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Sparks, D.L. 1998. Kinetics of soil chemical phenomena: Future directions. p. 81-101. In. P.M. Huang, D.L. Sparks, and S.A. Boyd (eds.) Future prospects for soil chemistry. SSSA Spec. Publ. 55, Soil Sci. Soc. Am., Madison, WI.
Kinetics of soil chemical phenomena: Future directions.
Donald L. Sparks
Historically, the emphasis in soil chemistry teaching and research has been on equilibrium processes and reactions. While these studies have been useful, they are not often relevant to field settings where chemical reactions are time-dependent.
In the late 1970s, and certainly in the 1980s and 1990s, the kinetics of environmentally important reactions on natural materials has become and will continue to be a major leitmotif in the soil and environmental chemistry. This intense interest is in large part due to the recognition that to accurately predict the fate of contaminants in the subsurface environment, a knowledge of the reaction kinetics is imperative.
While major advances have been made in understanding time-dependent reactions on natural materials such as soils and sediments, there are still many unknowns that are complicated by the complex, heterogeneous nature of natural materials. This review will focus on the future research needs, particularly in the area of sorption-release processes in the soil environment, and not on past findings and accomplishments. To learn about the latter, the reader can consult a number of books and reviews. Future research needs that will be discussed in this review include: models that accurately describe both chemical kinetics and transport processes in multiple site,heterogeneous systems; more extensive studies on the effect of residence time or aging on contaminant retention-release; and mechanistic studies that employ both kinetic and in situ (drying and high vacuums are not employed; aqueous suspensoins can be examined) microscopic and spectroscopic techniques.