title: Quantitative 3-D elemental mapping by LA-ICP-MS of a basaltic clast from the Hanford 300 Area, Washington, USA.
abstract: Laser ablation with inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to measure elemental concentrations at the 100-μm scale in a 3-dimensional manner within a basaltic clast sample collected from the Hanford 300 Area in south-central Washington State, United States. A calibration method was developed to quantify the LA-ICP-MS signal response using a constant-sum mass fraction of eight major elements; the method produced reasonable concentration measurements for both major and trace elements when compared to a standard basalt sample with known concentrations. 3-Dimensional maps (stacked 2-D contour layers, each representing 2100 μm × 2100 μm) show relatively uniform concentration with depth for intrinsic elements such as Si, Na, and Sr. However, U and Cu accumulation were observed near the sample surface, consistent with the site's release history of these contaminants. U and Cu show substantial heterogeneity in their concentration distributions within horizontal slices, while the intrinsic elements are essentially uniformly distributed. From these measured U concentrations and published grain size distributions, gravel and cobbles were estimated to contain about 1% of the contaminant U, implicating the coarse fraction as a long-term release source.
authors.affiliation: Department of Earth and Environmental Sciences, University of Texas at Arlington, Arlington, Texas 76019, United States.
authors.forename: Sheng
authors.initials: S
authors.lastname: Peng
authors.forename: Qinhong
authors.initials: Q
authors.lastname: Hu
authors.forename: Robert P
authors.initials: RP
authors.lastname: Ewing
authors.forename: Chongxuan
authors.initials: C
authors.lastname: Liu
authors.forename: John M
authors.initials: JM
authors.lastname: Zachara
mesh_terms: D004602:Elements; D019015:Geologic Sediments / Q000032:analysis*; D053685:Laser Therapy; D013058:Mass Spectrometry / Q000379:methods; D010316:Particle Size; D011850:Radioactive Waste; D012037:Refuse Disposal; D014861:Washington
chemical_list: D004602:Elements; D011850:Radioactive Waste