HR: 1340h
AN: PP43A-0595    [Abstracts]
TI: Enhancing spatial and temporal resolution of trace elements in sediment cores
AU: * Johnson, B E
EM: bjohnson@ce.berkeley.edu
AF: University of California, Berkeley, Civil and Environmental Engineering, Berkeley, Ca 94720
AU: Jimenez-Cruz, M
EM: mpjimenezcruz@ucdavis.edu
AF: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, Ca 94720
AU: Cliff, S
EM: sscliff@ucdavis.edu
AF: University of California, Davis, Applied Science One Shields Ave, Davis, Ca 95616
AU: Hunt, J R
EM: hunt@ce.berkeley.edu
AF: University of California, Berkeley, Civil and Environmental Engineering, Berkeley, Ca 94720
AB: Sediment cores provide an historical record of seasonality, yearly pollution inputs and longer term climate changes if the resolution of the sampling tool matches that needed for the analysis of the sediment record. While X-ray florescence has been routinely used for elemental analysis in environmental samples, the intense beam of X-rays produced at the Advanced Light Source, Lawrence Berkeley National Laboratory on beamline 10.3.1 provides a unique opportunity to quantitatively probe trace element concentrations in wet samples at sub-millimeter resolution. Detailed analyses of both sediment standards and prepared mixtures of sediment standards have demonstrated linear calibration over three orders of magnitude dynamic range. Calibration was established for eleven elements including; Ti, Fe, Cu, Zn, Mn, Cr, Sr, Pb, Ca, Cl, K. The nondestructive technique rapidly (i.e. less than 20 seconds per spot) quantifies multi-element concentrations at specified locations. Collimating slits are used to control the vertical and horizontal width of the analysis area, varying from 50 to 500 microns. Analysis of frozen wet sediment cores from the former Alameda Naval Air Station's Seaplane Lagoon have resolved trends in the spatial variability of trace metal deposition corresponding to seasonal timescales. Although this method was developed for estuarine sediments, it is well suited to analyze a wide range of linear timescale samples from ice cores to deep ocean sediment cores.
DE: 9805 Instruments useful in three or more fields
DE: 4235 Estuarine processes
DE: 4251 Marine pollution
DE: 1815 Erosion and sedimentation
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting