GEOC 87 |
| Tae Hyun Yoon1, Stephen B. Johnson2, Karim Benzerara2, Tolek Tylszczak3, and Gordon E. Brown Jr.1. (1) Department of Geological & Environmental Sciences, STANFORD UNIVERSITY, Stanford, CA 94305-2115, (2) Geological & Environmental Sciences, Stanford University, Stanford, CA 94305-2115, (3) Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 |
| Colloid-facilitated transport of contaminants has been suggested as one of the primary transport mechanisms in subsurface waters. In this study, we utilized soft x-ray spectromicroscopy tools to investigate the behavior of colloidal systems containing natural organic matter (NOM), aluminum (oxy)hydroxides, and arsenic minerals. STXM (scanning transmission x-ray microscopy) and XANES (x-ray absorption near edge structure) measurements have been performed for these systems under in-situ condition at the 11.0.2 MES beamline at the ALS. Al K-edge (~1567 eV) and As L3-edge (~1323 eV) XANES spectra are sensitive tools for distinguishing different mineral phases, coordination environments, and oxidation states of both elements. Under various pH and concentration ratio conditions, STXM image stacks at both the Al K and As L edges were obtained and analysed by using Al and As XANES spectral database. From these studies, we can identify nanometer-sized mineral particles and characterize their state of aggregation in mixed suspensions of various mineral-NOM colloids. |
|
Interfacial Phenomena: Linking Atomistic and Macroscopic Properties
1:00 PM-5:50 PM, Tuesday, March 30, 2004 Marriott -- Marquis NW, Oral
Division of Geochemistry |