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Fine particulate matter (PM 2.5) has been implicated in various health concerns. However, a comprehensive understanding of the specific PM 2.5 components affecting depression remains limited. This study conducted a Cox proportional-hazards model to assess the effect of PM 2.5 components on the incidence of depression based on the China Health and Retirement Longitudinal Study (CHARLS). Participants with 10-item Center for Epidemiologic Studies Depression Scale (CESD-10) score of 10 or higher were classified as exhibiting depression. Our findings demonstrated a significant positive correlation between long-term exposure to black carbon (BC), sulfate (SO 4 2−), and organic matter (OM) components of PM 2.5 and the prevalence of depression. Per 1 Interquartile Range (IQR) increment in 3-year average concentrations of BC, OM, and SO 4 2− were associated with the hazard ratio (HR) of 1.54 (95 % confidence intervals (CI): 1.44, 1.64), 1.24 (95% CI : 1.16, 1.34) and 1.25 (95% CI : 1.16, 1.35). Notably, females, younger individuals, those with lower educational levels, urban residents, individuals who were single, widowed, or divorced, and those living in multi-story houses exhibited heightened vulnerability to the adverse effects of PM 2.5 components on depression. Firstly, pollutant data is confined to subjects' fixed addresses, overlooking travel and international residence history. Secondly, the analysis only incorporates five fine particulate components, leaving room for further investigation into the remaining fine particulate components in future studies. This study provides robust evidence supporting the detrimental impact of PM 2.5 components on depression. The identification of specific vulnerable populations contributes to a deeper understanding of the underlying mechanisms involved in the relationship between PM 2.5 components and depression. • This study explore the association between PM 2.5 components and depression. • Black carbon, sulfate, and organic matter have significant impacts on depression. • Females, who living in multi-story house were susceptible to the PM 2.5 components. [ABSTRACT FROM AUTHOR]

• ALWC contributed 66.68% to PM 2.5 , with higher mass – based growth factor appearing when RH > 85%. • NO 3 – tended to form under higher ALWC conditions (RH > 80%), while SOC was favorable under lower ALWC levels. • ALWC was more sensitive to NO 3 – (R = 0.94) than SO 4 2– (R = 0.90) under heavy pollution. • SOC had a good correlation with ALWC (daytime: R = 0.84; nighttime: R = 0.54) with high atmospheric oxidation capacity (daytime: O X = 130 – 140 µg/m3; nighttime: O X = 100 – 140 µg/m3) in winter. Aerosol liquid water content (ALWC) plays an important role in secondary aerosol formation. In this study, a whole year field campaign was conducted at Shanxi in north Zhejiang Province during 2021. ALWC estimated by ISORROPIA-II was then investigated to explore its characteristics and relationship with secondary aerosols. ALWC exhibited a highest value in spring (66.38 µg/m3), followed by winter (45.08 µg/m3), summer (41.64 µg/m3), and autumn (35.01 µg/m3), respectively. It was supposed that the secondary inorganic aerosols (SIA) were facilitated under higher ALWC conditions (RH > 80%), while the secondary organic species tended to form under lower ALWC levels. Higher RH (> 80%) promoted the NO 3 – formation via gas-particle partitioning, while SO 4 2– was generated at a relative lower RH (> 50%). The ALWC was more sensitive to NO 3 – (R = 0.94) than SO 4 2– (R = 0.90). Thus, the self-amplifying processes between the ALWC and SIA enhanced the particle mass growth. The sensitivity of ALWC and O X (NO 2 + O 3) to secondary organic carbon (SOC) varied in different seasons at Shanxi, more sensitive to aqueous-phase reactions (daytime R = 0.84; nighttime R = 0.54) than photochemical oxidation (daytime R = 0.23; nighttime R = 0.41) in wintertime with a high level of O X (daytime: 130–140 µg/m3; nighttime: 100–140 µg/m3). The self-amplifying process of ALWC and SIA and the aqueous-phase formation of SOC will enhance aerosol formation, contributing to air pollution and reduction of visibility. [Display omitted] [ABSTRACT FROM AUTHOR]

Past studies have documented contrasting geochemical responses of the Great Lakes to anthropogenic disturbances of the carbon and sulfur cycles. Yet, it is unclear whether these responses were induced by differences in tributary inputs or different behaviors controlled by in-lake biogeochemical processes. To yield insight into the carbon and sulfur dynamics across the land-lake interface, concentrations of chloride (Cl-), sulfate (SO 4 2-), dissolved inorganic carbon (DIC), and dissolved organic carbon (DOC) were measured in water samples from nearshore and offshore sites at Lake Erie, the Detroit River, and other tributaries. The stable isotope ratios of water (δ18O and δ2H), sulfate (δ34S SO4 and δ18O SO4), and the stable and radio isotope ratios of DIC (δ13C DIC and Δ14C DIC) were also measured. Our results confirm that waters from Lake Erie characterized by low Cl- and SO 4 2- , low deuterium excess (d -excess = δ2H – 8 δ18O), and high δ13C DIC , Δ14C DIC , δ34S SO4 , and δ18O SO4 , were chemically and isotopically different from tributary waters. The nearshore waters exhibited significant correlations between various pairs of chemical and isotopic parameters revealing the influence of inputs from the tributaries. Moreover, the nearshore waters had lower averages of Cl-, SO 4 2-, DOC, DIC, and δ18O, but higher averages of δ13C DIC , Δ14C DIC , and δ34S SO4 than those estimated from binary mixing between lake and tributary waters, suggesting an effect of in-lake biogeochemical transformations. But the rates of carbon and sulfur transformations differed considerably. Thus, we suggest that the contrasting geochemical responses were induced by both their different in-lake transformation rates and their different histories of tributary inputs. [ABSTRACT FROM AUTHOR]

• Impact of NO 2 and O 3 on SO 2 -SO 4 2− conversion is identified based on MFDCCA method. • NO 2 has stronger promoting effect on SO 2 -SO 4 2− conversion in winter than in summer. • The higher the efficiency of SO 2 -SO 4 2− conversion, the lower the O 3 level. • Reductions in SO 4 2−/NO 3 − ratio may make O 3 pollution more severe in Hong Kong. As an important component of secondary aerosols, sulfate plays a crucial role in regulating atmospheric radiative balance and influencing the secondary formation of ozone (O 3). In real atmosphere, atmospheric oxidants NO 2 and O 3 can promote the oxidation of SO 2 to form sulfate (SO 4 2−) through multiphase chemistry that occur at different time scales. Due to the combined impact of meteorology, pollution sources, atmospheric chemistry, etc., time-scale dependence of SO 2 -SO 4 2− conversion makes the impact of NO 2 /O 3 on it more complex. In this study, based on long-term time series (2013-2020) of air pollution variables from seven stations in Hong Kong, the Multifractal Detrended Cross-Correlation Analysis (MFDCCA) method has been employed to quantify the cross-correlations between SO 2 and SO 4 2− in real atmosphere at different time scales, for examining the time-scale dependence of SO 2 -SO 4 2− conversion efficiency. Furthermore, the Pearson correlation analysis has been used to study the influence of NO 2 /O 3 on SO 2 -SO 4 2− conversion, and the regional and seasonal differences have been analyzed by considering factors such as meteorology, pollution sources, and regional transport. Changes in the main components of secondary aerosols are closely linked with the co-control of regional PM 2.5 and O 3. Therefore, the exploration of the impact of co-existing NO 2 /O 3 gases on the secondary formation of sulfates in real atmosphere is significant. [Display omitted] [ABSTRACT FROM AUTHOR]

Early diagenesis of marine organic matter dramatically impacts Earth's surface chemistry by changing the burial potential of carbon and promoting the formation of authigenic mineral phases including carbonate concretions. Marine sediment-hosted carbonate concretions tend to form as a result of microbial anaerobic diagenetic reactions that degrade organic matter and methane, some of which require an external oxidant. Thus, temporal changes in the oxidation state of Earth's oceans may impart a first-order control on concretion authigenesis mechanisms through time. Statistically significant variability in concretion carbonate carbon isotope compositions indicates changes in shallow marine sediment diagenesis associated with Earth's evolving redox landscape. This variability manifests itself as an expansion in carbon isotope composition range broadly characterized by an increase in maximum and decrease in minimum isotope values through time. Reaction transport modelling helps to constrain the potential impacts of shifting redox chemistry and highlights the importance of organic carbon delivery to the seafloor, marine sulfate concentrations, methane production and external methane influx. The first appearance of conclusively anaerobic oxidation of methane-derived concretions occurs in the Carboniferous and coincides with a Paleozoic rise in marine sulfate. The muted variability recognized in older concretions (and in particular for Precambrian concretions) likely reflects impacts of a smaller marine sulfate reservoir and perhaps elevated marine dissolved inorganic carbon concentrations. Causes of the increase in carbon isotope maximum values through time are more confounding, but may be related to isotopic equilibration of dissolved inorganic carbon with externally derived methane. Ultimately the concretion isotope record in part reflects changes in organic matter availability and marine oxidation state, highlighting connections with the subsurface biosphere and diagenesis throughout geologic time. [ABSTRACT FROM AUTHOR]

Impure ions in the precursor can cause the structural transition of prepared MnO 2 catalysts and influence their activity in toluene catalytic oxidation. Here, the effects of K+ and SO 4 2- on the catalytic activity of MnO 2 are examined. Removing absorbed SO 4 2- by repeating water washing facilitates the exposure of active sites on the surface of MnO 2. The temperature for toluene conversion reaches 90% (T 90) of catalysts decreases from 247 ºC to 238 ºC. While the loss of K+ during the water washing leads to the inferior performance of MnO 2. Re-impregnating of K+ can stimulate the generation of active oxygen species on the surface of catalysts (K/MnO 2), which showed elevated catalytic activity in toluene conversion (T 90 , 229 ºC). In addition, K/MnO 2 performs good stability for toluene combustion in long-term operation. Density Function Theory calculations reveal that the formation energy of oxygen vacancy and the adsorption energy of toluene on the surface of catalyst decrease from 6.996 eV and − 0.079 to 5.482 eV and − 0.468 eV as the introduction of K+, respectively. Our results provide a complete understanding of the effects of impurity ions on the performance of manganese oxide for catalytic oxidation of toluene. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Effects of different pretreatments on the properties of MSWIFA were studied. • Emission of NH 3 (gas), apart from H 2 (gas), was detected during the washing process. • A set of system for collecting H 2 (gas) and NH 3 (gas) was devised. • Pretreatments reduced the leaching toxicities of MSWIFA and removed anions. • Pretreatments enhanced the pozzolanic activity of MSWIFA. Swelling caused by gas generated from municipal solid waste incineration fly ash (MSWIFA) when it is mixed with alkali limits its uses. Besides, the leaching of anion salts and heavy metals contained in MSWIFA poses a high risk to environment. This study presents the feasibility of a one-step alkaline washing, one-step thermal quenching and two-step combination of alkaline washing and thermal quenching pretreatment methods in altering the key properties of MSWIFA for promoting its reusability. It was found that apart from H 2 (gas), NH 3 (gas) was also generated during the alkaline washing of the MSWIFA. Besides, pretreatments led to the reduction in particle size, the increase in pore volume and specific surface area of the MSWIFA, as well as the removal of chloride and sulfate anions. All the pretreatment methods were effective in reducing leaching of heavy metals to below levels of nonhazardous waste except Cd and Pb with alkaline washing. Furthermore, both the chemical Frattini test and the mechanical activity index test showed improvement in pozzolanic activities of the MSWIFA after the pretreatments. Overall, the combined pretreatment method was most effective in eliminating gas emission, and reducing leaching of metal ions and anions from the ash, while enhancing the pozzolanic activity of the ash. [ABSTRACT FROM AUTHOR]

We report new results from inorganic experiments in which the effects of several oxyanions on the concentration and isotopic composition of boron (B/Ca and δ11B, respectively) in calcite were explored. The oxyanions examined here (sulfate, phosphate, nitrate, and nitrite) differ in their size, charge, and geometric configuration, but they are all common dissolved constituents in natural aqueous solutions including seawater. Of those, sulfate and phosphate which are known to inhibit calcite nucleation/precipitation had pronounced impacts on the B incorporation and isotope fractionation during calcite precipitation. Additions of up to 5 mmol sulfate and up to 2 μmol phosphate into experimental solutions of otherwise unaltered condition caused comparable declines in calcite precipitation rates R , increases in B/Ca, and decreases in calcite δ11B towards the calculated δ11B of B(OH) 4 −. The pattern of changes in B/Ca and δ11B as a function of R observed here is at odds with normal kinetic effects confirmed in previous studies, where B/Ca and δ11B were shown to increase and decrease, respectively, with an increase in degrees of calcite saturation in solutions and thus R. We argue that the paradoxical and apparently reversed kinetic trends in B/Ca and δ11B in the presence of sulfate and phosphate can be attributed to deformations of the calcite lattice structure due to their substitutions for lattice CO 3 , which in turn enhances the retainment and eventual incorporation of B(OH) 4 −. Our new findings could have important implications for paleo-reconstructions of ocean carbonate chemistry using B/Ca and δ11B, if the mechanism proposed above is similarly in effect during natural precipitation of biogenic calcite (e.g., foraminiferal tests) in seawater. Though this needs further testing, if true, the gradual but sizable increase in seawater sulfate over the Cenozoic could have biased foraminiferal B/Ca and δ11B. Our experimental data additionally indicate that Na+ has the capability of providing charge compensations for substitutions of CO 3 by B(OH) 4 −. However, our data also demonstrate that changes in Na+ concentration do not control the degrees of B incorporation. [ABSTRACT FROM AUTHOR]

• No precipitation of As(III) with Fe(III) in aqueous SO 4 (-II)-rich media is observed. • Mixing Cl(-I) into SO 4 (-II) solution markedly promotes As(III) precipitated removal. • The optimal As(III) removal occurs at SO 4 (-II)/Cl(-I) molar ratio of 1:4 and 25 °C. • Tooeleite and (Cl(-I)-free) ferric arsenite hydroxychloride are the main As sink. • Fe(III)-As(III) precipitate is affected by FeH 2 AsO 3 2+, FeSO 4 + and FeCl2+ complexes. An advanced cost-saving method of removal of high-As(III) from SO 4 (-II)-rich metallurgical wastewater has been developed by diluting the SO 4 (-II) content with As(III)-Cl(-I)-rich metallurgical wastewater and then by the direct precipitation of As(III) with Fe(III) at pH 2.3. As(III) removal at various SO 4 (-II)/Cl(-I) molar ratios and temperatures was investigated. The results showed that 65.2‒98.2% of As(III) immobilization into solids occurred at the SO 4 (-II)/Cl(-I) molar ratios of 1:1‒32 and 15‒60 °C in 3 days, which were far higher than those in aqueous sole SO 4 (-II) or Cl(-I) media at the equimolar SO 4 (-II) or Cl(-I) and the same temperature. SO 4 (-II)/Cl(-I) molar ratio of 1:4 and 25 °C were optimal conditions to reach the As removal maximum. Mixed aqueous SO 4 (-II) and Cl(-I) played a synergetic role in the main tooeleite formation together with (Cl(-I)-free) ferric arsenite hydroxychloride (FAHC) involving the substitution of AsO 3 3− for Cl(-I) for enhanced As fixation. The competitive complexation among FeH 2 AsO 3 2+, FeSO 4 + and FeCl2+ complexes was the main mechanism for the maximum As(III) precipitation at the SO 4 (-II)/Cl(-I) molar ratio of 1:4. Low As(III) immobilization at high temperature with increased Fe(III) hydrolysis was due to the formation of As(III)-bearing ferrihydrite with the relatively high Fe/As molar ratio at acidic pH. [Display omitted] [ABSTRACT FROM AUTHOR]

We investigated variations of PM 2.5 and water-soluble inorganic ions chemical characteristics at nine urban and rural sites in China using ground-based observations. From 2015 to 2019, mean PM 2.5 concentration across all sites decreased by 41.9 µg/m3 with a decline of 46% at urban sites and 28% at rural sites, where secondary inorganic aerosol (SIAs) contributed to 21% (urban sites) and 17% (rural sites) of the decreased PM 2.5. SIAs concentrations underwent a decline at urban locations, while sulfate (SO 4 2–), nitrate (NO 3 –), and ammonium (NH 4 +) decreased by 49.5%, 31.3% and 31.6%, respectively. However, only SO 4 2– decreased at rural sites, NO 3 – increased by 21% and NH 4 + decreased slightly. Those changes contributed to an overall SIAs increase in 2019. Higher molar ratios of NO 3 – to SO 4 2– and NH 4 + to SO 4 2– were observed at urban sites than rural sites, being highest in the heavily polluted days. Mean molar ratios of NH 3 /NH x were higher in 2019 than 2015 at both urban and rural sites, implying increasing NH x remained as free NH 3. Our observations indicated a slower transition from sulfate-driven to nitrate-driven aerosol pollution and less efficient control of NO x than SO 2 related aerosol formation in rural regions than urban regions. Moreover, the common factor at urban and rural sites appears to be a combination of lower SO 4 2– levels and an increasing fraction of NO 3 – to PM 2.5 under NH 4 +-rich conditions. Our findings imply that synchronous reduction in NO x and NH 3 emissions especially rural areas would be effective to mitigate NO 3 –-driven aerosol pollution. [Display omitted] [ABSTRACT FROM AUTHOR]

• Sulfate promotes SRB bioactivity and microbial corrosion as an electron accepter. • Chloride ions increase the osmotic pressure of SRB cells and promote EPS secretion. • EPS complexes with Fe2+ to promote corrosion and acts as an electron shuttle to promote EET. Sulfate-reducing bacteria (SRB) present in sea mud pose a challenge to the safe operation of subsea pipelines. Chlorides and sulfates in sea mud promote the microbial corrosion of subsea pipelines by SRB. This study investigates the effects of sulfate and chloride on the microbial corrosion of X80 pipeline steel in the sea mud environment. The results indicate that sulfate serves as an electron acceptor, promoting the growth of SRB, while chloride regulates the osmotic pressure of SRB cells, affecting their bioactivity. SRB exhibit more aggressive corrosion behavior in sea mud with high concentrations of both chloride and sulfate. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of hot corrosion on the lifetime of TBCs with and without top coat under cyclic thermal loading. The tests were performed on two types of samples: Type A coating consisting solely of a bond coat (BC) fabricated by the HVOF method, and type B coating comprising a BC fabricated by the HVOF method and a TC fabricated by the APS method. The lifetime and degradation mechanism of these two types of coatings under hot corrosion in the presence of sulfate and vanadate molten salts were compared. The lifetime of type A and B coatings under the hot corrosion test is 31 and 24 cycles, respectively. Results indicate that the TGO acts as a barrier against the penetration of corrosive salts and delays the degradation of the type A coating. XRD patterns reveal that the reaction products of BC with molten salts are (Co,Ni) 3 (VO 4) 2 and (Cr,Al)VO 4. In the type B coating, YVO 4 is formed as a hot corrosion product due to the reaction of molten salts with yttria. With the depletion of yttria, the phase transition of zirconia from tetragonal to monoclinic causes volumetric expansion and coating degradation. • Analysis two types of TBCs under cyclic heat treatment and hot corrosion, comparing coatings with and without top coat. • Examination of HVOF-applied bond coat behavior under hot corrosion conditions, elucidating the corrosion mechanism. • Characterization of structural alterations in top coat layer during exposure to hot corrosion environments. • Investigating of bond coats oxidation under hot corrosion and cyclic thermal loading, revealing degradation mechanisms. [ABSTRACT FROM AUTHOR]

Several MICRORNA genes belonging to same family or different families are often found in homologous or non-homologous clusters. Among the various classes, head-to-head arranged genes form one of the largest categories of non-canonically organized genes. Such head-to-head arranged, non-canonically organized genes possibly share cis-regulatory region with the intergenic sequence having the potential to function as bi-directional promoter (BDP). The transcriptional regulation of head-to-head arranged genes, especially with bidirectional promoters, remains an enigma. In the past, bidirectional promoters have been characterized for a small set of protein-coding gene pairs in plants; however, to the best of our knowledge, no such study has been carried so far for MICRORNA genes. The present study thus functionally characterizes bidirectional promoters associated with members of MIR395 family, which is evolutionary conserved and is most frequently occurring cluster across plant kingdom. In Arabidopsis thaliana , the MIR395 gene family contains six members with two head-to-head arranged gene pairs- MIR395A-B and MIR395E-F. This organization was found to be conserved at seven loci for MIR395A-B , and eleven loci for MIR395E-F in five Brassica sps. Sequence analysis of the putative bidirectional promoters revealed variation in length, GC content and distribution of strict TATA-box. Comparatively higher level of conservation at both the ends of the bidirectional promoters, corresponding to ca. 250 bp upstream of 5'end of the respective MIRNA precursor, was observed. These conserved regions harbour several abiotic stress (nutrient, salt, drought) and hormone (ABA, ethylene) responsive cis-motifs. Functional characterization of putative bidirectional promoters associated with MIR395A-B and MIR395E-F from Arabidopsis and their respective orthologs from Brassica juncea (Bj_A08 MIR395A-B, Bj_B03 MIR395A-B, Bj_A07.1 MIR395E-F and Bj_A07.2 MIR395E-F) was carried out using a dual-reporter vector with β-glucuronidase (GUS) and Green Fluorescent Protein (GFP). Analysis of transcriptional regulation of the two reporter genes - GUS and GFP during developmental stages confirmed their bidirectional nature. Orientation-dependent differential reporter activity indicated asymmetric nature of the promoters. Comparison of the reporter activity amongst orthologs, paralogs and homeologs revealed regulatory diversification, an outcome expected in polyploid genomes. Interestingly, reporter gene activities driven by selected bidirectional promoters were also observed in anther and siliques apart vegetative tissues indicating role of miR395 in anther and fruit development. Finally, we evaluated the activity of reporter genes driven under transcriptional regulation of bidirectional promoters under normal and sulfate-deprived conditions which revealed asymmetric inducibility under sulfate-starvation, in agreement with the known role of miR395 in sulfate homeostasis. [Display omitted] • Head-to-head arranged genes form one of the largest category of non-canonically organized gene. • Head-to-head arranged genes share cis-element and the intergenic sequence has the potential to act as bi-directional promoterr. • MIR395 associated bidirectional promoters exhibit orientation-dependent differential transcriptional activity. • Reporter activity analysis of orthologs, paralogs, homeologs from Arabidopsis, Brassica reveal regulatory diversification. [ABSTRACT FROM AUTHOR]

One major problem with waste incineration is the corrosion of superheater tubes at high temperatures. The presence of sulfate and chloride in this setting poses a severe risk to the boiler's service life. In this work, pack aluminizing was used to prepare titanium aluminide coatings, which was then subjected to five distinct NaCl+Na 2 SO 4 salt combination proportions for 168 h at 600 °C. The outcomes demonstrated that in the presence of solid Na 2 SO 4 deposits, titanium aluminide coatings displayed remarkably low corrosion rates. Adding 1/6 NaCl significantly accelerated the rate of corrosion. The electrochemical corrosion resulting from eutectization between NaCl and Na 2 SO 4 was again considerably amplified when the NaCl level was raised to 1/4. • TiAl 3 coating showed good corrosion resistance properties. • With the diffusion of Al element, TiAl 2 appeared in the near-surface area. • The content of NaCl in the mixed salt greatly affected the corrosion rate. • The corrosion caused by the deposition of pure NaCl salt is the most severe. • The corrosion caused by a salt mixture of NaCl and Na 2 SO 4 at a 1:2 ratio is comparable to that of pure NaCl salt. [ABSTRACT FROM AUTHOR]

The interfacial transition zone (ITZ) between the aggregates and the matrix in concrete is the main reason for the low prediction accuracy of the effective diffusion coefficient of sulfate ions in concrete. To solve this problem, a new multi-scale prediction model of the effective diffusion coefficient for the transport of sulfate in concrete was established based on the Mori-Tanaka scheme, which fully reflects the characteristics of the imperfect ITZ, the morphological characteristics of the aggregates, the aggregate grading, and the time-varying characteristics of the content of the ITZ, the porosity and the tortuosity of the pore structure. The results showed that the prediction results of the model were basically consistent with the experimental and literature results, and the maximum error was only 20.43 %. In addition, taking the commonly used strength grades C30 and C50 concrete in engineering as examples, the changes in effective diffusion coefficient under different concentrations of sulfate erosion were predicted, showing a trend of first decreasing, plateauing, then increasing, and objectively reflecting the objective law of sulfate transport-reaction-filling-expansion damage in concrete. The predicted results confirmed that at the concentration of 3 % Na 2 SO 4 solution, the starting time of expansion for C50 concrete is approximately 3 years later than that for C30 concrete, verifying that enhancing the concrete's strength grade significantly improves its sulfate corrosion resistance. • A model for the effective diffusion coefficient of sulfate ions in concrete. • A model reflected the characteristics of the heterogeneous ITZ. • Multi-scale prediction of the effective diffusion coefficient. [ABSTRACT FROM AUTHOR]

The electronic property of a catalyst is crucial to the generation of key reaction intermediates for targeted synthesis. Herein, we reported a strategy by modifying iron catalysts with sulfate and alkali metal (Li, Na, or K) to regulate the electronic property and optimize the reaction pathways for CO 2 hydrogenation to higher alcohols. The characterizations demonstrated the influencing relationship between the electronic property of iron catalysts and the catalytic capabilities for CO dissociation, non-dissociated CO activation and catalytic hydrogenation, which were critical to selective synthesis of higher alcohols. Na-S modification was proven more effective to balance the multiple capabilities required for higher alcohols synthesis and the NaS-Fe catalyst gave a higher C 2+ OH yield in CO 2 hydrogenation. DFT calculations further validated the advantage of Na-S modification from the aspects of CO adsorption and C−C coupling. This strategy provides more flexibility in site regulation and applies to catalyst design for many reactions. [Display omitted] • The relationship between electronic property and catalytic capability was studied. • Alkali metal and sulfate act as dual-promoter to regulate the electronic property. • A balance between alkyl, *CO and *H species is required for alcohol formation. • Moderate electronic modification optimizes the generation of key intermediates. • Higher alcohols synthesis is favored on Na-S modified iron catalyst. [ABSTRACT FROM AUTHOR]

Chromium (Cr) soil contamination is a critical global environmental concern, with hexavalent chromium (Cr[VI]) being especially perilous due to its high mobility, bioavailability, and phytotoxicity. This poses a significant threat to the cultivation of crops, particularly rice, where the mechanisms of Cr(VI) absorption remain largely unexplored. This study uncovered a competitive interaction between Cr(VI) and essential nutrients—sulfate and phosphate during the uptake process. Notably, deficiencies in sulfate and phosphate were associated with a marked increase in Cr(VI) accumulation in rice, reaching up to 76.5 % and 77.7 %, respectively. Employing q-PCR, this study identified significant up-regulation of the sulfate transporter gene, OsSultr1;2 , and the phosphate transporter gene, OsPht1;1 , in response to Cr(VI) stress. Genetic knockout studies have confirmed the crucial role of OsSultr1;2 in Cr(VI) uptake, with its deletion leading to a 36.1 % to 69.6 % decrease in Cr uptake by rice roots. Similarly, the knockout of OsPht1;1 resulted in an 18.1 % to 25.7 % decrease in root Cr accumulation. These findings highlight the key role of the sulfate transporter OsSultr1;2 in Cr(VI) uptake, with phosphate transporters also contributing significantly to the process. These insights are valuable for developing rice varieties with reduced Cr(VI) accumulation, ensuring the safety of rice grain production. [Display omitted] • A notable competitive interaction between Cr(VI) and the uptake of sulfate and phosphate. • During Cr(VI) uptake in rice, the sulfate transporter OsSultr1;2 plays a key role. • Phosphate transporters OsPht1;1 are responsible for the absorption of Cr(VI) in rice. [ABSTRACT FROM AUTHOR]

Sulfate aerosol (SO 4 2−) is an important factor leading to acid rain and aggravating atmospheric particulate pollution. SO 4 2− is mainly converted from gaseous SO 2 , in which the oxidant gas NO 2 may play a key role. In real atmosphere with complexity and nonlinearity, the impact of NO 2 on SO 2 –SO 4 2- conversion exhibits scale dependence due to the combined effect of meteorology, atmospheric chemistry, and pollution emission. Here, based on the long-term atmospheric precipitation data from 2014 to 2021 of Nanchong City in the Sichuan Basin, the Extended Ensemble Empirical Mode Decomposition (EEMD) and Multifractal Detrended Cross-Correlation Analysis (MF-DCCA) methods have been employed to analyze the nonlinear correlations between gaseous SO 2 and SO 4 2− in rainwater at different time scales. A multifractal parameter Δ h has been described as the scaling features of SO 2 –SO 4 2- conversion efficiency in the real atmosphere. Then, the impact of NO 2 on SO 2 –SO 4 2- conversion in cold and warm seasons has been quantified, using sliding window analysis and Pearson correlation analysis. The results show that NO 2 significantly promoted SO 2 –SO 4 2- conversion in the cold season, but had little effect on it in the warm season. As direct evidence from atmospheric precipitation analysis, this finding has provided a new theoretical basis for evaluating the impact of NO 2 on secondary aerosol generation. [Display omitted] • Long-term precipitation data from the southwestern city of China are analyzed. • Decomposing data shows that SO 4 2− responded nonlinearly to changes of gaseous precursors. • Multifractal method is introduced as a tool for describing the effect of NO 2 on SO 2 –SO 4 2- conversion. • NO 2 promotes the conversion of SO 2 –SO 4 2- in cold season. • The precipitation component analysis reveals the key information of sulfate aerosol formation mechanism. [ABSTRACT FROM AUTHOR]

• Electron trapping centers in the range of 2.95–3.1 eV was studied by vacuum ultraviolet and thermal activation spectroscopy; • Sulfate anion and D y 3 + ( O 2 - → D y 3 + ) and the creation of a combined radiative state S O 4 3 - → S O 4 - , • During thermal or optical excitation process, D y 2 + and S O 4 3 - electronic centers are ionized. The formation of new radiative states from the combination of D y 2 + - S O 4 - and S O 4 3 - - S O 4 - electron trapping centers in the range of 2.95–3.1 eV has been investigated using VUV and thermal activation spectroscopy. During the excitation process, there is a charge transfer between the oxygen ion of the sulfate anion and D y 3 + leading to the formation of a combined emissive state S O 4 3 - → S O 4 -. These states can be formed from the electron-hole trapping centers of D y 2 + - S O 4 - and S O 4 3 - - S O 4 -. The combined radiative state at 2.95–3.1 eV and impurity emission at 2.16 eV and 2.56 eV are excited simultaneously by photons of 3.95 eV and 4.5 eV, respectively. During the thermal or optical excitation process, the D y 2 + and S O 4 3 - electronic centers are ionized. Electrons recombine with a hole trapped by the ground state of the impurity (S O 4 - - D y 3 +), and the released energy is transferred to the D y 3 + impurities. [ABSTRACT FROM AUTHOR]

Aromatic compounds persist as hazardous contaminants in both aquatic and terrestrial environments, needing rapid and effective remediation strategies. This study evaluated toluene and benzene biodegradation under sulfate and nitrate-reducing conditions in column experiments, utilizing aquifer sediments from a contaminated site. Over a period of 36 weeks, four glass columns were operated simultaneously in an alternating flow-batch regime. Each column received either nitrate or sulfate as an electron acceptor while being exposed to different substrate compositions in varied exposure orders. A redox dependent contaminant removal efficiency was observed, with toluene removal efficiency at 81% under sulfate and 55% under nitrate-reducing conditions, and benzene removal efficiency approximately at 44% and 59%, respectively, within 4–6 weeks. The rapid removal under anaerobic conditions was attributed to the alternating flow-batch regime, allowing biomass growth in batch mode, and applying selection pressure to non-specific biodegraders during flow regime. Toluene removal remained unaffected by benzene's presence but exhibited slight inhibition in the presence of an aromatic mixture composed of BTEX, indene, indane, and naphthalene. Benzene removal efficiency dropped to 8% in the presence of toluene but remained unaffected by the mixture. Pre-exposure to a single compound enhanced breakdown efficiency when further faced with a more complex mixture. Additionally, beta-diversity analysis conducted on the four columns revealed distinct microbial community clustering between sulfate and nitrate-reducing conditions, emphasizing the determining role of redox conditions. Findings of this study can be used to develop more effective pollution cleanup strategies, specifically targeting parameters like redox conditions, substrate interactions, and pollution history, thus improving our ability to mitigate contamination across diverse environments. [Display omitted] • Redox conditions impact microbial dynamics more than substrate and pollution history. • Toluene biodegraded better with sulfate; benzene with nitrate-reducing conditions. • Adaptation with single compound enhances subsequent biodegradation in mixtures. [ABSTRACT FROM AUTHOR]

In hydrothermal fluids, disulfur (S 2 •−) and trisulfur (S 3 •−) radical anions have been observed to coexist with the major hydrogen sulfide and sulfate species. These radical ions have potentially important effects on the solubility, transport and fractionation of metals and sulfur, with consequences for ore deposit formation and, more generally, for geochemical cycles of metals and volatiles. It is therefore essential to know the intrinsic isotopic properties of these important sulfur species in order to use sulfur isotopes for tracing different geological processes. Here, the theoretical equilibrium isotopic properties of the disulfur and trisulfur radical ions are computed and compared to the hydrogen sulfide (H 2 S) and sulfate ion (SO 4 2−), using, for the first time, a first-principles molecular dynamics (MD) approach. The isotopic properties are calculated directly from molecular dynamics trajectories using the vibrational density of states and the atomic kinetic energy, and then compared to the more established method based on sampling of several snapshots. This comparison allowed us to validate the new modelling method and to assess its advantages and limitations. The predicted equilibrium isotope fractionation in terms of 34S/32S between S 2 •− and S 3 •− is small, i.e. <1‰, with a slight enrichment in the heavier isotope for S 3 •−, over the temperature range 200–500 °C. Both radical ions are slightly depleted in the heavier isotope, by 1 to 2‰, relative to aqueous H 2 S. Our results help tuning sulfur isotope fractionation models used for tracing the origin and evolution of hydrothermal fluids. Our method opens large perspectives for using the rapidly growing body of MD simulation data in geosciences on structure and stability of aqueous complexes to assess in parallel element isotope fractionations from MD-generated trajectories. • S isotope fractionation among SO 4 2−, H 2 S, S 3 •− and S 2 •− in hydrothermal fluids. • Direct quantification of isotopic properties from molecular dynamics trajectories. • Assessing advantages and limitations of the novel molecular dynamics (MD) approach. • Perspectives opened by the MD method for predicting element isotope fractionations. [ABSTRACT FROM AUTHOR]

Triple-oxygen isotope (δ 18O and Δ ′ 17 O) analysis of sulfate is becoming a common tool to assess several biotic and abiotic sulfur-cycle processes, both today and in the geologic past. Multi-step sulfur redox reactions often involve intermediate sulfoxyanions such as sulfite, sulfoxylate, and thiosulfate, which may rapidly exchange oxygen atoms with surrounding water. Process-based reconstructions therefore require knowledge of equilibrium oxygen-isotope fractionation factors (18 α and 17 α) between water and each individual sulfoxyanion. Despite this importance, there currently exist only limited experimental 18 α data and no 17 α estimates due to the difficulty of isolating and analyzing short-lived intermediate species. To address this, we theoretically estimate 18 α and 17 α for a suite of sulfoxyanions—including several sulfate, sulfite, sulfoxylate, and thiosulfate species—using quantum computational chemistry. We determine fractionation factors for sulfoxyanion "water droplets" using the B3LYP/6-31G+(d,p) method; we additionally calculate higher-order method (CCSD/aug-cc-pVTZ and MP2/aug-cc-pVTZ) scaling factors, and we qualitatively estimate the importance of anharmonic zero-point energy (ZPE) corrections using a suite of gaseous sulfoxy compounds. Methodological scaling factors greatly impact 18 α predictions, whereas ZPE corrections are likely small (i.e., ⩽ 1 ‰) at Earth-surface temperatures; existing experimental data best agree with 18 α predictions when including redox state-specific CCSD/aug-cc-pVTZ scaling factors. Theoretical pH- and temperature-specific bulk-solution (i.e., abundance-weighted average of all species) 18 α values yield root-mean-square errors for sulfate/water, sulfite/water, and thiosulfate/water equilibrium of 4.5‰ (n = 18 experimental conditions), 3.7‰ (n = 27), and 2.2‰ (n = 3), respectively. However, sulfate- and sulfite-system agreement improves considerably when comparing experimental results only to SO 3 (OH)−/H 2 O (RMSE = 1.6‰) and SO 2 (OH)−/H 2 O (RMSE = 2.2‰) predictions, rather than bulk solutions. This is particularly true for the sulfite system at high and low pH, when SO 2 (OH)− is not the dominant species. We discuss potential experimental and theoretical biases that may lead to this apparent improvement. By combining 18 α and 17 α predictions, we additionally estimate that sulfate, sulfite, sulfoxylate, and thiosulfate species can exhibit Δ ′ 17 O values as much as 0.199‰, 0.205‰, 0.101‰, and 0.186‰ more negative than equilibrated water at Earth-surface temperatures (reference line slope = 0.5305). This theoretical framework provides a foundation to interpret experimental and observational triple-oxygen isotope results of several sulfur-cycle processes including pyrite oxidation, microbial metabolisms (e.g., sulfate reduction, thiosulfate disproportionation), and hydrothermal anhydrite precipitation. We highlight this with several examples. [ABSTRACT FROM AUTHOR]

Given the increasing interest that is being paid to polysaccharides derived from algae as plant natural defense stimulators, the degree of sulfation of exopolysaccharides produced by P. sordidum for inducing defense responses in date palm vitroplants was investigated. Firstly, the culture parameters of P. sordidum were optimized to maximize the amount of sulfate in EPS using a Box–Behnken experimental design and the elicitor effects of two EPS which differ in the sulfation degrees were compared. Results demonstrated that the concentrations of NaCl, NaNO 3 and MgSO 4 set at 28, 0.54 and 16.31 g/L, respectively yielded the best sulfate contents. To elucidate defense-inducing activities in date palm vitroplants, EPS with the highest sulfate content (EPS1) were prepared for comparison with those obtained under standard conditions (EPS0). A fucoidan extracted from Cystoseira compressa was used as positive control and MgSO 4 as negative control. Both EPS and the fucoidan displayed H 2 O 2 accumulation and expression of PR1, SOD, PAL and WRKY genes. Interestingly, EPS1 was significantly more bioactive than EPS0 and the fucoidan suggesting that the elicitor activity is positively correlated with the sulfate groups content of this polysaccharide. • Optimize the culture conditions of P. sordidum to maximize the sulfate content in EPS. • Comparison of the elicitor effect of two EPS which differ in the degree of sulfation on date palm vitroplants. • The elicitor activities is positively correlated with the degree of sulfation in EPS. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chlorine in MSWI fly ash is the main barrier to its recycling in cement kiln. • CO 2 injection during washing promoted decomposition of hardly soluble salts. • CO 2 -aided washing increased Cl removal rates by 6–9% than water washing. • CO 2 -aided washing could promote recycling of fly ash in cement kiln. Municipal solid waste incineration (MSWI) fly ash contains many harmful components that may limit its potential for recycling. An effective pretreatment is therefore required before any recycling can be implemented. In this study, the effects of four pretreatment methods (water washing, CO 2 -aided washing, CO 3 2–-aided washing, and CO 2 and CO 3 2–-aided washing) on the extraction behavior of chloride, sulfate, and heavy metals were evaluated. Water washing was found to be effective for the extraction of all easily and moderately soluble Cl-bearing salts, achieving Cl extraction ratios of 88%, 90%, and 96% for ash from Chongqing (CQ), Qingdao (QD), and Tianjin (TJ), respectively. Injection of CO 2 during washing facilitated decomposition of the hardly soluble Cl-bearing salts, increasing the Cl extraction efficiency by 6% for CQ ash and 9% for QD ash. However, for the TJ ash that contained few insoluble Cl-bearing minerals, CO 2 injection decreased the Cl extraction rate. The addition of CO 3 2– had a negative influence on Cl extraction for all ashes, but it slightly promoted sulfate extraction. Despite the high Cl removal rate, only 23–37% of the sulfate and 0.1–12% of heavy metals were removed. Overall, water-based pretreatment, especially CO 2 -aided washing, significantly altered the physical, chemical, and mineralogical characteristics of the fly ash, making it more suitable for recycling. Consequently, the blending ratio of the fly ash for cement clinker manufacture increased from 0.2 to 0.3% in the raw ash to 3.5–5.5% in the treated ash, enabling the extensive use of ash materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Accordion-like tubular carbon nitride was fabricated to immobilize atomically dispersed Co. • The resultant Co- at CN efficiently removed 4-chlorophenol via triggering peroxymonosulfate. • The Co- at CN/PMS system exhibited good tolerance to environmental interferences. • The decent performance was benefited from dominant roles of 1O 2 and SO 4 • − during the degradation. Carbon nitride (C 3 N 4) was fabricated as an accordion-like tubular morphology with hollow interior. The atomically dispersed Co sites were successfully confined within the accordion-like tubular C 3 N 4 (at CN) matrix and coordinated with N in the Co-N 4 configuration. The resulting Co- at CN catalysts were employed for peroxymonosulfate (PMS) activation towards 4-chlorophenol (4-CP) degradation. The optimal 2.9Co- at CN/PMS system took merely 10 min to completely degrade 4-CP (k = 0.426 min−1). While the accordion-like tubular C 3 N 4 with semi-hollow interior (at CN-sh) was applied, the 2.9Co- at CN-sh/PMS system took 60 min on eliminating barely 72.0 % of 4-CP (k = 0.020 min−1). Moreover, 2.9Co- at CN/PMS exhibited excellent activity on the removal of diverse contaminants, for example, methyl orange (MO), methylene blue (MB), 2,4,6-trichlorophenol (TCP), and acetaminophen (ACT). The 100 % removal efficiency reached within only 5, 45, 45, and 20 min, respectively. In addition, good resistance to environmental interferences was also unveiled in the 2.9Co- at CN/PMS system. Electron paramagnetic resonance (EPR) and quenching tests showed that •OH, SO 4 • −, O 2 • − and 1O 2 were produced in the reaction system of 2.9Co- at CN/PMS for 4-CP degradation, and the dominant oxygen species were determined to be not only conventional SO 4 • − but also favorable 1O 2 , and the latter contributed to the good resistance to environmental disturbances. [ABSTRACT FROM AUTHOR]

Developing potentiometric chemical sensors for sulfate determination is a rather challenging task due to a considerable hydrophilicity of this anion and its poor affinity to lipophilic plasticized polymeric membranes – one of the most popular sensor membrane materials nowadays. Not too many research works were devoted to this problem in the last years. Here we report on the successful development of several novel sulfate ionophores based on the synthetic modification of the commercially available sulfate ionophore I. The newly developed sensors outperform commercial analogue in terms of elelctrochemical sensitivity and selectivity. We have highlighted certain problems with numerical selectivity assessment in case when primary and interfering ions have different charges. The counterintuitive results yielded by conventional selectivity quantification methods implies the relevance of using alternative approach – visualizing sensor response curves towards primary ion in the presence of interfering ions. Novel sulfate sensors were applied for direct potentiometric measurements of sulfate content in river water samples demonstrating real applicability of the developed sensor membranes. • Novel ligands for potentiometric sensing of sulfate. • Unambiguous way for potentiometric selectivity assessment for ions with different charges. • Direct potentiometric determination of sulfate in surface waters. [ABSTRACT FROM AUTHOR]

The cycling of sulfur (S) to the upper crust and surface via thermal springs at convergent margins has not been explored outside areas with active arc volcanism, even though subduction plays a key role in the Earth's long-term S cycle. To address this knowledge gap, we analyzed stable sulfur and oxygen isotope compositions (δ34S and δ18O values) of dissolved sulfate (SO 4 2−) in 55 thermal springs from five distinct settings in the Andean orogen. These regions are the Peruvian flat slab and backarc, transition between these two, Argentinian backarc, and Chilean forearc. Although the flat-slab settings had lower SO 4 2− concentrations (<2000 mg/L) compared to the steep-slab settings (<12,700 mg/L), there was no significant relationship between isotope composition of SO 4 2− and slab geometry. The δ34S and δ18O values of SO 4 2− varied widely across the studied areas (+0.2 to +23.5 ‰ and − 3.3 to +16.0 ‰, respectively) and reflected the isotope compositions of local bedrock endmembers from dissolution of marine evaporites (+5 to +25 ‰ and + 10 to +20 ‰, respectively) and oxidation of magmatic and/or hydrothermal S and ore sulfide minerals with variable δ34S (0 to +16 ‰). The δ18O and δ2H values of thermal spring water (−18.5 to −3.3 ‰ and − 141.1 to −23.7 ‰, respectively) were consistent with meteoric precipitation, and in most cases decreased with increasing altitude following precipitation in the Andes. Generally, our isotope results do not support the direct transfer of slab-derived S/SO 4 2− to thermal springs in the investigated settings. Rather, the δ34S and δ18O of SO 4 2− in the thermal springs are a sensitive indicator of local water-rock interactions that remobilize bedrock S originating from a complex orogenic cycle reflecting tectonic uplift, erosion, weathering, and exhumation history across the duration of Andean Mountain building. • Sulfate in Cordilleran thermal springs record the entirety of the orogenic cycle. • δ34S of sulfate in Andean thermal springs mimics near-surface S sources. • δ18O of sulfate in Andean springs represents local meteoric water or marine sulfate. • Regardless of slab geometry, spring sulfate represents weathering of lithologic S. • Clear evidence of deep S transfer is not present in springs throughout the Andes. • Release of bedrock S in springs represents the final stage of the orogenic S cycle. [ABSTRACT FROM AUTHOR]

• Well-defined crystal contributed to the formation of Fe-O-Ce after sulfidation. • Redox capability of S-CP-Fe-Ce could be improved by sulfidation. • Generation of Brönsted acid sites enhanced the activation of NH 3 -adsorption. • NH 3 -SCR reaction over S-CP-Fe-Ce involved E-R and l -H mechanisms. Fe-Ce catalysts were prepared and then sulfated with SO 2 in the selective catalytic reduction of NO by NH 3. S-CP-Fe-Ce with precipitation method exhibited the highest activity, which is due to large specific surface area, the abundance of oxygen vacancies as well as the formation of Fe-O-Ce structure, thus contributing to the strong redox capacity. Furthermore, sulfates on S-CP-Fe-Ce facilitate the conversion of Lewis acid sites to Brönsted acid sites, and promote the transformation of low-active nitrates to highly active nitrates, which is crucial for enhancing its activity. Besides, NH 3 adsorbed over S-CP-Fe-Ce easily undergoes oxidation and dehydrogenation to form -NH 2 , which further reacts with gaseous NO, causing the superior catalytic performance. Additionally, NO was activated to form highly active monodentate nitrate and cis-N 2 O 2 2-, enabling the rapid reaction with NH 3 , leading to the outstanding the catalytic activity. The NH 3 -SCR reaction of S-CP-Fe-Ce simultaneously involves E-R and l -H mechanisms. [Display omitted] Fe-Ce catalysts modified by SO 2 were investigated in the selective catalytic reduction reaction. The formation of Fe-O-Ce structure, the excellent redox ability and the abundance of Brönsted acid sites could improve the adsorption of NH 3 , and promoted the formation of more highly active nitrate species, resulting in the improvement of catalytic activity in the NH 3 -SCR reaction. [ABSTRACT FROM AUTHOR]

Fe-rich cementitious phases, such as tetracalcium aluminate (C 4 AF), are likely the least characterized and understood components of ordinary cements, in terms of their reactivity and early-age reactions. In this study, we provided the first in-situ measurements of C 4 AF's absolute dissolution rates in water and aqueous sulfate solutions (Na 2 SO 4 , MgSO 4 and CaSO 4) along with its early-age hydration characterization. Upon contact with water, C 4 AF dissolved at a rate of 1.74 ± 0.23 μmol·m−2·s−1, and sulfates were found to inhibit its reaction. Among the three types of sulfates tested, CaSO 4 exhibited the strongest inhibition effect, while Na 2 SO 4 showed the weakest inhibition. Soon after the initial dissolution, the precipitation of hydrates occurred, and the presence of sulfates affected the overall hydration process of C 4 AF. These results enhance our understanding of C 4 AF's dissolution and early-age hydration behaviours, thereby advancing our knowledge of its hydration mechanisms. [ABSTRACT FROM AUTHOR]

Removal of selenate (SeO 4 2-) from selenate-contaminated wastewater is challenging due to the commonly co-existing and competing anions of sulfate (SO 4 2-) and nitrate (NO 3 -). This study investigates SeO 4 2− reduction to elemental selenium (Se0) in a cathode-based bioelectrochemical (BEC) reactor and a conventional biofilm reactor (i.e. , an upflow anaerobic reactor). The simulated wastewater contained SeO 4 2− at a typical concentration of 5 mg Se/L, SO 4 2− at a typical concentration of 1000 mg S/L, and NO 3 − at concentrations that varied from 0 to 10 mg N/L. The impact of sulfate on the BEC reactor was much lower than that on the conventional reactor: The selenium removal, defined as (selenate in influent – dissolved selenium in effluent)/selenate in influent, was 99 % in the BEC reactor versus 69 % in the conventional biofilm reactor. The lower selenium removal in the conventional reactor was mainly due to the >10 times higher reduction of sulfate, which directly caused competition between sulfate and selenate for the common resources such as electrons. The more reduction of sulfate in the conventional reactor further led to 45 times higher production of selenide. Selenide is usually assumed to be minimal and therefore not measured in the literature. This simplification may significantly overestimate selenium removal when the influent sulfate concentration is very high. NO 3 - in the influent of the BEC reactor promoted selenium removal when it was less than 5.0 mg N/L but inhibited selenate removal when it was more than 7.5 mg N/L. This was supported by the microbial community analysis and intermediate (nitrite) analysis. [Display omitted] • Impact of sulfate on selenate removal was minimal in BEC reactor. • Selenium removal was higher in the BEC reactor due to less selenide production. • The BEC reactor-treated wastewater could met EPA standard for selenium. • Selenide measurement was essential when sulfate-laden wastewater was treated. • Selenium removal efficiency in the BEC reactor decreased with higher nitrate concentrations due to resource competition. [ABSTRACT FROM AUTHOR]

Cloud chemistry is of paramount importance in the secondary production of atmospheric aerosols, influencing the spatial-temporal distribution of gases and aerosols in the atmosphere. Using WRF/CUACE (China Meteorological Administration Unified Atmospheric Chemistry Environment), this study assesses the seasonal impacts of cloud chemistry on the concentrations of SO 2 , sulfate, as well as two oxidizers, H 2 O 2 and O 3 , in the most east-central areas of China, including four key pollution zones (the North China Plain (NCP), the Yangtze River Delta (YRD), the Pearl River Delta (PRD), and the Sichuan Basin (SCB)). Near the surface, H 2 O 2 -oxidation was the dominant pathway for cloud chemistry in four key pollution zones in four seasons. H 2 O 2 consumption is most pronounced in summer, especially in the SCB and NCP, while O 3 consumption peaks in autumn, particularly in the PRD and southeastern coastal areas. While at higher altitudes, oxidation by O 3 and H 2 O 2 is compatible with the cloud chemistry process. Near the surface, cloud chemistry consumes SO 2 ranging from approximately 0.1 ppb–5.0 ppb, resulting in the generation of about 6.0–25.0 μg m−3 of sulfate. Higher SO 2 reduction and sulfate increase are in both summer and winter, especially for the SCB and NCP in summer, and the SCB in winter. Vertically, the cloud chemistry process primarily concentrates its influence on SO 2 and sulfate concentrations below 5 km, particularly within the turbulent zone of the troposphere below 2 km in all the four pollution zones and four seasons. The most notable seasonal variation occurs in the NCP compared to other zones. This study also shows that cloud chemistry effectively improves the seasonal simulation accuracy of SO 2 and sulfate, resulting in improved correlation and a notable reduction in RMSE. • With cloud chemistry, higher SO 2 reduction and higher sulfate increase in summer and winter. • At higher altitudes, the oxidation by O 3 and H 2 O 2 in cloud chemistry is compatible. • This study also shows that cloud chemistry effectively improves the simulation accuracy of SO 2 and sulfate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Original IS had lower denitrification and S cycle genes in IS than those of AS. • Biofilm inoculated by IS enriched more functional genes than by AS in SAD systems. • Biofilm domesticated by IS had more S cycle genes at high stress of S2- and SO 4 2- • Microbes for S cycle more sensitive to the toxicity of S2- than denitrifiers. To develop a reliable sulfide (S2-) autotrophic denitrification (SAD) process under S2- and SO 4 2- salinity stresses, the biofilm performance and microbial mechanisms were comparatively studied using different inocula of activated sludge (AS) and intertidal sediment (IS). Biofilm IS enriched more denitrification genes (0.34 %) and S2- oxidation genes (0.29 %) than those with AS. Higher denitrification performance was obtained under S2- (100 mg/L) and SO 4 2- (5–15 g/L Na 2 SO 4) stresses, but no significantly differences were observed under levels of 0–200 mg/L S2- and 30 g/L Na 2 SO 4. Notably, biofilm samples in SAD systems with IS still had more S2- oxidation genes at high S2- levels of 100–200 mg/L and Na 2 SO 4 level of 30 g/L. The key functional genus Thiobacillus accumulated well at 30 g/L Na 2 SO 4 , but was strongly inhibited at 200 mg/L S2-. The findings were advantage to SAD application under sulfide and salinity stresses. [ABSTRACT FROM AUTHOR]

The present study explores low-carbon steel corrosion in simulated concrete pore solutions with varying pH, focusing on the influence of chloride and/or sulfate ions. Employing electrochemical techniques, ToF-SIMS, XRD and DFT calculations, the results reveals that higher pH strengthens the passivation film and reduces corrosion by limiting corrosive ions adsorption. Notably, sulfate triggers corrosion at higher thresholds, while chloride alone significantly elevates corrosion rates. The presence of both ions shows mitigated corrosion risk due to competitive absorption onto steel interface of sulfate. The two-stage mechanism involving competitive adsorption and catalytic corrosion is initially proposed and elucidates the interaction mechanism of chloride and sulfate during steel corrosion process. • Mild steel corrosion subjected to chloride and sulfate in simulated concrete pore solutions with different pH was studied. • Electrochemical methods, ToF-SIMS, XRD and DFT were used to investigate corrosion behavior and underlying mechanism. • The two-stage mechanism involving competitive adsorption and catalytic corrosion is proposed to elucidate the mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • A closed-loop anion recovery process from phosphogypsum leachate was proposed. • 98.80 % of fluoride, 99.91 % of phosphate and 99.89 % of sulfate were recovered. • The effluent met the discharge standards in phosphate fertilizer industry. • Detailed insights during the recovery process have been discussed. Phosphogypsum (PG) is a large-scale industrial by-product generated during the production of phosphoric acid, typically being deposited in landfills worldwide. The leaching of fluoride (F−), phosphate (PO 4 3−), and sulfate (SO 4 2−) anions from PG into water bodies through rainfall results in significant environmental pollution. Herein, we propose a stepwise precipitation combined with electrodialysis and crystallization strategy for efficient recovery and valorization of multiple anions from PG leachate. Our method demonstrates effectiveness both theoretically and practically. Consequently, fluoride anions were precipitated as CaF 2 and Ca 5 (PO 4) 3 F at pH 4.7, with a recovery rate of 98.80 %; phosphate anions as MgNH 4 PO 4 ·H 2 O at pH 8.5, with a recovery rate of 99.91 %; and sulfate anions through electrodialysis and crystallization with a recovery efficiency of 99.89 %, ensuring effluent met discharge standards. In addition, the concentrated sulfate-rich solution was employed for electrochemical production of persulfate, yielding ammonium persulfate salts after cooling crystallization. Our integrated approach for multiple anion recovery from PG leachate offers significant environmental and economic benefits, providing valuable insights and references for future research and practical production. [ABSTRACT FROM AUTHOR]

Shortly after casting, offshore reinforced concrete structures are exposed to sulfate and chloride ions without undergoing any proper curing procedures, which are crucial for enhancing their strength and durability. Furthermore, there persists a lack of comprehensive understanding concerning the coupled impact of the attack of sulfate and chloride ions on cementitious materials with current existing research still yielding conflicting outcomes. This paper investigates the influence of curing on the chemical interactions between low-carbon cementitious materials (substituting 45 % of cement with industrial by-products like slag, fly ash, and metakaolin to reduce CO 2 emissions) and coupled sulfate and chloride ions. To achieve this, powder samples were obtained from prismatic-shaped specimens of ordinary Portland cement (CEM I) paste, binary, ternary, and quaternary blends. Some solid specimens were ground into powder after 24 hours post-casting while others were powdered after a 90-day curing period. Subsequently, the acquired powders underwent exposure to chloride, sulfate, and sulfate-chloride solutions over a duration of 25 days. Results indicate that curing time does not alter the interplay between sulfate and chloride ions in the cementitious matrix. Sulfate presence accelerates chloride ion ingress, while chloride presence mitigates sulfate attack in both uncured and pre-cured samples. However, the curing process accelerates sulfate attack, proven through excessive ettringite and gypsum formation, high consumption of portlandite and AFm, diminution of sulfate ions concentration in the attacking solution after 5 days of exposure, increase of pH of more than 0.5 units, aspect changes observed through visual inspections, and porosity distribution changes showed by an increase of 10 % of the total porosity in the reference mix. Additionally, curing promotes the formation of Friedel's salt, thereby attenuating chloride ions ingress. [Display omitted] • Chemical interactions of sulfate-chloride attack are highlighted. • The presence of sulfate accelerates the chloride ingress in the materials. • Chloride diffusion mitigates the sulfate attack in the materials. • Curing duration does not affect the sulfate-chloride coupling chemical process. • Raman spectroscopy serves as a quick chemical characterization technique on solutions. [ABSTRACT FROM AUTHOR]

• Preservation of aragonite in the geologic record is a key issue in sedimentology. • Moderate concentrations of sulfate inhibit the transformation of aragonite to calcite. • The interaction of aragonite with sulfate minerals also blocks transformation. • Sulphate has a similar effect to Mg in the preservation of aragonitic fragments. Aragonite (CaCO 3) is a stable calcium carbonate phase under high pressure conditions. However, its formation in (sub)surface environments, where calcite is the stable polymorph, is widespread. Regardless of its origin, aragonite is expected to undergo transformation into calcite under moderate pressures and temperatures. However, this transformation does not always take place, which results in the presence of abundant aragonitic relics in the geological record. Traditionally, this preservation has been explained by the presence of chemical inhibitors that prevent the conversion of aragonite to calcite. While it is widely accepted that magnesium (Mg) plays a key role in the polymorphic selection of CaCO 3 , the influence of other ions has also been suggested. This work evaluates the effect that different concentrations of sulfate (SO 4 2−) in the fluid has on the progress of the aragonite-to-calcite transformation at 220 °C. Our results show that, upon reaction with deionized water or sulfate-poor solutions ([SO 4 2−] aq < 0.1 mM), aragonite single crystals are extensively replaced by calcite aggregates (crystal size > 15 µm) through an interface coupled dissolution-precipitation reaction. The replacement starts at the aragonite crystal surfaces and advances inwards thanks to the development of an extensive network of fractures. Contrarily, when the solution bears higher concentrations of sulfate ([SO 4 2−] aq > 0.1 mM), only a thin layer of smaller crystals of calcite (< 10 µm) form on the aragonite substrates, without any further transformation taking place. We interpret that these smaller crystals exert too little crystallization pressure and fail to promote the development of a network of fractures. In the absence of this network, the aragonite-calcite transformation cannot take place. The transformation does not occur neither when the experiments are conducted with deionized water and fragments of gypsum or anhydrite together with the aragonite grains. The results of this study shed light on the influence of dissolved sulfate in the kinetics of the fluid-driven transformation of aragonite into calcite. These results are useful to understand the preservation of aragonite in a variety of current geological settings and provide valuable insights for better understanding the diagenesis of sedimentary carbonates. [Display omitted] [ABSTRACT FROM AUTHOR]

Mineral scale refers to the hard inorganic solids nucleated on substrates or deposited from the aqueous phase. The formation and deposition of barium sulfate and strontium sulfate in various industries, such as water treatment and oilfield operations, can significantly impact facility operations, posing serious threats. Machine learning (ML) approaches have been adopted recently in scale threat predictions to address the limitations of conventional scaling prediction models. However, there are few reports on collecting sulfate mineral scaling data, employing ML methods for data analysis, and evaluating the modeling results to gain deeper insights of sulfate mineral scaling process and to improve the accuracy of sulfate scaling threat prediction. Despite comprehensive experimental studies, the literature does not provide adequate guidance for identifying the influence on the solubility of barium sulfate and strontium sulfate under different aqueous environments and actual operating conditions. To this end, this study collected 1600 experimental datasets of barium/strontium sulfate from the literature to construct and evaluate the reliability and versatility of a ML-based model for sulfate solubility calculations. Single neural networks, hybrid neural networks, and optimization algorithms were employed to build solubility prediction models for barium sulfate and strontium sulfate across a wide range of temperatures, pressures, and different ions. The model's applicability in predicting sulfate scaling threats in various actual operating environments demonstrated its broad usability, consistent with its actual performance. This study marks the first stride towards constructing a reliable model for identifying the scaling trends of barium sulfate and strontium sulfate across various operating conditions, underscoring the importance of developing robust and accurate prediction models to address challenges in various industrial systems. [Display omitted] • Utilize multiple hybrid neural networks to establish sulfate solubility model. • Employ novel optimization algorithms to enhance model performance. • MLP-POA model exhibits the highest accuracy in prediction capabilities. • Impurity ion concentrations have the most significant impact on sulfate solubility. • This model can predict sulfate scaling threats in various operating environments. [ABSTRACT FROM AUTHOR]

Adding an appropriate amount of chloride or sulfate salts to molten nitrates is an effective way to improve the thermal stability temperature and energy density of solar salts. However, the corrosivity of the mixed solar salts is enhanced significantly. In this paper, the effect of chlorides and sulfates on the corrosion of SS347 and GH3539 in molten solar salt is investigated. The high oxygen pressure and basic environment in molten nitrates causes the formation of an external Fe oxides layer and inner FeCr 2 O 4 layer for SS347. Unlike SS347, the corroded GH3539 presents an exclusive film of NiO and many core-shell structured nodules with Ni as core and NiO as shell, followed by a region of internal oxidation involving Ni, W and Cr. The additives chlorides produce an oxidation-chlorination environment, causing spallation of oxide scale from SS347, but without significant effect on GH3539 due to lower thermodynamic stabilities of Ni and W chlorides than Fe and Cr chlorides. The addition of sulfates to solar salt also harms the adhesion of the scale on SS347 to a certain extent. While the additives sulfides accelerate the corrosion of GH3539, forming a thick porous NiO layer and a serious internal sulfidation zone. • The corrosion of SS347 and GH3539 at 600 ℃ in molten solar salt without and with chlorides and sulfates is studied. • The high oxygen partial pressure and the highly basic property are the main reasons for high corrosivity of molten nitrates. • The addition ofchlorides to solar salt produces an oxidation-chlorination environment, causing separation and spallation of the oxide scale from SS347. • Apart from the outer NiO layer, a region of internal oxidation involving Ni, W and Cr are also formed for GH3539. • The additives sulfates accelerate greatly the corrosion of GH3539, but without significant effect on SS347. [ABSTRACT FROM AUTHOR]

• Thin beds of barite crystal fans occur in the basal Ediacaran, East Finnmark, Norway; • Barite formed in a shallow marine to subaerial, freshwater-dominated setting; • Barite's Δ17O and δ18O values are among the lowest in all palaeocontinents; • Barite in cracks and fissures is post-depositional. Basal Ediacaran barite, which has mass-anomalous depleted 17O, supporting Snowball Earth models, likely grew in shallow-marine settings, but sedimentological constraints lack details. Environmental conditions in the Varanger Palaeovalley during the basal Ediacaran are well preserved in the Nyborg Formation, where barite forms < 15 mm high syn syn-sedimentary crystal fans on Archean basement or thin intervening sediments. Sedimentary evidence suggests crystal fans formed in low-energy, very shallow-marine to subaerial facies. Rare earth element and yttrium signatures in associated carbonates suggest non-saline growth environments. Post-depositional fluid-flow replaced crystal fan barite with silica (now quartz) and redeposited barite as: <1 × 0.2 mm "dispersed" grains in sediments below fans; <5 mm grains replacing calcite filling desiccation cracks; <1 mm grains in basement fissures; <3 µm grains replacing matrix calcite; irregular grains in detrital sheet-silicate + calcite grains. Caledonian dissolution-reprecipitation reworked barite into brittle fractures and stylolites. Barite Δ17O values are amongst the most negative (-0.9 – -1.25 ‰) and δ18O values the lowest recorded (9.9 – 16.9 ‰) anywhere, consistent with a high latitude Baltica at ∼ 635 Ma. δ34S values (17.7 – 24.5 ‰) lie within the known range for basal Ediacaran barite. [ABSTRACT FROM AUTHOR]

Long-term exposure to fine particulate matter (PM 2.5) is associated with an increased total mortality. However, the association of PM 2.5 with mortality in people living with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS, PLWHA) and the relationship between its constituents and adverse outcomes remain unknown. In this cohort study, 28,140 PLWHA were recruited from the HIV/AIDS Comprehensive Response Information Management System of the Hubei Provincial Centre for Disease Control and Prevention in China between 2001 and 2020. The annual PM 2.5 chemical composition data, including sulfate (SO 4 2−), nitrate (NO 3 −), ammonium (NH 4 +), black carbon (BC), and organic matter (OM), was extracted from the Tracking Air Pollution (TAP) dataset in China. A Cox proportional hazard model with time-varying exposure and time-to-event quantile-based generalized (g) computation was used to assess the associations between PM 2.5 chemical constituents, and mortality in PLWHA. A multivariate Cox proportional hazard model estimated an excess hazard ratio (eHR) of 0.32% [95% confidence interval (CI): (0.01%, 0.64%)] for AIDS-related death (ARD), associated with 1 μg/m3 rise in PM 2.5 exposure. An increase of 1 μg/m3 in NH 4 + was associated with 5.13% [95% CI: (2.89%, 7.43%)] and 2.97% [95% CI: (1.52%, 4.44%)] increase in the risk of ARD and all-cause deaths (ACD), respectively. When estimated using survival-based quantile g-computation, the eHR for ARD with a joint change in a decile increase in all five components was 6.10% [95% CI: 3.77%, 8.48%)]. Long-term exposure to PM 2.5 chemical composition, particularly NH 4 + increased the risk of death in PLWHA. This study provides epidemiological evidence that SO 4 2− and NH 4 + increased the risk of ARD and that NH 4 + increased the risk of ACD in PLWHA. Multi-constituent analyses further suggested that NH 4 + may be a key component in increasing the risk of premature death in patients with HIV/AIDS. Individuals aged ≥65 with HIV/AIDS are more vulnerable to SO 4 2−, and consequent ACD. [Display omitted] • People living with HIV/AIDS (PLWHA) aged 65 and older are more vulnerable to SO 4 2−. • Long-term exposure to SO 4 2− and NH 4 + increased AIDS-related deaths in PLWHA. • NH 4 + may be the most critical component in the increased mortality among PLWHA. [ABSTRACT FROM AUTHOR]

The substantial amount of pollutants produced by crop burning leads to particulate matter (PM 2.5) formation through chemical reactions in the atmosphere. In this study, we quantitatively examined the characteristics of PM 2.5 component concentration changes and the production mechanism of sulfate (SO 4 2−) due to crop burning in China, during a period of high PM 2.5 concentrations in South Korea. Crop burning emissions were obtained from the Fire INventory from NCAR (FINN), and simulations were conducted using the Community Multi-scale Air Quality (CMAQ) model. The concentrations of PM 2.5 , nitrate, ammonium, organic carbon, and elemental carbon caused by crop burning were the highest in Northeast China, while the SO 4 2− concentration was higher in the Shandong Peninsula and the Yellow Sea. SO 4 2− was mainly produced through the oxidation reaction by hydrogen peroxide (H 2 O 2) (H 2 O 2 + S(IV) = S(VI) + H 2 O) (1.44 μg/m3, 80.49%). H 2 O 2 that contributed to SO 4 2− production was primarily produced through the self-reaction of hydroperoxy radical (HO 2). Moreover, HO 2 , which contributed to the production of H 2 O 2 , was mainly formed through the decomposition of peroxynitric acid (PNA), which is produced by nitric oxide (NO x) emissions from crop burning. SO 4 2− in the Yellow Sea was reported to be predominantly produced by the oxidation of sulfur dioxide (SO 2) by hydroxyl radical (OH) (OH + SO 2 = SULF + HO 2); however, our study suggests that the PNA formed by NO x emissions from crop burning could contribute to an increase in H 2 O 2 , which subsequently promotes SO 4 2− production. The produced SO 4 2− was then transported across the Yellow Sea, impacting the elevated PM 2.5 concentrations in Jeju Island, a suburban area of South Korea. These findings demonstrate that the mechanisms of SO 4 2− production by crop burning emissions differ from those of anthropogenic emissions. [Display omitted] • Characteristics of transboundary transport of SO 4 2− concentrations induced by crop burning were investigated. • The SO 4 2− due to crop burning was primarily produced by the reaction of H 2 O 2 with S(IV), differing from that by anthropogenic emissions. • The H 2 O 2 was produced through the self-reaction of HO 2 , which was formed by the decomposition reaction of PNA. • The transported SO 4 2− contributed to an increase in the proportion of SO 4 2− in the PM 2.5 concentrations in South Korea. [ABSTRACT FROM AUTHOR]

Sulphate and aluminium play important roles in cement paste chemistry. They are closely linked through AFm, ettringite, and C-A-S-H. This study quantifies the distributions of sulphate and aluminium in cement pastes with limestone, fly ash, and a volcanic pozzolan, cured for 180 days at 20, 38, and 60 °C. Elevated temperatures convert carbonate AFm and ettringite to sulphate AFm and calcite. Only minor amounts of sulphate and aluminium are in the pore solution. SCMs increases the total aluminium content of the paste but do not increase greatly the amounts of aluminium present in AFm and ettringite. Instead, the additional aluminium is mainly incorporated in the C-A-S-H. C-A-S-H incorporates 25–55 % of sulphate and 20–40 % of aluminium in hydrated cement pastes. This is a significant portion that must be accounted for in thermodynamic models and mass balances. [ABSTRACT FROM AUTHOR]

Anthropogenic sulfate loading into otherwise low-sulfate freshwater systems can cause significant ecological consequences as a biogeochemical stressor. To address this challenge, in situ bioremediation technologies have been developed to leverage naturally occurring microorganisms that transform sulfate into sulfide rather than implementing resource-intensive physio-chemical processes. However, bioremediation technologies often require the supply of electron donors to facilitate biological sulfate reduction. Bioelectrochemical systems (BES) can be an alternative approach for supplying molecular hydrogen as an electron donor for sulfate-reducing bacteria through water electrolysis. Although the fundamental mechanisms behind BESs have been studied, limited research has evaluated the design and operational parameters of treatment systems when developing BESs on a scale relevant to environmental systems. This study aimed to develop an application-based mathematical model to evaluate the performance of BESs across a range of reactor configurations and operational modes. The model was based on sulfate transformation by hydrogenotrophic sulfate-reducing bacteria coupled with the recovery of solid iron sulfide species formed by the oxidative dissolution of dissolved ferrous iron from a stainless steel anode. Sulfate removal closely corresponded to the rate of electrolytic hydrogen production and hydraulic residence time but was less sensitive to specific microbial rate constants. The mathematical model results were compared to experimental data from a pilot-scale BES tested with nonacidic mine drainage as a case study. The close agreement between the mathematical model and the pilot-scale BES experiment highlights the efficacy of using a mathematical model as a tool to develop a conceptual design of a scaled-up treatment system. [Display omitted] • Low electrical potential promoted desired biogeochemical reactions to treat sulfate pollution. • Sulfate removal in the BES corresponded closely to the rate of electrolytic hydrogen production. • Sulfate removal in the BES was less sensitive to biokinetics of sulfate reducers. • The model validated with experimental data is a useful tool to develop a scale-up BES system. [ABSTRACT FROM AUTHOR]

β-Cyclodextrin (β-CD), a macrocyclic oligosaccharide cavitand, is a well-known candidate for drug delivery and formulation. In this study, we extended the application of β-CD using a β-cyclodextrin sulfate (β-CDS) as a possible therapeutic for fibrotic diseases caused by excess deposition of collagen fibrils. We have strategically chosen β-CDS, which mimics the natural existence of dermatan sulfate in the extracellular matrix, for limiting collagen fibrillation. The hydrophobic nature of the inner core β-CDS is expected to form an inclusion complex with hydrophobic side chain amino acids with the simultaneous action of forming an ionic bond through a negative charge on sulfate group with positively charged amino acids side chain in collagen. Various results suggested that such dual action not only limited the collagen fibrillation but also reduced the fibril size formed in the presence of β-CDS. The contemporary results thus indicate that β-CDS can be explored as a therapeutic molecule in fibrotic diseases. [Display omitted] [ABSTRACT FROM AUTHOR]

Rare Earth elements (REE) are gaining importance due to their increasing industrial applications and usefulness as petrogenetic indicators. REE-sulfate complexes are some of the most stable REE aqueous species in hydrothermal fluids, and may be responsible for REE transport and deposition in a wide variety of geological environments, ranging from sedimentary basins to magmatic hydrothermal settings. However, the thermodynamic properties of most REE-sulfate complexes are derived from extrapolation of ambient temperature data, since direct information on REE-sulfate complexing under hydrothermal conditions is only available for Nd, Sm and Er to 250 °C (Migdisov and William-Jones, 2008, 2016). We employed ab initio molecular dynamics (MD) simulations to calculate the speciation and thermodynamic properties of yttrium(III) in sulfate and sulfate-chloride solutions at temperatures and pressures up to 500 °C and 800 bar. The MD results were complemented by in situ X-Ray Absorption Spectroscopy (XAS) measurements. Both MD and XAS show that yttrium(III) sulfate complexes form and become increasingly stable with increasing temperature (≥200 °C). The MD results also suggest that mixed yttrium-sulfate-chloride complexes (that cannot be distinguished from mixtures of chloride and sulfate complexes in XAS experiments) form at ≥ 350 °C. Two structures with two different Y(III)-S distances (monodentate and bidentate) are observed for Y(III)-sulfate bonding. The formation constants, derived via thermodynamic integration, for the Y(III) mono- and di-sulfate complexes parallel the trends for those of Nd, Sm and Er determined experimentally to 250 °C. The derived formation constants were used to fit revised Helgeson-Kirkham-Flowers equation-of-state parameters that enabled calculation of formation constants for Y(SO 4)+ and Y(SO 4) 2 − over a wide range of temperatures and pressures. The presence of sulfate increases the solubility of Y(III) under specific conditions. Since the stability of sulfate is redox sensitive, Y(III) solubility becomes highly redox-sensitive, with rapid precipitation of Y minerals upon destabilisation of aqueous sulfate. [ABSTRACT FROM AUTHOR]