Wednesday, November 7, 2007
288-11
STXM / NEXAFS to Investigate C and N Distribution on Fe-Bearing Mineral Particles from Density Fractions.
Markus Kleber1, Peter Nico2, and Phil Sollins1. (1) 3017 Agricultural and Life Science Building, Oregon State University, Department of Crop & Soil Science, Corvallis, OR 97331, (2) One Cyclotron Road, Lawrence Berkeley National Lab, Lawrence Berkeley National Laboratory, Earth Sciences Division, 90R1116, Berkeley, CA 94720
There is increasing evidence that associations of nitrogeneous compounds with mineral surfaces can be particularly resistant to decomposition. At the same time, pedogenic iron is increasingly considered to play a major role in carbon stabilization. We examined the soil fraction with a density between 2.3 – 2.6 g cm-3 from A horizons of an Inceptisol, Oxisol and Alfisol to investigate whether organic matter associated with mineral surfaces shows variations in chemical composition that relate to the distribution of iron oxides on particle surfaces. To do so, we employed STXM (Scanning Transmission X-ray Microscopy) to obtain images of the C, N, and Fe distribution on individual mineral particles and obtained C-1s NEXAFS spectra from N-rich and N-poor locations of organic matter accretions on particle surfaces.