Accumulated Potentially Toxic Metals in Soil, Irrigation Water, and Edible Part of Selected Vegetables Along Dambo Dam, Jigawa State Nigeria

Even though heavy metals are important plant nutrients when grown on contaminated soil or irrigated with polluted water, plants accumulate high levels of heavy metals and if consumed, negative health consequences occur. In this study, the accumulated potentially toxic metals in the edible part of selected vegetables, soil, and irrigation water along the Dambo Dam of Jigawa state, Nigeria were assessed using the AAS method. Additionally, the translocation factor, the Monomial Ecological Risk (Eir), and the potential ecological risk index of these potentially toxic metals on the selected vegetables were evaluated. The result revealed that the concentrations of these potentially toxic metals in water, soil, and vegetables are in the order Mn Pb Zn Ni Cd Cu, except for lettuce where Pb was found to be higher than Mn. Furthermore, the concentrations of Zn, Mn, Cd, Pb, Cu, and Ni were all within the permissible limits set by World Health Organization. All the samples analyzed contained high levels of these metals, indicating evidence of contamination, which may be due to anthropogenic activity. The monomial ecological Risk (Eir) of these metals in lettuce is in the order; Cd Pb Ni Zn Mn. While for cabbage, the order is Cd Ni Pb Zn Mn. The Eir of Zn and Mn are within the Low-Risk values of Eir ˂40, and that of Cd is the range of 160 ≤ Eir ˂320, considered very high, in both lettuce and cabbage. Whereas, Ni and Pb in cabbage are within 40 ≤ Eir ˂ 80, considered a Moderate Risk. The highest Potential Ecological Risk Index (RI) was observed to be 400.24 in cabbage and 284.55 in lettuce, which is deemed very dangerous, as it is above the range of 200 ≤ RI ˂ 400.