Groundwater Pollution Problems Research Articles

Weighted Finite Difference and Boundary Element Methods Applied to Groundwater Pollution Problems

The purpose of the paper is to apply two methods to groundwater pollution in porous media. The methods are the weighted finite difference method and the boundary element method, which were proposed or developed by Kanoh et al. (1986,1988) for advective diffusion problems. Numerical modeling of groundwater pollution is also investigated in this paper. By subdividing the domain into subdomains, the nonlinearity is localized to a small region. Computational time for groundwater pollution problems can be saved by the boundary element method; accurate numerical results can be obtained by the weighted finite difference method. The computational solutions to the problem of seawater intrusion into coastal aquifers are compared with experimental results.

Soak-away Systems and Possible Groundwater Pollution Problems in Developing Countries

People in the developing countries do not have adequate sanitation and everyone defaecates somewhere. Those who do not have a toilet or latrine have to resort to indiscriminate defaecation either in the sea shore such as in the Lagos lagoon in Nigeria, or vacant plots and open drains as in Iddo area of Lagos and sides of rural footpaths. Water closets (W.C.s) are the most accepted sanitation system, but the cost of operating and maintaining them is high. As a result sewerage is not appropriate for the majority of people in developing countries whose greater population live in rural areas and small towns. The majority of people in urban areas use septic tanks and very often most of these septic tanks are not properly designed or sometimes located too close to sources of water supply, which then become contaminated. It is generally believed that systems like septic tanks, pit latrines and aqua privies are capable of totally eliminating these pathogens. There are many problems associated with the physical, chemical and biological processes that may result in groundwater pollution from septic tanks. Many experiments have shown that faecal organisms do not travel any significant distance radially as a result of concentration gradient. They are, however, carried with groundwater flow. The task is to prevent pathogens from getting into the aquifer. This paper attempts to highlight the ability of some enteric viruses to survive septic tank wastewater treatment.

Industrial Impact on the Quality of Groundwater in a Large Basin: Case of the Rhine Aquifer

ABSTRACT Proliferation and intensification of industrial and agricultural activity have created pollution of the natural environment. This has made itself felt both at the level of surface water, in soils, and in the very vulnerable groundwater. What distinguishes the problems ofgroundwaterpollution from those of surface water is primarily the time scale. Pollution takes many forms (physical, chemical, organic, thermal, toxic, radioactive,…) and its consequences vary according to the nature and function of the polluted medium. Furthermore, it is appropriate to distinguish two types of pollution: that which results from specific sources and which can be localized easily, and that which is the result of latent and diffuse contamination. Examples are presented relating to industrial pollution by dissolved salts and toxic substances (micro-pollutants) as well as to the impact of gravel pits or accidents.

Groundwater Pollution: Environmental and Legal Problems

Groundwater contamination is now receiving long‐overdue attention from scientists, engineers, water managers, politicians, environmental groups, and the general public. As these diverse groups begin to grapple with the causes and effects of and remedies for groundwater contamination, each must acquire at least a basic understanding of the physical, biomedical, and legal problems and processes that influence groundwater management decisions. Groundwater Pollution: Environmental and Legal Problems is a short, useful book that (from the preface) …highlights the methodological and conceptual difficulties inherent in protecting the nation's groundwater supplies and provides up‐to‐date information on groundwater hydrology, the nature and extent of the groundwater pollution problem, and the possible effects of exposure to contaminated drinking water.

Groundwater Contamination From Hazardous Wastes

Preparation of a good introductory textbook on groundwater contamination is a challenge, since it requires treating a complex topic in a scientifically rigorous way while maintaining an introductory level. Of necessity, tradeoffs must be made to achieve this objective and brevity as well. Another difficulty arises because research into the fate of chemicals in the subsurface is a relatively new and evolving area. The authors of this book note that, “In the investigation and analysis of a groundwater pollution problem involving hazardous wastes, there is no established method or procedure.” Despite this handicap, the authors do succeed in demonstrating that although any given case of contamination is unique, it is possible to identify common attributes and outline a general framework for monitoring and remedial action.

The influence of vadose zone conditions on groundwater pollution: Part I: Basic principles and static conditions

The significance of the vadose soil zone (i.e., above a water table) is of the utmost importance in groundwater pollution problems. Much of this zone is unsaturated, such that fluid movement and contaminant attenuation conditions are favorable for mitigation of aquifer pollution. In this paper, the basic principles of moisture retention and the implications for leachate control are described in a state-of-the-art format. To illustrate the use of these concepts six generalized examples are presented. They cover a wide range of practical situations, including: • vadose zone storage • land treatment of wastewater and sludges • waste dewatering • hydrocarbon spill storage • capillary break situations • air and water drainage under liners Since this paper treats only the static condition, a companion paper will be offered shortly dealing with leachate flow and seepage in a wide range of applications.

Dispersion in Three Dimensions: Approximate Analytic Solutions

Solutions to three-dimensional convection dispersion equation under different boundary conditions are obtained by integrating the appropriate Green's functions. Two approximations are used during the integration. First, error function differences are approximated by exponential functions through Taylor expansion. Second, the time integral is approximated by Laplace method. The error introduced due to these approximations is analysed and discussed. The pollution source is assumed to be an arbitrary function of time and of finite size in space. The boundary conditions considered are of a stream in a horizontal flow field and a water table in a vertical flow field. Such solutions have potential use in quick preliminary analysis of groundwater pollution problems.

Ground-Water pollution and its sources

Everybody wants clean water for drinking, bathing and other domestic uses, but not everybody appreciates the fact that our own actions are often the worst enemy in achieving that goal. Ground water is one of the most misused and misunderstood resources. Because ground water and its movement, and consequently also its pollution, is hidden from view beneath the land surface, the seriousness of ground-water pollution problems has not been recognized until recently.

A Graphical Approach to Prediction of Groundwater Pollutant Movement

Important to any analysis of a potential or actual groundwater pollution problem is the ability to predict when and where any pollutant may interface with the biologic realm. It is also necessary to know the amounts that may appear at an outflow boundary over a period of time. Thus a geography-time distribution and a geography-quantity distribution can assist decision-makers in evaluating and comparing different waste disposal schemes. A graphical procedure based upon flow net analysis coupled with vector analysis permits estimation of pollutant arrival times at an outflow boundary. The procedure also aids in determination of variations of pollutant concentrations across the outflow boundary with time and in space. The technique utilizes contour maps and simple graphs. Intraformational (macroscale) and interformational (megascale) aspects of groundwater pollution can be analyzed with the technique. Examples of applications to which the technique can be applied are potential groundwater contamination from a sanitary landfill leachate, the case of a leaky waste-holding pond, and the pattern of contamination from a leaky underground gasoline storage tank. The technique also can be applied in reconnaissance studies for hazardous waste site evaluation using available hydrogeologic data. Detailed site evaluation can be guided through use of the approach. It can be utilized relatively inexpensively to predict longterm, downstream effects of pollutant leakage from a disposal site.