A5085831965- Paleontology and Stratigraphy of Fossils
- Geology and Paleoclimatology Research
- Astro and Planetary Science
- Geochemistry and Elemental Analysis
- Geological and Geochemical Analysis
- Isotope Analysis in Ecology
- Hydrocarbon exploration and reservoir analysis
- Planetary Science and Exploration
- Methane Hydrates and Related Phenomena
- Groundwater and Isotope Geochemistry
- Geochemistry and Geologic Mapping
- Selenium in Biological Systems
- Marine Biology and Ecology Research
- Heavy metals in environment
- Mercury impact and mitigation studies
- Nuclear Physics and Applications
- Metabolism and Genetic Disorders
- Electron and X-Ray Spectroscopy Techniques
- Geological and Geophysical Studies
- Radioactive element chemistry and processing
- Marine and coastal ecosystems
- Metal Extraction and Bioleaching
- Global Energy and Sustainability Research
- Gamma-ray bursts and supernovae
- Characterization and Applications of Magnetic Nanoparticles
Planetary Science Institute
2012-2021
Harvard University
2020-2021
Life Science Institute
2015-2020
Tokyo Institute of Technology
2015-2020
Earth-Life Science Institute
2015-2017
Princeton University
2016
University of Washington
2006-2015
Washington University in St. Louis
2011-2015
Earth and Space Research
2015
Centre National de la Recherche Scientifique
2003-2004
Rationale The denitrifier method allows for highly sensitive measurement of the 15N/14N (δ15N value) and 18O/16O (δ18O nitrate dissolved in natural waters δ15N other N forms (e.g., organic N) that can be converted into nitrate. Here, updates to instrumentation protocols are described, improvements data quality demonstrated. Methods A 'heart cut' N2O was implemented extraction system (1) minimize introduction contaminants mass spectrometer, reducing isotopic drift (2) decrease fraction sample...
Summary We report here a molecular survey based on 16S rRNA genes of the bacterial diversity found in two deep‐sea vent niches at Mid‐Atlantic Ridge: hydrothermal sediment (Rainbow site), and microcolonizers made three different substrates (organic‐rich, iron‐rich pumice) that were exposed for 15 days to emission. Bacterial samples was scattered through many divisions. The most abundant diverse environmental sequences (phylotypes) our libraries corresponded Gammaproteobacteria, followed by...
We report a new method for precise analysis of gallium (Ga) isotopic composition in geological samples. The purification Ga is achieved by three-step ion exchange chromatography to remove matrix and interfering elements. 71Ga/69Ga ratios are analyzed multi-collector inductively-coupled-plasma mass-spectrometer (MC-ICP-MS). external reproducibility the measurements (0.05‰, 2 s.d.) was assessed replicate analyses USGS BCR-2 BHVO-2 standards. This newly developed technique then used investigate...
Selenium has a complex biogeochemical cycle with many similarities to that of sulfur. Fractionations selenium isotopes induced in bacterial respiration reactions have been recognized as potential recorders environmental oxidation states, opening up the possibility further constraining bioproductivity and redox evolution Earth's atmosphere ocean over time. However, analyses are complicated by interferences organic compounds well number isobaric interferences. Application existing sample...
Alzheimer's disease is associated with abnormal homeostasis of Zn, because deposits Zn-rich amyloid-β fibrils.This connection between Zn and brain aging provides a possibility to use changes in study the evolution disease.Here, we studied isotopic composition brain, serum red blood cells from APPswe/ PSEN1dE9 transgenic mice, which develop Alzheimer's-like (including Aβ deposition starting after 6 months), comparison wild type controls.We found that brains become progressively enriched...
Research Article| September 01, 2009 Major perturbation in sulfur cycling at the Triassic-Jurassic boundary Kenneth H. Williford; Williford 1University of Washington, Seattle, Washington 98195, USA *Current address: Curtin University Technology, Perth, Australia; E-mail: k.williford@curtin.edu.au. Search for other works by this author on: GSW Google Scholar Julien Foriel; Foriel Peter D. Ward; Ward Eric J. Steig Geology (2009) 37 (9): 835–838. https://doi.org/10.1130/G30054A.1 Article...
Abstract– High‐precision Cu isotopic compositions have been measured for the metal phase of 29 iron meteorites from various groups and four terrestrial standards. The data are reported as δ 65 permil deviation Cu/ 63 ratio relative to NIST SRM 976 standard. Terrestrial mantle rocks a very narrow range variations scatter around zero. In contrast, show approximately 2.3‰ variations. Different distinct values. Nonmagmatic IAB‐IIICD similar (0.03 ± 0.08 0.12 0.10, respectively), close values...
Abstract The 3.6 Ma, 18‐km‐diameter El'gygytgyn impact structure (Arctic Russia) is unique among the currently known terrestrial craters in that it only one was formed acid volcanic rocks. Previous analyses of impactites from showed minor enrichments siderophile elements, including Ir, which, together with distinct Cr enrichments, gave rise to speculation an achondritic projectile involved. We studied major and trace element composition samples new ICDP drill core obtained near center...
Stepwise dissolution of primitive meteorites exhibits large 54Cr anomalies but no collateral effects on 58Fe and 48Ca, two other neutron-rich nuclides from the iron peak. These results suggest that must have been produced in particular zones rare Type Ia supernovae or 48Ca and/or were together II chemically separated into some mineral phase favors Cr over Ca Fe, it is properties driving isotopic effect leaching. The recent findings nanometer-size oxide grains with very excesses favored...