Showing papers in "Geochimica et Cosmochimica Acta in 2016"

TL;DR: In this paper, the authors explored the mechanisms of hydroxyl radicals (OH) production from pyrite oxidation under anoxic and oxic conditions using benzoic acid (BA) as an OH probe.

TL;DR: In this paper, the authors measured the δ18O and δ17O values of selected low temperature quartz and silica samples in order to derive the quartz-water fractionation-temperature relationship for the three oxygen isotope system.

TL;DR: In this article, a high-resolution study showed that, despite the extensive transport of eroded soil material by the river to the sea, terrestrial organic matter and brGDGTs are only deposited on a relatively small part of the shelf.

TL;DR: In this article, the effect of Bacillus subtilis on the adsorption of U(VI) onto sericite was investigated using batch, EXAFS and modeling techniques.

TL;DR: In this paper, a paragenetic model of post-depositional manganese mineralization with kutnohorite and calcian rhodochrosite as the earliest diagenetic mineral phases was developed.

TL;DR: In this article, a combination of quantitative electron backscatter diffraction analysis, ion microprobe imaging, synchrotron XFM mapping and geochemical modelling was used to investigate the origin of the unusually high gold concentrations.

TL;DR: A series of laboratory experiments were conducted to examine how partitioning of Fe among solid reaction products and rates of H 2 generation vary as a function of temperature during serpentinization of olivine as discussed by the authors.

TL;DR: In this article, the authors present new observational data for Nd isotopes and concentrations from twelve seawater depth profiles, which follow the flow path of North Atlantic Deep Water (NADW) from its formation region in the North Atlantic to the northern equatorial Atlantic.

TL;DR: In this article, an investigation using electrospray ionization coupled to Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) and nuclear magnetic resonance spectroscopy (NMR) has given new insight into the distinctive molecular characteristics of humic acids which suggest a possible pathway for their formation.

TL;DR: In this paper, the authors quantify the processes that determine catchment-scale solute fluxes for two lithologic end-members (basalt and granite) by applying a recently developed solute production model that links weathering fluxes to both discharge and the reactivity of the weathering material.

TL;DR: In this article, major, trace, and volatile element (CO2, H2O, F, Cl, S) contents and Sr, Nd, and Pb isotopes of mid-ocean ridge basalt (MORB) glasses from the Northern East Pacific Rise (NEPR) off-axis seamounts, the Quebrada-Discovery-GoFar (QDG) transform fault system, and the Macquarie Island were reported.

TL;DR: In this article, the authors investigated variations in the GDGT distribution across a SWC gradient (0-61%) around Qinghai Lake in the Tibetan Plateau, an arid to semiarid region in China.

TL;DR: In this article, a pelagic succession of marine carbonate sediment deposited during Cretaceous Ocean Anoxic Event 2 (OAE 2) in the Western Interior Seaway, Colorado (WIS), using the USGS Portland #1 Core was used to explore the potential of using a redox sensitive isotopic proxy with potential for tracing past oxygen levels in the oceans.

TL;DR: In this article, a method for high-precision potassium isotope measurements that improves by an order of magnitude the precision compared to previous methods is reported. But this method requires a hexapole collision gas cell.

TL;DR: The trace element composition of planktic foraminiferal calcite provides a useful means of determining past surface ocean conditions as discussed by the authors, which may be used together in multi-proxy paleoceanographic studies.

TL;DR: In this article, the authors developed and evaluated reactive surface area estimates for their ability to predict dissolution rates in a well-stirred flow-through reactor experiment using disaggregated samples from the Nagaoka pilot CO2 injection site (Japan).

TL;DR: In this paper, geochemical analysis of rocks and fluids from the subsurface of the Samail ophiolite provides new insights into the operative reactions in serpentinizing aquifers.

TL;DR: In this paper, an investigation of abiotic nitrite (NO 2 − ) reduction by Fe(II) or "chemodenitrification" is presented, focusing on dual (N and O) isotope systematics under a variety of environmental conditions.

TL;DR: In this article, the ability of existing pore scale conceptual models (single porosity models) to link molecular and macroscopic scale data on adsorption and diffusion in compacted smectite was examined.

TL;DR: In this paper, the authors used xylem and leaf samples for analysis of plant water and plant leaf wax hydrogen isotopic compositions in forest canopy trees across a highly biodiverse, 3 km elevation range on the eastern flank of the Andes.

TL;DR: In this article, the impacts of O isotopic exchange involving NOy molecules, the hydroxyl radical ( OH), and water (H2O) using reduced partition function ratios (xβ) calculated by hybrid density functional theory were evaluated.

TL;DR: It is demonstrated that differences in net methylation in sediments with high and low organic carbon content may be explained by differences in the availability of carbon to stimulate the activity of Hg methylating bacteria rather than, as previously proposed, be due to differences in HgII binding capacities between sediments.

TL;DR: In this paper, compound specific sulfur isotopes of different organosulfur compounds, with different thermal stabilities and formation pathways, not only differentiate between oils of TSR and non-TSR origin, but can also reveal information about relative timing of secondary charge events and migration pathways.

TL;DR: In this article, stable isotope data for precipitation and drip water from eight cave sites in the monsoon regions of China (MRC), with monthly to bi-monthly sampling intervals from May-2011 to April-2014, were used to investigate the regional-scale climate forcing on δ18Op and how the isotopic signals are transmitted to various drip sites.

TL;DR: The composition of the fine-grained matrix of glacial diamictites from the Meso-archean, Neoproterozoic, and Paleozoic has been studied in this paper.

TL;DR: In this paper, a multielement approach reveals a relationship between Δ17O and the degree of variability in 50Ti and 48Ca, and suggests a physical link between anomalous 48Ca and 50Ti carriers and an 16O-poor reservoir, suggesting that the solar nebula was isotopically heterogeneous shortly after collapse of the protosolar molecular cloud.

TL;DR: In this article, the isotopic signatures of ground and surface waters at a known arsenic hotspot in Cambodia were analyzed and it was shown that recharge through ponds and/or clay windows can transport young, surface derived organic matter into groundwater to depths of 44 m under natural flow conditions.

TL;DR: In this article, the authors reported new data for W concentrations, stable W isotopic compositions, high-precision 182W/184W ratios, highly siderophile element (HSE) abundances and 187Re-187Os systematics in a suite of 3.8-3.3-Ga mafic and ultramafic rocks from the Isua supracrustal belt, and the Paleoarchean terrane in the northwestern part of the belt.

TL;DR: In this paper, the Nyakabingo vein system was studied and it was shown that the fluid saturation started prior to or at the granite-pegmatite transition stage resulting in apical to peribatholitic tungsten veins systems that are paragenetically older than the final pegmatite stage.

TL;DR: In this article, a multi-parameter mixing model was developed to deconvolve the relative importance of physical transport (i.e., water mass mixing) from biogeochemical controls on the dREE distribution in the deep Atlantic.