Hydrogeochemistry and microbial diversity assessment of anthropogenic activities on a suburban ecosystem within Ibadan, SW Nigeria
摘要
Leachates from hotspots related to anthropological activities, such as unregulated dumpsites and abattoir-effluents, can adversely affect the hydrogeochemistry of surface and groundwater and microbial community within the environment. Some selected hotspots were studied to assess the influence of anthropological activities within the Akinyele ecosystem, a sub-urban settlement in Ibadan, Oyo State, Nigeria. Water samples were analysed for physicochemical parameters including pH, EC, and TDS, and for major anions and cations. For the microbial characterisation, isolates were prepared from soil and water samples from which colonies of bacteria and fungi were enumerated and identified. Physical properties of the water samples, measured in situ, revealed pH values from 5.7 to 7.5 (av. 6.5), Total Dissolved Solid (TDS) from 45 mg/l to 1294 mg/l (av. 506 mg/l), and Electrical Conductivity (EC) from 30 µS/cm to 1790 µS/cm (av.700 µS/cm). Values recorded were, mostly, below the allowed World Health Organisation (WHO) limits except for a few instances where lower pH and higher TDS, possibly linked to released-leachates around the market area, were observed. For the water chemistry, compositions (mg/l) of major ions (Ca2+, Mg2+, Na+, K+) and major anions (Cl−, SO42−, NO3−, and CO32−) were analysed ion chromatography at the SMO Laboratories in SW Nigeria. Average values of Ca+2 (37.5 mg/l), Mg+2 (1.1 mg/l), and Na+ (22.1 mg/l) were within their respective WHO (2022) limits except for values obtained for K+. Similarly, safe levels were observed for the anion concentrations. Hydrogeochemical facies suggest predominantly calcium-bicarbonate and alkali/alkaline earth-chloride water types while the water quality index indicated generally good to excellent quality, with one sample located south of the market classified as fair. Microbial diversity and enumeration showed relatively high bacterial and fungal densities in waste-impacted soils. The coexistence of decomposer taxa, faecal indicators, and opportunistic pathogens may reflect localised ecological stress associated with anthropogenic activities.