Includes bibliographical references and index.

"This book examines mathematical modeling and computer simulations that estimate the distribution of chemical contaminants in environmental media in time and space. Discussing various modeling issues in a single volume, this text provides an introduction to a specific numerical modeling technique called the compartment approach and offers a practical user's guide to the GEM. It includes the Generic Environmental Model (GEM) software package, which implements the techniques described. The author presents algorithms for solving linear and nonlinear systems of algebraic equations as well as systems of linear and nonlinear partial differential equations"-- Chapter 1 Introduction -- 1.1 GEM Highlights -- 1.2 Getting Started: Two Examples -- 1.3 Organization and Suggested Reading Strategy -- Chapter 2 GEM User's Guide -- 2.1 Two Alternative Formulations of PRAM-Like Model -- 2.2 GEM Input Files -- 2.3 GEM Output files -- Chapter 3 Compartment Approach, Transport Mechanisms, and Boundary Conditions -- 3.1 Compartment Approach -- 3.2 Mass Balance Equation for Compartment i -- 3.3 System of Transport Mass Balance Equations for Single Chemical -- 3.4 System of Transport Mass Balance Equations for Multiple Chemicals -- 3.5 Extension to Porous Media -- 3.6 Boundary Conditions and Types of Compartments -- Chapter 4 Source and Sink Terms -- 4.1 Linear Source and Sink Terms -- 4.2 System of Fate and Transport, Mass Balance Equations for Multiple Chemicals -- 4.3 Source and Sink Terms for Nonlinear Systems -- Chapter 5 Solution Techniques for Steady-State Problems -- 5.1 Linear Systems -- 5.2 Nonlinear Systems -- 5.3 Accuracy of Solutions -- Chapter 6 Solution Techniques for Dynamic Problems -- 6.1 Introduction -- 6.2 Explicit Forward Time (Euler) Method -- 6.3 Explicit Centered Time (MacCormack) Method -- 6.4 Implicit Back Time Method -- 6.5 Implicit Centered Time (Crank -- Nicolson) Method -- 6.6 Cross-Method Comparisons and Summary of Error Characteristics for Linear Problems.