Research and publications

This study evaluates the physico-chemical, heavy metal, and microbial characteristics of groundwater from borehole well heads and groundwater in storage tanks from the University of Benin campus community and its surrounding areas, Benin City, Nigeria, to determine potential contamination sources and propose mitigation strategies. Thirty-eight samples (19 wellhead and 19 storage) were analysed for pH, electrical conductivity (EC), total dissolved solids (TDS), salinity, trace metals (Fe, Zn, Cu, Mn, Ni, Cr, Co, Pb, and Cd), and bacteriological indicators (total coliform count and Escherichia coli) using standard methods. The pH ranged from 6.04 to 8.2, while EC and TDS ranged from 68–198 µS/cm and 24–97 mg/L, respectively, below WHO/NSDWQ permissible limits. Fe concentrations (0.352–1.863 mg/L) exceeded the NSDWQ guideline value (0.3 mg/L) in all samples, and Ni exceeded the NSDWQ limit (0.02 mg/L) in 36/38 samples. Pb exceeded 0.01 mg/L in 8 samples (maximum 0.1025 mg/L), while Cd was below detection limits. E. coli was detected in 10 of 20 samples, indicating intermittent faecal contamination. Results suggest mixed geogenic (lateritic/ironstone leaching) and anthropogenic (sanitation and infrastructure-related) inputs. Mitigation strategies include enforcing the 30 m setback between boreholes and septic systems, routine tank cleaning/disinfection, and regular monitoring.

This study evaluates the Se concentration and examines the geologic controls on Se concentration in Upper Cretaceous and Palaeogene mudrocks in parts of Southern Nigeria. Geochemical analysis (major and trace elements, total organic and inorganic carbon [TOC and TIC]) and pH measurements were conducted on seventy-three mudrock outcrop samples from the estuarine Late Campanian to Mid-Maastrichtian Mamu Formation and ditch cuttings from water wells that penetrated the marine Palaeogene Imo Formation from the Anambra basin and Niger Delta basin in the Southern Benue Trough. Selenium concentration in the Palaeogene calcareous marine mudrock samples reaches up to 21 ppm, significantly exceeding data observed in the Upper Cretaceous estuarine mudrock samples. Covariation charts suggest Se adsorption onto clay, Fe-minerals, and limited sorption by organic matter in the estuarine mudrock samples, compared to adsorption onto clays, calcite, and very limited sequestration by Fe-minerals in the calcareous marine mudrocks. Principal component analysis and redundancy analysis reveal a dominant influence of carbonate minerals on selenium sequestration. The Palaeogene calcareous marine mudrock samples are less acidic (mean pH 5.92) than the Upper Cretaceous estuarine mudrocks (mean pH 5.02). Higher pH is hypothesized to slightly promote Se bioavailability, resulting in higher Se intake by plants in areas underlain by the Palaeogene calcareous mudrocks.

Ten soil samples from a spare part market at Uwelu, Benin City, and two control samples from the University of Benin were analysed for physicochemical properties and heavy metals. Principal component analysis and hierarchical clustering separated the market soils from the controls and pointed to a lead and zinc association from human activity. Contamination indices put the site in the moderate to severe range, with a Pollution Load Index of 3.87 to 5.27 and lead as the dominant contaminant, which calls for prompt monitoring and remediation.

Twelve soil samples (11 soil samples and 1 control sample) were collected to assess the level of pollution and its distribution in soils around Ifie Community, Warri South, Delta State, Nigeria, including one control sample from Federal Government College Warri. An Atomic Absorption Spectroscopy (AAS) machine (model 210 VGP) was used and seven heavy metal parameters were analyzed: iron (Fe), nickel (Ni), chromium (Cr), lead (Pb), cadmium (Cd), zinc (Zn), and Copper (Cu). The results showed: Fe (110.5–201.5 mg/kg), Ni (20.5–47.5 mg/kg), Cr (1–23 mg/kg), Pb (1–3.5 mg/kg), Zn (8–20 mg/kg), Cu (27–46 mg/kg). The heavy metal distribution pattern from highest to lowest: Fe > Cu > Ni > Zn > Cr > Pb > Cd. Cadmium was below the detection level in all samples. High Ni and Cu levels surpassed WHO target values and CONAMA prevention values, suggesting that industrial and domestic activities contribute to heavy metal pollution. The Contamination Factor (CF) and Geo-accumulation Index (GeoI) indicate moderate to considerable levels of Ni and Cu contamination, with statistical analysis showing these metals likely share a common source.