Impact of upstream industrial effluents on irrigation water quality, soils and plant in Alakia Area of Ibadan

Abstract

Knowledge of irrigation water quality is critical to predicting, managing and reducing salt affect on soils. The study assessed the effect of industrial effluents on irrigation water quality, soils and plant tissues in Ibadan, Southwest Nigeria. The degree of pollution was evaluated using Sodium adsorption ratio, pH, cations – Cl and NO₃ and 4 heavy metals including Pb, Cu, Cd and Zn using standard procedures. The study established the presence of High pH (pH= 6.65) that caused high alkalinity leading to high SAR of 11.1 which is as a result of calcium and magnesium ions forming insoluble minerals leaving sodium as the dominant ion in solution. Presence of heavy metals in concentration higher than the recommended limits in irrigation water samples analyzed with Cd (0.05 ppm), Cu (0.3 ppm), Pb (0.03 ppm) and Zn (4.0 ppm) in the study location. It was concluded that Eleshin stream and the surrounding ground water is fit for irrigation in relation to sodium hazard, although it is acidic, thus enhancing leaching and corrosive tendencies of the irrigation water. High level of heavy metals in the soil indicated contamination from the effluent from the factories in the area. Plant sampled indicated the presence of higher level of Pb and Cd in the tissues of leaf and roots than that of the reference samples.

Keywords: Pollution, discharge, effluent, irrigation, SAR, heavy metals