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<p>This study investigates soil leachate contamination at a dumpsite in Ikare-Akoko, southwestern Nigeria. This investigation combines regression-based geohydraulic parameters, non-destructive geophysical (electrical resistivity tomography (ERT) and Schlumberger vertical electrical soundings (VES)), geochemical and engineering-geological methods . Eight ERT profiles and eight VES points were used to determine subsurface resistivity distribution, while twelve soil samples from four trial pits at varied vertical depths (0.5&#xa0;m, 1.0&#xa0;m and 1.5&#xa0;m) were analyzed for engineering-geological and geochemical tests. VES inverted models revealed four lithologic layers with HA, AA and KH curve types while ERT models revealed that most traverses showed probable leachate plume accumulation, with resistivity values of &lt; 40 Ωm, reaching an average depth of 3.0&#xa0;m. Geochemical data showed that the concentrations (mg/kg) of Na (7.45–19.85), Ca (5.375–15.065), Cr (0.039–0.110), Pb (0.006–0.031), Mn (0.012–0.092) and Zn (0.024–1.004) in soils were within permissible limits for agricultural purpose only. Additionally, the compaction (MDD) and permeability properties of the soil samples revealed fair to good strength ratings with a low-medium infiltration rate (1.67 × 10<sup>–5</sup>—7.00 × 10<sup>–5</sup>&#xa0;cm/s). The geohydraulic parameters: longitudinal conductance (0.000294–0.095271 mhos) and aquifer vulnerability index (-0.1612 to -0.051806) showed that the near surface soil had poor protective capacity against leachate infiltration. Human health risk assessment revealed negative health implications while pollution indices (geo-accumulation index (I<sub><i>geo</i></sub>) and contamination factor (CF)) suggested moderate to very high pollution levels, confirming the presence of leachate plumes identified by ERT models at the sampling depth. Regression analysis identified three strong positive correlations (CF-Fine, Igeo-Fine and MDD-Res) indicating high pollution levels in fine-grained soils. Based on these findings, proactive measures such as impermeable liners and leachate collection systems should be implemented to mitigate the impacts of leachate plumes on the environment.</p>

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Geophysical and geoenvironmental assessment of open dumpsite leachates on near-surface soil and health risk hazards

  • 期刊论文

  • 发表日期：

    2025年9月16日

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  • Temitayo Olamide Ale

摘要

This study investigates soil leachate contamination at a dumpsite in Ikare-Akoko, southwestern Nigeria. This investigation combines regression-based geohydraulic parameters, non-destructive geophysical (electrical resistivity tomography (ERT) and Schlumberger vertical electrical soundings (VES)), geochemical and engineering-geological methods . Eight ERT profiles and eight VES points were used to determine subsurface resistivity distribution, while twelve soil samples from four trial pits at varied vertical depths (0.5 m, 1.0 m and 1.5 m) were analyzed for engineering-geological and geochemical tests. VES inverted models revealed four lithologic layers with HA, AA and KH curve types while ERT models revealed that most traverses showed probable leachate plume accumulation, with resistivity values of < 40 Ωm, reaching an average depth of 3.0 m. Geochemical data showed that the concentrations (mg/kg) of Na (7.45–19.85), Ca (5.375–15.065), Cr (0.039–0.110), Pb (0.006–0.031), Mn (0.012–0.092) and Zn (0.024–1.004) in soils were within permissible limits for agricultural purpose only. Additionally, the compaction (MDD) and permeability properties of the soil samples revealed fair to good strength ratings with a low-medium infiltration rate (1.67 × 10–5—7.00 × 10–5 cm/s). The geohydraulic parameters: longitudinal conductance (0.000294–0.095271 mhos) and aquifer vulnerability index (-0.1612 to -0.051806) showed that the near surface soil had poor protective capacity against leachate infiltration. Human health risk assessment revealed negative health implications while pollution indices (geo-accumulation index (Igeo) and contamination factor (CF)) suggested moderate to very high pollution levels, confirming the presence of leachate plumes identified by ERT models at the sampling depth. Regression analysis identified three strong positive correlations (CF-Fine, Igeo-Fine and MDD-Res) indicating high pollution levels in fine-grained soils. Based on these findings, proactive measures such as impermeable liners and leachate collection systems should be implemented to mitigate the impacts of leachate plumes on the environment.