Index-Based Assessment of Groundwater Vulnerability, Metal Pollution and Human Health Risk: A Case Study of Oghe Area, Southeastern Nigeria
Abstract
Groundwater resources (GWR) are among the most important sources of freshwater for human populations. Assessing groundwater for pollution and protecting it from contamination is crucial, as remediation of contaminated groundwater is challenging. Given the limited freshwater resources, the presence of coal, and the heavy reliance on a few accessible sources, assessing the vulnerability and pollution status of groundwater in the Oghe area is critical. Vertical electrical sounding (VES) was conducted at 20 locations to collect field data for estimating geohydraulic parameters and generating vulnerability indices using manual and computer modeling techniques. Physicochemical analysis was carried out using the American Public Health Association standard methods (APHA) on eight groundwater samples from different locations in the study area. To assess the potential toxic elements (HM) pollution index and the health risks (HR) associated with its consumption, Atomic Absorption spectrophotometer (AA-7000 Shimadzu, Japan) was used. The VES results revealed four to five geoelectric layers, with twelve characteristic curve types with resistivity range of 59.6 Wm (VES 7) to 2445.4 Wm for the topmost (VES 1). The third and fourth layers were observed as the aquifer layers in different study locations with its resistivities varying from 135.8 Wm to 79552.1 Wm and 803.7 Wm to 14457.1 Wm respectively. The dynamic intrinsic vulnerability index classified the study area into moderate and high-vulnerability categories. The hydraulic conductivity ranged from 0.01 m/day (VES 5) to 3.968 m/day (VES 1), porosity ranged from 25.686 % (VES 5) to 31.567 % (VES 1), tortuosity values ranged from 0.284 (VES 1) to 0.301 (VES 5). The permeability values estimated in two different units ranged from 0.003 m2 (VES 5) to 1.017 m2 (VES 1) and from 21.253 mD (VES 5) to 8571.435 mD (VES 1). Physicochemical analysis showed that the groundwater is slightly acidic (pH 5.8) to slightly alkaline (pH 7.1). The metal index and Nemerow's pollution index classified the groundwater in all the locations as highly polluted (Class V). Additionally, the results of non-carcinogenic and carcinogenic risk assessments indicated high chronic health risks with in Iwollo Oghe I, Iwollo Oghe II and Amansiodo Oghe groundwater revealing a high chronic risk of the fourth level with target hazard indices of 42.943, 41.327, and 34.386 for children and 17.24, 16.591 and 13.805 for adult respectively. Children are more vulnerable due to unique behavior, higher metabolic rates, and immature detoxification systems. Elevated THI in children as observed around Neke Oghe II, suggests increased risk for neurological disorders, developmental problems, and chronic illness, as they absorb pollutants like lead up to 40% more efficiently than adults. Arsenic, which contributed the most to the THI, is known to enter groundwater through several means, especially through natural processes, though human activity accelerates its release and through coal mining. All these processes are common within the study area. These observations could be used as a signpost to the inhabitants and health professionals in formulating measures that will help to preserve the quality of groundwater in Oghe area. It is also strongly recommended that urgent steps should be taken by the relevant authorities to remediate the polluted zone.
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References
- 1. Bhatia SC. Environmental pollution and control in chemical process industries. Delhi: Khanna Publishers; 2009. 181–193 p.
- 2. Alum OL, Okoye CO, Abugu HO. Quality assessment of groundwater in an agricultural belt in eastern Nigeria using a water quality index. African J Aquat Sci [Internet]. 2021 Jul 3;46(3):304–18. Available from:
. - 3. Biswas T, Pal SC, Saha A, Ruidas D, Islam ARMT, Shit M. Hydro-chemical assessment of groundwater pollutant and corresponding health risk in the Ganges delta, Indo-Bangladesh region. J Clean Prod [Internet]. 2023 Jan;382:135229. Available from:
. - 4. Jaydhar AK, Chandra Pal S, Saha A, Islam ARMT, Ruidas D. Hydrogeochemical evaluation and corresponding health risk from elevated arsenic and fluoride contamination in recurrent coastal multi-aquifers of eastern India. J Clean Prod [Internet]. 2022 Oct;369:133150. Available from:
. - 5. National population commission (NPC) (2006) Nigeria national census population distribution by sex, state, LGAs and senatorial district 2006 census priority tables (Vol. 3). - references - Scientific research publishing [Internet]. [cited 2023 Mar 9]. Available from:
. - 6. Rezaei A, Hassani H, Hassani S, Jabbari N, Fard Mousavi SB, Rezaei S. Evaluation of groundwater quality and heavy metal pollution indices in Bazman basin, southeastern Iran. Groundw Sustain Dev [Internet]. 2019 Oct;9:100245. Available from:
. - 7. Wang L, Tao Y, Su B, Wang L, Liu P. Environmental and health risks posed by heavy metal contamination of groundwater in the sunan coal mine, China. Toxics [Internet]. 2022 Jul 12;10(7):390. Available from:
. - 8. Ekpete KI, Igbo PE, Abugu HO, Onwuka SO, Obasi NL, Okoye CO. Appraisement of groundwater quality status within Enugu, Nigeria, using physicochemical evaluation and water quality indices. African J Aquat Sci [Internet]. 2024 Jan 2;49(1):64–74. Available from:
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Details
Primary Language
English
Subjects
Quality Assurance, Chemometrics, Traceability and Metrological Chemistry
Journal Section
Research Article
Authors
Ngozi Agatha Okwesili
This is me
0000-0002-0248-0189
Nigeria
Emmanuel Tochukwu Omeje
This is me
0009-0001-6662-3230
Nigeria
Hillary Abugu
*
0000-0002-6045-8449
Nigeria
John Akor
0000-0002-9812-5295
Nigeria
Francisca Okeke
0000-0002-8819-8861
Nigeria
Publication Date
June 11, 2026
Submission Date
January 27, 2026
Acceptance Date
April 30, 2026
Published in Issue
Year 2026 Volume: 2026 Number: 2
