Assessments of Heavy Metals in Local Fertilizers in Nigeria

Sani U and Sani A

Published on: 2024-06-01

Abstract

The rapid increase of heavy metal contamination is related to the industries, agricultural, domestic and medical purposes. There is much concern over the hazardous effects of heavy metals on plants, animals and human life. Their effects mainly depend on the level of exposure, dose and chemical toxicity risk index. The town of Kankara in Katsina state is a farming and agricultural settlement with a high number of local fertilizers industries. The evaluation of toxic metals in the local fertilizers is not underestimated due to the practical implications of heavy metals to health and environment. This research is aimed to assess the level of heavy metals such as lead, arsenic, cadmium and mercury in local fertilizers. The samples were collected from four major soils that are used in making the local fertilizer. The samples were analysed using Energy Disperse X-ray Fluorescence (EDXRF) in order to determine the elemental concentration in the samples. The Atomic Absorption Spectroscopic (AAS) analysis was performed in order to determine the targeted toxic metals. The results showed that in all the four soil samples, there is presence of heavy metals. The following metal oxides and heavy metals were recorded in all the four soil samples; PbO, CuO, ZnO, MgO, Fe2O3, NiO, Fe, K, Ca, Cu, Zn, Rb, Sr, Zr and Si were found in all the 4 collected samples. The results for the Dark brown soil showed that 0.20, 0.10, 0.29, 0.10 and 0.80 mg/kg for Cu, Zn, Fe, Zr and Ga respectively. For White soil, 0.42, 0.05, 0.30, 0.20, 0.25 and 0.23 mg/kg of Fe, K, Ca, Cu, Zr and Sr were recorded. Black soil, 0.30, 0.40, 0.10, 0.05, 0.02, 0.05 and 0.08 mg/kg of Si, K, Fe, Cu, Zn, Rb and Sr were recorded. For red soil, 0.34, 0.50, 0.01, 0.10, 0.20 and 0.40 mg/kg of Si, K, Fe, Cu, Zn and Mn were recorded. The results obtained from AAS analysis showed the presence of Cu, Cd, As and Pb in all the four soil samples. The concentration is within the recommended dose limit as recommended by WHO and FAO. However, heavy metals have hazardous effects even at low concentration as revealed in the literature. The research recommends that the workers should adhere to the safety precautions during the working hours by using facemasks and google glasses. The workers should also avoid long staying and inhaling the dust from the local fertilizer.