Smucker, A.J.M. and E.J. Park
Presented at the All Scientist Meeting (2002-10-04 )
Biophysical polymorphic aggregate structures, ranging in size from sub-millimeter to many millimeters across, control the absorption, storage, and losses of most soil constituents. In relatively undisturbed regions of soil aggregates, root derived carbon © and subsequent C decomposition products, located within aggregate pores, contribute to the formation and stabilization of newly established internal pores in many feed-forward processes that influence mineral orientation, ionic charge, hydration phenomena and the microbial ecology. Computer microtomographic (CMT) reconstructions of soil aggregates provide many unique opportunities to identify pore geometries within these highly dynamic building structures of the soil profile. Intra-aggregate porosities are the primary storage sites of sequestered soil C. Associated respiratory activities of microbial communities generate gradients of oxygen deficiency within the central regions of aggregates (Park and Smucker poster). Oxygen gradients within aggregates control both the genetic diversity of microbial communities and regulate the decomposition of C stored within these interior porous regions. Renderings of CMT reconstructions into 3D images greatly facilitate the visualization of numerous pore formation processes located inside natural soil aggregates. More than 18 bottleneck and “dumbbell shaped” pores, with diameters ranging from 5 to 100 microns can be identified within a single soil aggregate approximately 1000 microns across. Biophysical polymorphic aggregate structures, ranging in size from sub-millimeter to many millimeters across, control the absorption, storage, and losses of most soil constituents. In relatively undisturbed regions of soil aggregates, root derived carbon © and subsequent C decomposition products, located within aggregate pores, contribute to the formation and stabilization of newly established internal pores in many feed-forward processes that influence mineral orientation, ionic charge, hydration phenomena and the microbial ecology.Computer microtomographic (CMT) reconstructions of soil aggregates provide many unique opportunities to identify pore geometries within these highly dynamic building structures of the soil profile. Intra-aggregate porosities are the primary storage sites of sequestered soil C. Associated respiratory activities of microbial communities generate gradients of oxygen deficiency within the central regions of aggregates (Park and Smucker poster). Oxygen gradients within aggregates control both the genetic diversity of microbial communities and regulate the decomposition of C stored within these interior porous regions. Renderings of CMT reconstructions into 3D images greatly facilitate the visualization of numerous pore formation processes located inside natural soil aggregates. More than 18 bottleneck and “dumbbell shaped” pores, with diameters ranging from 5 to 100 microns can be identified within a single soil aggregate approximately 1000 microns across.
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