Bioenergetics of microbial sulfur-redox reactions in a glacial environment     

Katherine E. Wright  Stephen E. Grasby  Charles Williamson  John Spear  Alexis S. Templeton 《Applied Geochemistry》2011

The authors are studying microbial sulfur redox metabolisms in a glacial environment. The energy available from sulfur redox reactions at this site has been calculated using geochemical data obtained from the site. DNA has been extracted from the same site and is being analyzed for the presence and relative quantities of sulfur redox genes, to determine whether bioenergetic calculations can predict the sulfur redox reactions that microbes are in fact utilizing.  相似文献   

Identification of major moisture sources across the Mediterranean Basin     

Batibeniz  Fulden  Ashfaq  Moetasim  &#;nol  Bar&#;&#;  Turuncoglu  Ufuk Utku  Mehmood  Shahid  Evans  Katherine J. 《Climate Dynamics》2020,54(9):4109-4127

Climate Dynamics - We employ a Lagrangian based moisture back trajectory method on an ensemble of four reanalysis datasets to provide a comprehensive understanding of moisture sources over the...  相似文献   

H and Cl isotope systematics of apatite in brecciated lunar meteorites Northwest Africa 4472, Northwest Africa 773, Sayh al Uhaymir 169, and Kalahari 009     

Romain Tartèse  Mahesh Anand  Katherine H. Joy  Ian A. Franchi 《Meteoritics & planetary science》2014,49(12):2266-2289

We have investigated the H and Cl systematics in apatite from four brecciated lunar meteorites. In Northwest Africa (NWA) 4472, most of the apatites contain ～2000–6000 ppm H₂O with δD between ?200 and 0‰, except for one grain isolated in the matrix, which contains ～6000 ppm H₂O with δD of ～500–900‰. This low‐δD apatite contains ～2500–7500 ppm Cl associated with δ³⁷Cl of ～15–20‰, while the high‐δD grain contains ～2500 ppm Cl with δ³⁷Cl of ～7–15‰. In NWA 773, apatites in a first group contain ～700–2500 ppm H₂O with δD values averaging around ～0 ± 100‰, while apatites in a second group contain ～5500–16500 ppm H₂O with δD ～250 ± 50‰. In Sayh al Uhaymir (SaU) 169 and Kalahari (Kal) 009, apatites are similar in terms of their H₂O contents (～600–3000 ppm) and δD values (?100 to 200‰). In SaU 169, apatites contain ～6000–10,000 ppm Cl, characterized by δ³⁷Cl of ～5–12‰. Overall, most of the analyzed apatite grains have δD within the range reported for carbonaceous chondrites, similar to apatite analyzed in ancient (>3.9 Ga) lunar magmatic. One grain in NWA 4472 has H and Cl isotope compositions similar to apatite from mare basalts. With an age of 4.35 Ga, this grain could be a representative of the oldest known lunar volcanic activity. Finally, since numerous evolved clasts in NWA 773 formed through silicate liquid immiscibility, the apatite grains with extremely high H₂O contents, reaching pure hydroxylapatite composition, could provide insights into the effects of such process on the evolution of volatiles in lunar magmas.  相似文献   

On the Binary Nature of SS 433     

Linda Schmidtobreick  Katherine Blundell 《Astrophysics and Space Science》2006,304(1-4):271-274

We present time–resolved optical spectroscopy of the famous X-ray binary SS 433. We obtained 61 medium resolution spectra spread over three months and thus cover roughly five orbits and about half a precession phase. We used various emission lines, that we attribute to the accretion disc, to determine the radial velocities of the compact component. They are of course modulated with the orbital period but in addition show a variation of the system velocity on a longer time scale. With the present data it is not possible to determine whether this is a transient effect or a periodic variation, although we present various possible interpretations of this effect.  相似文献   

Bedding Angle Identification from BIF Marker Shales via Modified Dynamic Time Warping     

George  Mark A.  Silversides  Katherine L.  Zigman  John  Melkumyan  Arman 《Mathematical Geosciences》2021,53(7):1567-1585

Mathematical Geosciences - When modelling a stratified orebody, accurately representing the dip and dip direction is important for accurate resource estimation. In the banded iron formation-hosted...  相似文献   

Boundary Identification and Surface Updates Using MWD     

Silversides  Katherine L.  Melkumyan  Arman 《Mathematical Geosciences》2021,53(5):1047-1071

Mathematical Geosciences - In the banded iron formation-hosted iron ore deposits in the Hamersley Range of Western Australia, the stratigraphic boundaries are generally modelled using data from...  相似文献   

The Moon: An Archive of Small Body Migration in the Solar System     

Katherine H. Joy  Ian A. Crawford  Natalie M. Curran  Michael Zolensky  Amy F. Fagan  David A. Kring 《Earth, Moon, and Planets》2016,118(2-3):133-158

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North American Earth Science Megaproject Continuum, Part 3: New Canadian EON-ROSE Program     

Katherine Boggs  David Eaton  Thomas James  Roy Hyndman  Malaika Ulmi  Pascal Audet  Ed Johnston  Michael Sideris  Ron Clowes  Julie Elliott  Jeff Freymueller  Paul Kushner  Kristin Morell  Derek Schutt  Rick Aster  Frank Vernon  Michael Hedlin  Catherine de Groot-Hedlin  Eric Donovan  Roland Stull 《《地质学报》英文版》2018,92(Z1):12-13

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Increasing Use of Human-Dominated Habitats as CO<Subscript>2</Subscript> Emissions Warm and Acidify Oceans     

Katherine A. Heldt  Sean D. Connell  Pablo Munguia 《Estuaries and Coasts》2018,41(6):1660-1666

Urban and artificial structures are increasingly added to the world’s coasts during a time in which changing climate is forecast to drive shifts in naturally occurring habitats. We ask whether the role of artificial structures as marine habitats will increase in importance relative to their natural counterparts, particularly as natural habitats are negatively affected by ocean warming and acidification. To evaluate this model, we contrasted use of natural (kelp forest and turfing algae) and artificial habitat (plastic pier-piling) by a nest-building amphipod (Cymadusa pemptos) under current and future climate conditions of CO₂ and temperature. Under future conditions, amphipod populations in mesocosms increased, but this did not lead to greater proportional colonization of kelp and turf. Instead, colonization doubled in artificial habitats, and there was increasing production and occupation of nests on artificial habitats relative to natural habitats. In an age when human modification of natural substrata is increasingly cited as an agent of wildlife decline, understanding the future role of artificial habitats as replacement dwellings for natural habitats is critical. We pioneer an understanding of the future role of natural and artificial habitats, identifying the possibility that the role of urban structures as marine habitats may only increase.  相似文献   

Machine Learning Predictions of pH in the Glacial Aquifer System,Northern USA     

Paul E. Stackelberg  Kenneth Belitz  Craig J. Brown  Melinda L. Erickson  Sarah M. Elliott  Leon J. Kauffman  Katherine M. Ransom  James E. Reddy 《Ground water》2021,59(3):352-368

A boosted regression tree model was developed to predict pH conditions in three dimensions throughout the glacial aquifer system of the contiguous United States using pH measurements in samples from 18,386 wells and predictor variables that represent aspects of the hydrogeologic setting. Model results indicate that the carbonate content of soils and aquifer materials strongly controls pH and, when coupled with long flowpaths, results in the most alkaline conditions. Conversely, in areas where glacial sediments are thin and carbonate-poor, pH conditions remain acidic. At depths typical of drinking-water supplies, predicted pH >7.5—which is associated with arsenic mobilization—occurs more frequently than predicted pH <6—which is associated with water corrosivity and the mobilization of other trace elements. A novel aspect of this model was the inclusion of numerically based estimates of groundwater flow characteristics (age and flowpath length) as predictor variables. The sensitivity of pH predictions to these variables was consistent with hydrologic understanding of groundwater flow systems and the geochemical evolution of groundwater quality. The model was not developed to provide precise estimates of pH at any given location. Rather, it can be used to more generally identify areas where contaminants may be mobilized into groundwater and where corrosivity issues may be of concern to prioritize areas for future groundwater monitoring.  相似文献