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Abstract
During weathering, Fe in primary minerals is solubilized by ligands and/or reduced by bacteria and released into soil porewaters. Such Fe is then removed or reprecipitated in soils. To understand these processes, we analyzed Fe chemistry and isotopic composition in regolith of the Shale Hills watershed, a Critical Zone Observatory in central Pennsylvania overlying iron-rich shale of the Rose Hill Formation. Elemental concentrations were measured in soil from a well-drained catena on a planar hillslope on the south side of the ...
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by Guillaume Charbonnier, Emmanuelle Pucéat, Germain Bayon, et al.Delphine Desmares, Guillaume Dera, Christophe Durlet, Jean-François Deconinck, Francis Amédro, Alexandra T. Gourlan, Pierre Pellenard, Brahimsamba Bomou
Abstract
The Fe–Mn oxide fraction leached from deep-sea sediments has been increasingly used to reconstruct the Nd isotope composition of deep water masses, that can be used to track changes in oceanic circulation with a high temporal resolution. Application of this archive to reconstruct the Nd isotope composition of bottom seawater in shallow shelf environments remained however to be tested. Yet as the Nd isotope composition of seawater on continental margins is particularly sensitive to changes in erosional inputs, establishment of neritic ...
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Abstract
Chalk is a sedimentary rock consisting mostly of micrometer sized particles of biogenic calcite (CaCO3). It forms the reservoirs for oil in the Danish part of the North Sea and important drinking water aquifers in northern Europe. The interaction between organic molecules and the particle surfaces has a strong influence on the migration of oil in the reservoirs. Adhesion of oil components to chalk particle surfaces is thought to significantly reduce production and efforts are being made to determine the mechanisms ...
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by Chuan-Chou Shen, Chung-Che Wu, Hai Cheng, et al.R. Lawrence Edwards, Yu-Te Hsieh, Sylvain Gallet, Ching-Chih Chang, Ting-Yong Li, Doan D. Lam, Akihiro Kano, Masako Hori, Christoph Spötl
Abstract
To facilitate the measurement of U–Th isotopic compositions suitable for high-precision and high-resolution 230Th dating of coral and speleothem carbonates, secondary electron multiplier (SEM) protocol techniques for multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) have been developed. The instrumental sensitivities are 1–2%, with a precision of ±1–2‰ (2Ï) for abundance determination of 50–200 fg 234U (1–4 ng 238U) or 230Th. This method features chemistry refinements, improvements to procedural and instrumental blanks, spectral inference reductions, and careful consideration of non-linear SEM behavior. Measurement consistency ...
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Abstract
In order to study bacterial activity, and turnover times of bacterial necromass and biomass in marine sediment, two stations from the Aarhus Bay, Denmark were analyzed. Sediment cores were up to 11 m deep and covered a timescale from the present to ∼11,000 years ago. Sediment was analyzed for total hydrolysable amino acids (THAA), total hydrolysable amino sugars, the bacterial endospore marker dipicolinic acid (DPA), and amino acid enantiomers (l- and d-form) of aspartic acid. Turnover times of bacterial necromass and vegetative cells, ...
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Abstract
Cm(III) speciation in natural kaolinite (St. Austell, UK) suspensions under alkaline conditions was studied by time-resolved laser fluorescence spectroscopy (TRLFS). The spectroscopic investigations were performed under argon atmosphere (O2 < 1 ppm) using a constant curium concentration, ionic strength and mineral content of 2 × 10−7 M, 1 mM NaClO4 and 0.25 g/L, respectively, throughout the study. The impact of kaolinite mineral dissolution on the speciation of the trivalent actinide was investigated in oversaturation experiments where excess amounts of aluminum and/or silicon were added to alkaline kaolinite suspensions. Only ...
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Abstract
Glass cosmic spherules are a sub-type of S-type cosmic spherules that are almost at the end phase of fractionation and volatilization during atmospheric entry. A focused investigation of 36 glass spherules out of several hundred spherules reveals fractionation and fragmentation phenomena. During atmospheric entry, some of the glass spherules largely preserve relict pyroxene normative crystals within. The spherules appear to have experienced temperatures of ∼1700 °C that resulted in vaporization of Fe and other volatile elements such as S, Na, and K ...
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Abstract
We present the first systematic study of the silicon isotope composition in the water column (δ30SiSi(OH)4) and in diatoms (δ30Sidiatom) from the underlying surface sediments in a coastal upwelling region. The surface waters upwelling on the shelf off Peru are mainly fed by southward flowing subsurface waters along the coast, which show a mean δ30SiSi(OH)4 of +1.5‰. The concentration of dissolved silicic acid (Si(OH)4) increases towards the south in these waters and with increasing water depth, suggesting lateral mixing with water ...
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Abstract
The micro- and ultra-structural skeletal growth dynamics of the scleractinian coral Pocillopora damicornis (Linnaeus 1758) was studied with pulsed 86Sr-labeling and high spatial resolution NanoSIMS isotopic imaging. Average extension rates for the two basic ultra-structural components of the skeleton, Rapid Accretion Deposits (RAD) and Thickening Deposits (TD), were compared between corallite wall, spines and dissepiments. The RAD, forming the basal part of the dissepiment, were found to form extremely fast compared with RAD and TD in other parts of the skeleton. ...
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Abstract
This paper demonstrates a method for systematic analysis of published mineral dissolution rate data using forsterite dissolution as an example. The steps of the method are: (1) identify the data sources, (2) select the data, (3) tabulate the data, (4) analyze the data to produce a model, and (5) report the results. This method allows for a combination of critical selection of data, based on expert knowledge of theoretical expectations and experimental pitfalls, and meta-analysis of the data using statistical methods. ...
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Abstract
Mn(IV) and Mn(II) are the most stable and prevalent forms of manganese in natural environments. The occurrence of Mn(III) in minerals and the detection of soluble Mn(III) in natural waters, however, suggest that Mn(III) is an intermediate in both the oxidation of Mn(II) and the reduction of Mn(IV). Mn(III) has recently been proposed as an intermediate during the oxidation of Mn(II) by Mn-oxidizing bacteria but has never been considered as an intermediate during the bio-reduction of Mn(IV). Here we show for ...
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Abstract
The Northwest Africa (NWA) 1664 and 1769 howardites contain fragments of low-Mg lithologies. These clasts consist of plagioclase, Fe-rich pyroxenes (high-Ca pyroxene and an Fe-rich pigeonite (or pyroxferroite) partially to totally converted to a silica–fayalite–hedenbergite symplectite), K–Ba-feldspars (hyalophane), silica, troilite, phosphates (merrillite and apatite), ilmenite, baddeleyite and zircon. Textural considerations and phase compositions show that these clasts cannot be unrepresentative debris of mesostasis-rich areas from eucrites, but are instead remnants of evolved rocks. The occurrence of hyalophane and the modal abundances ...
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Abstract
Two new approaches to quantify sulfur functionalities in natural organic matter from S K-edge XANES spectroscopy are presented. In the first, the K-edge spectrum is decomposed into Gaussian and two arctangent functions, as in the usual Gaussian curve fitting (GCF) method, but the applicability of the model is improved by a rigorous simulation procedure that constrains the model-fit to converge toward chemically and physically realistic values. Fractions of each type of functionality are obtained after spectral decomposition by correcting Gaussian areas ...
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Abstract
Geochemical variations in shallow water corals provide a valuable archive of paleoclimatic information. However, biological effects can complicate the interpretation of these proxies, forcing their application to rely on empirical calibrations. Carbonate clumped isotope thermometry (Î47) is a novel paleotemperature proxy based on the temperature dependent “clumping” of 13C–18O bonds. Similar Î47-temperature relationships in inorganically precipitated calcite and a suite of biogenic carbonates provide evidence that carbonate clumped isotope variability may record absolute temperature without a biological influence. However, large departures ...
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by Jean-Jacques Braun, Jean-Christophe Marechal, Jean Riotte, et al.Jean-Loup Boeglin, Jean-Pierre Bedimo Bedimo, Jules R. Ndam Ngoupayou, Brunot Nyeck, Henri Robain, M. Sekhar, Stéphane Audry, Jérôme Viers
Abstract
The comparison between contemporary and long-term weathering has been carried out in the Small Experimental Watershed (SEW) of Nsimi, South Cameroon in order to quantify the export fluxes of major and trace elements and the residence time of the lateritic weathering cover. We focus on the hillside system composed of a thick lateritic weathering cover topped by a soil layer. This study is built on the recent improvements of the hillside hydrological functioning and on the analyses of major and trace ...
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Abstract
Halite (NaCl) and gypsum or anhydrite (CaSO4) are water-soluble minerals found in soils of the driest regions of Earth, and only modest attention has been given to the hydrological processes that distribute these salts vertically in soil profiles. The two most notable chloride and sulfate-rich deserts on earth are the Dry Valleys of Antarctica and the Atacama Desert of Chile. While each is hyperarid, they possess very different hydrological regimes. We first show, using previously published S and O isotope data ...
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Abstract
The application of Hf–W chronometry to determine the timescales of core formation in the parent bodies of magmatic iron meteorites is severely hampered by 182W burnout during cosmic ray exposure of the parent meteoroids. Currently, no direct method exists to correct for the effects of 182W burnout, making the Hf–W ages for iron meteorites uncertain. Here we present noble gas and Hf–W isotope systematics of iron meteorite samples whose W isotopic compositions remained essentially unaffected by cosmic ray interactions. Most selected ...
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Abstract
A petrographic and electron microscopic study of the carbonate-poor lithology of the Tagish Lake carbonaceous chondrite reveals that most chondrules contain many pseudomorphs of opaque nodules and are surrounded by phyllosilicate-rich altered zones that were formed by replacing enstatite and opaque nodules along the chondrule peripheries. Most chondrules and other coarse-grained components are surrounded by fine-grained rims, which are commonly disaggregated and partly lacking. The altered zones and the rims are compositionally and texturally similar, although they exhibit some differences in ...
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Abstract
We measured chlorate (ClO3−) and perchlorate (ClO4−) concentrations in ice covered lakes of the McMurdo Dry Valleys (MDVs) of Antarctica, to evaluate their role in the ecology and geochemical evolution of the lakes. ClO3− and ClO4− are present throughout the MDV Lakes, streams, and other surface water bodies. ClO3− and ClO4− originate in the atmosphere and are transported to the lakes by surface inflow of glacier melt that has been differentially impacted by interaction with soils and aeolian matter. Concentrations of ...
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Abstract
Diffusion of Ti has been characterized in natural orthopyroxene and clinopyroxene under buffered conditions (IW, NNO, and QFM) and in air. In all pyroxene compositions studied, titanium diffusion appears relatively insensitive to crystallographic orientation and oxygen fugacity under the range of investigated conditions. For Ti diffusion in a natural enstatite and a Kilbourne Hole orthopyroxene (KBH opx), we obtain the following Arrhenius relations for diffusion over the temperature range 950–1150 °C, For Ti diffusion in a natural diopside and a chromian diopside ...
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Abstract
Studies of hydrothermal reactions involving organic compounds suggest complex, possibly reversible, reaction pathways that link functional groups from reduced alkanes all the way to oxidized carboxylic acids. Ketones represent a critical functional group because they occupy a central position in the reaction pathway, at the point where CC bond cleavage is required for the formation of the more oxidized carboxylic acids. The mechanisms for the critical bond cleavage reactions in ketones, and how they compete with other reactions are the focus ...
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Abstract
We determined the Cd isotopic composition of seawater and sinking particles collected in the deep basin of the northern South China Sea (SCS) to investigate the controlling mechanisms on the Cd isotopic composition in the water column. The isotopic composition in the water column decreased with depth, with ε114/110Cd values (ε114/110Cd = [(114Cd/110Cd)sample/(114Cd/110Cd)JMC Cd Münster − 1] × 104) ranging from +8.7 to +9.9 in the top 80 m, from +4.6 to +5.5 between 100 and 150 m, decreasing from +5.5 to +3.6 at depths from 150 to 1000 m, ...
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Abstract
In the present study, we test the ability of B isotopes to trace past and present weathering reactions in the case of two forest soils formed by a polyphasic sequence involving early hydrothermal alteration of the bedrock and pedogenesis. We provide B chemical and isotopic compositions in two 2-m soil profiles sampled in the Strengbach watershed (Vosges, France). The two soils belong to different soil series, an ochreous podzol (Haplorthod) and a brown acidic soil (dystrochrept), developed on the same granitic ...
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Abstract
A δ44/40Ca excursion of −0.5‰ is recorded during the Hirnantian glaciation event in carbonate rocks of the Monitor Range section in Nevada. The timeframe for the glaciation is 1.03 ± 0.2 Ma. The δ44/40Ca changes are synchronous with lithofacies and biofacies indicators of sea-level change, and co-vary negatively with a large positive δ13C excursion of 7‰ that was previously interpreted to reflect local C-cycling effects in circulation-restricted waters of the (epeiric) Martin Ridge Basin. The synchronousness of the Ca and C isotope excursions is ...
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Abstract
Ureolytic bacteria have been proposed as model organisms to investigate the potential of subsurface microorganisms to enhance carbon capture and storage through solubility- and mineral-trapping of CO2 induced by bacterial ureolysis and carbonate formation. Ideally, CO2 incorporation into carbonates can be readily traced using carbon isotope measurements. However, the carbon isotope systematics of bacterial ureolysis and associated carbonate precipitation is still poorly known. We determined the carbon isotope fractionations expressed during ureolysis and carbonate precipitation induced by Sporosarcina pasteurii at 30 °C. ...
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Abstract
Argon–argon dating (a variation of potassium–argon dating) of ordinary chondrites is being used to reconstruct the collisional impact history of their parent bodies. However, due to the fine-grained, multi-mineral, highly shocked nature of chondrites, the sources of potassium (K) in these meteorites have not been fully identified. By locating and isolating the different sources prior to analysis, better ages can be obtained. To distinguish between possible sources, we have analyzed Chico and Northwest Africa 091 (both L6 chondrites) via K mass ...
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Abstract
About ten percent of type I, FeO-poor chondrules in unequilibrated CO chondrites contain plagioclase that appears to be igneous in origin, crystallizing at a late stage of solidification of host chondrule melts. We have studied plagioclase-bearing chondrules in detail, and compared them with plagioclase-free chondrules, in order to determine the formation conditions of plagioclase and the constraints that the presence of plagioclase places on the conditions of chondrule formation. Plagioclase-bearing chondrules have similar textures, mineral compositions and bulk compositions to plagioclase-free ...
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Abstract
The behaviour of the four Ra isotopes (measured by gamma spectrometry) and 222Rn (measured with an AlphaGUARD ionisation chamber) has been investigated in NaCl-rich thermal waters of Balaruc-les-Bains on the Mediterranean coast (South of France). This study allows identification of the deep thermal water signature and reveals the influence of seawater or karst water inflows on Ra isotopes and 222Rn. The deep thermal water has 226Ra and 222Rn activities of 840 and 1900 mBq/l, respectively, a (228Ra/226Ra) activity ratio of 0.59, and ...
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Abstract
The large discrepancy between field and laboratory measurements of mineral reaction rates is a long-standing problem in earth sciences, often attributed to factors extrinsic to the mineral itself. Nevertheless, differences in reaction rate are also observed within laboratory measurements, raising the possibility of intrinsic variations as well. Critical insight is available from analysis of the relationship between the reaction rate and its distribution over the mineral surface. This analysis recognizes the fundamental variance of the rate. The resulting anisotropic rate distributions ...
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Abstract
Three surface complexation models (SCMs) developed for, respectively, ferrihydrite, goethite and sorption data for a Pleistocene oxidized aquifer sediment from Bangladesh were used to explore the effect of multicomponent adsorption processes on As mobility in a reduced Holocene floodplain aquifer along the Red River, Vietnam. The SCMs for ferrihydrite and goethite yielded very different results. The ferrihydrite SCM favors As(III) over As(V) and has carbonate and silica species as the main competitors for surface sites. In contrast, the goethite SCM has ...
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Abstract
Effective radium concentration (ECRa) of 622 rock samples from 6 different sites in the Nepal Himalayas was measured in the laboratory using radon accumulation experiments. These sites, located from Lower Dolpo in Western Nepal to Eastern Nepal, are divided into 9 transects which cut across the Main Central Thrust zone (MCT zone) separating low-grade metamorphic Lesser Himalayan Sequence (LHS) units to the south and higher-grade metamorphic Greater Himalayan Sequence (GHS) units to the north. This boundary remains difficult to define and ...
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Abstract
Glycerol dibiphytanyl glycerol tetraether lipids (GDGTs) have proven to be important biomarker lipids for specific archaeal lineages and their distribution is used as a paleotemperature proxy. In this study, we analyzed GDGTs in suspended particles in the water column of the Arabian Sea at different positions above, in and below the oxygen minimum zone (OMZ). GDGTs, both as intact polar lipid (IPL) and as core lipids, were detected throughout the water column but were most abundant at the upper part of ...
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Abstract
The TEX86 is a proxy based on a ratio of pelagic archaeal glycerol dibiphytanyl glycerol tetraether lipids (GDGTs), and used for estimating past sea water temperatures. Concerns exist that in situ production of GDGTs lipids by sedimentary Archaea may affect its validity. In this study, we investigated the influence of benthic GDGT production on the TEX86 by analyzing the concentrations and distributions of GDGTs present as intact polar lipids (IPLs) and as core lipids (CLs) in three sediment cores deposited under ...
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Abstract
The wollastonite far from equilibrium dissolution kinetics and the formation and evolution of surface leached layers have been measured in mixed-flow reactors at 25 °C, 0.9 ⩽ pH ⩽ 12 and reaction times to more than 3000 h. Wollastonite dissolution rate decreases with increasing pH consistent with Dissolution stoichiometry, and the texture, structure and chemistry of wollastonite surfaces strongly depend on solution pH and duration of reaction. At 4.8 ⩽ pH ⩽ 12, after an initial period of non-stoichiometric dissolution, stoichiometric release of Ca and Si was observed. No significant change ...
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Abstract
X-ray Absorption Fine Structure techniques have been used on Comet Wild2/81P tracks from the Stardust mission. Fe-XANES and EXAFS have been performed on aerogel sections from Tracks 41 and 162 as well as the mid and terminal positions of Track 134. This is the first use of EXAFS in the study of early Solar System materials. With EXAFS, we have measured Fe–O and Fe–S bond lengths and thus, together with complementary XANES measurements, identified Fe-rich phases. In particular, we show that ...
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Abstract
We present here new experimental data on H2O–CO2 solubility in mafic melts with variable chemical compositions (alkali basalt, lamproite and kamafugite) that extend the existing database. We show that potassium and calcium-rich melts can dissolve ∼1 wt% CO2 at 3500 bar (350 MPa) and 1200 °C, whereas conventional models predict solubilities of 0.2–0.5 wt%, under similar P–T conditions. These new data, together with those in the literature, stress the fundamental control of melt chemical composition on CO2 solubility. We present a semi-empirical H2O–CO2 solubility model for ...
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Abstract
Leaf-wax hydrogen isotope composition (δDwax) is increasingly applied as a proxy for hydroclimate variability in tropical paleoclimate archives, but the factors controlling δDwax in the tropics remain poorly understood. We measured δDwax and the stable carbon isotope composition of leaf-waxes (δ13Cwax), including both n-alkanes and n-alkanoic acids, from modern lake sediments and soils across a marked aridity gradient in southeastern Mexico and northern Central America to investigate the importance of aridity and vegetation composition on δDwax. In this region the estimated ...
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Abstract
A series of experiments, with run durations of ∼100–240 h, have been carried out on H solubility in natural labradorite, albite and anorthoclase at 2–10 kbar and 700–850 °C, in equilibrium with different oxygen buffer materials: Fe–FeO, Ni–NiO, Re–ReO2 and Fe2O3–Fe3O4. Attainment of equilibrium water contents were examined by conducting experiments with different run-durations and by performing profile analysis along crystal core-to-rim paths. The annealed products generally show typical OH-related infrared absorption bands in the range 3700–2600 cm−1: the spectra of the labradorite and anorthoclase ...
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Abstract
The structure of the calcite (1 0 4)–water interface is reassessed using a new set of high-precision specular X-ray reflectivity measurements. In situ measurements of the specular reflectivity signal to a vertical structural resolution of 0.45 Å are used to define the interfacial structure, including vertical displacement patterns of the Ca and CO3 groups as well as the nature of interfacial water. These new data show two organized interfacial water layers, consistent with previous results, and distortion of the interfacial calcite structure to a ...
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Abstract
Chondrite normalized rare earth element (REE) patterns of zircons generally have enriched Ce values relative to La and Pr, and depleted Eu values relative to Sm and Gd. High Ce contents in zircon may imply oxidizing conditions (Ce4+ is more compatible than Ce3+), whereas depleted Eu contents may imply reducing conditions (Eu2+ does not substitute into the zircon lattice). We report 41 experiments in which temperature, melt composition, and oxygen fugacity (fO2) were varied in order to explore the details of ...
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Abstract
The stable silicon isotopic composition (δ30Si) of waters and diatoms has increasingly been used to investigate the biogeochemical cycling of Si in the major ocean basins. Here we present the first Si isotope data set from the northern South China Sea (NSCS), a large marginal sea system in the western North Pacific to examine sources and utilization of silicic acid (Si(OH)4). During two cruises in July–August 2009 (summer) and January 2010 (winter), samples for isotope measurements of dissolved Si(OH)4 (δ30SiSi(OH)4) and ...
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Abstract
Secondary alteration phases, such as carbonates, smectite clays and Fe-oxides, are found within the martian meteorites. If these meteorites were seen to fall, the assumption can be reasonably made that the secondary phases have a martian origin. However, for martian meteorite finds, this is not the case. Deuterium/hydrogen (D/H) ratio analysis can be used to distinguish between terrestrial and martian secondary alteration phases – the martian atmosphere is currently five times enriched in deuterium compared to terrestrial seawater, producing a deuterium ...
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Abstract
The micas are a unique class of minerals because of their layered structure. A frequent question arising in mica dissolution studies is whether this layered structure radically changes the dissolution mechanism. We address this question here, using data from VSI and AFM experiments involving muscovite to evaluate crystallographic controls on mica dissolution. These data provide insight into the dissolution process, and reveal important links to patterns of dissolution observed in framework minerals. Under our experimental conditions (pH 9.4, 155 °C), the minimal ...
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Abstract
A wide selection of thermal, chemical and optical methods have been proposed for the quantification of black carbon (BC) in environmental matrices, and the results to date differ markedly depending upon the method used. A new approach is hydropyrolysis (hypy), where pyrolysis assisted by high hydrogen pressures (150 bar) facilitates the complete reductive removal of labile organic matter, so isolating a highly stable portion of the BC continuum (defined as BChypy). Here, the potential of hypy for the isolation and quantification of ...
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Abstract
Dolomite is a common mineral in the rock record. However, the rarity of modern dolomite and the notorious difficulty in synthesizing dolomite abiotically under normal Earth-surface conditions result in the long-standing “dolomite problem” in sedimentary geology. Some modern dolomites are associated with sediments where microbial sulfate reduction is active; however, the role of sulfate-reducing bacteria in dolomite formation is still under debate. In this study, we tested the effect of dissolved sulfide on the precipitation of Ca–Mg carbonates, which has been ...
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by Chen Xu, Junyan Zhong, Patrick G. Hatcher, et al.Saijin Zhang, Hsiu-Ping Li, Yi-Fang Ho, Kathleen A. Schwehr, Daniel I. Kaplan, Kimberly A. Roberts, Robin Brinkmeyer, Chris M. Yeager, Peter H. Santschi
Abstract
129I is a major by-product of nuclear fission and had become one of the major radiation risk drivers at Department of Energy (DOE) sites. 129I is present at elevated levels in the surface soils of the Savannah River Site (SRS) F-Area and was found to be bound predominantly to soil organic matter (SOM). Naturally bound 127I and 129I to sequentially extracted humic acids (HAs), fulvic acids (FAs) and a water extractable colloid (WEC) were measured in a 129I-contaminated wetland surface soil ...
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Abstract
We present distribution coefficients, log iKS, for the sorption of yttrium and the rare earth elements (YREEs) on BCR-279, a dehydrated tissue homogenate of a marine macroalga, Ulva lactuca, resembling materials featured in chemical engineering studies aimed at designing renewable biosorbents. Sorption experiments were conducted in NaCl solutions of different ionic strength (0.05, 0.5, and 5.0 M) at T = 25 °C over the pH range 2.7–8.5. Distribution coefficients based on separation of the dissolved and particulate phase by conventional filtration (<0.22 μm) were corrected for the ...
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Abstract
Measurements of the fractional abundance (m) of high temperature nonstoichiometric (HTN) hydrogen in goethite are shown to predict the reduction in O2 yield associated with removal of HTN oxygen by routine pre-treatment of a sample with BrF5 at 22 °C. The predicted relationship between smaller O2 yields and m is linear and defines an “oxygen yield limit” (OYL), which is introduced for use in oxygen isotope analyses of goethite. The OYL sets lower limits for O2 yields that would be consistent with: ...
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Abstract
Laser-ablation (LA) multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) is ideally suited to in situ determination of isotope ratios in sulphide minerals. Using samples of magmatic sulphide ore from the Sudbury impact structure, we test LA-MC-ICPMS analytical protocols that aim to meet a range of analytical challenges in the analysis of Pb isotopes. These include: potential matrix sensitive isotopic fractionation; interferences on Pb isotopes; low melting points of many sulphide minerals; the availability of standards. Magmatic sulphides of wide ranging mineralogy ...
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