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241 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I18-Microfocus Spectroscopy	Deep anoxic aquifers could act as sinks for uranium through microbial-assisted mineral trapping Ivan N. Pidchenko , John N. Christensen , Martin Kutzschbach , Konstantin Ignatyev , Ignasi Puigdomenech , Eva-Lena Tullborg , Nick M. W. Roberts , E. Troy Rasbury , Paul Northrup , Ryan Tappero , Kristina O. Kvashnina , Thorsten Schäfer , Yohey Suzuki , Henrik Drake Communications Earth & Environment 4 DOI: 10.1038/s43247-023-00767-9 Diamond Proposal Number(s): [28254] Open Access Show Abstract ▼ Abstract: Uptake of uranium (U) by secondary minerals, such as carbonates and iron (Fe)-sulfides, that occur ubiquitously on Earth, may be substantial in deep anoxic environments compared to surficial settings due to different environment-specific conditions. Yet, knowledge of U reductive removal pathways and related fractionation between 238U and 235U isotopes in deep anoxic groundwater systems remain elusive. Here we show bacteria-driven degradation of organic constituents that influences formation of sulfidic species facilitating reduction of geochemically mobile U(VI) with subsequent trapping of U(IV) by calcite and Fe-sulfides. The isotopic signatures recorded for U and Ca in fracture water and calcite samples provide additional insights on U(VI) reduction behaviour and calcite growth rate. The removal efficiency of U from groundwater reaching 75% in borehole sections in fractured granite, and selective U accumulation in secondary minerals in exceedingly U-deficient groundwater shows the potential of these widespread mineralogical sinks for U in deep anoxic environments.	Apr 2023
I18-Microfocus Spectroscopy	Observational constraints on the process and products of Martian serpentinization Benjamin M. Tutolo , Nicholas J. Tosca Science Advances 9 DOI: 10.1126/sciadv.add8472 Diamond Proposal Number(s): [15947] Open Access Show Abstract ▼ Abstract: The alteration of olivine-rich rocks to serpentine minerals, (hydr)oxides, and aqueous hydrogen through serpentinization is long thought to have influenced the distribution of habitable environments on early Mars and the evolution of the early Martian hydrosphere and atmosphere. Nevertheless, the planetary importance of Martian serpentinization has remained a matter of debate. To constrain the process and products of Martian serpentinization, we studied serpentinized iron-rich olivines from the 1.1-billion-year Duluth Complex. These data indicate that serpentinized iron-rich olivine would have been accompanied by a fivefold increase in hydrogen production relative to serpentinized terrestrial mantle peridotites. In contrast to previous expectations, this style of serpentinization yields hisingerite as the dominant iron serpentine mineral at comparatively low temperature and pH, consistent with meteorite mineralogy and in situ rover data. The widespread occurrence of oxidized iron-bearing phyllosilicates in highly magnetized regions of the Martian crust supports the hypothesis that serpentinization was more pervasive on early Mars than currently estimated.	Feb 2023
I08-Scanning X-ray Microscopy beamline (SXM)	Biogeochemical and historical drivers of microbial community composition and structure in sediments from Mercer Subglacial Lake, West Antarctica Christina L. Davis , Ryan A. Venturelli , Alexander B. Michaud , Jon R. Hawkings , Amanda M. Achberger , Trista J. Vick-Majors , Brad E. Rosenheim , John E. Dore , August Steigmeyer , Joel D. Barker , Liane G. Benning , Matthew R. Siegfried , John C. Priscu , Brent C. Christner , Carlo Barbante , Mark Bowling , Justin Burnett , Timothy Campbell , Billy Collins , Cindy Dean , Dennis Duling , Helen A. Fricker , Alan Gagnon , Christopher Gardner , Dar Gibson , Chloe Gustafson , David Harwood , Jonas Kalin , Kathy Kasic , Ok-Sun Kim , Edwin Krula , Amy Leventer , Wei Li , W. Berry Lyons , Patrick Mcgill , James Mcmanis , David Mcpike , Anatoly Mironov , Molly Patterson , Graham Roberts , James Rot , Cathy Trainor , Martyn Tranter , John Winans , Bob Zook , Mark L. Skidmore Isme Communications 3 DOI: 10.1038/s43705-023-00216-w Diamond Proposal Number(s): [25828] Open Access Show Abstract ▼ Abstract: Ice streams that flow into Ross Ice Shelf are underlain by water-saturated sediments, a dynamic hydrological system, and subglacial lakes that intermittently discharge water downstream across grounding zones of West Antarctic Ice Sheet (WAIS). A 2.06 m composite sediment profile was recently recovered from Mercer Subglacial Lake, a 15 m deep water cavity beneath a 1087 m thick portion of the Mercer Ice Stream. We examined microbial abundances, used 16S rRNA gene amplicon sequencing to assess community structures, and characterized extracellular polymeric substances (EPS) associated with distinct lithologic units in the sediments. Bacterial and archaeal communities in the surficial sediments are more abundant and diverse, with significantly different compositions from those found deeper in the sediment column. The most abundant taxa are related to chemolithoautotrophs capable of oxidizing reduced nitrogen, sulfur, and iron compounds with oxygen, nitrate, or iron. Concentrations of dissolved methane and total organic carbon together with water content in the sediments are the strongest predictors of taxon and community composition. δ¹³C values for EPS (−25 to −30‰) are consistent with the primary source of carbon for biosynthesis originating from legacy marine organic matter. Comparison of communities to those in lake sediments under an adjacent ice stream (Whillans Subglacial Lake) and near its grounding zone provide seminal evidence for a subglacial metacommunity that is biogeochemically and evolutionarily linked through ice sheet dynamics and the transport of microbes, water, and sediments beneath WAIS.	Jan 2023
I14-Hard X-ray Nanoprobe	A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu Takaaki Noguchi , Toru Matsumoto , Akira Miyake , Yohei Igami , Mitsutaka Haruta , Hikaru Saito , Satoshi Hata , Yusuke Seto , Masaaki Miyahara , Naotaka Tomioka , Hope A. Ishii , John P. Bradley , Kenta K. Ohtaki , Elena Dobrică , Hugues Leroux , Corentin Le Guillou , Damien Jacob , Francisco De La Peña , Sylvain Laforet , Maya Marinova , Falko Langenhorst , Dennis Harries , Pierre Beck , Thi H. V. Phan , Rolando Rebois , Neyda M. Abreu , Jennifer Gray , Thomas Zega , Pierre-M. Zanetta , Michelle S. Thompson , Rhonda Stroud , Kate Burgess , Brittany A. Cymes , John C. Bridges , Leon Hicks , Martin R. Lee , Luke Daly , Phil A. Bland , Michael E. Zolensky , David R. Frank , James Martinez , Akira Tsuchiyama , Masahiro Yasutake , Junya Matsuno , Shota Okumura , Itaru Mitsukawa , Kentaro Uesugi , Masayuki Uesugi , Akihisa Takeuchi , Mingqi Sun , Satomi Enju , Aki Takigawa , Tatsuhiro Michikami , Tomoki Nakamura , Megumi Matsumoto , Yusuke Nakauchi , Masanao Abe , Masahiko Arakawa , Atsushi Fujii , Masahiko Hayakawa , Naru Hirata , Naoyuki Hirata , Rie Honda , Chikatoshi Honda , Satoshi Hosoda , Yu-Ichi Iijima , Hitoshi Ikeda , Masateru Ishiguro , Yoshiaki Ishihara , Takahiro Iwata , Kousuke Kawahara , Shota Kikuchi , Kohei Kitazato , Koji Matsumoto , Moe Matsuoka , Yuya Mimasu , Akira Miura , Tomokatsu Morota , Satoru Nakazawa , Noriyuki Namiki , Hirotomo Noda , Rina Noguchi , Naoko Ogawa , Kazunori Ogawa , Tatsuaki Okada , Chisato Okamoto , Go Ono , Masanobu Ozaki , Takanao Saiki , Naoya Sakatani , Hirotaka Sawada , Hiroki Senshu , Yuri Shimaki , Kei Shirai , Seiji Sugita , Yuto Takei , Hiroshi Takeuchi , Satoshi Tanaka , Eri Tatsumi , Fuyuto Terui , Ryudo Tsukizaki , Koji Wada , Manabu Yamada , Tetsuya Yamada , Yukio Yamamoto , Hajime Yano , Yasuhiro Yokota , Keisuke Yoshihara , Makoto Yoshikawa , Kent Yoshikawa , Ryohta Fukai , Shizuho Furuya , Kentaro Hatakeda , Tasuku Hayashi , Yuya Hitomi , Kazuya Kumagai , Akiko Miyazaki , Aiko Nakato , Masahiro Nishimura , Hiromichi Soejima , Ayako I. Suzuki , Tomohiro Usui , Toru Yada , Daiki Yamamoto , Kasumi Yogata , Miwa Yoshitake , Harold C. Connolly , Dante S. Lauretta , Hisayoshi Yurimoto , Kazuhide Nagashima , Noriyuki Kawasaki , Naoya Sakamoto , Ryuji Okazaki , Hikaru Yabuta , Hiroshi Naraoka , Kanako Sakamoto , Shogo Tachibana , Sei-Ichiro Watanabe , Yuichi Tsuda Nature Astronomy 121 DOI: 10.1038/s41550-022-01841-6 Open Access Show Abstract ▼ Abstract: Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe3+ to Fe2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (–OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss.	Dec 2022
I18-Microfocus Spectroscopy	The bonding environment of chlorine in silicate melts Richard W. Thomas , Jon Wade , Bernard J. Wood Chemical Geology 25 DOI: 10.1016/j.chemgeo.2022.121269 Diamond Proposal Number(s): [28784] Open Access Show Abstract ▼ Abstract: The local bonding environment of chlorine in silicate melts has a profound influence over the thermodynamic properties and structure of a melt, affecting the viscosity, rheology, and volatile degassing potential. To constrain the bonding environment of Cl in natural silicate melts, we have determined Cl K-edge X-ray absorption fine structure (XAFS) spectra for 44 experimentally produced silicate glasses in both the X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) regions. In the pre-edge region, the presence of a pre-edge peak indicates covalent bonding of chlorine with silicon. Addition of divalent cations suppresses this pre-edge feature, and its centroid shifts to higher energy, indicating a change to increasingly more ionic bonding. In the XANES region the main absorption edge energy, E0, and the energy of maximum intensity, EMax, are also compositionally dependent. SiO2- rich glasses have relatively low values of E0 and EMax while the addition of 2+ ions increases both to values close to those found in the end-member chlorides CaCl2, MgCl2, and FeCl2. In two Na-rich glasses, E0 and EMax are close to corresponding energies in NaCl. It appears, therefore that bonding in the glasses is closely related to that found in the simple chlorides. This may be due to clustering which generates Casingle bondCl, Mgsingle bondCl, Fesingle bondCl and Nasingle bondCl linkages either in the melts themselves or in the glasses due to rearrangements during quenching. The EXAFS parts of the glass spectra confirm the conclusions derived from the XANES region. These show that, as expected from the XANES region, addition of Ca and Fe2+ leads to R-space peaks which are closely related to those found in anhydrous CaCl2 and FeCl2 respectively. In order to determine if the spectra depend on pressure, temperature or chlorine fugacity of synthesis, 9 experiments were conducted using a single starting composition (Fe-free haplobasalt, An50Di28Fo22) across a range of temperatures (1300–1400 °C), pressures (5–20 kbar), chlorine fugacities (f(Cl2)) (1.38E−03 to 1.66E−06), and water contents (expected 0–8 wt% H2O). The results show that there is almost no change in the spectra across the XANES and EXAFS regions, indicating either that chlorine bonding is independent of the intensive parameters of the experiment or that all melts quench to glasses with the same local structure around the Cl atoms.	Dec 2022
B18-Core EXAFS	Vadose-zone alteration of metaschoepite and ceramic UO2 in Savannah River Site field lysimeters Connaugh M. Fallon , William R. Bower , Brian A. Powell , Francis R. Livens , Ian C. Lyon , Alana E. Mcnulty , Kathryn Peruski , J. Frederick W. Mosselmans , Daniel I. Kaplan , Daniel Grolimund , Peter Warnicke , Dario Ferreira-Sanchez , Marja Siitari Kauppi , Gianni F. Vettese , Samuel Shaw , Katherine Morris , Gareth T. W. Law Science Of The Total Environment DOI: 10.1016/j.scitotenv.2022.160862 Diamond Proposal Number(s): [16611, 16939, 17243] Open Access Show Abstract ▼ Abstract: Uranium dioxide (UO2) and metaschoepite (UO3•nH2O) particles have been identified as contaminants at nuclear sites. Understanding their behavior and impact is crucial for safe management of radioactively contaminated land and to fully understand U biogeochemistry. The Savannah River Site (SRS) (South Carolina, USA), is one such contaminated site, following historical releases of U-containing wastes to the vadose zone. Here, we present an insight into the behavior of these two particle types under dynamic conditions representative of the SRS, using field lysimeters (15 cm D x 72 cm L). Discrete horizons containing the different particle types were placed at two depths in each lysimeter (25 cm and 50 cm) and exposed to ambient rainfall for 1 year, with an aim of understanding the impact of dynamic, shallow subsurface conditions on U particle behavior and U migration. The dissolution and migration of U from the particle sources and the speciation of U throughout the lysimeters was assessed after 1 year using a combination of sediment digests, sequential extractions, and bulk and μ-focus X-ray spectroscopy. In the UO2 lysimeter, oxidative dissolution of UO2 and subsequent migration of U was observed over 1–2 cm in the direction of waterflow and against it. Sequential extractions of the UO2 sources suggest they were significantly altered over 1 year. The metaschoepite particles also showed significant dissolution with marginally enhanced U migration (several cm) from the sources. However, in both particle systems the released U was quantitively retained in sediment as a range of different U(IV) and U(VI) phases, and no detectable U was measured in the lysimeter effluent. The study provides a useful insight into U particle behavior in representative, real-world conditions relevant to the SRS, and highlights limited U migration from particle sources due to secondary reactions with vadose zone sediments over 1 year.	Dec 2022
B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS	Atomic-scale characterisation of sodium aluminosilicate hydrates (N-A-S-H) and Mg-substituted N(-M)-A-S-H using XANES Xinyuan Ke , Vahiddin Alperen Baki , Alexander I. Large , Georg Held , Brant Walkley , Jiaqi Li Applied Geochemistry 298 DOI: 10.1016/j.apgeochem.2022.105515 Diamond Proposal Number(s): [28470] Show Abstract ▼ Abstract: The chemical structures of aluminosilicate hydrates presented in alkali-activated geopolymer materials underpin their performances. Mg-substituted sodium aluminosilicate hydrates (N(-M)-A-S-H) are likely to be present in alkali-activated geopolymer materials prepared using MgO-containing precursors, however, their atomic-level structures remain unclear. The lack of such knowledge made it challenging to identify and distinguish N(-M)-A-S-H from complex alkali-activated geopolymer systems (i.e., alkali-activated slag, alkali-activated Mg-rich minerals), and therefore brought challenges in understanding and predicting their durability. This study characterised for the first time the atomic structures of the synthetic N(-M)-A-S-H gels, prepared through ion-exchange or co-synthesis, using X-ray absorption near-edge spectroscopy (XANES) at Si, Al and Mg K-edge. The results suggest that the substitution of Mg in the extra-framework locations of the alkali aluminosilicate hydrates (N-A-S-H) leads to negligible changes in the coordination environments of the aluminosilicate framework. However, the Mg coordination environment is distinguishably different from other Mg-containing phases in the systems, e.g., hydrotalcite. The Mg K-edge XANES of N(-M)-A-S-H shows a 0.8–1.2 eV shift compared with hydrotalcite. The results presented in this study can be used as the fingerprint to probe the presence of N(-M)-A-S-H in alkali-activated geopolymer materials containing Mg element.	Nov 2022
I12-JEEP: Joint Engineering, Environmental and Processing	Pore-scale imaging of hydrogen displacement and trapping in porous media Eike M. Thaysen , Ian B. Butler , Aliakbar Hassanpouryouzband , Damien Freitas , Fernando Alvarez-Borges , Samuel Krevor , Niklas Heinemann , Robert Atwood , Katriona Edlmann International Journal Of Hydrogen Energy 105 DOI: 10.1016/j.ijhydene.2022.10.153 Diamond Proposal Number(s): [26730] Open Access Show Abstract ▼ Abstract: Hydrogen can act as an energy store to balance supply and demand in the renewable energy sector. Hydrogen storage in subsurface porous media could deliver high storage capacities but the volume of recoverable hydrogen is unknown. We imaged the displacement and capillary trapping of hydrogen by brine in a Clashach sandstone core at 2–7 MPa pore fluid pressure using X-ray computed microtomography. Hydrogen saturation obtained during drainage at capillary numbers of <10−7 was ∼50% of the pore volume and independent of the pore fluid pressure. Hydrogen recovery during secondary imbibition at a capillary number of 2.4 × 10−6 systematically decreased with pressure, with 80%, 78% and 57% of the initial hydrogen recovered at 2, 5 and 7 MPa, respectively. Injection of brine at increasing capillary numbers up to 9.4 × 10−6 increased hydrogen recovery. Based on these results, we recommend more shallow, lower pressure sites for future hydrogen storage operations in porous media.	Nov 2022
B18-Core EXAFS I20-Scanning-X-ray spectroscopy (XAS/XES)	Sulfidation and reoxidation of U(VI)-incorporated goethite: implications for U retention during sub-surface redox cycling Olwen Stagg , Katherine Morris , Luke T. Townsend , Kristina O. Kvashnina , Michael L. Baker , Ryan L. Dempsey , Liam Abrahamsen-Mills , Samuel Shaw Environmental Science & Technology 2 DOI: 10.1021/acs.est.2c05314 Diamond Proposal Number(s): [21441, 24074] Open Access Show Abstract ▼ Abstract: Over 60 years of nuclear activity have resulted in a global legacy of contaminated land and radioactive waste. Uranium (U) is a significant component of this legacy and is present in radioactive wastes and at many contaminated sites. U-incorporated iron (oxyhydr)oxides may provide a long-term barrier to U migration in the environment. However, reductive dissolution of iron (oxyhydr)oxides can occur on reaction with aqueous sulfide (sulfidation), a common environmental species, due to the microbial reduction of sulfate. In this work, U(VI)–goethite was initially reacted with aqueous sulfide, followed by a reoxidation reaction, to further understand the long-term fate of U species under fluctuating environmental conditions. Over the first day of sulfidation, a transient release of aqueous U was observed, likely due to intermediate uranyl(VI)–persulfide species. Despite this, overall U was retained in the solid phase, with the formation of nanocrystalline U(IV)O2 in the sulfidized system along with a persistent U(V) component. On reoxidation, U was associated with an iron (oxyhydr)oxide phase either as an adsorbed uranyl (approximately 65%) or an incorporated U (35%) species. These findings support the overarching concept of iron (oxyhydr)oxides acting as a barrier to U migration in the environment, even under fluctuating redox conditions.	Nov 2022
I08-Scanning X-ray Microscopy beamline (SXM) I18-Microfocus Spectroscopy	Evolution of the Piauí Laterite, Brazil: mineralogical, geochemical and geomicrobiological mechanisms for cobalt and nickel enrichment Agnieszka Dybowska , Paul Schofield , Laura Newsome , Richard Herrington , Julian F. W. Mosselmans , Burkhard Kaulich , Majid Kazemian , Tohru Araki , Thomas J. Skiggs , Jens Kruger , Anne Oxley , Rachel L. Norman , Jonathan R. Lloyd Minerals 12 DOI: 10.3390/min12101298 Diamond Proposal Number(s): [14882, 14908, 17882] Open Access Show Abstract ▼ Abstract: The Piauí laterite (NE Brazil) was initially evaluated for Ni but also contains economic concentrations of Co. Our investigations aimed to characterise the Co enrichment within the deposit; by understanding the mineralogy we can better design mineral processing to target Co recovery. The laterite is heterogeneous on the mineralogical and lithological scale differing from the classic schematic profiles of nickel laterites, and while there is a clear transition from saprolite to more ferruginous units, the deposit also contains lateral and vertical variations that are associated with both the original intrusive complex and also the nature of fluid flow, redox cycling and fluctuating groundwater tables. The deposit is well described by the following six mineralogical and geochemical units: SAPFE, a clay bearing ferruginous saprolite; SAPSILFE, a silica dominated ferruginous saprolite; SAPMG, a green magnesium rich chlorite dominated saprolite; SAPAL, a white-green high aluminium, low magnesium saprolite; saprock, a serpentine and chlorite dominated saprolite and the serpentinite protolith. Not all of these units are ‘ore bearing’. Ni is concentrated in a range of nickeliferous phyllosilicates (0.1–25 wt%) including serpentines, talc and pimelite, goethite (up to 9 wt%), magnetite (2.8–14 wt%) and Mn oxy-hydroxides (0.35–19 wt%). Lower levels of Ni are present in ilmenites, chromites, chlorite and distinct small horizons of nickeliferous silica (up to 3 wt% Ni). With respect to Co, the only significant chemical correlation is with Mn, and Mn oxy-hydroxides contain up to 14 wt% Co. Cobalt is only present in goethite when Mn is also present, and these goethite grains contain an average of 0.19 wt% Co (up to a maximum of 0.65 wt%). The other main Co bearing minerals are magnetite (0.41–1.89 wt%), chlorite (up to 0.45 wt%) and ilmenite (up to 0.35 wt%). Chemically there are three types of Mn oxy-hydroxide, asbolane, asbolane-lithiophorite intermediates and romanechite. Spatially resolved X-ray absorption spectroscopy analysis suggests that the Co is present primarily as octahedrally bound Co3+ substituted directly into the MnO6 layers of the asbolane-lithiophorite intermediates. However significant levels of Co2+ are evident within the asbolane-lithiophorite intermediates, structurally bound along with Ni in the interlayer between successive MnO6 layers. The laterite microbial community contains prokaryotes and few fungi, with the highest abundance and diversity closest to ground level. Microorganisms capable of metal redox cycling were identified to be present, but microcosm experiments of different horizons within the deposit demonstrated that stimulated biogeochemical cycling did not contribute to Co mobilisation. Correlations between Co and Mn are likely to be a relic of parent rock weathering rather than due to biogeochemical processes; a conclusion that agrees well with the mineralogical associations.	Oct 2022

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