TDS-Eh graph analysis: a new water quality index and rural water supply implications of a river affected by mining in south-eastern Nigeria

Abstract

The Ivo River Basin of south-eastern Nigeria is a water scarce and mining region, which suffers from water scarcity. The influence of mining activities on the quality of the Ivo River and its capacity for community water supply was investigated. Also the efficacy of TDS-Eh graph in explaining water quality was presented. Results indicated that the TDS-Eh graph highlights subtle chemical relationships which control water quality and provide a simple but generic pollution index for rapid water quality assessment. It was also discovered that the Ivo River could become an adequate alternative to groundwater as a source of rural water supply in the study area with an estimated average daily discharge of 6726000 L and a rural population of less than 200000 persons. The Ivo River meets the WHO drinking water standards in 20 physicochemical water quality parameters (pH, temperature, conductivity, turbidity, salinity, TDS, Eh, alkalinity, chloride, nitrate, sulfate, phosphate, calcium, magnesium, iron, manganese, zinc, lead and cadmium) analyzed and can therefore (with little treatment) provide up to 133.4% of average community water demand and 83.8% of maximum community water demand. The impact of mining on Ivo River quality was found to have been moderated by the presence of carbonate rocks which may have enhanced the precipitation of heavy metals from the river.