Investigation of groundwater quality and stability nearby active municipal solid waste dumpsite in Ibadan Metropolis, Nigeria

Groundwater contamination in dumpsite-adjacent residential areas presents a critical environmental and public health issue. The current research assesses the quality status, geochemical characteristics and stability of shallow groundwater in proximity to Aba Eku dumpsite in Nigeria. During 2018, leachates and groundwater samples were collected from the DS and ten (10) shallow hand-dug wells, respectively, and analyzed for physicochemical parameters. Hydrogeochemical studies, water quality index and stability indices were employed to investigate data from physicochemical analysis. The order of cations and anions dominance in leachates is $$\text{K}^{ + } > \text{Na}^{ + } > \text{Ca}^{2 + } > \text{Mg}^{2 + }$$ and $$\text{HCO}_{3}^{ - }$$ > $$\text{Cl}^{ - }$$ > $$\text{CO}_{3}^{2 - }$$ > $$\text{SO}_{4}^{2 - }$$ > $$\text{NO}_{3}^{ - }$$ , respectively. In groundwater, the order is $$\text{Ca}^{2 + } > \text{Mg}^{2 + } > \text{Na}^{ + } > \text{K}^{ + }$$ and $$\text{HCO}_{3}^{ - }$$ > $$\text{CO}_{3}^{2 - }$$ > $$\text{Cl}^{ - }$$ > $$\text{SO}_{4}^{2 - }$$ > $$\text{NO}_{3}^{ - }$$ . The groundwater chemistry is mainly controlled by water–rock interaction, reverse ion exchange and carbonate dissolution. Water quality index values varied from very poor (10%) to poor quality for drinking water purposes (20%), with good quality dominant at most sampling sites (70%). Drinking water quality standards from both the World Health Organization and Nigeria government were not exceeded for all except total hardness. Based on stability indices. Groundwater samples show corrosive behaviour based on the average values of Puckorius scaling index (10.59), Aggressiveness index (10.98) and Chloride-to-Sulfate Mass Ratio (1.96). However, mean values of Larson-Skold index (0.14), Langelier Saturation Index (0.62) and Ryznar stability index (5.60) for groundwater samples indicate scale forming tendency. The groundwater quality can be said to be fair-good for drinking purpose at present, but should be used with caution for industrial purposes. Proper water management schemes and policies are needed to protect the shallow aquifers.