Physico-Chemical Assessment of Water Quality in the Gidan Gulbi Shallow Floodplain Aquifer, Northwestern Nigeria

摘要

Water quality of shallow floodplain aquifers in the Gidan Gulbi Fadama area of Gada, Sokoto State, Nigeria was assessed using water quality pollution indices for both irrigation and domestic use. Drinking water quality was assessed using pollution indices including concentration factor (CF), contamination degree (CD) and heavy metal pollution index (HPI), while irrigation water quality parameters such as sodium adsorption ratio (SAR), magnesium adsorption ratio (MAR), soluble sodium percentage (SSP), Kelly ratio (KR), residual sodium carbonate (RSC), permeability index (PI) and total hardness (TH) were used to evaluate the suitability of the water for irrigation purposes. Five heavy metals (Fe, Zn, Mn, Cr, and Cd) were selected to be assessed alongside other inorganic elements. The CF shows low intensities of contamination for Mn, Cr, and Zn while Fe and Cd have high and very high contamination intensities respectively. The results of CD and HPI indicate moderate to high contamination in the study area. The Fe most likely originates from the surrounding rocks of Taloka Formation, during fluid-rock interaction while the high degree of Cd contamination suggests an anthropogenic source. Given the land use pattern in the study area, the most likely source of the anthropogenic Cd is from pesticides, herbicides and fertilizers utilized for agricultural purposes. The areas with highest intensity of contamination (GW2, GW4 and GW7) are within or proximal to farmlands, consistent with the earlier inferred anthropogenic (agriculture) source for the major heavy metal pollutant (Cd). Furthermore, all of the water in the study area falls within the Ca-Mg/HCO3 type as revealed by the piper diagram and Schoeller plots, moreover, except for the total hardness (with a mean level of 253.13 mg/l), all other irrigation quality parameters suggest that the water is suitable for irrigation.