New frontiers in elucidating the kinetics and mechanisms of metal and oxyanion sorption at the soil mineral/water interface

An understanding of the kinetics and mechanisms of metal and oxyanion sorption on soil minerals and soils is fundamental in assessing the speciation, mobility, and bioavailability of metals and oxyanions in natural systems. Traditionally, sorption has been studied using macroscopic equilibrium approaches. It is now well recognized that the kinetics of metal and oxyanion sorption/release must be understood if accurate predictions are to be made about metal/oxyanion fate/mobility and soil remediation. This paper covers aspects of kinetic models acid their applicability to heterogenous systems and the rates and mechanisms of rapid and slow metal and oxyanion sorption reactions. With some metals (e.g. Co, Ni, Zn) residence lime affects the rate of metal release with other metals such as Pb, there is little effect of residence time, To definitively understand the dynamics of sorption mechanisms, one must employ molecular scale approaches. Over the past decade, with the advent of cutting-edge molecular-scale in-situ analytical techniques, significant advances have occurred in determining the speciation and sorption/release mechanisms of and oxyanions in the subsurface environment. These in environmental science have major impacts on: soil frontiers on strategies, development of predictive models, and contaminant/bioavailability assessments. Frontiers in metal sorption at the soil mineral/water interface are highlighted in this review.