A sulfate conundrum: Dissolved sulfates of deep-saline brines and carbonate-associated sulfates
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Geochemistry & Geophysics↗
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Results for “SULFATES”
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The compression behavior of blödite at low and high temperature up to ∼10 GPa: Implications for the stability of hydrous sulfates on icy planetary bodies
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Comodi, Paola (ORCID:0000000218990589)↗
Raman Spectra of Polycrystalline Lithium Sulfate, Sodium Sulfate, and Potassium Sulfate in the Pretransition Temperature Range Lower the Structural Phase Transition
Molecular relaxation processes in lithium sulfate (Li{sub 2}SO{sub 4}), sodium sulfate (Na{sub 2}SO{sub 4}), and potassium sulfate (K{sub 2}SO{sub 4}) are studied using Raman spectroscopy (RS). The order parameter decreases in the low-temperature phase as it approaches the phase transition. For example, this is typical of a first-order phase transition close to a second-order phase transition. The existence of the pretransition region in the investigated sulfates Li{sub 2}SO{sub 4}, Na{sub 2}SO{sub 4}, and K{sub 2}SO{sub 4} is proven.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Structural unit charge density and molecular cation templating effects on orientational geometric isomerism and interlayer spacing in 2-D uranyl sulfates
The new uranyl aqua sulfate compound [({CH_3}{sub 3}N{sub 2}C{sub 3}H{sub 3}{CH_2COOH})(H{sub 3}O)] [(UO{sub 2}){sub 2}(SO{sub 4}){sub 3}(H{sub 2}O)]·1.5H{sub 2}O was synthesized and the crystal structure determined. The two-dimensional uranyl-aqua sulfate compound exhibits a previously reported anionic structural unit topology, but features an interstitial complex incorporating hydronium in the form of a disorder Zundel cation and the cation moiety from the ionic liquid 1-carboxymethyl 3-methylimidazolium bistriflimide [HBetMIm][Tf{sub 2}N], which forms hydrogen bonding dimer pairs. An analysis of similar uranyl sulfate complexes from the literature is conducted to explore the relative importance and role of structure directing factors in alkylammonium charge-balanced two-dimensional uranyl sulfates. A correlation is observed between structural unit charge density and interlayer spacing, with a concomitant direction of structural and orientational geometric isomerism of the anionic structural unit. We discuss the role of synthetic conditions and molecular cation properties in directing structural unit formation through charge density matching and hydrogen bonding.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Stratigraphic Change from Ca-Sulfate to Mg-Sulfate in the Sedimentary Bedrock of Gale Crater, Mars: Recent Results from Curiosity’s APXS
Curiosity’s APXS instrument has been quantifying sulfates over >30 km of traverse in Gale crater. The rover recently arrived at sedimentary strata where orbital data predicted hydrated Mg-sulfates that may record a change to a drier paleoenvironment. The sequence of strata is in the Marker Band Valley (MBV), the ~10-m-thick, metal-rich Marker Band (MB), and strata above the MB. Here, we report recent sulfate observations by the APXS and provide constraints on the occurrence of Mg-sulfate and the implications for paleoenvironment interpretations. In sedimentary strata below the MBV, Mg-sulfate enrichment (~5-10 wt%) is generally limited to larger diagenetic nodules (~1-3 cm). Ca is positively correlated with S at proportions consistent with Ca-sulfate addition to the bedrock matrix. S variation is thus controlled primarily by Ca-sulfate, which increases ~30% in transitional units below the MBV. The MBV contains the first evidence of Mg-sulfate enrichment in the bedrock matrix, confirmed by the detection of crystalline Mg-sulfate by CheMin. The MBV bedrock has the same overall bulk composition as the underlying Mt. Sharp gp. strata, but with an additional ~5-15 wt% Mg-sulfate. The MB has contrasting sulfate content: (1) targets with very high concentrations of MnO (1.5 wt%), FeO (47 wt%), and Zn (2.2 wt%) are depleted in S and (2) targets with lower metal content have evidence of Mg-sulfate addition. Strata above the MB have a bulk composition that is distinct from other rocks in Gale. For example, the bedrock has molar Fe/Mn (50-60) and Cr/Ti (0.4-0.7) similar to basaltic soil, but ~3X higher Zn and high Ge (50 ppm). Median SO3 above the MB (15 wt%) is higher than the MBV (14 wt%) as well as strata below the MBV (~8 wt%). S does not correlate with Ca or Mg above the MBV. MgO (~9 wt%) is higher than below the MBV (~5 wt%) and the SO3/MgO (1.7) is in the same range as the Mg-sulfate-bearing MBV, suggesting Mg-sulfate enrichment. APXS data indicate that the MBV and above the MB preserve a relatively sharp vertical transition (~5-10 m) from Ca-sulfate to Mg-sulfate in the rock matrix. The sharp contacts with the sulfate-depleted MB and the notable change in bulk composition above the MB may indicate a complex depositional and/or diagenetic history under conditions where enrichments in the highly soluble Mg-sulfates were ultimately preserved.
Jeffrey Allan Berger↗
Importance of sulfate radical anion formation and chemistry in heterogeneous OH oxidation of sodium methyl sulfate, the smallest organosulfate
Organosulfates are important organosulfur compounds present in atmospheric particles. While the abundance, composition, and formation mechanisms of organosulfates have been extensively investigated, it remains unclear how they transform and evolve throughout their atmospheric lifetime. To acquire a fundamental understanding of how organosulfates chemically transform in the atmosphere, this study investigates the heterogeneous OH radical-initiated oxidation of sodium methyl sulfate (CH 3 SO 4 Na) droplets, the smallest organosulfate detected in atmospheric particles, using an aerosol flow tube reactor at a high relative humidity (RH) of 85%. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (direct analysis in real time, DART) coupled with a high-resolution mass spectrometer showed that neither functionalization nor fragmentation products are detected. Instead, the ion signal intensity of the bisulfate ion (HSO 4 - ) has been found to increase significantly after OH oxidation. We postulate that sodium methyl sulfate tends to fragment into a formaldehyde (CH 2 O) and a sulfate radical anion (SO 4 .- ) upon OH oxidation. The formaldehyde is likely partitioned back to the gas phase due to its high volatility. The sulfate radical anion, similar to OH radical, can abstract a hydrogen atom from neighboring sodium methyl sulfate to form the bisulfate ion, contributing to the secondary chemistry. Kinetic measurements show that the heterogeneous OH reaction rate constant, k , is (3.79 ± 0.19) × 10 -13 cm 3 molecule -1 s -1 with an effective OH uptake coefficient, γ eff , of 0.17 ± 0.03. While about 40% of sodium methyl sulfate is being oxidized at the maximum OH exposure (1.27 × 10 12 molecule cm -3 s), only a 3% decrease in particle diameter is observed. This can be attributed to a small fraction of particle mass lost via the formation and volatilization of formaldehyde. Overall, we firstly demonstrate that the heterogeneous OH oxidation of an organosulfate can lead to the formation of sulfate radical anion and produce inorganic sulfate. Fragmentation processes and sulfate radical anion chemistry play a key role in determining the compositional evolution of sodium methyl sulfate during heterogeneous OH oxidation.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Laboratory Simulated Acid-Sulfate Weathering of Basaltic Materials: Implications for Formation of Sulfates at Meridiani Planum and Gusev Crater, Mars
Acid-sulfate weathering of basaltic materials is a candidate formation process for the sulfate-rich outcrops and rocks at the MER rover Opportunity and Spirit landing sites. To determine the style of acid-sulfate weathering on Mars, we weathered basaltic materials (olivine-rich glassy basaltic sand and plagioclase feldspar-rich basaltic tephra) in the laboratory under different oxidative, acid-sulfate conditions and characterized the alteration products. We investigated alteration by (1) sulfuric-acid vapor (acid fog), (2) three-step hydrothermal leaching treatment approximating an open system and (3) single-step hydrothermal batch treatment approximating a "closed system." In acid fog experiments, Al, Fe, and Ca sulfates and amorphous silica formed from plagioclase-rich tephra, and Mg and Ca sulfates and amorphous silica formed from the olivine-rich sands. In three-step leaching experiments, only amorphous Si formed from the plagioclase-rich basaltic tephra, and jarosite, Mg and Ca sulfates and amorphous silica formed from olivine-rich basaltic sand. Amorphous silica formed under single-step experiments for both starting materials. Based upon our experiments, jarosite formation in Meridiani outcrop is potential evidence for an open system acid-sulfate weathering regime. Waters rich in sulfuric acid percolated through basaltic sediment, dissolving basaltic phases (e.g., olivine) and forming jarosite, other sulfates, and iron oxides. Aqueous alteration of outcrops and rocks on the West Spur of the Columbia Hills may have occurred when vapors rich in SO2 from volcanic sources reacted with basaltic materials. Soluble ions from the host rock (e.g., olivine) reacted with S to form Ca-, Mg-, and other sulfates along with iron oxides and oxyhydroxides.
Golden, D. C.↗
Effect of Sulfate Sequestration by Ba-Sn Composite Material on Re Retention in Low-Activity Waste Glass
Difficulty incorporating radioactive Tc-99 into glass during vitrification of low-activity waste (LAW) at the Hanford Site is a technical challenge. Previous studies suggested that the presence of sulfate salts in the melt hinder the incorporation of Re, a non-radioactive surrogate for Tc-99, into nuclear waste glass. In this study, we assessed the capability of a Ba-Sn composite to sequester sulfate during vitrification of AN-102 LAW feed and the resulting effects on Re retention in the glass. We also investigated a feed where the initial soluble sulfate source in the simulated LAW (Na2SO4) was replaced with insoluble BaSO4. The Ba-Sn composite-treated feed and BaSO4-substitute feed were compared to a control, AN-102 baseline. The feeds were prepared and then heated to temperatures from 400-1000 °C at 5 °C/min and air-quenched to room temperature. The heated samples and dried feeds were leached in deionized water. The solutions from the leach test were analyzed by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) to determine the amount of soluble sulfate as a function of temperature and the resulting solids were analyzed for Re retention. Although the Ba-Sn composite material successfully sequestered sulfate in the as-prepared LAW feed, heating to 400 °C resulted in most of the sulfate partitioning to a soluble salt phase. By 700°C, sulfate partitioning in the composite-treated feed was identical to the baseline feed. Throughout the entire temperature range the BaSO4-substitute feed behaved similarly to the composite-treated feed. The results of the study show that sequestering sulfate into a BaSO4 phase is ineffective for rhenium retention as the sulfate salt behavior was identical in the three feeds at =700 °C. The fraction of rhenium retained in the glass at 1000°C varied from 39.4-46.6% for the three feeds, which is shown to be an insignificant difference.
George, Jaime L.↗
Effects of sulfate on biotite interfacial reactions under high temperature and high CO 2 pressure
Anions affect water–biotite interfacial interactions to different extents and subsequently alter surface wettability.
Zhang, Lijie↗
Modelling the sulfate capacity of simulated radioactive waste borosilicate glasses
The capacity of simulated high-level radioactive waste borosilicate glasses to incorporate sulfate has been studied as a function of glass composition. Combined Raman, 57 Fe Mössbauer and literature evidence supports the attribution of coordination numbers and oxidation states of constituent cations for the purposes of modelling, and results confirm the validity of correlating sulfate incorporation in multicomponent borosilicate radioactive waste glasses with different models. A strong compositional dependency is observed and this can be described by an inverse linear relationship between incorporated sulfate (mol% SO 4 2- ) and total cation field strength index of the glass, Σ(z/a 2 ), with a high goodness-of-fit (R 2 ≈ 0.950). Similar relationships are also obtained if theoretical optical basicity, Λ th (R 2 ≈ 0.930) or non-bridging oxygen per tetrahedron ratio, NBO/T (R 2 ≈ 0.919), are used. Results support the application of these models, and in particular Σ(z/a 2 ), as predictive tools to aid the development of new glass compositions with enhanced sulfate capacities.
36 MATERIALS SCIENCE↗
Formation of Inorganic Sulfate and Volatile Nonsulfated Products from Heterogeneous Hydroxyl Radical Oxidation of 2-Methyltetrol Sulfate Aerosols: Mechanisms and Atmospheric Implications
Chemical transformation of 2-methyltetrol sulfates (2-MTS), key isoprene-derived secondary organic aerosol (SOA) constituents, through heterogeneous hydroxyl radical ( • OH) oxidation can result in the formation of previously unidentified atmospheric organosulfates (OSs). However, detected OSs cannot fully account for the sulfur content released from reacted 2-MTS, indicating the existence of sulfur in forms other than OSs, such as inorganic sulfates. This work investigated the formation of inorganic sulfates through heterogeneous • OH oxidation of 2-MTS aerosols. Remarkably, high yields of inorganic sulfates, defined as the moles of inorganic sulfates produced per mole of reacted 2-MTS, were observed in the range from 0.48 ± 0.07 to 0.68 ± 0.07. These could be explained by the production of sulfate (SO 4 •- ) and sulfite (SO 3 •- ) radicals through the cleavage of C-O(S) and (C)O-S bonds, followed by aerosol-phase reactions. Additionally, non-sulfated products resulting from bond cleavage were likely volatile and evaporated into gas phase, as evidenced by observed aerosol mass loss (up to 25%) and concurrent size reduction upon oxidation. This investigation highlights the significant transformation of sulfur from its organic to inorganic forms during the heterogeneous oxidation of 2-MTS aerosols, potentially influencing the physicochemical properties and environmental impacts of isoprene-derived SOA.
54 ENVIRONMENTAL SCIENCES↗
Stimulation of Dissimilatory Sulfate Reduction in Response to Sulfate in Microcosm Incubations from Two Contrasting Temperate Peatlands near Ithaca, NY, USA
Abstract Peatlands are responsible for over half of wetland methane emissions, yet major uncertainties remain regarding carbon flow, especially when increased availability of electron acceptors stimulate competing physiologies. We used microcosm incubations to study the effects of sulfate on microorganisms in two temperate peatlands, one bog and one fen. Three different electron donor treatments were used (13C-acetate, 13C-formate, and a mixture of 12C short-chain fatty acids) to elucidate the responses of sulfate-reducing bacteria (SRB) and methanogens to sulfate stimulation. Methane production was measured and metagenomic sequencing was performed, with only the heavy DNA fraction sequenced from treatments receiving 13C electron donors. Our data demonstrate stimulation of dissimilatory sulfate reduction in both sites, with contrasting community responses. In McLean Bog (MB), hydrogenotrophic Deltaproteobacteria and acetotrophic Peptococcaceae lineages of SRB were stimulated, as were lineages with unclassified dissimilatory sulfite reductases. In Michigan Hollow Fen (MHF), there was little stimulation of Peptococcaceae populations, and a small stimulation of Deltaproteobacteria SRB populations only in the presence of formate as electron donor. Sulfate stimulated an increase in relative abundance of reads for both oxidative and reductive sulfite reductases, suggesting stimulation of an internal sulfur cycle. Together, these data indicate a stimulation of SRB activity in response to sulfate in both sites, with a stronger growth response in MB than MHF. This study provides valuable insights into microbial community responses to sulfate in temperate peatlands and is an important first step to understanding how SRB and methanogens compete to regulate carbon flow in these systems.
Microbiology↗
Rationally designed fluorescently labeled sulfate-binding protein mutants: evaluation in the development of a sensing system for sulfate
Periplasmic binding proteins from E. coli undergo large conformational changes upon binding their respective ligands. By attaching a fluorescent probe at rationally selected unique sites on the protein, these conformational changes in the protein can be monitored by measuring the changes in fluorescence intensity of the probe which allow the development of reagentless sensing systems for their corresponding ligands. In this work, we evaluated several sites on bacterial periplasmic sulfate-binding protein (SBP) for attachment of a fluorescent probe and rationally designed a reagentless sensing system for sulfate. Eight different mutants of SBP were prepared by employing the polymerase chain reaction (PCR) to introduce a unique cysteine residue at a specific location on the protein. The sites Gly55, Ser90, Ser129, Ala140, Leu145, Ser171, Val181, and Gly186 were chosen for mutagenesis by studying the three-dimensional X-ray crystal structure of SBP. An environment-sensitive fluorescent probe (MDCC) was then attached site-specifically to the protein through the sulfhydryl group of the unique cysteine residue introduced. Each fluorescent probe-conjugated SBP mutant was characterized in terms of its fluorescence properties and Ser171 was determined to be the best site for the attachment of the fluorescent probe that would allow for the development of a reagentless sensing system for sulfate. Three different environment-sensitive fluorescent probes (1,5-IAEDANS, MDCC, and acylodan) were studied with the SBP171 mutant protein. A calibration curve for sulfate was constructed using the labeled protein and relating the change in the fluorescence intensity with the amount of sulfate present in the sample. The detection limit for sulfate was found to be in the submicromolar range using this system. The selectivity of the sensing system was demonstrated by evaluating its response to other anions. A fast and selective sensing system with detection limits for sulfate in the submicromolar range was developed. Copyright 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 517-526, 2002.
Evaluation Studies↗
Effects of Sulfate on Rhenium Incorporation into Low-Activity Waste Glass
Technetium-99 (99Tc) is a major radionuclide of concern in the Hanford low-activity waste (LAW), which will be vitrified into borosilicate glass at the Waste Treatment and Immobilization Plant (WTP). Sulfate content in LAW has been known to be a critical factor affecting the volatile loss of 99Tc during melting of the LAW glass feed (a mix of liquid LAW and mineral/chemical additives). We investigated rhenium (a nonradioactive surrogate for 99Tc) incorporation into glass by performing crucible melting tests of two representative simulated LAW glass feeds, each prepared with varied sulfur levels. The sulfate content varied from the original content to half of the original (½S) and to zero (0S), in the range of 0 to 0.8 mass % SO3 in glass if 100% retained. The slurry feeds were dried at 105°C and heated to 400–1100°C. Deionized water leach at room temperature and at 80°C was conducted on the dried feed and heat-treated samples to analyze the chemical compositions of soluble and insoluble phases separately and to profile the partitioning of various components into different phases during the melting process. Different partitioning behavior of rhenium, sulfate, and chlorine is discussed in connection with major feed-to-glass conversion reactions. The mechanism on how sulfate affects rhenium incorporation during feed-to-glass conversion reactions, and so final retention of rhenium in glass, is proposed based on the two hypotheses that segregated sulfate-rich phase forms during feed conversion reactions and Re preferentially partitions to this sulfate-rich phase.
Jin, Tongan↗
Sulfated glycopeptide nanostructures for multipotent protein activation
Biological systems have evolved to utilize numerous proteins with capacity to bind polysaccharides for the purpose of optimizing their function. A well-known subset of these proteins with binding domains for the highly diverse sulfated polysaccharides are important growth factors involved in biological development and tissue repair. Here, we report on supramolecular sulfated glycopeptide nanostructures, which display a trisulfated monosaccharide on their surfaces and bind five critical proteins with very different polysaccharide binding domains. Binding does not disrupt the filamentous shape of the nanostructures or their internal β-sheet backbone, but must involve accessible adaptive configurations to interact with such different proteins. The glycopeptide nanostructures amplified signaling of bone morphogenetic protein 2 significantly more than the natural sulfated polysaccharide heparin, and promoted regeneration of bone in the spine with a protein dose that is 100-fold lower than expected. These super-bioactive nanostructures may enable many therapies in the horizon involving proteins.
36 MATERIALS SCIENCE↗
Degradation mechanism of blended cement pastes in sulfate-bearing environments under applied electric fields: Sulfate attack vs. decalcification
Applied electric fields, the reason behind stray currents, accelerate the ingress of sulfate into cementitious materials. To identify mitigation approaches, this study investigates the effects of slag and fly ash on sodium sulfate attacks of cement pastes under a constant electric current. The mineralogical alterations induced by the attacks were analyzed using X-ray diffractometry, thermogravimetric analysis, scanning electron microscopy, and thermodynamic modeling. The dissolution of aluminates in the slag and fly ash induced a monosulfate-rich area (>~20 mm from the cathode surface) to form next to the ettringite-rich area on the sample surface (<~20 mm). This effect reduced the availability of SO 4 2– in the pore solution, thereby hindering the penetration of sulfate. Meanwhile, the consumption of portlandite by the pozzolanic reaction lowered the decalcification resistance of the materials. This produced a wide area that endured the decomposition of portlandite and carbonate-AFm. Altogether, blending 30% fly ash did not improve the resistance of the material to either sulfate attacks or decalcification; blending 50% slag can effectively mitigate sulfate ingress, though decalcification may become a governing mechanism in the degradation process.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Thermal Emission Spectroscopy of Sulfates: Possible Hydrous Iron-Sulfate in the Soil at the MER-A Gusev Crater Landing Site
Sulfates are likely to be present on Mars as indicated by the sulfur abundances measured at the Viking and Pathfinder landing sites (approx. 5-10% by weight SO3) [1-3] and because of Mars strongly oxidizing environment. Telescopic observations of Mars tentatively identified weak sulfate bands in near infrared [4] and thermal infrared [5] data. The currently orbiting midinfrared instruments (TES, THEMIS) and the Mini-TES on the Mars Exploration Rover landers may enable a positive identification [6] and determination of the chemistry of the sulfates. Critically important to the identification of these minerals is the presence of their spectra in a spectral library. There exist approximately 370 sulfate-mineral species [7]. Sulfate minerals occur in volcanic, hydrothermal, evaporitic, and chemical-weathering environments.
Lane, Melissa D.↗