HR: 0830h
AN: B11C-0703    [PDF]
TI: The Application of Synchrotron X-ray Fluorescence to Dendroanalysis: Nickel in Salix nigra L.
AU: * Punshon, T
EM: punshon@srel.edu
AF: Consortium for Risk Evaluation with Stakeholder Participation, Rutgers University, 604 Allison Road, Piscataway, NJ 08854 United States
AU: Bertsch, P M
EM: bertsch@srel.edu
AF: Savannah River Ecology Laboratory, University of Georgia, Drawer E,, Aiken, SC 29803 United States
AU: Lanzirotti, A
EM: lanzirotti@bnl.gov
AF: Consortium for Advanced Radiation Sources, University of Chicago, 5640 S. Ellis Avenue, Chicago, IL 60637 United States
AU: McLeod, K W
EM: mcleod@srel.edu
AF: Savannah River Ecology Laboratory, University of Georgia, Drawer E,, Aiken, SC 29803 United States
AU: Burger, J
EM: Burger@Biology.Rutgers.Edu
AF: Consortium for Risk Evaluation with Stakeholder Participation, Rutgers University, 604 Allison Road, Piscataway, NJ 08854 United States
AB: Synchotron X-ray Fluorescence microanalysis (SXRF) has been applied to annual rings of willows (Salix nigra L.) collected from an eroding former radiological settling basin and the impacted depositional area downstream. In 1984 the enclosing spillway of Steed Pond breached, and a pulse of U and Ni contaminated sediments moved downstream, accumulating in Lower Tims Branch (LTB), continuing during storm events. The aim of the study was to correlate fluctuations in contaminant concentrations within annual rings of impacted trees with the contaminant history, specifically the major contaminant pulse of 1984. Trees were sampled at Steed Pond, LTB and an uncontaminated reference site. Their rings were measured, aged and sectioned for SXRF analysis. Analysis took several forms: one-dimensional line scans (from pith to cambium) to show fluctuations in metal concentration over the lifetime of the tree; two-dimensional elemental maps to show metal distribution between and within annual rings, and three-dimension fluorescence tomography, to show the structure and composition of regions of interest. Trees from LTB clearly showed a marked increase in Ni concentration within the annual ring formed in 1984, and a series of peaks in subsequent years. Notably, lesser contaminants Cu, Zn and Cr showed an identical pattern. U was not present. Compositional mapping showed Ni associated with annual rings, with a clear demarcation between rings. Closer examination revealed smaller areas (10 to 20 microns in diameter) containing approximately 1000 ppm Ni. These discrete areas were exclusively Ni containing features, and were examined further with three-dimensional fluorescence tomography, showing that the Ni features occurred inside the lumen of vessel elements. We concluded that the Ni signature in annual rings of willows from LTB correlated with known contaminant pulses. Further, the technique quantitatively distinguished between trees growing on the radiological settling pond (having a high Ni content) and those growing further away in the LTB depositional area. Mapping elemental distribution showed that Ni was associated with annual rings, and appeared in both a diffuse form across annual rings, and in a concentrated form within the lumen of xylem elements. Work continues to determine the binding environment and chemical speciation of Ni within annual rings of black willows.
UR: http://www.er.doe.gov/production/ober/ERSD/hl_treerings.html
DE: 1065 Trace elements (3670)
DE: 1094 Instruments and techniques
SC: Biogeosciences [B]
MN: 2003 Fall Meeting