TY - JOUR. T1 - Positional isotope exchange analysis of the Mycobacterium smegmatis cysteine ligase (MshC). AU - Williams, La Kenya. AU - Fan, Fan. AU - Blanchard, John S.. AU - Raushel, Frank M.. PY - 2008/4/22. Y1 - 2008/4/22. N2 - MshC catalyzes the ATP-dependent condensation of GlcN-Ins and cysteine to form Cys-GlcN-Ins, which is an intermediate in the biosynthetic pathway of mycothiol, i.e., 1-D-myo-inosityl-2-(N-acetyl-L-cysteinyl)amido-2-deoxy-α- D-glucopyranoside (MSH or AcCys-GlcN-Ins). MSH is produced by Mycobacterium tuberculosis, members of the Actinomycetes family, to maintain an intracellular reducing environment and protect against oxidative and antibiotic induced stress. The biosynthesis of MSH is essential for cell growth, and therefore, the MSH biosynthetic enzymes present potential targets for inhibitor design. The formation of kinetically competent adenylated intermediates was suggested by the observation of positional isotope exchange (PIX) reaction using [βγ-18O6]-ATP in ...

PANGAEA - Publishing Network for Geoscientific and Environmental Data. (Appendix E) Stable carbon and oxygen isotope composition of Globigerinoides sacculifera of ODP Hole 121-758B. Occurrence Dataset https://doi.org/10.1594/pangaea.759093 accessed via GBIF.org on 2017-12-15 ...

Single garnet crystals from a large, multicyclic hydrothermal system in Far East Russia are strongly growth zoned. Microscale ion microprobe analysis reveals consistent intracrystalline patterns in oxygen isotope composition and boron and iron contents, reflecting evolution of the hydrothermal system from magmatic- to meteoric-dominated conditions, and repetitive influx of magmatic fluids. Large intracrystalline variations in oxygen isotope composition (,12‰ δ18O) delimit temporal evolution of magmatic and meteoric fluid input within different portions of the hydrothermal system, and suggest that fluid-flow regimes differed between central and distal portions of the system. These results provide compelling evidence that microanalytical data can be extrapolated from intracrystalline scales to study macroscale processes in complex, large-scale fluid-rock systems. ...

Topographic development of the southern Washington Cascade Range and its influence on regional climate on the leeward side of the range for the past 15.6 m.y. are evaluated, using oxygen isotope ratios (δ18O) of ancient meteoric water recorded in authigenic smectites. The δ18O values of authigenic smectites from paleosols and altered tuffs on the east side of the range exhibit a temporal and continuous decrease of ∼3‰-4‰ from 15.6 Ma to the present. Taking into account a regional temperature change in eastern Washington since the middle Miocene, the calculated δ18O values of regional meteoric water show a negative shift of ∼3.5‰-4.5‰ over the same interval. Such a decrease is similar to the change in the δ18O values of modern precipitation from the coastal side to a region downwind of the Washington Cascades. This negative shift of the calculated δ18O values on the east side of the range is best explained by the development of a rain shadow due to the tectonic rock uplift of the ...

A recurrent interpretation of ancient climate based on the oxygen isotopic composition of marine carbonates and cherts suggests that Earths climate was substantially warmer in the distant past and remained so until as recently as 400 Myr ago. This interpretation is difficult to reconcile with the long-term glacial record, with evidence for modest weathering rates during most of Earths history, with biomarker and fossil evidence for eukaryotes and even vertebrates at times of anomalously low δ18O values, and with the predicted faintness of the young Sun. We argue here, following earlier suggestions, that the low δ18O values in ancient rocks are a consequence of the low δ18O of ancient seawater. A modest increase in ocean depth with time, together with progressive increases in pelagic sedimentation on midocean ridge flanks since about 550 Ma, could account for the variation in seawater isotopic composition. The required change in ocean depth, coupled with thinning of the oceanic crust, is a ...

Abstract The paper presents the principle of a method to measure infiltration rates in sewer systems based on the use of oxygen isotopes and its application in Lyon (France). Investigations in the urban area of Lyon benefit from the isotopic differences between underground waters originating from the two rivers Rhône and Saône and from their associated alluvial aquifers. The oxygen isotopic composition of the Rhône water is roughly 3 ‰ lighter than that of the Saône river, due to the large differences in the mean altitude and topographic situation of their catchments. Large amounts of water are pumped from the Rhône aquifer for drinking water supply. As a consequence, this difference in the oxygen isotopic composition between wastewater and local groundwater can be used to evaluate infiltration in sewers in some parts of the city. The results obtained in a case study allow to evaluate the reliability and the uncertainties of this method. ...

This dissertation investigates hydrological variability within tropical Asia over the past several few centuries as reflected in the stable oxygen isotope composition of atmospheric moisture. The stable isotopes of water in the climate system are unique tracers of moisture transport and tropical rainfall variability. The isotopic signal of atmospheric moisture within the tropics is transferred to cellulose of tropical trees during photosynthesis. Thus, the isotopic composition of tree cellulose can provide an archive of past hydrologic variability through isotopic reconstructions of the cellulose extracted from annual rings of long lived trees. The tropical atmospheric variability reflected in tropical trees can include variations in the Indian Monsoon and changes in moisture availability over Asia in response to the El Niño-Southern Oscillation (ENSO). Here an attempt has been made to better understand how the atmospheric dynamics associated within these climate phenomena influence the ...

This dissertation investigates hydrological variability within tropical Asia over the past several few centuries as reflected in the stable oxygen isotope composition of atmospheric moisture. The stable isotopes of water in the climate system are unique tracers of moisture transport and tropical rainfall variability. The isotopic signal of atmospheric moisture within the tropics is transferred to cellulose of tropical trees during photosynthesis. Thus, the isotopic composition of tree cellulose can provide an archive of past hydrologic variability through isotopic reconstructions of the cellulose extracted from annual rings of long lived trees. The tropical atmospheric variability reflected in tropical trees can include variations in the Indian Monsoon and changes in moisture availability over Asia in response to the El Niño-Southern Oscillation (ENSO). Here an attempt has been made to better understand how the atmospheric dynamics associated within these climate phenomena influence the ...

Oxygen isotope composition of main-group pallasites and mesosiderites. Data for main-group pallasites and mesosiderites from Greenwood et al. (2006). Solid lines through data points show the mean Δ17O value for each group. Grey-shaded boxes depict the 2σ error on the mesosiderite and main-group pallasite population Δ17O and δ18O mean values. Open squares are individual mesosiderite analyses, open circles individual pallasite analyses. The dashed line labelled (1) is the eucrite fractionation line of Greenwood et al. (2005); the dashed line labelled (2) shows the range of HED values obtained by Weichert et al. (2004). Δ17O is linearized using the format of Miller (2002): Δ17O = 1000 ln (1+ (δ17O/1000)) - λ1000 ln (1+ ( δ18O/1000)) where λ = 0.5247. TFL = Terrestrial Fractionation Line ...

Oxygen isotope composition of Martian meteorites. Data for Martian meteorites from Franchi et al. (1999) and compiled from laser fluorination analyses in the Meteoritical Bulletin. MFL: Martian fractionation line of Franchi et al. (1999), TFL: terrestrial fractionation line.Δ17O calculated as: Δ17O = δ17O - 0.52δ18O ...

The Antarctic Glaciological Data Center (AGDC) at NSIDC is pleased to announce the release of a new data set, the WAIS Divide WDC06A Oxygen Isotope Record. This data set contains complete low resolution (0.25 to 100 cm) oxygen isotope data from the WAIS Divide Ice Core WDC06A, 0 to 3404.7 m depth. Also included is the WDC2014 timescale.. ...

We measured the δ18O of cellulose (δ18Ocel) extracted from fossil wood collected at 9 sites in the northern and southern hemispheres as a potential source of information about precipitation δ18O (δ18Oppt) in the past and paleotemperatures. The samples had been buried in fluvial sediments for periods of time ranging from ca. 45 million to 250 years. At the oldest localities (high latitude, Eocene- through Pliocene-age sites in Canada and Russia), mean annual temperature (MAT) estimates derived from the modern relationship between MAT and δ18Ocel are 6-16°C lower than the MAT estimates derived from other biological proxies. Estimates of Pleistocene and Holocene mean annual temperatures are close to the modern values at those sites. These results are consistent with other recent findings that the MAT/δ18Oppt relationship across North America was not constant throughout the Cenozoic. Paleo-δ18Oppt estimates derived from fossil cellulose and the modern North American relationship between ...

Margaret Barbour holds a BSc in Biology and Earth Sciences and an MSc in Biology from the University of Waikato, New Zealand, and a PhD in Plant Science from the Australian National University. During her PhD she developed new understanding, and mechanistic models, of variability in the oxygen isotope composition of plant tissue. Her work was the first to theoretically describe and demonstrate the record of leaf evaporative environment present in the oxygen isotope composition of plant material. This work has subsequently been applied to reconstruct past climates from tree ring stable isotopes, as an indicator of plant regulation of water loss, and as a selection tool for yield in grain crops. Margaret was employed by Landcare Research in New Zealand from 2001 to 2009, where she led a Foundation-funded objective investigating the exchange of carbon dioxide in terrestrial systems at site scales, and the sensitivities and uncertainties of these processes to variation in climate, environmental and ...

TY - JOUR. T1 - Vein growth mechanisms and fluid sources revealed by oxygen isotope laser microprobe. AU - Kirschner, D. L.. AU - Sharp, Z. D.. AU - Teyssier, Christian. PY - 1993/1/1. Y1 - 1993/1/1. N2 - In situ, laser microprobe analyses of millimetre-wide quartz veins has revealed the largest δ 18 O gradients (9‰/mm) yet documented in terrestrial samples. The systematic isotopic variations indicate a crack-seal growth mechanism that variably interleaved 18 O-enriched quartzite porphyroclasts with newly precipitated, 18 O-depleted vein quartz. The isotopically light quartz requires open-system infiltration of meteoric fluids into the quartzite during its incorporation into the Ruby Gap duplex (central Australia). Documentation of the fluid source in these small veins would not be possible without submillimetre isotopic sampling capabilities. Application of this laser-based technology to other geological problems should result in similar documentation of large isotopic gradients and provide ...

We investigate the helium (He-3/He-4) and carbon (delta C-13) isotope compositions and relative abundance ratios (CO2/He-3) of gas samples together with the stable isotope compositions of dissolved carbon and sulfur and the oxygen and hydrogen isotopic compositions of the associated water phase from a number of geothermal fields located around Lake Van in eastern Anatolia, Turkey. The mantle-derived helium component, which is likely transferred to the crust beneath eastern Turkey by recent magmatism, is found to constitute up to 96% (e.g. Nemrut Caldera) of the total He content in fluids. As regards the spatial distribution of He, samples collected from areas of Pliocene-Quaternary volcanics are characterized by a wide and generally higher range of R/R-A ratios (0.93 to 7.76 R-A) compared to those of non-volcanic regions ((1.85 to 1.0 R-A). CO2/He-3 ratios vary over a wide range (2.4 x 10(5)-3.8 x 10(13)) but are mostly higher than that of the nominal upper mantle (similar to 2 x 10(9)). ...

Deep-water pockmarks are frequently accompanied by the occurrence of massive gas hydrates in shallow sediments. A decline in pore-water Cl− concentration and rise in δ18O value provide compelling evidence for the gas hydrate dissociation. Mega-pockmarks are widely scattered in the southwestern Xisha Uplift, northern South China Sea (SCS). Pore water collected from a gravity-core inside of a mega-pockmark exhibits a downward Cl− concentration decrease concomitant with an increase in δ18O value at the interval of 5.7-6.7 mbsf. Concentrations of Cl−, Na+, and K+ mainly cluster along the seawater freshening line without distinct Na+ enrichment and K+ depletion. Thus, we infer that the pore water anomalies of Cl− concentrations and δ18O values are attributed to gas hydrate dissociation instead of clay mineral dehydration. Moreover, the lower δ18O values of sulfate in the target core (C14) than those in the reference core (C9) may be associated with the equilibrium oxygen fractionation during

Granger, J., M. G. Prokopenko, D. M. Sigman, C. W. Mordy, Z. M. Morse, L. V. Morales, R. N. Sambrotto, and B. Plessen (2011), Coupled nitrification-denitrification in sediment of the eastern Bering Sea shelf leads to (15)N enrichment of fixed N in shelf waters, J. Geophys. Res., 116, C11006, doi:10.1029/2010JC006751 ...

This thesis work is aimed at examining the oxygen atom mixing between common iron(III) oxides and Fe(II)aq solution during the sorption process. First, O labeled iron(III) minerals were used in batch sorption reactors to study the exchange of oxygen atom within the Fe(II)aq - iron(III) oxide system. Results showed a much lesser extent of oxygen mixing than reported Fe mixing from previous studies, even when dissolved Fe(II) is present. The oxygen mixing extents are 3.95 % more for goethite and 9.66 % more for ferrihydrite than their respective controls within 14 days. A consecutive atom exchange kinetic study indicated that O exchange is not inhibited by surface Fe sorptive site saturation, and that after 40d sorption experiment, the maximum O exchange is 54.96 % across reactors with different initial solid loadings and Fe(II)aq levels. The second part of this work examined the influence of aqueous Fe(II) on the sorption of selenium oxyanions (selenite and selenate) in Fe(II)aq - iron(III) systems. It

On the previous Isotope page, you learned a bit about what isotopes are, how they are obtained, and how the isotopes of certain elements are measured. Here, well elaborate on how to read carbon and oxygen isotope data and how the values are often interpreted by paleoclimatologists. Reading Isotope Data Measurements of carbon and oxygen…

Langer, G. , Ziveri, P. , Geisen, M. and Thoms, S. (2008): Oxygen isotope fractionation during calcification in Calcidiscus leptoporus: The influence of carbonate chemistry , European Geosciences Union, General Assembly 2008, 13 18 April, Vienna, Austria ...

Abstract. Stable oxygen isotope composition of atmospheric precipitation (δ18Op) was scrutinized from 39 stations distributed over Switzerland and its border zone. Monthly amount-weighted δ18Op values averaged over the 1995-2000 period showed the expected strong linear altitude dependence (−0.15 to −0.22‰ per 100 m) only during the summer season (May-September). Steeper gradients (~ −0.56 to −0.60‰ per 100 m) were observed for winter months over a low elevation belt, while hardly any altitudinal difference was seen for high elevation stations. This dichotomous pattern could be explained by the characteristically shallower vertical atmospheric mixing height during winter season and provides empirical evidence for recently simulated effects of stratified atmospheric flow on orographic precipitation isotopic ratios. This helps explain anomalous deflected altitudinal water isotope profiles reported from many other high relief regions. Grids and isotope distribution maps of the ...

In the next two lectures we will examine past climates (paleoclimates) and the forces. We have already discussed the importance of isotopes for rock dating. The ratio of these two oxygen isotopes has changed over the ages and these. Other factors which work in conjunction with the Earths orbital changes include.

The very neutron-rich oxygen isotopes 25O and 26O are investigated experimentally and theoretically. The unbound states are populated in an experiment performed at the R3B-LAND setup at GSI via proton-knockout reactions from 26F and 27F at relativistic energies around 442 and 414 MeV/nucleon, respectively. From the kinematically complete measurement of the decay into 24O plus one or two neutrons, the 25O ground-state energy and width are determined, and upper limits for the 26O ground-state energy and lifetime are extracted. In addition, the results provide indications for an excited state in 26O at around 4 MeV. The experimental findings are compared to theoretical shell-model calculations based on chiral two- and three-nucleon (3N) forces, including for the first time residual 3N forces, which are shown to be amplified as valence neutrons are added ...

Carbon mineralogy, phosphorus and oxygen isotope records from the Late Pleistocene at ODP Hole 1198 A (Leg 194 Marion Plateau, Australia ...

Fertilizers Res. 45, 91-100. , 1961. Precipitation of silver phosphate from homogeneous solution. Anal. Chem. 33, 873-887. , 1982. UV-sensitive complex phosphorus: association with dissolved humic material and iron in a bog lake. Limnol. Oceonogr. 27, 564-569. , 2012. Variation in the photochemical lability of dissolved organic matter in a large boreal watershed. Aquatic Sci. 74, 751-768. , 1996. Inter- and intra-tooth variation in the oxygen isotope composition of mammalian tooth enamel: some implications for paleoclimatological and paleobiological research. Orig. Life Evol. Biosphere 29, 555-561. , 2005. Phosphine in soils, sludges, biogases and atmospheric implications-a review. Ecolog. Eng. 24, 457-463. , 2011a. Phosphate oxygen isotopes: insights into sedimentary phosphorus cycling from the Benguela upwelling system. Geochim. Cosmochim. Acta 75, 3741-3756. , 2011b. Marine sediment pore-water profiles of phosphate delta O-18 using a refined micro-extraction. Limnol. Oceanogr. Met. 9, ...

In order to investigate mid-Cretaceous terrestrial climates of low paleolatitudes, Moroccan, Tunisian and Brazilian vertebrate apatites have been analyzed for their oxygen and carbon isotope compositions of phosphates (delta O-18(p)) and carbonates (delta O-18(c), delta C-18(c)). At each site, coexisting theropod dinosaurs, titanosaurid sauropods, pterosaurs, crocodilians, turtles and fish have distinct delta O-18(p) and delta C-18(c) values reflecting their ecologies, diets and foraging environments. Oxygen isotope compositions of surface waters (delta O-18(w)) estimated from turtle and crocodile delta O-18(p) values range from -5.0 +/- 1.0 parts per thousand to -2.4 +/- 1.0 parts per thousand, which do not differ from mean annual rainwater values occurring today under inter-tropical sub-arid to arid climates. High water temperatures ranging from 21 +/- 6 degrees C to 34 +/- 2 degrees C deduced from fish delta O-18(p) values are in agreement with those published for mid-Cretaceous low ...

Abstract: Few long and well-dated summer precipitation reconstructions that extend beyond the longest records of instrumental measurements exist in Europe. Further understanding of the past trends in summer precipitation and the mechanisms driving that variability are necessary to improve the predictions of climate models. Tree rings are unique in their ability to provide high-resolution, absolutely dated climate signals for the study of palaeoclimatology. The physiological processes controlling oxygen isotope composition (δ18O) in wood are reasonably well understood highlighting its potential as a climate proxy in a variety of environments. Significant correlation between wood δ18O and precipitation has been demonstrated worldwide reflecting both direct rainout processes and indirectly evaporative enrichment. We present an annually resolved reconstruction of precipitation based upon oxygen isotope variations in tree ring cellulose covering the most recent ˜400 years for England. The ...

Contribution of soil respiration in tropical, temperate, and boreal forests to the18O enrichment of atmospheric O2 Academic Article ...

The authors report the analysis of the oxygen isotopic composition of sulfates dissolved in 102 samples of thermal waters coming from different contexts: sedimentary (Parisian Basin), volcanic (New Mexico, West Indies, Mont Dore in France), or base (France), with t

The site-specific quantitation of N- and O-glycosylation is vital to understanding the function(s) of different glycans expressed at a given site of a protein under physiological and disease conditions. Most commonly used precursor ion intensity based quantification method is less accurate and other labeled methods are expensive and require enrichment of glycopeptides. Here, we used glycopeptide product (y and Y0) ions and (18)O-labeling of C-terminal carboxyl group as a strategy to obtain quantitative information about fold-change and relative abundance of most of the glycoforms attached to the glycopeptides. As a proof of concept, the accuracy and robustness of this targeted, relative quantification LC-MS method was demonstrated using Rituximab. Furthermore, the N-glycopeptide quantification results were compared with a biosimilar of Rituximab and validated with quantitative data obtained from 2-AB-UHPLC-FL method. We further demonstrated the intensity fold-change and relative abundance of 46 ...

The Akiri vein copper mineralization was investigated for its carbon and oxygen isotopic composition to determine the characteristics of the mineralizing fluid. Carbon and oxygen isotope analyses of Akiri siderite range between δ13C values (-1.05 to -1.71‰) and δ13O values (-14.94 to -15.18) respectively. δ13C isotopic composition is comparable to values expected for Cretaceous marine carbonates. The 18O depletion in the vein siderite indicates dominant meteoric water sources involved for carbonates precipitation. This significant depletion between the δ18O compositions of Akiri siderite compared with carbonates from other parts of the basin probably indicate differential formational temperature or fluid composition ...

Biologic rhythms give insight into normal physiology and disease. They can be used as biomarkers for neuronal degenerations. We present a diverse data set to show that hair and teeth contain an extended record of biologic rhythms, and that analysis of these tissues could yield signals of neurodegenerations. We examined hair from mummified humans from South America, extinct mammals and modern animals and people, both healthy and diseased, and teeth of hominins. We also monitored heart-rate variability, a measure of a biologic rhythm, in some living subjects and analyzed it using power spectra. The samples were examined to determine variations in stable isotope ratios along the length of the hair and across growth-lines of the enamel in teeth. We found recurring circa-annual periods of slow and fast rhythms in hydrogen isotope ratios in hair and carbon and oxygen isotope ratios in teeth. The power spectra contained slow and fast frequency power, matching, in terms of normalized frequency, the ...

Ikaite crystals incorporate ocean bottom water into their structure as they form. During cooling periods, when ice sheets are expanding, ocean bottom water accumulates heavy oxygen isotopes (oxygen 18). When glaciers melt, fresh water, enriched in light oxygen isotopes (oxygen 16), mixes with the bottom water. The scientists analyzed the ratio of the oxygen isotopes in the hydration water and in the calcium carbonate. They compared the results with climate conditions established in Northern Europe across a 2,000-year time frame. They found a direct correlation between the rise and fall of oxygen 18 in the crystals and the documented warming and cooling periods. ...

This thesis investigates how variations in the oxygen isotopic composition of lake waters in northern Fennoscandia are recorded in lake sediment archives, especially diatoms, and how these variations can be used to infer past changes in climate and atmospheric circulation. Results from analyses of the oxygen isotopic composition of lake water samples (δ18Olakew) collected between 2001 and 2006 show that δ18O of northern Fennoscandian lakes is mainly controlled by the isotopic composition of the precipitation (δ18Op). Changes in local δ18Op depend on variations in ambient air temperature and changes in atmospheric circulation that lead to changes in moisture source, vapour transport efficiency, or winter to summer precipitation distribution. This study demonstrates that the amount of isotopic variation in lake water δ18O is determined by a combination of the original δ18Olakew, the amount and timing of the snowmelt, the amount of seasonally specific precipitation and groundwater, any ...

ABSTRACT: In 2007 a ceremonial complex representing the Globular Amphora Culture was discovered in Kowal (the Kuyavia region, Poland). Radiocarbon dating demonstrated that the human remains associated with the complex are of similar antiquity, i.e. 4.105 ± 0.035 conv. and 3.990 ± 0.050 conv. Kyrs. After calibration, this suggests a period between 2850 and 2570 BC (68.2% likelihood), or more specifically, 2870 to 2500 BC (95.4% likelihood). Morphological data indicate that the skeleton belonged to a male who died at 27-35 years of age. The unusual morphology of his hard palate suggests this individual may have had a speech disorder. Stable oxygen isotope values of the individuals teeth are above the locally established oxygen isotope range of precipitation, but due to sample limitations we cannot conclusively say whether the individual is of non-local origin. Stable carbon and nitrogen isotope ratios were analyzed to reconstruct the diet of the studied individual, and show a terrestrial-based ...

You know that water is made of hydrogen and oxygen atoms arranged in molecules of H2O, but you may not be aware that there are different types of oxygen atoms. Different atoms of the same element are called isotopes. All oxygen atoms have 16 protons and 16 electrons, but some oxygen atoms have 16, 17, or 18 neutrons in the nucleus. The most abundant isotopes of oxygen in seawater are oxygen sixteen (16O) and oxygen eighteen (18O). Water molecules with 16O atoms evaporate more easily than water molecules with 18O atoms, so the relative numbers of 16O and 18O atoms that remain in the water change as evaporation occurs. Water from which 16O atoms have preferentially evaporated has a higher ratio of 18O to 16O atoms than water that has experienced less evaporation. As salinity also increases as evaporation occurs, we can generalize the relationship to state that water with an increased 18O to 16O ratio is saltier than water with a lower 18O to 16O ratio.. ! Click the red dot in the Caribbean to see ...

Euxinic conditions, which are defined by the presence of sulfide in the water column, were common in ancient oceans. However, it is not clear how the presence of sulfide in the water column affects the balance between rates of sulfide oxidation and sulfate reduction, which plays a major role in regulating the net redox state of the ocean-atmosphere system. Euxinia could lead to higher rates of sulfide oxidation because sulfide may diffuse more rapidly into the oxic zone in solution than in sediment. Alternatively, sulfide oxidation could be inhibited by low overall availability of suitable oxidants in euxinic settings. Here, we constrain rates of sulfide oxidation versus sulfate reduction in four euxinic water columns in coastal ponds by modeling the evolution of the concentration and sulfur and oxygen isotope compositions of sulfate from post-hurricane, well-oxygenated conditions to modern, euxinic conditions. The results of the one-dimensional, depth-dependent models of water column sulfate ...

Ehleringer, J.R., Bowen, G.J., Chesson, L.A., West, A.G., Podlesak, D.W. & Cerling, T.E. (2008) Hydrogen and oxygen isotope ratios in human hair are related to geography. Proceedings of the National Academy of Sciences of the United States of America, 105, 2788-2793 ...

Munich, Germany (SPX) Oct 05, 2012 - Oxygen isotopes in tree rings are an excellent archive of precipitation dynamics in the tropical Amazon region. The precise determination of the ratios of stable oxygen isotopes (18O/16O) proves to

Ng, J., B. Williams, D.M Thomson, and J. Halfar. Developing a forward model of encrusting coralline algae. Geochimica et Cosmochimica Acta, 194, 2016, 279-290.. Abstract: An increased number of climate proxy records and more refined interpretation of proxy data are crucial to improve projections of future climate at high latitudes, where internal feedbacks amplify warming and established high-resolution climate archives are especially sparse. Encrusting coralline algae are being developed as a mid- to high-latitude marine climate archive. These long-lived algae form a solid high-Mg calcite skeleton with annual growth bands similar to those of trees and tropical corals. The oxygen isotope ratio of the algal skeleton (d18Oalg) records local environmental and climatic factors, notably sea surface temperature and seawater d18O. Here we assess the d18Oalg-climate relationship in diverse environments across the algal habitat range utilizing two species of coralline algae from the genus ...

Teeth provide remarkable evidence about the early years of an individuals life. The region where a person grew up can be traced in the tooth enamel laid down in their first 14 years because strontium and oxygen isotope ratios in the teeth reflect the food a person ate and the water they drank. When rocks form, they contain minute traces of radioactive rubidium 87, which decays to strontium 87. Over millions of years, the ratio of strontium 87 to the stable isotope strontium 86 changes, so, in very young rocks, the ratio will be smaller than in very old rocks.. These rocks weather and become the soils where animals are grazed and crops grown. Some of the strontium in the soil gets into the meat and cereals produced from it and then into the teeth of the people who eat them. The strontium ratio in a persons teeth thus mirrors the strontium ratio of the geology of the area in which they spent their childhood. For example, someone who grew up in southern England would have a much lower ratio than ...

The isotope mass-balance approach was used to estimate ground-water inflow to 81 lakes in the central highlands and coastal lowlands of central Florida. The study area is characterized by a subtropical climate and numerous lakes in a mantled karst terrain. Ground-water inflow was computed using both steady-state and transient formulations of the isotope mass-balance equation. More detailed data were collected from two study lakes, including climatic, hydrologic, and isotopic (hydrogen and oxygen isotope ratio) data. For one of these lakes (Lake Starr), ground-water inflow was independently computed from a water-budget study. Climatic and isotopic data collected from the two lakes were similar even though they were in different physiographic settings about 60 miles apart. Isotopic data from all of the study lakes plotted on an evaporation trend line, which had a very similar slope to the theoretical slope computed for Lake Starr. These similarities suggest that data collected from the detailed ...

Roden, J & Farquhar, G 2012, A controlled test of the dual-isotope approach for the interpretation of stable carbon and oxygen isotope ratio variation in tree rings, Tree Physiology, vol. 32, no. 4, pp. 490-503. ...

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Knowledge and management of aquatic ecosystems (formerly Bulletin Français de la Pèche et de la Pisciculture), an international journal on freshwater ecosystem

Whole-plant 13C discrimination, Δ13Cp, showed a strong correlation with instantaneous measurements of ci/ca (Fig. 7), suggesting that in general Δ13Cp was a faithful recorder of ci/ca, as predicted by Equation 6. The mean value for d that we estimated for the full data set was 3.1‰, reasonably similar to a value of 4.0‰, recently estimated for Ficus insipida (Cernusak et al., 2007b). The Δ13Cp was also a reasonably good predictor of variation in TEc, Dg·TEc, and vg·TEc (Table VI). We previously observed that the relationship between Δ13Cp and TEc broke down at the species level, appearing to reflect species-specific offsets in the relationship between the two parameters (Cernusak et al., 2007a). Whereas there was some evidence of similar behavior in this study, as can be seen in Figure 8, the species-level relationship between Δ13Cp and Dg·TEc was generally much stronger in this study. For example, in a least-squares linear regression between Δ13Cp and Dg·TEc using species means, ...

palindrom (#27 on the WUWT article)- Im doing my graduate work in the area of oxygen isotope paleothermometry (which I do think has a lot of advantage over dendroclimatology), so Ill just say a few general things, but I dont plan on reading the WUWT article in enough depth to disentangle it piece by piece (note for people who reply that Id rather continue this in the April Open Thread since it is OT and this thread is still young).. First, I do think that there is a lot of work to be done in the interpretation of oxygen/hydrogen isotope values obtained at a site, and theres still plenty of disagreement in the paleo-community on how to best connect the isotopic signal in a record with climate. However, there are also many well understood thermodynamic, physical principles at play. There are also a number of paleoclimatic recorders of oxygen isotopes, including lake/ocean records, speleothems (in caves), corals, ice cores, etc. The factors and caveats that impact all of these different ...

Ocean anoxic events were periods of high carbon burial that led to drawdown of atmospheric carbon dioxide, lowering of bottom-water oxygen concentrations and, in many cases, significant biological extinction (Arthur et al., 1990; Erbacher et al., 1996, doi:10.1130/0091-7613(1996)0242.3.CO;2; Kuypers et al., 1999, doi:10.1038/20659; Jenkyns, 1997; Hochuli et al., 1999, doi:10.1130/0091-7613(1999)0272.3.CO;2). Most ocean anoxic events are thought to be caused by high productivity and export of carbon from surface waters which is then preserved in organic-rich sediments, known as black shales. But the factors that triggered some of these events remain uncertain. Here we present stable isotope data from a mid-Cretaceous ocean anoxic event that occurred 112 Myr ago, and that point to increased thermohaline stratification as the probable cause. Ocean anoxic event 1b is associated with an increase in surface-water temperatures and runoff that led to decreased bottom-water formation and elevated carbon ...

Anderson, Lesleigh, 1999, Holocene paleoclimatology of northern Alaska from oxygen isotope geochemistry of sediment cellulose and authigenic carbonate in lake sediments: University of Massachusetts, Amherst, M.S. thesis, 139 p., illust., maps.. ...

François Fourel, Francois Martineau, Emoke Toth, Agnes Görög, Gilles Escarguel, et al.. Carbon and oxygen isotope variability among foraminifera and ostracod carbonated shells. Physica, 2015, 70, pp.133-156. ⟨10.17951/aaa.2015.70.133⟩. ⟨hal-02334191⟩ ...

Johnsen, S. J. , Dahl-Jensen, D. , Gundestrup, N. , Steffensen, J. P. , Clausen, H. B. , Miller, H. , Masson-Delmotte, V. , Sveinbjörnsdottir, A. E. and White, J. (2001): Oxygen isotope and palaeotemperature records from six Greenland ice-core stations: Camp Century, Dye-3, GRIP, GISP2, Renland and NorthGRIP , Journal of Quaternary Science ...

Basak, C, Rathburn, T, Pérez, E et al 2009, Carbon and oxygen isotope geochemistry of live (stained) benthic foraminifera from the Aleutian Margin and the Southern Australian Margin, Marine Micropaleontology, vol. 70, pp. 89-101. ...

The oxygen isotopic composition of vertebrate bone phosphate (δp) is related to ingested water and to the body temperature at which the bone forms. The δp is in equilibrium with the individuals body water, which is at a physiological steady state throughout the body. Therefore, intrabone temperature variation and the mean interbone temperature differences of well-preserved fossil vertebrates can be determined from the δp variation. Values of δp from a well-preserved Tyrannosaurus rex suggest that this species maintained homeothermy with less than 4°C of variability in body temperature. Maintenance of homeothermy implies a relatively high metabolic rate that is similar to that of endotherms. ...

The oxygen isotope ratio of dissolved inorganic phosphate (δ18Op) represents a novel and potentially powerful stable isotope tracer for biogeochemical research. Analysis of δ18Op may offer new insights into the relative importance of different sources of phosphorus within natural ecosystems. Due to the isotope fractionations that occur alongside metabolism of phosphorus-containing compounds, δ18Op could also be used to better understand the intracellular and extracellular reaction mechanisms that control phosphorus cycling. In this thesis, new methods were developed and tested for the extraction of dissolved inorganic phosphate (Pi) from freshwaters and its isolation from other oxygen-containing compounds, including nitrate, sulfate and dissolved organic matter. Excluding contaminant sources of oxygen during δ18Op analysis is a critical analytical challenge that has constrained δ18Op research in freshwaters to date. These new methods were evaluated against existing protocols for analysis of ...

We have a strong theoretical, computational, experimental, and observational establishment in geochemistry. Research interest encompasses high-dimensional stable isotope fractionation, atmospheric chemistry, martian surface processes, early Earth, impacts, the Great Oxidation Event, snowball Earth, Paleozoic Earth climate, coupled mountain-building and climate change, coupled evolution of life and environment, paleoceanography, cryosphere geochemistry, property of man-made materials, and isotope equilibrium and kinetics. The department has fully equipped wet-chemistry laboratories, trace-element laboratory, organic geochemistry laboratory, and state-of-art stable isotope facilities that have the unique capability including analyzing triple oxygen isotope compositions of diverse compounds, and first-principles atomistic modeling with access to high-performance computers on campus. Faculty members ...

This data set reports the measurement of stable carbon, nitrogen, and oxygen isotope ratios in organic material (plant, litter and soil samples) in forest canopy profiles and pasture (grasses and shrubs) as well as corresponding carbon and nitrogen tissue concentrations in a number of different sites across Brazil. The sampling design captured the temporal variation in rainfall over the course of several years. Carbon and nitrogen isotope ratios can act as a proxy for interpreting aspects of the carbon and nitrogen cycles in Amazonian rainforests. Data are in three comma-delimited ASCII files. ...

...A new study of the High Arctic climate roughly 50 million years ago le...The new study which looked at temperatures during the early Eocene pe...The team used a combination of oxygen isotope ratios from fossil bone ...The team concluded the average temperatures of the warmest month on El...,New,study,shows,how,giant,tortoises,,alligators,thrived,in,High,Arctic,50,million,years,ago,biological,biology news articles,biology news today,latest biology news,current biology news,biology newsletters

Moon formed of mostly Earths mantle debris, which explains the compositional similarities, especially the similar Oxygen isotope ratios. There are still lingering questions, but it does the best so far at explaining the observed properties of the Moon ...

The [delta]13rmC of CH4 emitted from the tropical Amazon river floodplain, temperate peat bogs in Washington and Minnesota, and the arctic Alaskan tundra was 59, 73, 66, and 65‰, respectively. The [delta]D of CH4 from these sites was 294, 308, 339, and 391‰, respectively, and a linear relationship was observed between the [delta]D of CH4 and soil water. A 13C balance between CH4, CO2, and soil organic matter indicated a higher percentage of CH4 production via methyl conversion at the Amazon floodplain than at the other wetland sites and that the anoxic CO2 flux was 1.5 to 2.0 times the CH4 flux. The 13C balance provided greater constraint on the anoxic CO2 flux than calculations based on soil water gradients. An in situ value of 0.774 for the hydrogen kinetic isotope effect during microbial CH4 oxidation was estimated from the increase in the [delta]13rmC of CH4 and [delta]D of CH4 in flux samples from the Amazon site. The average [delta]13rmC of CH4 released from an acidic peat bog in ...

Mauna Loa, Hawaii and Sunnyvale, CA, USA - Climate scientists from the University of Colorado and the University of New Mexico studying the water cycle have successfully deployed a Picarro precision water isotope analyzer at a remote monitoring station near the top of Mauna Loa, Hawaii. Sampling water vapor at this extreme altitude (11,000 feet above sea level) is notoriously difficult because the water concentration can drop as low a few hundred parts per million. Yet the Picarro G1102-i, which utilizes WS-CRDS (wavelength scanned cavity ring down spectroscopy), is directly sampling the outside air at this location and providing simultaneous measurement of both δD and δ18O every ten seconds. The absolute calibration is checked with liquid water standards every few hours, which confirms that the instrument has virtually no drift over a six day period. During this extended period the standard deviation of all measurements has been 0.650/00 for δD and 0.080/00 for δ18O - levels of absolute ...

Knowledge and management of aquatic ecosystems (formerly Bulletin Français de la Pèche et de la Pisciculture), an international journal on freshwater ecosystem

Models for the growth of continental crust rely on knowing the balance between the generation of new crust and the reworking of old crust throughout Earths history. The oxygen isotopic composition of zircons, for which uranium-lead and hafnium isotopic data provide age constraints, is a key archive of crustal reworking. We identified systematic variations in hafnium and oxygen isotopes in zircons of different ages that reveal the relative proportions of reworked crust and of new crust through time. Growth of continental crust appears to have been a continuous process, albeit at variable rates. A marked decrease in the rate of crustal growth at ~3 billion years ago may be linked to the onset of subduction-driven plate tectonics.. ...

TY - JOUR. T1 - Vertical sheep mobility along the altitudinal gradient through stable isotope analyses in tooth molar bioapatite, meteoric water and pastures: A reference from the Ebro valley to the Central Pyrenees. AU - Tornero, Carlos. AU - Aguilera, Mónica. AU - Ferrio, Juan Pedro. AU - Arcusa, Héctor. AU - Moreno-García, Marta. AU - Garcia-Reig, Sheila. AU - Rojo-Guerra, Manuel. PY - 2018/8/10. Y1 - 2018/8/10. N2 - © 2016 Elsevier Ltd and INQUA Although the frequency of pastoral activities involving vertical sheep mobility has decreased over the last century, this is a herding strategy still used in the Ebro basin, where animals move from overwintering valley locations up to the Pyrenees from late spring to early autumn. Such practice allows herders to avoid the worst climatic conditions, seasonally balancing the great contrast between ecological zones in this region, from dry lowland Mediterranean steppe to wet mountain subalpine grasslands. As recent regional archaeological works have ...

Close The Infona portal uses cookies, i.e. strings of text saved by a browser on the users device. The portal can access those files and use them to remember the users data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser. ...

Many studies of climate variability in the Tropical Ocean have used high-resolution chemical tracer records contained in coral skeletons. The complex architecture of coral skeletons may lead to the possibility of biases in coral records and it is therefore important to access the fidelity of coral geochemical records as environmental proxies. Coral skeletal records from the same coral colony, and even the same corallite, may show large variation due to differing extension rates, formational timing of the skeletal elements, colony topography, and sampling resolution. To assess the robustness of the skeletal record, we present d13C and d18O data based on different sampling resolutions, skeletal elements, and coral colonies of Montastraea faveolata species complex, the primary coral used for climate reconstruction in the Atlantic. We show that various skeletal elements produce different isotopic records. The best sampling rate to resolve the full annual range of sea surface temperature (SST) is 40 ...

A new study published in Science suggests that the great predators of Mesozoic seas, the plesiosaurs, icthyosaurs, and mosasaurs, maintained an average body temperature around 100 degrees Fahrenheit. This conclusion was achieved by studying the oxygen isotopes in their teeth; fish from the mesozoic and today - all cold-blooded, of course - show variation in their oxygen isotopes based on the temperature of water they live in. The marine reptiles of the Mesozoic dont show this variation. No matter what temperature water they lived in, they maintained a constant temperature and thus can be assumed to have been active predators adept at cornering the apex predator niche in all sorts of marine environments ...

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The irons display a range in values which is to too large to be the result of fractionation processes in the nebula. An explanation involving primordial heterogeneity is favoured, with the iron meteorite parent bodies having sampled at least four isotopically distinct nitrogen reservoirs. One of the factors controlling the variation may be an input of 1%-rich nitrogen, together with 26Al, from a nova event prior to solar nebula collapse. The behaviour of nitrogen during core formation processes is also considered and compared with the observed nitrogen variation in the non-magmatic group lAB. Other secondary processes affecting nitrogen in the iron meteorites are also identified. The isotopic composition of nitrogen has been used to identify genetic links between iron and stony meteorites, thereby enhancing the normal technique based on oxygen isotopic composition (prohibited by the rarity of oxygen bearing minerals ...

The complex between 17O-enriched DOTA (tetraazacyclododecanetetraacetic acid) and praseodymium(iii) (Pr3+) was studied in aqueous solution by variable-temperature 17O NMR at 14.1 T. pH effects as well as the influence of metal ions free in solution were investigated. At low temperature, the so-called TSAP an

Laboratory experiments with stable isotopes (13C and 15N) were conducted to determine the importance of bacteria and algae as food sources for free-living nematodes. All tested bacterivorous nematodes (Caenorhabditis elegans, Acrobeloides tricornis, Poikilolaimus sp. and Panagrolaimus sp.) were found to be depleted in δ13C (on average by −1.71 ± 0.56‰) and enriched in δ15N (on average by 3.17 ± 1.27‰) relative to their bacterial diets of Escherichia coli and Matsuebacter sp. The nematode species showed considerable differences in their stable isotope composition with respect to food sources. Moreover, they differed significantly in δ13C and δ15N values when placed on the same bacterial diet of E. coli, consistent with differences in their trophic shifts. Conversely, no differences in δ13C values were observed among nematode species placed on the same Matsuebacter sp. diet. In mixed food sources of E. coli and Matsuebacter sp., E. coli contributed 71% of the carbon to C. elegans and

1. Mitchell P. Coupling of phosphorylation to electron and hydrogen transfer by a chemiosmotic type of mechanism. Nature. 1961;191:144-8 2. Brand MD. The stoichiometry of proton pumping and ATP synthesis in mitochondria. The Biochemist. 1994;16:20-4 3. Chance B, Williams GR. The Respiratory Chain and Oxidative Phosphorylation. Adv Enzymol Relat Subj Biochem. 1956;17:65-134 4. Berg JM, Tymoczko JL, Stryer L. The rate of oxidative phosphorylation is determined by the need for ATP. Biochemistry, 5thEdition. New York, USA: Freeman WH & Co. 2002:552 5. Boyer PD, Cross RL, Momsen W. A new concept for energy coupling in oxidative phosphorylation based on a molecular explanation of the oxygen exchange reactions. Proc Natl Acad Sci USA. 1973;70:2837-39 6. Kayalar C, Rosing J, Boyer PD. An alternating site sequence for oxidative phosphorylation suggested by measurement of substrate binding patterns and exchange reaction inhibitions. J Biol Chem. 1977;252:2486-91 7. Milgrom YM, Cross RL. ...

Rugby League is a high-intensity collision sport competed over 80 min. Training loads are monitored to maximize recovery and assist in the design of nutritional strategies although no data are available on the total energy expenditure (TEE) of players. We therefore assessed resting metabolic rate (RMR) and TEE in six Super League players over 2 consecutive weeks in-season including one game per week. Fasted RMR was assessed followed by a baseline urine sample before oral administration of a bolus dose of hydrogen (deuterium 2H) and oxygen (18O) stable isotopes in the form of water (2H2 18O). Every 24 hr thereafter, players provided urine for analysis of TEE via DLW method. Individual training load was quantified using session rating of perceived exertion (sRPE) and data were analyzed using magnitude-based inferences. There were unclear differences in RMR between forwards and backs (7.7 ± 0.5 cf. 8.0 ± 0.3 MJ, respectively). Indirect calorimetry produced RMR values most likely lower than ...

The identical oxygen isotopic composition of Earth and Moon might be explained by exchange of material between the proto-Earth and the surrounding proto-lunar disk: Planetary Science Research Discoveries (PSRD) educational on-line space science magazine.

The linearity of the assays run with D2O and H218O are quite remarkable. The decrease in speed for the D2O assay is about 21% and the decrease in the H218 assay is about 5%. The viscosity of D2O is about 20% greater than H2O while H218 is 5% greater than H2O. The speed differences measured would suggest in light of the viscosity numbers that we measured a viscous change in the solvent and not an osmotic pressure change. These results are quite remarkable as they indicate that gliding motility speeds can measure small viscous changes in solutions. Kotyk et. al. (Kotyk 1990) showed that ATP activity was not affected by the addition of D2O using yeast as the test subject. Our data would suggest that ATP activity of kinesin is also not affected by the addition of D2O. If ATP activity was hindered by the addition of D2O then I would have expected to see slower speeds than what I measured using D2O because clearly, there is a viscous affect and anything lower than what I measured would indicate that ...

Burkhardt, C., Dauphas, N., Tang, H., Fischer-Gödde, M., Qin, L., Chen, J. H., Rout, S. S., Pack, A., Heck, P. R. and Papanastassiou, D. A.. Meteoritics & Planetary Science. doi: 10.1111/maps.12834. LINK. High-precision isotope data of meteorites show that the long-standing notion of a chondritic uniform reservoir is not always applicable for describing the isotopic composition of the bulk Earth and other planetary bodies. To mitigate the effects of this isotopic crisis and to better understand the genetic relations of meteorites and the Earth-forming reservoir, we performed a comprehensive petrographic, elemental, and multi-isotopic (O, Ca, Ti, Cr, Ni, Mo, Ru, and W) study of the ungrouped achondrites NWA 5363 and NWA 5400, for both of which terrestrial O isotope signatures were previously reported. Also, we obtained isotope data for the chondrites Pillistfer (EL6), Allegan (H6), and Allende (CV3), and compiled available anomaly data for undifferentiated and differentiated meteorites. The ...

A three-fold exercise was conducted to assess the groundwater potentiality in the Eastern Desert (ED) of Egypt. First, a database was generated to host all relevant data sets in a GIS environment for a better understanding of the spatial relationships between these data sets. Co-registered digital mosaics were generated from relevant data sets including remote sensing (e.g., Landsat TM, SIR-C, SRTM, TRMM), geochemical (solute concentrations, O and H stable isotope composition), geological (geologic maps), and hydrological (lithology, depth to water table) data sets. Second, a web-based GIS interface (ArcIMS) was developed to provide a vehicle for data analysis, visualization, and dissemination. Finally, using the developed web-based GIS, locations for potential productive wells (168) targeting four types of shallow ( |200m) reservoirs were identified. The targeted reservoir types are: (1) Nubian Aquifer groundwater residing in shallow alluvial aquifers, (2) meteoric groundwater reservoirs in fractured

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source of synonymy Beu A.G. 2006. Marine Mollusca of oxygen isotope stages of the last 2 million years in New Zealand. Part 2. Biostratigraphically useful and new Pliocene to recent bivalves. Journal of the Royal Society of New Zealand, 36(4): 151-338 ...

John, Take a look at the analysis of the Oxygen Isotopes of the three burials that were excavated consisting of an adult woman and two children. For the life of me I cannot remember the place but it featured on Meet the Ancestors and had teh biggest hole I have ever seen in Archaeology. Th eisotope analysis showed the woman and children to have walked a considerable distance Rob http://acorngenealogy.co.uk http://www.enchantedtimes.co.uk ----- Original Message ----- From: John Wood ,[log in to unmask], To: ,[log in to unmask], Sent: Monday, July 17, 2006 11:17 AM Subject: Re: [BRITARCH] Heritage & carbon emissions ,,,Kevin Tolley ,[log in to unmask], wrote: , , As such, if Stonehenge were a place to , visit, then why shouldnt people from distant places , visit? ,,, , , No doubt people from some distance would have visited Stonehenge but what , concerns me is the numbers along with the distances. , , Trades people no doubt moved about the countryside trading goods and , hence we get a spread ...

This data set consists of CO2 concentrations from oxygen isotopes in air trapped in the Taylor Dome (Antarctica) ice core from 20 to 60 kyr BP. The data set consists of depth (m), ice age (kyr BP ... ...

Using reconstructed unconformity-bounded stratigraphy, the geological evolution of Panarea and surrounding islets can be described in terms of the interaction between the growing volcano and sea-level fluctuations. From the recognition of marine deposits corresponding to marine oxygen isotope stage (MIS) 5 and of widespread Brown Tuff-type pyroclastic deposits on Panarea, two first-order unconformities (UI and UII) of regional stratigraphic significance can be correlated with the island of Lipari and adopted as a means of correlation on an inter-island scale in the Aeolian Volcanic District. Then, two second-order and three third-order unconfomities, consisting of erosional surfaces related to minor sea-level fluctuations or to subaerial reworking operating during the phases of volcanic inactivity, are introduced. The construction of the volcanic edifice occurred during seven successive eruptive epochs of local volcanic activity, between 150 and 10 ka, with intervening dormant periods ...

Affiliation：名古屋大学,環境学研究科,准教授, Research Field：Environmental dynamic analysis,Meteorology/Physical oceanography/Hydrology,Environmental dynamic analysis, Keywords：大気化学,化学輸送モデル,大気酸化能,対流圏オゾン,エアロゾル,化学気候モデル,大気汚染,メタン,成層圏オゾン,気候変動, # of Research Projects：7, # of Research Products：120, Ongoing Project：Quantifying nitrate dynamics in hydrosphere using triple oxygen isotopes as tracers

In most current designs of D-T fusion reactor blankets employing ceramic breeder materials, the use of a helium sweep gas containing 0.1 % of hydrogen is contemplated to extract tritium efficiently via isotopic exchange reactions. However, the isotope exchange reaction proceeds fast only at the more elevated temperatures, so that the rate of isotope exchange reactions is considerably low at lower temperatures. Taking into consideration that there is a broad temperature distribution within a blanket module, it is anticipated that the tritium bred in regions of lower temperatures will be poorly recovered. For this reason, there is still a need to develop techniques that contribute to the acceleration of the recovery of bred tritium at lower temperatures. In our previous works, the effect of catalytic active metal additives, such as Pt and Pd, on the heterogeneous isotope exchange reactions at the breeder-sweep gas interface was examined. The results indicate that the exchange reactions were ...

A mononuclear side-on peroxocobalt(III) complex with a tetradentate macrocyclic ligand, [CoIII(TBDAP)(O2)]+ (1), shows a novel and facile mode of dioxygenase-like reactivity with nitriles (R - C=N; R = Me, Et, and Ph) to produce the corresponding mononuclear hydroximatocobalt(III) complexes, [CoIII(TBDAP)(R - C(=NO)O)]+, in which the nitrile moiety is oxidized by two oxygen atoms of the peroxo group. The overall reaction proceeds in one-pot under ambient conditions (ca. 1 h, 40 °C). 18O-Labeling experiments confirm that both oxygen atoms are derived from the peroxo ligand. The structures of all products, hydroximatocobalt(III) complexes, were confirmed by X-ray crystallography and various spectroscopic techniques. Kinetic studies including the Hammett analysis and isotope labeling experiments suggest that the mechanistic mode of 1 for activation of nitriles occurs via a concerted mechanism. This novel reaction would be significantly valuable for expanding the chemistry for nitrile activation ...

Objectives. To assess the environmental impacts of handling, storage and field application of fermentates as influenced by the carbon and nutrient pools defined in WP3.. Method. A pilot-scale storage facility will be used to determine GHG and NH3 emission factors for selected fermentates; this will be planned and conducted in collaboration with ATB. As input for improved models of N2O emissions and carbon storage after field application, a mesocosm will be designed. It will allow fermentate to be added to soil at well-defined matric potential. Experiments with fermentates from a large variety of different biomasses, digested. using different retention times and temperatures, will be carried out. Interactions with soil type and water content will be studied. Fluxes of CH4, N2O and CO2 will be measured using gas chromatography, and fluxes of NH3 using an INNOVA photo-acoustic analyser. Sources of N2O will be studied using an LGR N2O isotope analyser. In order to determine the influence of ...

My research is focused on the ubiquitous presence of saline fluids at depth in the continental crust, either in sedimentary systems or within crystalline basement in fracture controlled systems. How did these fluids gain their actual salinities, which can be up to 10 times the modern seawater salinity? What is the time scale in which this deep reservoir of the hydrosphere exchanges with surface reservoir such as the oceans or more diluted shallower groundwaters? Conservative chlorine and bromine stable isotopes (respectively 37Cl/35Cl and 81Br/79Br) can be used as source tracers to identify mixing in this kind of fluids. Furthermore they have been used to identify processes at the origin of the salinity or to constrain diffusion in low permeability environments. Im also focusing on classic water isotope composition (18O and 2H) to assess the extent of water-rock interaction and its relation to the generation of abiogenic reduced gas such as CH4 or H2 in the Canadian Shield ...

Close The Infona portal uses cookies, i.e. strings of text saved by a browser on the users device. The portal can access those files and use them to remember the users data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser. ...

The catalytic mechanism of intra and extra catechol cleaving dioxygenases is still a matter of debate, because the intermediate transient oxygen adduct has never been isolated in these enzymes. The complex [(triphos)Ir(dtbc)]+ (triphos=MeC(CH2PPh2)3, DBTC2−=3,5-di-tert-butylcatecholate), reacts with molecular oxygen and exhibits a ring-cleaving catalytic activity, and a stable oxygen intermediate appears; this stimulates an opportunity for obtaining information that can be transferable to the above-mentioned enzymatic catalytic centers, therefore, giving a breakthrough into the strategy of oxygen activation in these natural systems. Here, we present the results of our computational approach, based on density functional theory, focusing on the following aspects: to explain the interaction with molecular oxygen and how to avoid the existing spin problem, to understand the formation of the bridging moiety, to clarify, if any, the possible influence on the structure of the formed adduct of the ...

TY - JOUR. T1 - Properties of and oxygen binding by albumin-tetraphenylporphyrinatoiron(II) derivative complexes. AU - Tsuchida, Eishun. AU - Ando, Katsutoshi. AU - Maejima, Hiromitsu. AU - Kawai, Noriyuki. AU - Komatsu, Teruyuki. AU - Takeoka, Shinji. AU - Nishide, Hiroyuki. PY - 1997/7/1. Y1 - 1997/7/1. N2 - A hydrophobic tetraphenylporphyrinatoiron(II) derivative bearing a covalently bound axial imidazole [Fe(II)P] was efficiently and noncovalently bound into human serum albumin (HSA) up to an average of eight Fe(II)P molecules per HSA molecule. The aqueous solutions of the HSA-Fe(II)P complex provided a reversible and relatively stable oxygen adduct under physiological conditions (pH 7.4 and 37 °C). The half-life of the oxygen adduct (τ( 1/4 )) was 1 h at 37 °C in an air atmosphere. With Fe(II)-TpivPP (the so-called picket-fence heme) having no axial base, an oxygenated HSA-Fe(II)TpivPP complex was obtained using a 20-fold molar excess of 1,2-dimethylimidazole, but the τ( 1/4 ) was ...

Altabet, Mark A; Francois, Roger (2003): Natural nitrogen and carbon stable isotopic composition of station NBP96-04-06-4. PANGAEA, https://doi.org/10.1594/PANGAEA.128214