ASSESSMENT OF HEAVY METAL CONTAMINATION IN IRRIGATION WATER, SOIL AND VEGETABLES AT FARIN GADA FARMLANDS, JOS NORTH, PLATEAU STATE, NIGERIA.
Urban irrigation farming contributes significantly to food supply in Nigerian cities but may pose environmental and public health risks due to the use of contaminated surface waters. This study evaluated the levels of selected heavy metals in irrigation water, soil, and vegetables from two irrigation farmlands, Before First Bank (BFB) and Before Permanent Site (BPS), in Farin Gada, Jos North, Plateau State, Nigeria. Samples of irrigation water, soil, and commonly cultivated vegetables were collected in February and analysed for Arsenic, Lead, Cadmium, Chromium, Copper, and Nickel using Atomic Absorption Spectrophotometry following aqua regia wet acid digestion. Irrigation water from BPS recorded higher concentrations of As (0.726 mg/L), Cd (0.394 mg/L), and Cu (0.254 mg/L) compared with BFB, with As and Cd exceeding FAO permissible limits at both sites. Heavy metal concentrations in irrigated soils were significantly elevated relative to control soils collected approximately 200 m away, indicating strong anthropogenic enrichment. BPS soils contained particularly high levels of Ni (27.44 mg/kg), Cu (70.95 mg/kg), As (49.00 mg/kg), Cd (20.58 mg/kg), and Cr (20.19 mg/kg). Pollution indices revealed severe contamination: Contamination Factor and Enrichment Factor values indicated pronounced anthropogenic impact; the Geo-accumulation Index classified soils as moderately to strongly polluted, while Pollution Load Index values were 39.61 (BFB) and 7.69 (BPS), indicating severe soil pollution at both sites. Vegetables analysed (Brassica oleracea var. capitata, Daucus carota, Lycopersicon esculentum, and Spinacia oleracea) showed variable heavy metal accumulation, with leafy and root crops recording higher Cd and As levels, often exceeding recommended food safety limits. These findings demonstrate a clear contamination pathway from irrigation water to soil and edible vegetables, highlighting potential health risks associated with urban irrigation farming in Farin Gada.
Keywords: Farin Gada, heavy metals, pollution indices, soil contamination, urban irrigation, vegetables
*Correspondence: gurumyenk@unijos.edu.ng; 08064567897
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