Monday, November 13, 2006 - 10:30 AM

Natural Nanocomposites: The Structure of Stable Mineral-Organic Associations in Soils.

Markus Kleber, Lawrence Berkeley National Laboratory, Earth Sciences Division, One Cyclotron Road, Mail Stop 90-1116, Berkeley, CA 94720, Phil Sollins, Oregon State Univ, College of Forestry, Corvallis, OR 97331, and Rebecca Sutton, UC Berkeley, Dept of Environmental Science, Policy and Management, 3114 Mulford Hall, Berkeley, CA 94720-3114.

We propose a structure for organo-mineral associations in soils based on recent insights concerning the molecular structure of soil organic matter (SOM), and on extensive published evidence from empirical studies of organo-mineral interfaces. Our conceptual model assumes that SOM consists of a heterogeneous mixture of compounds that display a range of amphiphilic or surfactant-like properties, and are capable of self-organization in aqueous solution. An extension of this self-organizational behavior in solution, we suggest that SOM sorbs to mineral surfaces in a discrete zonal sequence. The zonal concept of organo-mineral interactions presented here offers a new basis for understanding and predicting the retention of organic compounds, including contaminants, in soils and sediments.