Assessment of water quality and pollution source apportionment in Eleyele catchment area, Ibadan, south-western Nigeria

Poor water quality is becoming a global threat. This study aimed to evaluate the quality of surface and groundwater for drinking, agriculture, industry, urban, and domestic uses, and identify pollution sources in the Eleyele catchment, Ibadan, Oyo State, Nigeria. The catchment has been affected by agriculture, urbanization, industrialization, and other land use activities, which could have compromised water quality. Ten water samples were collected three times within the catchment for surface water, shallow, and deep groundwater between March and July 2019 (wet season) and October 2019 and January 2020 (dry season). The samples were analyzed for physicochemical parameters, metal concentrations, and microbial counts. Collected data were analyzed using descriptive statistics (mean and standard deviation) and inferential statistics (analysis of variance (ANOVA), principal component analysis (PCA), and Duncan Multiple Range Test) with SPSS for Windows (version 21). The seasonal assessment of water quality in the Eleyele catchment showed significant variations in various parameters like temperature, pH, EC, TS, TDS, TSS, calcium hardness, total hardness, magnesium hardness, calcium, magnesium, phosphorus, chloride, BOD, potassium, sodium, ammonium, acidity, turbidity, and total bacterial count. Differences in hydrochemistry were observed between shallow and deep groundwater and across seasons. PCA identified pollution sources as nutrient, anthropogenic, urban/traffic run-off, industrial waste, bedrock weathering, fecal pollution, organic waste, leachate, soil source, solids, and hardness. The study recommends necessary attention and treatment for water resources in this catchment, while promoting the use of groundwater from deep wells and boreholes as preferred sources for drinking, industrial, agricultural, and domestic purposes.