Sulfur Cycling Research Papers - Academia.edu (original) (raw)

Sulfide minerals commonly occur in sediments and basement rocks in southern New Zealand, as authigenic precipitates from groundwater below the oxygenated surface zone. There are two principal potential sources for sulfur in the... more

Sulfide minerals commonly occur in sediments and basement rocks in southern New Zealand, as authigenic precipitates from groundwater below the oxygenated surface zone. There are two principal potential sources for sulfur in the groundwater system: weathering of sulfide minerals in the meta-morphic basement and rainwater-derived marine aerosols. We present data for these two key sulfur sources: metamorphic sulfide and associated hydrothermal Au-bearing veins within the Otago Schist (average d 34 S ¼ À1.8 ± 2.4‰), and an inland saline lake (S derived entirely from rainwater, d 34 S ¼ 21.4 ± 0.8‰). We use these two end member d 34 S values to estimate the contributions of these sources of sulfur in authigenic groundwater sulfide minerals and in waters derived from oxidation of these sulfide minerals, across a range of environments. We show that authigenic groundwater pyrite along joints in the Otago schist is derived primarily from metamorphic basement sulfur. In contrast, authigenic groundwater pyrite cementing Miocene-Recent aquifers shows a substantial marine aerosol component, and represents a distinct hydrogeological system. We suggest that marine aerosols represent a significant flux to the terrestrial sulfur cycle that has been present through the groundwater system in Otago over the past 20 million years.

We report new sulfur isotope compositions (d 34 S) in carbonate associated sulfate (CAS) and pyrite from the lower Nama Group, Namibia ($550 to <547 Ma), and use these data to interrogate terminal Ediacaran sulfur cycle dynamics. Our... more

We report new sulfur isotope compositions (d 34 S) in carbonate associated sulfate (CAS) and pyrite from the lower Nama Group, Namibia ($550 to <547 Ma), and use these data to interrogate terminal Ediacaran sulfur cycle dynamics. Our extraction method utilizes an improved pre-leaching procedure that reduces the likelihood of contamination from matrix-bound sulfur. Data generated with the improved extraction method show CAS d 34 S as much as 12‰ higher (34 S-enriched) than previously reported which suggests a reevaluation of the phenomenon of 'superheavy' pyrite. The average d 34 S of seawater sulfate increases from 30 to 38‰ in the lower Nama Group, and we correlate this rise in d 34 S among contemporaneous marine basins. Global seawater sulfate d 34 S >35‰ is highly unusual in Earth history, and in the terminal Ediacaran is best explained by a high pyrite burial flux. Pyrite in the Nama Group is close in isotopic composition to coeval sulfate, but the sulfur isotope fractionation between sulfate and pyrite varies widely among different studied basins, suggesting highly heterogeneous redox and depositional conditions.

The Cenomanian-Turonian oceanic anoxic event (OAE2) is characterized by large perturbations in the oxygen and sulfur cycles of the ocean, potentially resulting from changes in oxygen supply (via oxygen solubility and ocean circulation)... more

The Cenomanian-Turonian oceanic anoxic event (OAE2) is characterized by large perturbations in the oxygen and sulfur cycles of the ocean, potentially resulting from changes in oxygen supply (via oxygen solubility and ocean circulation) and in marine productivity. We assess the relative impact of these mechanisms, comparing model experiments with a new compilation of observations for seafloor dysoxia/anoxia and photic-zone euxinia. The model employed is an intermediate-complexity Earth system model which accounts for the main ocean dynamics and biogeochemistry of the Cretaceous climate. The impact of higher temperature and marine productivity is evaluated in the model as a result of higher atmospheric carbon dioxide and oceanic nutrient concentrations. The model shows that temperature is not alone able to reproduce the observed patterns of oceanic redox changes associated with OAE2. Observations are reproduced in the model mainly via enhanced marine productivity due to higher nutrient content (responsible for 85% of the change). Higher phosphate content could have been sustained by increased chemical weathering and phosphorus regeneration from anoxic sediments, which in turn induced an enhanced nitrogen nutrient content of the ocean via nitrogen fixation. The model also shows that the presence of seafloor anoxia, as suggested by black-shale deposition in the proto-North Atlantic Ocean before the event, might be the result of the silled shape and lack of deep-water formation of this basin at the Late Cretaceous. Overall our model-data comparison shows that OAE2 anoxia was quasi-global spreading from 5% of the ocean volume before the event to at least 50% during OAE2.

Intermittently submergence and drainage status of paddy fields can cause alterations in morphological and chemical characteristics of soils. We conducted a sequential fractionation study to provide an insight into solubility of Sulfur (S)... more

Intermittently submergence and drainage status of paddy fields can cause alterations in morphological and chemical characteristics of soils. We conducted a sequential fractionation study to provide an insight into solubility of Sulfur (S) and Molybdenum (Mo) in flooded alluvial paddy soils. The samples (0–15 and 15–30 cm) were taken from marine and riverine alluvial soils in Kedah and Kelantan areas, respectively, and were sequentially extracted with NaHCO 3 , NaOH, HCl, and HClO 4 –HNO 3. Total S in upper and lower layers of Kedah and Kelantan ranged between 273 and 1121 mg kg −1 , and 177 to 1509 mg kg −1 , respectively. In upper layers and subsoil of Kedah, average total Mo were 0.34 and 0.27 mg kg −1 , respectively. Average total Mo in Kelantan were 0.25 mg kg −1 (surface layer) and 0.28 mg kg −1 (subsoil). Cation exchange capacity (CEC) was positively correlated with plant available amounts of Mo in upper layers of Kedah area. Also, total and medium-term plant-available S was correlated with total carbon (C) at lower layers of Kelantan soil series. But in surface layers of Kelantan soil series, CEC was strongly correlated with total and medium-term plant-available S. Our results indicates that the influence of flooding conditions on soil S and Mo contents in paddy fields may cause long-term changes in S and Mo chemical reactivities.

Polymeric waste products, when burned together with carbon dioxide spoil the hydrosphere and atmosphere with diverse poisoning substances. It is of vital importance to derive energy from the waste without burning and carbon dioxide... more

Polymeric waste products, when burned together with carbon dioxide spoil the hydrosphere and atmosphere with diverse poisoning substances. It is of vital importance to derive energy from the waste without burning and carbon dioxide emission. The ideal process can be described by the following equation: C n H m O l = C n + lH 2 O + (m:2-l) H 2 (1) Hydrogen and water are two essential substances for civilization. Carbon should be kept as emergency store for the mankind. However, simple pyrolysis is unable to produce sufficiently pure hydrogen for the use as energy source. So, this technology should be modified in a way that will allow the introduction of a new element and make the process more convenient for application. In this case the reaction with sulfur is the key element of technology. Nowadays research and development in this area is a problem of vital importance. The aim of this work is a study of the interaction of element sulfur with synthetic polymers, in particular with cross-linked copolymer of styrene and divinylbenzene, and the possibility of utilizing the evolving hydrogen sulfide. The sulfur is an accessible and cheap by-product in nonferrous metallurgy. In general, the chemical process of interaction of an organic substance with sulfur can be presented as follows C n H m O l (s) + [(m:2-l):8} S 8 (l) = C n (s) + lH 2 O (g) + (m:2-l) H 2 S (g) (2) The reaction should be well monitored as it proceeds at relatively low temperatures (from 473 up to 723K). The process has no strict limitations with respect to the purity of raw material, and is not inhibited by impurities. The reaction affords three easily separated substances: solid, liquid and gas. Hydrogen sulfide will be used for the preparation of hydrogen. The amount of heat liberated during the process was determined by thermo dynamical calculations. The process of sulfuration will be considered on the example of the reaction of polystyrene and polyethylene with elemental sulfur:

Massively parallel tag sequencing was applied to describe the bacterial diversity in the redox transition and anoxic zones of the Cariaco Basin. In total, 14 samples from the Cariaco Basin were collected over a period of eight years from... more

Massively parallel tag sequencing was applied to describe the bacterial diversity in the redox transition and anoxic zones of the Cariaco Basin. In total, 14 samples from the Cariaco Basin were collected over a period of eight years from two stations. A total of 244 357 unique bacterial V6 amplicons were sequenced. The total number of operational taxonomic units (OTUs) found in this study was 4692, with a range of 511–1491 OTUs per sample. Approximately 95% of the OTUs found in the redox transition zone and anoxic layers of Cariaco are represented by less than 50 amplicons suggesting that only about 5% of the bacterial OTUs are responsible for the bulk of the microbial processes in the basin redox transition and anoxic zones. The same dominant OTUs were observed across all eight years of sampling although periodic fluctuations in their proportion were apparent. No distinctive differences were observed between the bacterial communities from the redox transition and anoxic layers of the Cariaco Basin water column. The largest proportion of amplicons belongs to Gammaproteobacteria represented mostly by sulfide oxidizers, followed by Marine Group A (originally described as SAR406; Gordon and Giovannoni 1996), a group of uncultured bacteria hypothesized to be involved in metal reduction, and sulfate-reducing Deltaproteobacteria. Gammaproteobacteria, Deltaproteobacteria and Marine Group A make up 67–90% of all V6 amplicons sequenced in this study. This strongly suggests that the basin's microbial communities are actively involved in the sulfur-related metabolism and coupling of the sulfur and carbon cycles. According to detrended canonical correspondence analysis, ecological factors such as chemoautotrophy, nitrate and oxidized and reduced sulfur compounds influence the structuring and distribution of the Cariaco microbial communities.

The mechanisms by which soft-bodied organisms were preserved in late Ediacaran deep-marine environments are revealed by petrographic and geochemical investigation of fossil-bearing surfaces from the Conception and St. John's groups... more

The mechanisms by which soft-bodied organisms were preserved in late Ediacaran deep-marine environments are revealed by petrographic and geochemical investigation of fossil-bearing surfaces from the Conception and St. John's groups (Newfoundland, Canada). Framboidal pyrite veneers are documented on fossil-bearing horizons at multiple localities. The pyrite is interpreted to have formed via microbial processes in the hours to weeks following burial of benthic communities. This finding extends the ‘death mask' model for Ediacaran soft-tissue preservation to deep-marine settings. Remineralization of pyrite to iron oxides and oxyhydroxides is recognized to result from recent oxidation by meteoric fluids in the shallow subsurface. Consideration of other global Ediacaran macrofossil occurrences reveals that pyrite is observed in association with Ediacaran macrofossils preserved in all four previously described styles of moldic preservation (Flinders-, Conception-, Fermeuse- and Nama-type). This suggests that replication of external morphology by framboidal pyrite was a widespread mechanism by which soft-bodied organisms and associated organic surfaces were preserved, in multiple facies and depositional environments, 580–541 million years ago. The extensive global burial of pyrite in medium- to coarse-grained clastics and carbonates is a previously unrecognized yet potentially significant geological sink of iron and sulfur, and may have contributed to rising atmospheric and marine oxygen concentrations across the late Ediacaran interval.

Long-term secular variation in seawater sulfate concentrations ([SO4(2-)]SW) is of interest owing to its relationship to the oxygenation history of Earth’s surface environment, but quantitative approaches to analysis of this variation... more

Long-term secular variation in seawater sulfate concentrations ([SO4(2-)]SW) is of interest owing to its relationship to the oxygenation history of Earth’s surface environment, but quantitative approaches to analysis of this variation remain underdeveloped. In this study, we develop two complementary approaches for assessment of the [SO4(2-)] of ancient seawater and test their application to reconstructions of [SO4(2-)]SW variation since the late Neoproterozoic Eon (<650 Ma). The first approach is based on two measurable parameters of paleomarine systems: (1) the S-isotope fractionation associated with microbial sulfate reduction (MSR), as proxied by δ34SCAS-PY, and (2) the maximum rate of change in seawater sulfate, as proxied by ∂δ34SCAS/∂t(max). This “rate method” yields an estimate of the maximum possible [SO4(2-)]SW for the time interval of interest, although the calculated value differs depending on whether an oxic or an anoxic ocean model is inferred. The second approach is also based on δ34SCAS-PY but evaluates this parameter against an empirical MSR trend rather than a formation-specific ∂δ34SCAS/∂t(max) value. The MSR trend represents the relationship between fractionation of cogenetic sulfate and sulfide (i.e., δ34Ssulfate-sulfide) and ambient dissolved sulfate concentrations in 81 modern aqueous systems. This “MSR-trend method” is thought to yield a robust estimate of mean seawater [SO4(2-)] for the time interval of interest. An analysis of seawater sulfate concentrations since 650 Ma suggests that [SO4(2-)]SW was low during the late Neoproterozoic (<5 mM), rose sharply across the Ediacaran/Cambrian boundary (to ~5-10 mM), and rose again during the Permian to levels (~10-30 mM) that have varied only slightly since 250 Ma. However, Phanerozoic seawater sulfate concentrations may have been drawn down to much lower levels (~1-4 mM) during short (<~2-Myr) intervals of the Cambrian, Early Triassic, Early Jurassic, and possibly other intervals as a consequence of widespread ocean anoxia, intense MSR, and pyrite burial. The procedures developed in this study offer potential for future high-resolution quantitative analyses of paleoseawater sulfate concentrations.

Fe(III) reduction in the Magothy aquifer of Long Island, NY, results in high dissolved-iron concentrations that degrade water quality. Geochemical modeling was used to constrain iron-related geochemical processes and redox zonation along... more

Fe(III) reduction in the Magothy aquifer of Long Island, NY, results in high dissolved-iron concentrations that degrade water quality. Geochemical modeling was used to constrain iron-related geochemical processes and redox zonation along a ̄ow path. The observed increase in dissolved inorganic carbon is consistent with the oxidation of sedimentary organic matter coupled to the reduction of O2 and SO42P in the aerobic zone, and to the reduction of SO42P in the anaerobic zone; estimated rates of CO2 production through reduction of Fe(III) were relatively minor by comparison. The rates of CO2 production calculated from dissolved inorganic carbon mass transfer 􏰄2X55 £ 10P4 to 48X6 £ 10P4 mmol lP1 yrP1􏰅 generally were comparable to the calculated rates of CO2 production by the combined reduction of O2, Fe(III) and SO42P 􏰄1X31£10P4 to 15£ 10P4 mmol lP1 yrP1􏰅X The overall increase in SO42P concentrations along the ̄ow path, together with the results of mass- balance calculations, and variations in d 34S values along the ̄ow path indicate that SO42P loss through microbial reduction is exceeded by SO42P gain through diffusion from sediments and through the oxidation of FeS2. Geochemical and microbial data on cores indicate that Fe(III) oxyhydroxide coatings on sediment grains in local, organic carbon- and SO42P-rich zones have been depleted by microbial reduction and resulted in localized SO42P-reducing zones in which the formation of iron disul®des decreases dissolved iron concentrations. These localized zones of SO42P reduction, which are important for assessing zones of low dissolved iron for water-supply development, could be overlooked by aquifer studies that rely only on groundwater data from well-water samples for geochemical modeling.

Selected mineralized black shales of Devonian age from the Selwyn Basin, Northwest Territories (Canada) were analyzed by Nuclear Reaction Analyses (NRA) and electron microprobe for nitrogen and carbon in silicates, sulfides, phosphates... more

Selected mineralized black shales of Devonian age from the Selwyn Basin, Northwest Territories (Canada) were analyzed by Nuclear Reaction Analyses (NRA) and electron microprobe for nitrogen and carbon in silicates, sulfides, phosphates and organic matter in order to give new insights on nitrogen and carbon fractionation processes during diagenesis and hydrothermal infiltration. Hydrothermal feldspars show tri-modal composition: albite, high nitrogen-bearing K-feldspar (~56 mol% buddingtonite (NH4AlSi3O8 1/2H2O, hydrous ammonium-feldspar, ~51 mol% orthoclase) and hyalophane (~32 mol% celsian). Barium-rich feldspars (hyalophane) contain lowest nitrogen contents. Potassium and nitrogen are positively correlated, while nitrogen and barium are negatively correlated due to the replacement of monovalent NH4+ by divalent Ba2+. The Ba-rich K-feldspar rim shows penetrative textures towards an internal K–N-rich core that is interpreted as diffusive overgrowth. These feldspars are interpreted to be deposited from hot hydrothermal Ba- bearing fluids. The second important nitrogen carrier is organic matter (from 0.6 to 0.66 wt.%). Hydrothermal quartz (N=527 ppm), diagenetic biogenic F-rich apatite (conodonts: N=468 ppm,), biogenic Fe–Ni sulfides (N=380–620 ppm) and abiogenic Ni–Fe sulfides (N>440 ppm) contain homogeneously distributed nitrogen with amounts 10-fold lower than those measured in organic matter. A two-step nitrogen-release model is suggested to explain the nitrogen-partitioning in these minerals. Primary organic matter breakdown is considered to liberate nitrogen, phosphate and sulfur to pore fluids and the water column, providing nutrients for vent fauna growth. Sulfurization, due to microbial sulfate reduction, and silicification of the vent fauna releases nitrogen in a second step. Minor nitrogen was trapped as organic molecules in conodonts, while the majority was transported by hydrothermal fluids and was incorporated as ammonium in feldspars substituting for potassium.

Oceanic emissions of volatile dimethyl sulfide (DMS) represent the largest natural source of biogenic sulfur to the global atmosphere, where it mediates aerosol dynamics. To constrain the contribution of oceanic DMS to aerosols we... more

Oceanic emissions of volatile dimethyl sulfide (DMS) represent the
largest natural source of biogenic sulfur to the global atmosphere,
where it mediates aerosol dynamics. To constrain the contribution
of oceanic DMS to aerosols we established the sulfur isotope ratios
(34S/32S ratio, δ34S) of DMS and its precursor, dimethylsulfoniopropionate
(DMSP), in a range of marine environments. In view of the
low oceanic concentrations of DMS/P, we applied a unique method
for the analysis of δ34S at the picomole level in individual compounds.
Surface water DMSP collected from six different ocean
provinces revealed a remarkable consistency in δ34S values ranging
between +18.9 and +20.3‰. Sulfur isotope composition of DMS
analyzed in freshly collected seawater was similar to δ34S of DMSP,
showing that the in situ fractionation between these species is
small (<+1‰). Based on volatilization experiments, emission of
DMS to the atmosphere results in a relatively small fractionation
(−0.5 ± 0.2‰) compared with the seawater DMS pool. Because
δ34S values of oceanic DMS closely reflect that of DMSP, we conclude
that the homogenous δ34S of DMSP at the ocean surface represents
the δ34S of DMS emitted to the atmosphere, within +1‰.
The δ34S of oceanic DMS flux to the atmosphere is thus relatively
constant and distinct from anthropogenic sources of atmospheric
sulfate, thereby enabling estimation of the DMS contribution
to aerosols.

Cinder Pool is an acid-sulfate-chloride boiling spring in Norris Geyser Basin, Yellowstone National Park. The pool is unique in that its surface is partially covered with mm-size, black, hollow sulfur spherules, while a layer of molten... more