A multi-index appraisal and pollution risks of cadmium enrichment and corrosivity in the cretaceous Abeokuta formation, Ayetoro, Nigeria

Abstract Efficient groundwater monitoring is crucial for public health, especially in self-supplied communities like Ayetoro. This study comprehensively assessed groundwater contamination and corrosivity in fifteen water sources (11 shallow hand-dug wells and 4 drilled wells) within the Abeokuta Formation, Nigeria. The assessment utilized physicochemical, ionic, and metal analyses, along with pollution assessment metrics; Contamination factor ( $$C_{f}$$ ), Degree of Contamination ( $$C_{deg}$$ ), Geo-accumulation Index ( $$I_{geo}$$ ), Enrichment Factor ( $$EF$$ ), and the Langelier Saturation Index ( $$LSI$$ ) to measure contamination, enrichment, and water stability. Results showed slightly acidic pH, attributable to geogenic carbonate weathering and ion exchange. All samples exceeded the World Health Organization cadmium (Cd) acceptable threshold (0.003 mg/L), ranging 0.0032–0.0219 mg/L. Pollution index analyses confirmed significant to extremely severe Cd contamination ( $$C_{f}$$ and $$EF$$ values notably high, including $$EF$$ up to 80.4) across the section of Ayetoro, which can be linked to agricultural land use patterns, fertilizer inputs, and geogenic enrichment through the carbonate-rich lithology of the Abeokuta Formation. Furthermore, all sites recorded negative $$LSI$$ (− 5.3 to − 2.7), indicating corrosive water that can damage distribution infrastructure. These findings provide critical, nuanced insight into the extent of combined geogenic and anthropogenic groundwater contamination, particularly concerning metal enrichment and corrosivity. They underscore an urgent need for targeted water resource management strategies, including establishing site-specific Cd monitoring thresholds and implementing remediation approaches such as phytoremediation using metal-accumulating plants, protection of aquifer recharge zones from agricultural runoff, and deployment of low-cost household filtration systems, to safeguard public health and ensure a sustainable groundwater supply in Ayetoro and similar vulnerable regions.