Advances In Agronomy, Volume 74 Donald. L. Sparks. ed., University of Delaware, Newark, DE.
CHAPTER 2

Frontiers in Metal Sorption/precipitation Mechanisms on Soil Mineral Surfaces.

Robert G. Ford, Andreas C. Scheinost, and Donald L. Sparks

INTRODUCTION

Spectroscopic studies provide evidence that inorganic contaminants may be incorporated into precipitates at the surface of soil and sediment minerals. Surface precipitates may form via several mechanisms that are dependent on the unique characteristics of the interfacial region between solid and solution. In general, surface complexation models (SCMs) capture most of the salient features of the interfacial region. However, current SCMs fail to capture the dynamics of mineral surfaces, thus limiting their ability to predict the composition and structure of potential surface precipitates. This review outlines the current implementation of surface precipitation models, spectroscopic studies that highlight the need to develop more comprehensive SCMs, and future research directions that will help fill existing knowledge gaps. Successful modeling approaches to describe surface precipitation phenomena are a necessary component for the evaluation of long-term