Iron Speciation in Regolith Aquifers at Enugu, Southeastern Nigeria
DOI:
https://doi.org/10.58885/ijees.v6i1.44.eoKeywords:
Iron speciation, Regolith aquifers, Redox conditions, MIcrobial interactions, etc.Abstract
This study investigates the geochemical behavior and microbial interactions influencing iron speciation in regolith aquifers across Enugu, Southeastern Nigeria. A total of 30 groundwater samples from multiple locations such as Centenary, 9th mile, Ologo, Trans-Ekulu, New-artizan and Amechi were analyzed in relation to the Fe³⁺/Fe²⁺/Hematite/Magnetite/FeO system. Eh and pH were determined using the Standard Hydrogen Electrode and a pH meter respectively. The geochemist work bench was used to determine the Eh and pH relationship as regards the iron system. From the result, majority of the samples across both datasets fall within the Fe²⁺ (ferrous iron) domain, indicating reducing to moderately reducing subsurface conditions. Only a few samples such as PWD New Market and Elshammal Estate plot within the Hematite field, suggestive of more oxidizing environments. From the findings which reflects significant microbial influence, particularly from iron-reducing bacteria such as Geobacter sulfurreducens, Shewanella putrefaciens, and Desulfovibrio desulfuricans. These microbes actively mediate the redox transformation of iron under low-oxygen conditions, promoting Fe³⁺ reduction and the persistence of soluble Fe²⁺ in groundwater. The presence of facultative anaerobes like Pseudomonas stutzeri and Bacillus subtilis further supports the role of fluctuating redox conditions in shaping iron mobility and stability. The dominance of Fe²⁺ in most aquifers highlights concerns for water quality due to increased solubility of iron and associated trace metals. In oxidizing conditions in select sites suggest localized zones of lower microbial activity or enhanced recharge. These findings underscore the complex interplay between microbial processes and geochemical conditions in regolith aquifers and offer insight into the biogeochemical factors governing iron dynamics in tropical groundwater systems.
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