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Nigeria's free digital learning hub. Videos, lecture notes, practice questions and leaderboards aligned with CCMAS, NBTE, NCCE, WAEC, NECO, IJMB and JAMB curricula.
Geophysics · 400 Level
This is the complete lecture note for GPH 414 Environmental Geophysics, prepared for Geophysics students at 400 Level. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS COURSE CODE:GPH 414 COURSE TITLE: Environmental Geophysics COURSE UNIT LOAD (2 Units C: LH 30) • Foundations of Environmental Geophysics and Earth Science Concepts. • Geophysical Techniques in Environmental Pollution Studies. • Saline Water Intrusion and Groundwater Quality Mapping. • Geophysical Investigation of Chemical Pollution and Industrial Contamination. • Oil Spillage, Pollution Delineation, and Environmental Mapping. Part 1.1 Environmental geophysics within earth science. • Core earth science concepts relevant to environmental studies • Scope and definition of environmental geophysics • Relevance of geophysics to environmental problem-solving Part 1.2 Environmental processes and pollution pathways. • Natural and anthropogenic environmental processes • Types and sources of environmental pollution • Behaviour and movement of contaminants in the subsurface Part 1.3 Role of geophysical techniques in environmental investigations. • Physical principles underlying geophysical methods • Relationship between subsurface properties and environmental conditions • Overview of geophysical applications in environmental studies Introduction Environmental geophysics is an applied branch of geophysics that uses earth science principles and geophysical techniques to investigate environmental problems affecting the subsurface. These problems include pollution arising from human activities and natural processes that impact soil, groundwater, and near-surface geological materials. Because many environmental hazards are hidden beneath the ground surface, indirect geophysical methods provide valuable information for understanding subsurface conditions without extensive excavation or disturbance. The aim of this Series is to introduce you to the foundations of environmental geophysics and the essential earth science concepts that support its application to environmental investigations. We shall commence this Series by examining the place of environmental geophysics within the broader field of earth science, focusing on its definition, scope, and relevance to environmental problem-solving. We will then consider key environmental processes and pollution pathways, highlighting how contaminants are introduced into the environment and how they move through the subsurface. Finally, the Series will provide an overview of the role of geophysical techniques in environmental investigations, emphasising how variations in subsurface physical properties are used to detect and assess environmental conditions related to pollution and groundwater quality. Series learning outcomes
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Upon completing this Series, you should be able to: • SLO 1.1 explain the scope of environmental geophysics within the context of earth science and environmental studies. • SLO 1.2 describe key environmental processes and identify major types and sources of environmental pollution affecting the subsurface. • SLO 1.3 analyse how contaminants move through soil and groundwater systems using earth science principles. • SLO 1.4 explain the role of geophysical techniques in detecting, assessing, and monitoring environmental conditions related to pollution and groundwater quality. 1.1 Environmental Geophysics within Earth Science 1.1.1 Core earth science concepts relevant to environmental studies Earth science refers to the group of scientific disciplines that study the Earth as a system, including its physical structure, materials, processes, and interactions with the environment. In environmental studies, earth science concepts help explain how natural systems operate and how human activities disturb these systems, particularly in the near-surface environment. Key earth science concepts relevant to environmental geophysics include the nature of soils and rocks, groundwater systems, and surface–subsurface interactions. These elements control how contaminants enter the ground and how they are stored or transported underground. For example, porous soils allow fluids to move more easily than compact rocks, influencing the spread of pollutants. Understanding these basic earth science principles provides the foundation for applying geophysical techniques to environmental problems. Fill in the blank: Earth science provides the basic understanding of how the __________ system operates and responds to natural and human influences. [Insert figure here] Short description: Earth systems relevant to environmental studies Figure 1.1: Major components of the Earth system relevant to environmental geophysics Suggested AI prompt: Create a simple diagram showing soil, rock, groundwater, and human activities interacting within the Earth system 1.1.2 Scope and definition of environmental geophysics Environmental geophysics is the application of geophysical methods to investigate environmental problems, particularly those related to pollution, groundwater quality, and near-surface contamination. It focuses on detecting and characterising subsurface features that may pose risks to human health or the environment. The scope of environmental geophysics includes mapping contaminated zones, identifying saline water intrusion, locating chemical pollution at industrial sites, delineating pollutant plumes, and assessing groundwater quality. Unlike traditional exploration geophysics, which often targets deep structures, environmental geophysics concentrates on the shallow subsurface where environmental hazards are most likely to occur.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Because direct subsurface excavation is expensive and disruptive, environmental geophysics provides a non-invasive and cost-effective approach to environmental investigation. Pause and reflect: Environmental geophysics focuses mainly on the __________ subsurface environment. [Insert plate here] Short description: Environmental geophysics applied to near-surface investigations Plate 1.1: Use of geophysical surveys to investigate shallow environmental problems Suggested AI prompt: Create an illustration showing geophysical instruments investigating shallow subsurface contamination 1.1.3 Relevance of geophysics to environmental problem-solving Geophysical techniques are highly relevant to environmental problem-solving because many environmental hazards cannot be seen directly at the ground surface. Contaminants such as chemical plumes, saline water intrusion, and oil spills often spread underground, making detection and monitoring difficult using surface observations alone. By measuring variations in physical properties such as electrical resistivity or conductivity, geophysical methods help identify areas affected by pollution and distinguish contaminated zones from clean subsurface materials. These methods support environmental assessment, remediation planning, and long-term monitoring of pollution impacts. The ability of geophysics to provide continuous subsurface information over large areas makes it an essential tool in modern environmental management. Fill in the blank: Geophysical methods assist environmental problem-solving by providing __________ information about subsurface conditions. [Insert table here] Table 1.1: Role of geophysical techniques in environmental investigations [Insert table placeholder here] Short description: Examples of environmental problems and associated geophysical approaches Suggested AI prompt: Generate a table linking environmental problems to geophysical investigation methods Pilot questions 1.1 1. What is meant by earth science in the context of environmental studies? 2. Define environmental geophysics. 3. State two environmental problems investigated using geophysical techniques. 4. Why does environmental geophysics focus mainly on the near-surface? 5. Explain one reason why geophysics is important for environmental problem-solving. 1.2 Environmental Processes and Pollution Pathways 1.2.1 Natural and anthropogenic environmental processes
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Environmental processes are the physical, chemical, and biological activities that occur within the Earth system and influence the condition of the environment. These processes may be natural or human-induced. Natural processes include weathering of rocks, groundwater flow, erosion, and natural geochemical reactions, which operate continuously even in the absence of human activity. Anthropogenic processes arise from human actions such as industrial operations, waste disposal, agriculture, mining, and urban development. These activities can introduce contaminants into the environment or intensify natural processes, leading to environmental degradation. For example, excavation and construction may disrupt soil structure, while industrial discharge can alter groundwater chemistry. Distinguishing between natural and anthropogenic processes is important in environmental geophysics because it helps in identifying the origin of observed subsurface anomalies. Fill in the blank: Environmental processes may be natural or __________, depending on whether they arise from human activity. [Insert figure here] Short description: Natural and anthropogenic environmental processes Figure 1.2: Examples of natural and human-induced environmental processes affecting the subsurface Suggested AI prompt: Create a diagram showing natural processes such as weathering and groundwater flow alongside anthropogenic activities such as industrial discharge and waste disposal 1.2.2 Types and sources of environmental pollution Environmental pollution refers to the introduction of substances or energy into the environment that cause harm to ecosystems, human health, or natural resources. Pollution may occur in solid, liquid, or gaseous forms and may be introduced intentionally or unintentionally. Common sources of environmental pollution include industrial effluents, petroleum products, agricultural chemicals, landfill leachate, and domestic waste. In the subsurface environment, pollutants frequently include hydrocarbons, heavy metals, saline water, and chemical solvents. These contaminants may enter soil and groundwater systems through leaks, spills, infiltration, or improper waste disposal practices. Identifying the type and source of pollution is a critical step in environmental investigation because it influences the choice of geophysical techniques and the interpretation of survey results. Pause and reflect: Industrial effluent, oil spillage, and landfill leachate are examples of __________ sources of environmental pollution. [Insert plate here] Short description: Common sources of environmental pollution Plate 1.2: Major anthropogenic sources of soil and groundwater pollution Suggested AI prompt: Create an illustration showing industrial sites, oil spills, and landfills as sources of subsurface pollution
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS 1.2.3 Behaviour and movement of contaminants in the subsurface Once pollutants enter the ground, their subsurface behaviour is controlled by physical, chemical, and biological interactions with soil, rock, and groundwater. Contaminants may move vertically through infiltration or laterally with groundwater flow, forming polluted zones known as plumes.
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