1.1 Introduction
Groundwater is defined as water that occupies the pores, fractures, and voids in underground rock formations, constituting a major source of freshwater for domestic, agricultural, and industrial use (Fetter, 2018). It is a critical natural resource that supports human livelihoods, especially in areas where surface water is scarce or seasonal. The quality and availability of groundwater are influenced by both natural processes, such as geological formations and hydrological cycles, and anthropogenic activities, including industrial operations, agricultural practices, and urban development (Todd & Mays, 2005). Water contamination occurs when physical, chemical, or biological substances are introduced into water resources in concentrations that pose a risk to human health, ecosystems, or industrial processes (Khan et al., 2020).
This chapter will address the background information that motivated this study, the challenges that prompted it, its aim, and its objectives as a preface to subsequent sections of the study. Additional factors include the study's significance, scope, limitations, research questions and hypotheses, and the definition of technical terms.
1.2 Background of Study
The study of groundwater contamination has evolved over several decades, driven by the need to understand the sources, pathways, and impacts of pollutants on subsurface water systems. According to Fetter (2018), the recognition of groundwater as a critical source of freshwater dates back to the early 20th century when urbanization and industrialization began to place unprecedented demands on water resources. Early investigations primarily focused on chemical analyses of water samples to determine the presence of contaminants such as nitrates, heavy metals, and organic pollutants (Todd & Mays, 2005). Over time, it became evident that traditional hydrochemical methods alone were insufficient for a complete understanding of subsurface contamination. Researchers reported that contaminants often migrate through complex geological formations, making it difficult to accurately map pollution using surface water sampling alone (Khan et al., 2020).
Reynolds (2011) stated that resistivity methods measure the ability of the subsurface materials to resist electrical current, enabling the identification of zones of high moisture, leachate, or contamination (Reynolds, 2011). Groundwater is an essential source of freshwater that supports domestic, and industrial activities, particularly in areas where surface water is insufficient or seasonal. According to Fetter (2018), groundwater exists within the pore spaces and fractures of subsurface geological formations and plays a crucial role in sustaining ecosystems and human settlements.
Todd and Mays (2005) reported that the quality of groundwater is influenced not only by natural geological and hydrological processes but also by anthropogenic activities, including industrial operations, agricultural runoff, and urban development. Khan et al. (2020) asserted that heavy metals, alkaline effluents, and particulate matter from industrial processes can infiltrate the soil and subsurface water, potentially contaminating aquifers. MDPI (2022) stated that cement manufacturing operations generate dust, wastewater, and solid waste that may alter the physicochemical properties of surrounding water resources and suitability for human consumption.
Studies conducted around industrial sites in Nigeria have affirmed that groundwater near cement factories may show elevated levels of electrical conductivity, turbidity, pH, and concentrations of heavy metals, thereby posing risks to both human health and agricultural productivity (Ameh et al., 2022). Egbelelulu et al. (2020) contend that traditional hydrochemical assessments alone are insufficient to determine the full spatial extent of groundwater contamination, emphasizing the need for geophysical investigations such as the Electrical Resistivity Method. This method involves measuring the subsurface resistance to electrical current, which allows for the identification of contaminant plumes and the characterization of aquifer vulnerability. Reynolds (2011) reported that resistivity surveys provide reliable information on subsurface heterogeneity and the depth and extent of potential pollution, complementing hydrochemical data for comprehensive groundwater assessment.
In the Obajana area, where the Dangote Cement Plant operates, local communities are heavily reliant on groundwater sources for drinking, farming, and other daily activities. According to Ameh et al. (2022), contamination from industrial effluents, dust deposition, and surface runoff poses a significant threat to groundwater sustainability. On the other hand, the application of geophysical methods in Nigeria is limited in scope, with few studies integrating electrical resistivity data and hydrochemical analysis to map pollution pathways comprehensively (Mepaiyeda et al., 2021). This study is set against the backdrop of the increasing need to evaluate groundwater contamination around industrial zones and provide robust data for environmental management and sustainable water resource utilization in Obajana.
1.3 Statement of Problems
Investigation revealed that there is growing concern about the quality and safety of these groundwater sources, particularly in areas influenced by industrial activities such as the Dangote Cement Plant in Obajana, one of Africa's largest cement manufacturing facilities. Previous studies around Obajana have shown physicochemical parameters of groundwater that in some instances exceed recommended thresholds for parameters such as turbidity, dissolved oxygen, electrical conductivity, and phosphate, suggesting potential stress on water quality related to industrial operations and environmental processes (Ameh et al., 2022).
Additionally, cement factories are known to produce a range of pollutants including dust, effluents, and heavy metals that are capable of affecting surface and subsurface water systems. The production processes generate particulate matter and solid waste, and runoff from facilities may introduce sediments and contaminants into the surrounding environment. These contaminants, whether through direct discharge or via rain driven transport, have the potential to infiltrate shallow aquifers, altering geochemical conditions and posing risks to human and ecological health (MDPI, 2022).
Furthermore, existing research around other industrial and landfill sites in Nigeria shows that resistivity surveys are effective at delineating contaminant movement and vulnerability of aquifers, highlighting differences in resistivity that correspond to leachate intrusion, lithologic variations, and groundwater flow dynamics (Mepaiyeda et al., 2021). It is against this backdrop that this study seeks to assess the extent and nature of groundwater contamination around Dangote Cement, Obajana, using Electrical Resistivity Method to provide robust geophysical evidence for environmental management and sustainable groundwater protection.
1.4 Aim and Objectives of Study
The aim of the study is to assess the extent of groundwater contamination using the Electrical Resistivity Method in the area surrounding Dangote Cement, Obajana. In achieving this aim, the following specific objectives were laid out as follows:
- To determine the extent and severity of groundwater contamination around Dangote Cement, Obajana.
- To map the subsurface contaminant plumes using Electrical Resistivity Method.
- To identify areas within the aquifer that are most vulnerable to contamination.
- To provide recommendations for sustainable groundwater management in the study area.
1.5 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- What is the extent and severity of groundwater contamination around Dangote Cement, Obajana?
- How are subsurface contaminant plumes distributed as revealed by the Electrical Resistivity Method?
- Which areas of the aquifer are most vulnerable to contamination?
- What measures can be recommended to ensure sustainable groundwater management in the study area?
1.6 Research Hypothesis
In order to pursue the objective of this study, the following generalized statements have been designed to guide and aids in obtaining the result for the experiment to be conducted. For this work, the null hypothesis will be represented with H0 while the alternative hypothesis will be represented with hypothesis H1.
Hypothesis One
- H0: There is no significant contamination of groundwater around Dangote Cement, Obajana, as determined by the Electrical Resistivity Method.
- H1: There is a significant contamination of groundwater around Dangote Cement, Obajana, as determined by the Electrical Resistivity Method.
Hypothesis Two
- H0: Groundwater around Dangote Cement, Obajana, is not significantly contaminated, and the Electrical Resistivity Method is able to identify subsurface contaminant plumes.
- H1: Groundwater around Dangote Cement, Obajana, is significantly contaminated, and the Electrical Resistivity Method is able to identify subsurface contaminant plumes.
1.7 Significance of Study
It is believed that at the completion of the study, the findings will provide reliable data for environmental monitoring, policymaking, and enforcement of water quality standards. Also, the findings will raise awareness about groundwater safety and inform residents about areas at risk of contamination.
Furthermore, the study will guide policymakers and industrial operators in implementing effective strategies for groundwater protection and sustainable resource utilization. In addition, the research will guide responsible waste management practices and environmental compliance measures.
Lastly, the study will contribute to knowledge on the application of Electrical Resistivity Method in groundwater contamination studies.
1.8 Scope of Study
The scope of the research is focused on groundwater contamination in Kogi State, Nigeria, specifically within and around the premises of Dangote Cement, Obajana. It will assess subsurface contamination using the Electrical Resistivity Method, combined with hydrochemical analysis, to evaluate water quality, identify pollution pathways, and determine aquifer vulnerability. The study is limited to selected boreholes and wells within a defined radius of the cement plant.
1.9 Limitations of the Study
A study of this nature is bound to experience certain problems as such the constraints imposed on the research include:
- Time Constraints: A study of this nature needs relatively long time during which information for accurate or at least near accurate inference could be drawn. The period of the study was short, time posed as constraints to the research.
- Financial Constraints: The research would have extended the survey to other area at the empirical level, but limitation as included cost of transportation to the source of material and the cost of time setting of the already completed work.
1.10 Definition of Terms
Groundwater: Water that exists beneath the earth's surface in soil pore spaces and rock formations, serving as a major source of freshwater for domestic, agricultural, and industrial use (Fetter, 2018).
Groundwater Contamination: The presence of pollutants, including chemicals, heavy metals, and pathogens, in groundwater at concentrations that pose a risk to health or ecosystems (Khan et al., 2020).
Electrical Resistivity Method: A geophysical technique used to measure the resistance of subsurface materials to electrical current, which helps to identify contaminant plumes, water-bearing layers, and variations in subsurface lithology (Reynolds, 2011).
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