Chapter 8 Fate and Effects of Pollutants on the Land Environment

This chapter discusses initially the different pathways (soils, sediments, water, and air) through which contaminants are transported and become available to organisms and people posing health risks. The concept of bioavailability, the physical, chemical, and biological processes that define the exposure of plants and animals to chemicals is discussed as it relates to different scientific disciplines. Inorganic and organic contaminants can be retained in soils and sediments, and hence not available to living organisms under variable conditions. The chapter details further the main mechanisms of retention of different classes of chemicals, the conditions under which they can be immobilized or become mobile and travel within the water, and the type of soil material that can react and retain chemicals. The chapter discusses also the ecotoxicological hazard potential of contaminants by detailing their most important physicochemical, fate and effect parameters, and some of the methods to determine them. Calculations are also provided through the hazard quotient risk tool for persistent organic pollutants (POPs), which enables risk-based analyses to prioritize and manage POPs and other hazardous substance contaminated sites. Finally, the chapter concludes with a discussion on particulate matter, its sources and health effects, and ambient air quality standards

Chapter 5 Groundwater

This chapter presents an introduction to the basic concepts and developments in the study of flow of water in the subsurface environment. The importance of groundwater as a natural freshwater reserve and for the public health is initially described. The relation between groundwater extraction and land subsidence is discussed, as well as the problems of coastal saltwater intrusion. Subsequently, an exposition is presented of the basic groundwater flow equations that include Darcy\u27s law and the continuity equation. Flow in fractured rocks is briefly discussed together with the cubic law that describes the velocity in such media. The concept of the effective hydraulic conductivity is introduced through the flow in stratified aquifers, followed by the mathematical exposition of one-dimensional (1-D) flow in confined and unconfined aquifers. Applications are provided for the cases of flow through earth dams, aquifers under rain, and groundwater flow to streams. The final part of this chapter introduces some basic concepts and solutions from well hydraulics. Steady-state flow to wells in confined and unconfined aquifer, the method of images, and De Glee\u27s solution for leaky aquifers are presented. The chapter concludes with an exposition of issues related to construction dewatering

Chapter 7 Soil and Contaminant Interaction

This chapter provides details of the complex interactions of the soil constituents and the chemicals that may exist in situ or find their way into a soil. These interactions have important implications for studies and predictions of the movement of contaminants in the subsurface environment as adsorption and other soil-contaminant binding mechanisms may affect the hydraulic conductivity of a geologic medium. Whereas the binding of chemicals on soils solid surfaces may render groundwater remediation techniques ineffective, other chemical and biological processes can provide natural attenuation of contaminated sites. The chapter begins with the commonly used methods to determine the amount of a solute bound by matrix surfaces by Freundich and Langmuir isotherms, together with a discussion of the S-, L-, H-, C-curve isotherms, as well as more advanced descriptions of multicomponent adsorption. Subsequently, the theories by Gouy-Chapman and Stern are presented together with detailed calculations of the electrical charges on the surface of clays, in the Stern layer and the diffuse layer. A brief introduction of first- and second-order kinetics is presented, followed by a detailed exposition of metal cation adsorption, organic contaminant-soil interaction, and of the biological processes that may lead to natural attenuation

Chapter 1 Geoenvironmental Engineering in a Global Environment

The global environmental problems and the demographic problem, which are the focus of the geoenvironmental engineering practice, and the actions toward restoration of the environment are the subjects of this chapter. In seeking solutions to restore the degradation of the environment, we need to consider the interconnecting nature of the various ecosystems and be aware of the developments in various allied disciplines and how these may impact on developing and implementing sound engineering solutions to various environmental problems. The impact of the exploitation and utilization of the natural systems by nations on the depletion of natural resources; elimination of species; flora and fauna local and regional changes; and deterioration of the environment through solid and liquid waste, air and water pollution, and by greenhouse gases is summarized with case studies from around the world. It is also highlighted that the impacts upon the natural systems vary geographically, depending on the existing states of both the natural environment and the economy, but in many cases these impacts extend to a regional or even a global scale. This chapter also discusses evidences of global environmental impacts such as: (a) pollution of air, land, and water, due to accidents during the transportation of oil or other products by ship, plastic debris in the rivers and oceans, effluent discharge into fresh water bodies; (b) water scarcity and degradation; (c) growing quantities of wastes as a result of chemical product utilizations in all human activities, from agriculture to medicine, to energy and industrial and manufacturing processes, to everyday products; (d) trans-boundary movement of hazardous waste; (e) acid rain; (f) deforestation and land degradation; (g) desertification and soil erosion; (h) depletion of the ozone layer; and (i) the decreasing species of wildlife. The greatest emphasis is given here to global warming and climate change, where, according to all scientific evidence the question no longer is if, but how abruptly a global climate change will happen. Several examples are provided of the most recent information on glaciers and ice sheets melting, extremes in the hydrologic cycle, rise in sea temperature and level, and flora and fauna changes as result of the global warming. This chapter also provides references and excerpts from important national and international conventions and legislation regarding the topics addressed. We further discuss the interconnections between global environmental problems and highlight the importance of the following: 1. Current processes are characterized by a nonlinear behavior and we lack the scientific understanding to predict what alterations in one would entail for another process. This means that we do not know the tipping point, which when reached changes can become unpredictable and the magnitude and impact of events may not be of the same order of what was experienced in the past. 2. If the present generation does not come up with adequate protective measures and solutions, and the environment continues to deteriorate on a global scale, many unpredictable events of large scale can eventually be faced by the next generation altering drastically its living conditions. Therefore it is urgent to comprehensively step up conservation efforts of the global environment, with a far-reaching long-term perspective that transcends the generations. 3. Development of solutions to restore the degradation of the environment is complicated by the interconnecting nature of the various ecosystems, i.e., atmosphere, hydrosphere, geosphere, and biosphere that constitute the land. This means that a cooperative and holistic global effort should be considered in developing a viable solution to global environmental problems. 4. Global environmental issues interlock in forming a group of issues which, with the joint cooperation of the international community, need to be comprehensively addressed under a broad and long-term perspective. It is important that all nations take up conservation of the global environment as an important policy task and take initiatives in realizing sustainable development on a global scale. All of the above pose great challenges to modern geoenvironmental engineers as they need to expand significantly their traditional knowledge base and professional role to consider as integral part of their activities an assessment of projects\u27 impact on ecosystems, air, water, and land, and in many cases, consider this beyond a limited, local level. We hope that this chapter aids in this goal of promoting a new definition of geoenvironmental engineering that is urgently needed to address current needs

Chapter 9 Subsurface Contaminant Transport

The mathematical description of groundwater flow, contaminant transport and diffusion through porous media, can be found in many textbooks devoted to the development of governing relationships and solution of the relationships subject to various initial and boundary conditions. The success of the mathematical modeling and the numerical analysis is highly dependent on the quality of the input data and the accuracy in the representation of the physical, chemical, and biological interactions with the transporting fluid and contaminants. In the absence of proper representation, model predication will continue to render unreliable results. Therefore, in this chapter we are concerned with the examination of contaminant transport from the viewpoint of how realistic the models are in representing the physical problem under investigation. The basic physical mechanisms by which miscible (soluble) and immiscible (nonsoluble) contaminants are transported in the subsurface environment were examined. Examples of various analytical models for column experiments, chemical spills, and chemical plumes from continuous releases of contaminants were discussed. In addition, the basic types of apparatus (rigid and flexible wall permeameters) used for the determination of hydraulic properties in laboratory testing were discussed. Experimental techniques (batch equilibrium and soil column leaching) used to determine the adsorption characteristics in the laboratory were examined. The laboratory methods (steady and transient states) used to estimate the transport parameters of chemical species diffusing through waste containment barriers were discussed. The common procedures used to calculate the transport parameters such as decreasing source concentration, time-lag method, and root time method were described and evaluated. The contaminant transport modeling of soluble and nonsalable contaminants using the second postulate of irreversible thermodynamics was presented. Finally, due to variability in parameters and variables in the governing transport equations, it becomes important to treat a variable (e.g., the head or the flux in groundwater flow problems, or the concentration in transport problems) not as a single deterministic solution, but into its mean, variance, and covariance function, or other high-order statistical moments. On that basis, the main issues in stochastic modeling of contaminant transport in soils were highlighted

Chapter 11 Stability and Safety of Engineered Barrier Systems for Waste Containment

The current chapter analyzes different engineered measures that are put in place in landfills to safeguard the environment and the population health from release of wastes. The functions and types of covering systems are initially presented. Subsequently, the basic components of the covering systems are discussed providing details about the physical, chemical, and environmental parameters that need to be attended in different climatic and geologic conditions. The engineered barriers in the mining waste industry are further presented together with the dry, water, and organic barrier concepts that are employed for various wastes. The different types of lining systems are analyzed with emphasis on the design and construction requirements, and the properties and potential problems of clay liners, owing to the widespread use of clay as a landfill barrier. Newer types of liners, such as soil-cement and sulfur-polymer cement and concrete are detailed in terms of their capacity to absorb and retain certain chemicals from the environment, as well as their behavior under harsh conditions. Finally, the flexible membrane liners are expounded in terms of their type and performance, and the chapter concludes by presenting the control and monitoring requirements of landfills in the United States and the European Union

Chapter 12 Radioactive Waste Disposal: Hosting Environment, Engineered Barriers, and Challenges

Radioactive material is being used in many aspects of our life, from medicine to energy generation and to weapon systems. The increasing energy needs and the quest for clean energy makes it very likely that the use of radioactive material will expand in the 21st century together with the need to safely dispose nuclear waste. This chapter provides a brief overview of the issues related to the disposal of radioactive waste, which depending on the material may require isolation from the environment and human populations of tens to hundreds of thousands of years. The basic elements of near-surface disposal facilities used for the disposal of short-lived low-level radioactive waste (SLLW) and intermediate-lived low-level radioactive waste (ILLW) are initially discussed. Subsequently, the chapter concentrates on the various geologic environments and technological solutions used, in several countries, for the disposal of high-level radioactive waste (HLW), providing also the background for the multiple measures taken for the safe disposal of HLW. Particular emphasis is given to the experience of United States and Canada because they represent emplacement in two contrasting geologic environments, the former sitting the repository in the unsaturated, and the latter in the saturated zone. The Canadian experience is discussed in detail as the use of the clay buffer and emplacement in the saturated zone represents an approach that is common to many countries, as a consequence of their difficulty to locate a desert, low precipitation, and remote location, as that of the Yucca Mountain in the United States. Given the need to contain HLW for 1 million years, as mandated in the United States, the chapter also discusses some of the challenges to attempt to make scientific predictions at such time frames and the need to rely on the natural barriers of the hosting environment rather than the engineered barriers

Chapter 4 The Soil System

Soil is a multicomponent system consisting of solid, liquid, and gaseous phases, and living organisms. The solid phase of soils consists of both inorganic and organic components. Inorganic components exert a tremendous effect on the physical and chemical properties, such as cation exchange capacity and surface area, and on the overall suitability of soil as a barrier for waste containment. The organic components, although normally present in much smaller quantities than inorganic components, may significantly alter the soil properties. The variability of these separate soil components and pore fluid chemistry will impact the nature of solid-pore fluid interaction mechanisms, adsorption capacity, and fluid transport properties such as hydraulic conductivity, diffusion, and dispersion. These mechanisms and properties are important in evaluating the fate of chemical substances in the terrestrial ecosystem and in determining the proper clay mixture for designing waste containment barrier systems. From a soil cleanup viewpoint, evaluation of the effectiveness of a decontamination procedure can be achieved from a closer consideration of how the pollutants are retained in the organic and inorganic solid phases. This chapter provides the background of the attributes and characteristics of the soil system, which are pertinent to its utility as a waste retention and/or decontaminating agent

Chapter 17 Advances in the Determination of Soil Moisture Content

This chapter discusses some advanced methods that are used to extract information from electrical signals, and how this could be used to predict soil moisture content. A brief explanation of what is meant by signal and various signal processing techniques, either by summation of elemental signals (synthesis) or by decomposition into elemental signals (analysis), is discussed. To demonstrate the synthesis methods, pulse and sinusoid signals are applied; whereas, for decomposition analysis, both time domain and frequency domain analyses are discussed. In frequency domain analysis of signals the use of the Time Domain Reflectometry (TDR) and Fourier spectral analysis to predict soil moisture content and salt concentration is demonstrated. Unlike Fourier decomposition, which partitions signals based on harmonic frequencies by using parametric sines and cosines, eigen-decomposition analysis, separates signal components by differences in their power. These methods are applied in several case studies for the determination of soil moisture content, soil density, clay content, salt concentration, and organic fluid content. In addition, a Neuro-Fuzzy Logic method of analysis, which simply uses both neural networks and fuzzy logic, is discussed. To demonstrate the use of this method to predict soil moisture content, the changes in spectral magnitude and phase angle of the tested soil systems were considered as specific signatures for different soil conditions and were used to train Neuro-Fuzzy Logic models. This method of analysis provided a powerful design technique that combines the ability to learn from data sets, the transparent representation of knowledge acquired, and the ability to cope with uncertainties