New type of filaments for improved accuracy of multiple sulfur isotope analyses by electron-impact gas-source mass spectrometry.

Rationale: The analysis of the three sulfur stable isotope ratios (S/S, S/S, S/S) is routinely performed by gas-source isotope ratio mass spectrometry (IRMS) on the SF gaseous molecule, collecting SF ions at m/z ~ 127, 128, 129 and 131. High precision and accuracy are commonly achieved owing to a lack of correction because fluorine has only one isotope and the inert nature of the SF molecule. The analysis of the S/S ratio is, however, complicated by the low abundance of S (~0.

Fully resolved high-precision measurement of S for sulfur reference materials.

Rationale: Advances in sulfur isotope measurement techniques have led to increased analytical precision. However, accurate measurement of S remains a challenge. This difficulty arises primarily from unresolved isobaric interferences of SF at m/z = 131 u, WF and CF , which lead to scale compression.

Deglacial volcanism and reoxygenation in the aftermath of the Sturtian Snowball Earth.

The Cryogenian Sturtian and Marinoan Snowball Earth glaciations bracket a nonglacial interval during which Demosponge and green-algal biomarkers first appear. To understand the relationships between environmental perturbations and early animal evolution, we measured sulfur and mercury isotopes from the Datangpo Formation from South China. Hg enrichment with positive ΔHg excursion suggests enhanced volcanism, potentially due to depressurization of terrestrial magma chambers during deglaciation.

Multi isotope systematics of precipitation to trace the sources of air pollutants in Seoul, Korea.

Multiple sulfur (δS, ΔS, & ΔS), nitrogen and oxygen (δN & δO) and strontium (Sr/Sr) isotope compositions of precipitation collected from Seoul, South Korea were analyzed to study the sources, transportation and deposition of air pollutants in East Asia. The δS values (from 1.9 to 14.

The origin and migration of the dissolved sulfate from precipitation in Seoul, Korea.

This study incorporated stable isotope analyses with chemical analyses to determine the origin and migration of sulfur sources in East Asia, and these findings were compared with our decadal research from 2000 to 2001 and 2002 to 2003. The multiple sulfur isotope composition (S, S and S) of the dissolved sulfate in precipitation was first measured from 2011 to 2013 in Seoul, South Korea. The δS values were -1.

Biological regulation of atmospheric chemistry en route to planetary oxygenation.

Emerging evidence suggests that atmospheric oxygen may have varied before rising irreversibly ∼2.4 billion years ago, during the Great Oxidation Event (GOE). Significantly, however, pre-GOE atmospheric aberrations toward more reducing conditions-featuring a methane-derived organic-haze-have recently been suggested, yet their occurrence, causes, and significance remain underexplored.

Redox chemistry changes in the Panthalassic Ocean linked to the end-Permian mass extinction and delayed Early Triassic biotic recovery.

The end-Permian mass extinction represents the most severe biotic crisis for the last 540 million years, and the marine ecosystem recovery from this extinction was protracted, spanning the entirety of the Early Triassic and possibly longer. Numerous studies from the low-latitude Paleotethys and high-latitude Boreal oceans have examined the possible link between ocean chemistry changes and the end-Permian mass extinction. However, redox chemistry changes in the Panthalassic Ocean, comprising ∼85-90% of the global ocean area, remain under debate.

Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets.

Achondrite meteorites have anomalous enrichments in (33)S, relative to chondrites, which have been attributed to photochemistry in the solar nebula. However, the putative photochemical reactions remain elusive, and predicted accompanying (33)S depletions have not previously been found, which could indicate an erroneous assumption regarding the origins of the (33)S anomalies, or of the bulk solar system S-isotope composition. Here, we report well-resolved anomalous (33)S depletions in IIIF iron meteorites (<-0.

Large sulfur isotope fractionations associated with Neoarchean microbial sulfate reduction.

The minor extent of sulfur isotope fractionation preserved in many Neoarchean sedimentary successions suggests that sulfate-reducing microorganisms played an insignificant role in ancient marine environments, despite evidence that these organisms evolved much earlier. We present bulk, microdrilled, and ion probe sulfur isotope data from carbonate-associated pyrite in the ~2.5-billion-year-old Batatal Formation of Brazil, revealing large mass-dependent fractionations (approaching 50 per mil) associated with microbial sulfate reduction, as well as consistently negative Δ(33)S values (~ -2 per mil) indicative of atmospheric photochemical reactions.

Sulfate was a trace constituent of Archean seawater.

In the low-oxygen Archean world (>2400 million years ago), seawater sulfate concentrations were much lower than today, yet open questions frustrate the translation of modern measurements of sulfur isotope fractionations into estimates of Archean seawater sulfate concentrations. In the water column of Lake Matano, Indonesia, a low-sulfate analog for the Archean ocean, we find large (>20 per mil) sulfur isotope fractionations between sulfate and sulfide, but the underlying sediment sulfides preserve a muted range of δ(34)S values. Using models informed by sulfur cycling in Lake Matano, we infer Archean seawater sulfate concentrations of less than 2.

Multiple sulfur isotopes fractionations associated with abiotic sulfur transformations in Yellowstone National Park geothermal springs.

Background: The paper presents a quantification of main (hydrogen sulfide and sulfate), as well as of intermediate sulfur species (zero-valent sulfur (ZVS), thiosulfate, sulfite, thiocyanate) in the Yellowstone National Park (YNP) hydrothermal springs and pools. We combined these measurements with the measurements of quadruple sulfur isotope composition of sulfate, hydrogen sulfide and zero-valent sulfur. The main goal of this research is to understand multiple sulfur isotope fractionation in the system, which is dominated by complex, mostly abiotic, sulfur cycling.

Isotopic links between atmospheric chemistry and the deep sulphur cycle on Mars.

The geochemistry of Martian meteorites provides a wealth of information about the solid planet and the surface and atmospheric processes that occurred on Mars. The degree to which Martian magmas may have assimilated crustal material, thus altering the geochemical signatures acquired from their mantle sources, is unclear. This issue features prominently in efforts to understand whether the source of light rare-earth elements in enriched shergottites lies in crustal material incorporated into melts or in mixing between enriched and depleted mantle reservoirs.

Anomalous sulphur isotopes in plume lavas reveal deep mantle storage of Archaean crust.

Basaltic lavas erupted at some oceanic intraplate hotspot volcanoes are thought to sample ancient subducted crustal materials. However, the residence time of these subducted materials in the mantle is uncertain and model-dependent, and compelling evidence for their return to the surface in regions of mantle upwelling beneath hotspots is lacking. Here we report anomalous sulphur isotope signatures indicating mass-independent fractionation (MIF) in olivine-hosted sulphides from 20-million-year-old ocean island basalts from Mangaia, Cook Islands (Polynesia), which have been suggested to sample recycled oceanic crust.

Pathways for Neoarchean pyrite formation constrained by mass-independent sulfur isotopes.

It is generally thought that the sulfate reduction metabolism is ancient and would have been established well before the Neoarchean. It is puzzling, therefore, that the sulfur isotope record of the Neoarchean is characterized by a signal of atmospheric mass-independent chemistry rather than a strong overprint by sulfate reducers. Here, we present a study of the four sulfur isotopes obtained using secondary ion MS that seeks to reconcile a number of features seen in the Neoarchean sulfur isotope record.

Sulfur isotope variability of oceanic DMSP generation and its contributions to marine biogenic sulfur emissions.

Oceanic dimethylsulfoniopropionate (DMSP) is the precursor to dimethylsulfide (DMS), which plays a role in climate regulation through transformation to methanesulfonic acid (MSA) and non-seasalt sulfate (NSS-SO(4)(2-)) aerosols. Here, we report measurements of the abundance and sulfur isotope compositions of DMSP from one phytoplankton species (Prorocentrum minimum) and five intertidal macroalgal species (Ulva lactuca, Ulva linza, Ulvaria obscura, Ulva prolifera, and Polysiphonia hendryi) in marine waters. We show that the sulfur isotope compositions (δ(34)S) of DMSP are depleted in (34)S relative to the source seawater sulfate by ∼1-3‰ and are correlated with the observed intracellular content of methionine, suggesting a link to metabolic pathways of methionine production.

Evidence of magnetic isotope effects during thermochemical sulfate reduction.

Thermochemical sulfate reduction experiments with simple amino acid and dilute concentrations of sulfate reveal significant degrees of mass-independent sulfur isotope fractionation. Enrichments of up to 13‰ for (33)S are attributed to a magnetic isotope effect (MIE) associated with the formation of thiol-disulfide, ion-radical pairs. Observed (36)S depletions in products are explained here by classical (mass-dependent) isotope effects and mixing processes.

Multiple S-isotopic evidence for episodic shoaling of anoxic water during Late Permian mass extinction.

Global fossil data show that profound biodiversity loss preceded the final catastrophe that killed nearly 90% marine species on a global scale at the end of the Permian. Many hypotheses have been proposed to explain this extinction and yet still remain greatly debated. Here, we report analyses of all four sulphur isotopes ((32)S, (33)S, (34)S and (36)S) for pyrites in sedimentary rocks from the Meishan section in South China.

Geological constraints on the origin of oxygenic photosynthesis.

This article examines the geological evidence for the rise of atmospheric oxygen and the origin of oxygenic photosynthesis. The evidence for the rise of atmospheric oxygen places a minimum time constraint before which oxygenic photosynthesis must have developed, and was subsequently established as the primary control on the atmospheric oxygen level. The geological evidence places the global rise of atmospheric oxygen, termed the Great Oxidation Event (GOE), between ~2.

Animal evolution, bioturbation, and the sulfate concentration of the oceans.

As recognized already by Charles Darwin, animals are geobiological agents. Darwin observed that worms aerate and mix soils on a massive scale, aiding in the decomposition of soil organic matter. A similar statement can be made about marine benthic animals.

A contemporary microbially maintained subglacial ferrous "ocean".

An active microbial assemblage cycles sulfur in a sulfate-rich, ancient marine brine beneath Taylor Glacier, an outlet glacier of the East Antarctic Ice Sheet, with Fe(III) serving as the terminal electron acceptor. Isotopic measurements of sulfate, water, carbonate, and ferrous iron and functional gene analyses of adenosine 5'-phosphosulfate reductase imply that a microbial consortium facilitates a catalytic sulfur cycle. These metabolic pathways result from a limited organic carbon supply because of the absence of contemporary photosynthesis, yielding a subglacial ferrous brine that is anoxic but not sulfidic.

Anomalous fractionations of sulfur isotopes during thermochemical sulfate reduction.

Anomalously fractionated sulfur isotopes in many sedimentary rocks older than 2.4 billion years have been widely believed to be the products of ultraviolet photolysis of volcanic sulfur dioxide in an anoxic atmosphere. Our laboratory experiments have revealed that reduced-sulfur species produced by reactions between powders of amino acids and sulfate at 150 degrees to 200 degrees C possess anomalously fractionated sulfur isotopes: Delta33S = +0.

Isotopic evidence for Mesoarchaean anoxia and changing atmospheric sulphur chemistry.

The evolution of the Earth's atmosphere is marked by a transition from an early atmosphere with very low oxygen content to one with an oxygen content within a few per cent of the present atmospheric level. Placing time constraints on this transition is of interest because it identifies the time when oxidative weathering became efficient, when ocean chemistry was transformed by delivery of oxygen and sulphate, and when a large part of Earth's ecology changed from anaerobic to aerobic. The observation of non-mass-dependent sulphur isotope ratios in sedimentary rocks more than approximately 2.