A. Herring, OSU, uses tomography at 13 BMD to quantify pore scale trapping and to analyze how mechanisms affect the efficiency of capillary trapping of CO2 in saline aquifers.

Tomography at 13 BMD

Work at GSECARS discovers water deep below Earth’s surface

A team utilizing GSECARS bealines has identified a weird form of crystallized water known as ice VII, suggesting that this material may circulate more freely at some depths within Earth than previously thought. Pockets of water may lay deep below Earth’s surface

Work at GSECARS discovers water deep below Earth’s surface

X-ray diffraction patterns from a diamond anvil cell (DAC).

X-ray diffraction is the most powerful technique for crystal structure determination. From left to right, patterns from a single crystal, polychrystalline, nano-cyrstalline and amorphous crystals.

X-ray diffraction patterns from a diamond anvil cell.

High pressure x-ray tomographic microscopy module

The HPXTM module helps researchers study the texture change of their sample under extreme pressure and temperature conditions by collecting in-situ HP/HT 3D x-ray tomographic images.

High Pressure X-ray Tomographic Microscopy Module sitting outside of the 250 ton press in 13 BMD.

GSECARS hosts experiments at 13 IDE for high school students in the Exemplary Student Research Program (ESRP) representing local area high schools. GSECARS Outreach

GSECARS Outreach

GSECARS is a national user facility
for frontier research in the earth sciences using synchrotron radiation at the
Advanced Photon Source, Argonne National Laboratory.

GSECARS provides earth scientists with access to the high-brilliance hard x-rays from this third-generation synchrotron light source. All principal synchrotron-based analytical techniques in demand by earth scientists are being brought to bear on earth science problems:

  • High-pressure/high-temperature crystallography and spectroscopy using the diamond anvil cell
  • High-pressure/high-temperature crystallography and imaging using the large-volume press
  • Powder, single crystal and interface diffraction
  • Inelastic x-ray scattering
  • X-ray absorption fine structure spectroscopy
  • X-ray fluorescence microprobe analysis
  • Microtomography

Science Highlights
 

Designing better extraction methods for
rare earth elements

Fig175.jpg

ABSTRACT: Crystal truncation rod (CTR) measurements and density functional theory (DFT) calculations were performed to determine the atomic structure of the mineral−water interface of the {100} surface of xenotime (nominally YPO4). This mineral is important, because it incorporates a variety of rare earth elements (REEs) in its crystal structure. REEs are critical materials necessary for a variety of renewable and energy efficient technologies. Current beneficiation techniques are not highly selective for REE ore minerals, and large amounts go to waste; this is a first step toward designing more efficient beneficiation. Evidence is found for minor relaxation of the surface within the topmost monolayer with little or no relaxation in subsurface layers. Justification for ordered water at the interface is
found, where water binds to surface cations and donates hydrogen bonds to surface phosphates. The average bond lengths between cations and oxygens on water are 228 pm in the best fit to the CTR data, versus 243 and 251 pm for the DFT. No agreement on water positions bound to surface phosphates is obtained. Overall, the findings suggest that ligands used in beneficiation with a single anionic headgroup, such as fatty acids, will have limited selectivity for xenotime relative to undesirable minerals.

Stack, A.G., Stubbs, J.E., Roy, S., Srinivasan, S.G., Roy, S., Bryantsev, V.S., Eng, P.J., Custelcean, R., Gordon, A.D., Hexel, C.R. (2018) Mineral-Water Interface Structure of Xenotime (YPO4) {100}.  J. Phys. Chem. C. 122:20232-20243. https://doi.org/10.1021/acs.jpcc.8b04015


The Hunt for Earth’s Deep Hidden Oceans

GSECARS users Steve Jaconbsen (Northwestern), Michele Wenz (Northwestern) and Oliver Tschauner (UNLV) and other researchers from around the world are working on unraveling the mystery of freely existing H2O in the mantle.  Quanta Magazine Interview


Computer microtomography at 13 BMD characterized spatial heterogeneity in soil matrix from varying long term management strategies.

Fig1crop75.jpg

An example of a μCT image from an Os stained soil sample from biologically based management at 4 μm resolution. (A) A 3D scan of an entire Os stained sample. The thickness of the sample was 1 mm. (B) Image of a slice of an Os stained sample above the K-edge (74 keV). (C) Image of a slice of an Os stained sample below the K-edge (73.8 keV). (D) Difference between above and below K-edge images with non-biological pore (E), POM-NS (G), and POM-Root (F) expanded. Total image size is 8 × 8 mm for (B–D).

Study Conclusion : Analysis of grayscale gradients near pores of biological origin were found to be a useful proxy for assessing SOM spatial distribution patterns at micro-scale. Grayscale gradients of non-biological pores, in contrast, were found to be different from SOM gradients due to a pore identification artifact. Utilizing a different thresholding method may overcome this limitation.

Michelle Y. Quigley, Mark L. Rivers, Alexandra N. Kravchenko, "Patterns and Sources of Spatial Heterogeneity in Soil Matrix From Contrasting Long Term Management Practices," Front. Environ. Sci. 6 (28), 1-15 (2018). DOI: 10.3389/fenvs.2018.00028


► Work at 13 IDE and other APS beamlines show iron oxides minimize arsenic mobility in soil material saturated
with saline wastewater.

jeq2018_01_0022fig5_50.jpg
Micro-xray fluorescence (XRF) maps showing the elemental distribution of As and Fe generated on untreated and ferrihydrite (Fh)-treated soil. As hotspots P1-UT, P2-UT, P3-UT and P4-UT (on untreated XRF map) and P1-FhT, P2-FhT, P3-FhT and P4-FhT (on Fh treated XRF map) were used for micro-X-ray absporption near edge structure spectroscopy.

Core Ideas
• Reductive dissolution of Fe minerals caused mobilization of native-soil As.
• Amending the soil with ferrihydrite (Fh) decreased this mobilization of As.
• Enhanced resorption reactions mitigated the mobility of As in the Fh-treated soil.
• Drying the soil caused remobilization of some sequestered trace elements.

Galkaduwa, M. B., G. M. Hettiarachchi, G. J. Kluitenberg, and S. L. Hutchinson. 2018. Iron Oxides Minimize Arsenic Mobility in Soil Material Saturated with Saline Wastewater. J. Environ. Qual. 0. doi:10.2134/jeq2018.01.0022


► Ultrasonic wave propagation, a new technique developed for determining the liquidus and eutectic temperatures of Fe-light element alloys.

Fig1cropsm80.jpg

Multianvil cell assembly used for ultrasonic measurements at high pressures. BR: buffer rod; BP: backing plate.

Abstract : We have developed a new technique for determining the liquidus and eutectic (or solidus) temperatures of Fe‐light element alloys at high pressures in a multianvil apparatus, by studying ultrasonic wave propagation through the sample. While the onset of melting is manifested by the loss of both compressional (P‐) and shear (S‐) wave signals due to the scattering of sound waves by partial melts, the completion of melting is confirmed by the reappearance of the P wave signal when the scattering due to residual crystals disappears. By applying this technique to the Fe‐P binary system with three different phosphorus contents, we were able to constrain the Fe‐rich portion of the phase diagram up to 7 GPa and 1,733 K.

Our results show that the liquidus temperatures of the Fe‐P alloys exhibit different pressure dependencies according to their phosphorus contents. Consequently, depending on their phosphorus contents, molten metallic cores of planetary bodies would start crystallization either from the bottom, extending upward resulting in a growing inner core, or start from the top and extend downward resulting in a “snowing” scenario.

Chantel, J., Jing, Z., Xu, M., Yu, T., Wang, Y. (2018). Pressure dependence of the liquidus and solidus temperatures in the Fe-P binary system determined by in situ ultrasonics: Implications to the solidification of Fe-P liquids in planetary cores. Journal of Geophysical Research: Planets, 123, 1113–1124. https://doi.org/10.1029/2017JE005376


► Work done at 13 BMC has provided evidence for using Fe-(oxyhydr) oxides as potential treatment substrates to remediate Pb contaminated soils.

FigureHR50.png

The structure above has been oriented to highlight the geometric relationship between Pb complex and the associated anchored Fe octahedra.

Abstract

A structural study of the surface complexation of Pb(II) on the (1102) surface of hematite was undertaken using crystal truncation rod (CTR) X-ray diffraction measurements under in situ   conditions. The sorbed Pb was found to form inner sphere (IS) complexes at two types of edge-sharing sites on the half layer termination of the hematite (1102) surface. The best fit model contains Pb in distorted trigonal pyramids with an average Pb_O bond length of 2.27(4) Å and two characteristic Pb-Fe distances of 3.19(1) Å and 3.59(1) Å. In addition, a site coverage model was developed to simulate coverage as a function of sorbate-sorbate distance. The simulation results suggest a plausible Pb-Pb distance of 5.42 Å, which is slightly larger than the diameter of Pb’s first hydration shell. This relates the best fit surface coverage of 0.59(4) Pb per unit cell at monolayer saturation to steric constraints as well as electrostatic repulsion imposed by the hydrated Pb complex. Based on the structural results we propose a stoichiometry of the surface complexation reaction of Pb(II) on the hematite (102) surface and use bond valence analysis to assign the protonation schemes of surface oxygens. Surface reaction stoichiometry suggests that the proton release in the course of surface complexation occurs from the Pb-bound surface O atoms at pH 5.5.

C. Qiu, F. Majs, P.J. Eng, J.E. Stubbs, T.A. Douglas, M. Schmidt, T. Trainor, "In situ structural study of the surface complexation of lead(II) on the chemically mechanically polished hematite (1102) surface", J. Colloid and Interface Science,(2018)  Vol. 524, pp. 65-75, DOI : 10.1016/j.jcis.2018.04.005