (Cr), and copper (Cu) concentration in soils collected at random at a depth of 0–30 cm within and around dumpsite environment in Ikhueniro, Iguomo, and Okhuahe suburban communities, Benin City, Nigeria was carried out. Cassava tubers, Pawpaw pods (manihot esculenta and carica papaya) cultivated and groundwater within and around the dumpsite environment were also tested for the selected heavy metal. The study employed integrated scientific methods in actualizing its aim. The results show that mean values of 520.97 ± 1.66 mg/kg Fe, 39.07 ± 0.33 mg/kg Ni, 1.41 ± 0.10 mg/kg Cd, 1.92 ± 0.00 mg/kg Pb, 1.24 ± 0.02 mg/kg Cr, and 24.97 ± 5.16 mg/kg Cu were recorded for soil. On the other hand, 127.00 ± 2.01: 22.36 ± 1.20 mg/kg Fe and 5.70 ± 2.11: 0.98 ± 1.11 mg/kg, respectively, amongst other metals measured in cassava and pawpaw. The results were compared to Standard Organization of Nigeria (SON), National Food and Drug Administration Control (NAFDAC), and Food and Agricultural Organisation/World Health Organisation (FAO/WHO) standards; it was observed that Fe, Ni, and Pb exceeded the threshold values for metal concentration in soil and drinking water. Policy formulation restricting farming and drilling of boreholes within the locus of dumpsite environment is advocated to fostering the attainment of green environment for sustainable development and public consciousness of the detrimental effects of heavy metals on human health.