Elucidating the fundamental chemistry of soils: past and recent achievements and future frontiers

Contributions in the field of soil chemistry have immensely benefited human kind, including enhanced agricultural production and the quality of our env ironment. This review focuses on research breakthroughs since the mid-1970s and delineates frontiers in soil chemistry for the upcoming decade. Howeve r, early contributions in ion exchange, sorption phenomena, and soil acidit y are highlighted. Beginning in the 1970s, soil chemistry paradigms shifted from the chemistry of plant nutrient reactions/processes in soils to studi es on environmental soil chemistry. The latter included research on: acid r ain effects on soils and waters; trace metal/metalloid, environmentally imp ortant plant nutrient, radionuclide, and organic chemical reaction mechanis ms and retention; speciation of soil contaminants using chemical extraction and molecular scale analytical techniques; facilitated colloid transport o f metals and organic chemicals; humic substance structure; kinetics of soil chemical processes; redox transformations of contaminants in soils; modeli ng of soil chemical reactions; and soil remediation. Frontiers in soil chem istry over the next decade will undoubtedly involve the use of advanced in situ technologies in combination with interdisciplinary research efforts to unlock important information on: speciation of contaminants in soils; cycl ing of trace elements and nutrients and impacts on global climate change; d evelopment of models to accurately predict the rate, fate, and transport of contaminants in the subsurface environment; elucidation of mechanisms for microbial transformations of contaminants; unraveling the precise structure of soil organic matter; and enhanced understanding of rhizosphere chemistr y. In summary, the future of soil chemistry is bright for the 21st century. (C) 2001 Elsevier Science B.V. All rights reserved.