Synchrotron X-Ray Fluorescence Imaging Sheds Light on The Uniformity of Elements Across Annual Growth Rings.

Dendrochemistry is used to understand the temporal dynamics of changes in elemental concentrations in the environment, including those associated with environmental pollution. However, fundamental questions remain about the mechanisms of elemental uptake, distribution of elements within annual growth rings, and the potential for translocation throughout sapwood. Many quantitative techniques used in dendrochemistry to assess where and which elements are present are destructive, time-consuming, and expensive to measure at an annual resolution. Synchrotron X-Ray Fluorescence (SXRF) imaging offers an innovative, non-destructive method for identifying which elements are present, where they are located within the sample, and their relative concentrations. In this presentation, we showcase novel dendrochemistry techniques using SXRF to document how elemental patterns change across the lateral and vertical dimensions of trees. Preliminary results show non-uniform elemental uptake and distribution throughout both mature uncontaminated trees and young saplings spiked with heavy metals. SXRF images of cross-sectional tree disk samples indicate hot spots of elemental concentrations associated with active growth areas (e.g., bark and branches) and wounds within the tree-rings rather than uniform elemental distribution. These results indicate a need for more robust sampling and analysis of dendrochemistry samples, and SXRF techniques are one method to help achieve this.