Reactive Transport Models (RTMs) provide quantitative tools to analyze the interaction between transport and biogeochemical processes in subsurface environments such as aquatic sediments and groundwater flow. A tremendous amount of research has shown the role and impact of scaling behavior of the reactive systems which stems from geologic heterogeneity. Depending on the kinetics of the reactions, different types of formulations have been proposed to describe reactions in RTMs. We introduce a novel quantitative criteria on the range of validity of local equilibrium assumption (LEA) in aquatic sediments with irreversible heterogeneous sorption reactions. Then we present a one-dimensional (1-D) early diagenetic module, MATSEDLAB, developed in MATLAB. The module provides templates for representing the reaction network, boundary conditions and transport regime, which the user can modify to fit the particular early diagenetic model configuration of interest. We describe the theoretical background of the model and introduce the MATLAB pdepe solver, followed by calibration and validation of the model by a number of theoretical and empirical applications. Finally, we introduce a new pore-scale model using lattice Boltzmann (LB) approach. It uses an iterative scheme for the chemical transport-reaction part and recent advances in the development of optimal advection-diffusion solvers within the lattice Boltzmann method framework. We present results for the dissolution and precipitation of a porous medium under different dynamical conditions, varying reaction rates and the ratio of advective to diffusive transport (Pe, Peclet number) for linear reactions. The final set of calculations considers sorption reactions on a heterogeneous porous medium. We use our model to investigate the effect of heterogeneity on the pore-scale distribution of sorption sites and the competition between three different sorption reactions.

Volume 34 of Reviews in Mineralogy focuses on methods to describe the extent and consequences of reactive flow and transport in natural subsurface systems. Since the field of reactive transport within the Earth Sciences is a highly multidisciplinary area of research, including geochemistry, geology, physics, chemistry, hydrology, and engineering, this book is an attempt to some extent bridge the gap between these different disciplines. This volume contains the contributions presented at a short course held in Golden, Colorado, October 25-27, 1996 in conjunction with the Mineralogical Society of America's (MSA) Annual Meeting with the Geological Society of America in Denver, Colorado.

Open system behavior is predicated on a fundamental relationship between the timescale over which mass is transported and the timescale over which it is chemically transformed. This relationship describes the basis for the multidisciplinary field of reactive transport (RT). In the 20 years since publication of Review in Mineralogy and Geochemistry volume 34: Reactive Transport in Porous Media, RT principles have expanded beyond early applications largely based in contaminant hydrology to become broadly utilized throughout the Earth Sciences. RT is now employed to address a wide variety of natural and engineered systems across diverse spatial and temporal scales, in tandem with advances in computational capability, quantitative imaging and reactive interface characterization techniques. The present volume reviews the diversity of reactive transport applications developed over the past 20 years, ranging from the understanding of basic processes at the nano- to micrometer scale to the prediction of Earth global cycling processes at the watershed scale. Key areas of RT development are highlighted to continue advancing our capabilities to predict mass and energy transfer in natural and engineered systems.

This research-based book provides a mathematical approach based on stochastic calculus which describes state-of-the-art information regarding porous media science and engineering - prediction of dispersivity from covariance of hydraulic conductivity (velocity). The complication is of great significance for tracer examination, for improved recovery by injection of miscible gases, etc. The book elucidates a generalized mathematical model and efficient numerical methodologies that may greatly affect the stochastic porous media hydrodynamics. It begins with a descriptive basic analysis of the complication of scale dependence of the dispersion coefficient in porous media. Furthermore, relevant topics of stochastic calculus which would be helpful in modeling are discussed subsequently. An in-depth elaborative discussion regarding the development of a generalized stochastic solute transport model for any provided velocity covariance without conferring to fickian expectations from laboratory scale to field scale is also illustrated in this book. The mathematical approaches described in this book will serve as useful solutions for several other complications associated with chemical dispersion in porous media.

This book provides a unified and comprehensive overview of physical explanations of the stochastic concepts of solute transport processes, important scaling issues, and practical tools for the analysis of solute transport.

Over the past several decades, analyses of solute migration in aquifers have widely adopted the classical advection-dispersion equation. However, misunderstandings over advection-dispersion concepts, their relationship with the scales of heterogeneity, our observation and interest, and their ensemble mean nature have created furious debates about the concepts' validity. This book provides a unified and comprehensive overview and lucid explanations of the stochastic nature of solute transport processes at different scales. It also presents tools for analyzing solute transport and its uncertainty to meet our needs at different scales. Easy-to-understand physical explanations without complex mathematics make this book an invaluable resource for students, researchers, and professionals performing groundwater quality evaluations, management, and remediation.