Understanding the kinetics of trace metals sorption and desorption on soils is important for better prediction of metal behavior in the environment. In this dissertation, the effect of solution chemistry and soil composition on trace metal sorption and desorption kinetics was investigated. Based on the experimental results, predictive kinetics models were formulated and successfully used to describe the kinetics of trace metals sorption and desorption on a variety of soils. The kinetics experiments were conducted with a stirred-flow method. A number of soil samples, which cover a wide range of soil properties from USA and European countries, were selected to test the effect of soil composition. The effects of solution chemistry, pH, metal loadings, and dissolved organic matter (DOM) concentration, were also systematically examined. Most of kinetics experiments were run with two trace metals, copper and zinc, which demonstrated very different kinetics behaviors. The solution pH has significant effect on the Cu and Zn sorption and desorption kinetics which can be accounted by the proton competition. DOM greatly enhanced Cu release but had little effect on Zn, attributed to formation of strong Cu-DOM complex decreasing the Cu ion re-adsorption on soils. Among all soil components, soil organic matter (SOM) is the dominant phase controlling Cu and Zn sorption and desorption kinetics. The effect of residence time was also tested. The kinetics models were formulated and successfully used to describe the Cu and Zn sorption and desorption kinetics under different solution chemistry and soil compositions. The models are based on the mass balance of the flow system and incorporate the chemical reactions between metals and soils. For Zn, a two-site kinetics model, including one fast and one slow site, was necessary. The soil organic carbon (SOC) is the major model parameter accounting for the effect of soil properties on Zn sorption and desorption kinetics. The organic carbon normalized sorption rate coefficients can be applied to different soils based on their SOC concentrations. One set of rate coefficients can be applied to different influent Zn concentrations, which corresponds to the linear portion of the Zn sorption isotherm. The sorption rate coefficients were dependent on solution pH which was accounted for by Zn and proton competition. The same model parameters can be applied to different flow rates. (Abstract shortened by UMI.).

Understanding the mechanisms associated with metal complexes and the sequestering metal contaminants in the environment is essential for effective remediation. Heavy Metal Release in Soils describes and quantifies desorption/release kinetics and dissolution reactions in the release of heavy metals from soil. The book focuses on: New techniques - microscopic surface techniques, NMR and electrophoresis, XAFS, SFM, and time-resolved ATR-FTIR Theoretical analysis and kinetic approaches - adsorption/desorption hysteresis, competitive sorption and transport, multi-component models, speciation kinetics, isotherms and soil and metal parameters, and the role of soil properties on transport Applications - arsenic speciation and mobility in contaminated soils, modeling activity of CD, Zn, and Cu in contaminated soils, and in situ chemical immobilization A timely addition to the literature, this book highlights the desorption/release mechanisms for the purpose of resolving remediation dilemmas in contaminated environments. It gives you the added advantage of case studies at both the microscopic and macroscopic scales, and provides both experimental and numerical investigations. With contributions from an international panel of authors, Heavy Metals Release in Soils fills a gap in the current literature concerned with subsurface contaminant fate and transport processes.

The chapters of this book were originally presented at the Fourth International Conference on the Biogeochemistry of Trace Elements, in June 1997 at Berkeley, California. The results of that symposium are now available to assist both specialists and those concerned with broader environmental issues. The first four chapters of Fate and Transport of Heavy Metals in the Vadose Zone are devoted to sorption-desorption processes. Subjects include the kinetics of trace metal sorption-desorption, adsorption of nickel and their isotherms, cadmium reactions, and retention mechanisms of both linear and nonlinear types. The next three sections describe complexation and speciation processes. The authors consider the effect of humic and fulvic acids, the binding of copper with organic matter, and the rate of dissolved selenium. Chapters eight through eleven scrutinize the bioavailability and retention of heavy metals and their mobility in the vadose zone. Twelve details plant-available concentration levels for heavy metals in the vadose zone. The last section relates case studies that are relevant to environmental affairs. Features

The fate of heavy metal particles in the environment is important because they tend to be reactive, mobile, and highly toxic. Reactivity and Transport of Heavy Metals in Soils examines the sometimes complex interactions that occur between metals and the soil they occupy. It discusses basic kinetic concepts and covers the predictability and consequences of metal-soil interactions. This practical guide presents and explains heavy metal issues crucial to hazardous waste site cleanup, including:

Many wetlands around the world act as sinks for pollutants, in particular for trace elements. In comparison to terrestrial environments, wetlands are still far less studied. A collaborative effort among world experts, this book brings the current knowledge concerning trace elements in temporary waterlogged soils and sediments together. It discusses factors controlling the dynamics and release kinetics of trace elements and their underlying biogeochemical processes. It also discusses current technologies for remediating sites contaminated with trace metals, and the role of bioavailability in risk assessment and regulatory decision making. This book is intended for professionals around the world in disciplines related to contaminant bioavailability in aquatic organisms, contaminant fate and transport, remediation technologies, and risk assessment of aquatic and wetland ecosystems.