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This study examined the associations of long-term exposure to ambient fine particulate matter (PM2.5) compositions/ozone with methylation of peripheral brain-derived neurotrophic factor (BDNF) promoters. A total of 101 participants were recruited from a cohort in Shijiazhuang, Hebei province, China. They underwent baseline and follow-up surveys in 2011 and 2015. DNA methylation levels were detected by bisulfite-PCR amplification and pyrosequencing. Participants' three-year average levels of PM2.5 compositions and ozone were estimated. Bayesian kernel machine regression (BKMR) models were used to examine the joint effects of pollutants on methylation levels. Exposure to PM2.5 compositions and ozone mixtures at the 75th percentile was associated with increased methylation levels at CpG2 of BDNF promoter (203%, 95% CI: 89, 316) than the lowest level of exposure, and sulfate dominated the effect in the BKMR models.Our findings provide clues to the epigenetic mechanisms for the associations of PM2.5 compositions and ozone with BDNF. [ABSTRACT FROM AUTHOR]

Based on environmental characteristics of reinforced concrete infrastructure in western China, cement mortar specimens were subjected to semi-immersed sulfate corrosion in low humidity and varying temperature. The influences of low humidity and varying temperature on semi-immersion sulfate attack cement-based materials were studied by combination of XRD, SEM, LF-NMR, and conductivity titration of sulfate ions. The results show that under low humidity and varying temperature, the mortar subjected to semi-immersion sulfate attack has a water film zone within 30 mm above the surface of sulfate solution, and the corrosion degree is relatively low. The evaporation zone above the solution surface of 30 ~ 60 mm has a higher degree of corrosion and obvious peeling phenomenon. Corrosion of evaporation zone of mortar semi-immersed in Na2SO4 solution is more seriously than that semi-immersed in MgSO4 solution due to their difference in saturation under different temperatures. The expansive salt crystallization within pores above 1 000 nm is prone to the occurrence in evaporation zone, which leads to the micro cracks inside mortar and an increase in the proportion of harmful pores, resulting in physical expansion damage being the main cause of this zone. Chemical corrosion in the immersion zone of mortar is dominant due to the formation of swelling corrosion products such as gypsum and ettringite. As corrosion products accumulated in the pores with pore sizes of 50 ~ 1 000 nm, the surface of mortar cracks and the proportion of macroscopic pores with pore sizes above 1 000 nm increases. The addition of ground granulated blast furnace slag in cement increases the sulfate corrosion resistance of the immersion zone of mortar via its secondary hydration effect, and the addition of limestone powder decreases the sulfate corrosion resistance of mortar due to its dilution effect. [ABSTRACT FROM AUTHOR]

Through microscopic analyses (e.g., organic macerals, thin section observation, scanning electron microscope (SEM) imaging of fresh bedding planes via argon ion milling, and energy spectrum tests) combined with Rock-Eval analyses, this study systematically investigated the organic matter and pyrites in the continental shales in the 3rd submember of the Chang 7 Member (Chang 7³ submember) in the Yanchang Formation, Ordos Basin and determined their types and the formation and evolutionary characteristics. The results are as follows. The organic matter of the continental shales in the Chang 7³ submember is dominated by amorphous bituminites and migrabitumens, which have come into being since the early diagenetic stage and middle diagenetic stage A, respectively. The formation and transformation of organic matter is a prerequisite for the formation of pyrites. The Ordos Basin was a continental freshwater lacustrine basin and lacked sulphates in waters during the deposition of the Chang 7 Member. Therefore, the syndiagenetic stage did not witness the formation of large quantities of pyrites. Since the basin entered early diagenetic stage A, large quantities of sulfur ions were released as the primary organic matter got converted into bituminites and, accordingly, pyrites started to form. However, this stage featured poorer fluid and spatial conditions compared with the syndepositional stage due to withdraw of water, the partial formation of bituminites, and a certain degree of compaction. As a result, large quantities of pyrrhotite failed to transition into typical spherical framboidal pyrites but grew into euhedral monocrystal aggregates. In addition, pyrites are still visible in the migrabitumens in both microfractures and inorganic pores of mudstones and shales, indicating that the pyrite formation period can extend until the middle diagenetic stage A. [ABSTRACT FROM AUTHOR]

• Stable isotopes of riverine sulfate in arid environment were investigated. • Contributions of riverine sulfate sources were identified by an inverse model. • Evaporites dissolution dominates riverine sulfate source with spatial variations. • Lithology, precipitation and temperature dominate sulfur behaviors in river basins. The fate of riverine sulfate ion (SO 4 2-) and its environmental effects in arid environment are difficult to evaluate due to its complicated sources and strongly coupled behaviors with water cycle which is significantly modified by humans. To understand the sulfur cycle in aquatic systems in arid environment, the chemical and sulfur and oxygen isotopic compositions (δ34S SO4 and δ18O SO4) of major rivers around the Badain Jaran Desert, northwestern China, were investigated. These rivers had averaged SO 4 2- content at 1336 µmol/L, over 10 times higher than the global average. The δ34S SO4 and δ18O SO4 values ranged from -5.3‰ to +11.8‰ and +1.6‰ to +12.8‰, respectively. The end-member analysis and the inverse model showed that riverine sulfate was mainly derived from evaporites dissolution (0-87%), sulfide oxidation (13%-100%) and precipitation (0-33%), indicating heterogeneity in sulfur sources and behaviors along the river drainage with the lithology variations and climate gradients. Multiple isotopic tools combining with hydro-chemistry compositions could be applied to reveal sulfur cycle in arid environment. Based on the calculation, sulfide oxidation plays the primary role in the headwater and upstream in the Qilian-Mountains area, where sulfide is widely exposed. While the proportion of evaporites dissolution contributing to riverine sulfate is much higher in downstream in a drier environment. Besides, less precipitation and higher temperature can lead to more intensive evaporation, affecting the process of sulfide oxidation and enhancing the rates of evaporites dissolution and sulfate precipitation in the basin. [Display omitted] [ABSTRACT FROM AUTHOR]

To explore the deformation behavior and failure strength of sulfate saline silty clay at a temperature of -10℃ and confining pressures of 6~10 MPa, we have performed low-temperature triaxial shear tests on sulfate saline silty clay in Hexi region of Gansu province, China. The variation trend of deviatoric stress, volumetric strain and initial deformation modulus with confining pressure were analyzed. The results demonstrated that the stress-strain curve of frozen sulfate saline silty clay was hyperbolic and the deviatoric stress increased as the axial strain increased and was eventually constant. Owing to particle breakage and melting of ice, when the confining pressure, σ3>6 the strength decreased as the confining pressure increased and the sample exhibited volumetric shrinkage throughout the entire confining-pressure range. A constitutive model of frozen sulfate saline silty clay under high confining pressure has been proposed in combination with the Duncan Chang model and the validity of the model has been confirmed by comparison with test data. [ABSTRACT FROM AUTHOR]

The sulfur biogeochemical cycle controls the sulfur dynamics in the soil. In contrast to almost all deposited sulfur leaching out in temperate catchments, approximately 80% of the deposited S is retained in the catchments in subtropical regions. However, the mechanisms for sulfur retention were unclear, hindering the understanding of potential threats of legacy sulfur with environmental changes. Here, we demonstrated that sulfate reduction (as sulfide fixed in soil) was a prominent yet overlooked mechanism for sulfur retention in addition to the widely recognized sulfate adsorption in soil, based on a study on soil sulfur storage and stable isotope signatures within entire soil profiles in a typical subtropical catchment in China. Using a dual‐isotopic model, the sulfate reduction flux was further determined to be 30% of the S deposition. Due to a lot of deposited sulfur fixed via sulfate reduction, the release of soil legacy sulfur would be less in response to decreasing sulfur deposition compared to the projections only considering adsorption. However, the remobilization of large amounts of reduced S should be regarded as a threat to the environment under climate change in the future. Plain Language Summary: Sulfur budget in catchments reveals substantial retention of around 80% of deposited sulfur in subtropical soils, mitigating acidification arising from heightened sulfur deposition. The substantial sulfur retention was previously ascribed to sulfate adsorption. However, our study unveils sulfate reduction as a prominent yet overlooked retention mechanism, evidenced by soil sulfur storage estimates and stable isotope signatures across complete soil profiles in a typical subtropical Chinese catchment. Sulfate adsorption displays reversibility with declining atmospheric deposition. However, sulfate reduction exhibits relatively stable except during periods of frequent drought attributed to climate change or the soil excavation induced by land‐use change. Key Points: A dual isotopic mass balance model was built to quantify the transformations of S in the ecosystemsSulfur retention accounted for approximately 80% of deposition based on the sulfur input–output budgets for 17 sites in subtropical ChinaSulfate reduction was a prominent mechanism for sulfur retention in addition to widely recognized sulfate adsorption [ABSTRACT FROM AUTHOR]

In Shanxi Province, China, concrete foundations of substations are widely exposed to environments with sulfate erosion, which results in severe damage. There are various avenues to enhance sulfate resistance, and one promising approach involves optimizing high-performance water reducers. Chain extender, which is an integral component of a water reducer, serves as a pore-blocking agent to effectively counter sulfate erosion. This study delves into the impact of a chain extender in the water reducer on the sulfate resistance and adaptability of ordinary concrete. The assessment begins with gauging the sensitivity of concrete to sulfate erosion, utilizing a 0–1 scoring method. Comparable conditions are maintained, allowing for a direct comparison between concrete with and without chain extender based on predefined criteria. A score of 1 denotes superior performance, while a score of 0 indicates a poorer performance. Following the evaluation of each criterion, scores are aggregated by the water reducer type, with higher scores signaling superior adaptability. The findings highlight that chain extender enhances the internal porosity of concrete, resulting in a more compact microstructure, heightened impermeability, and improved resistance to sulfate erosion. Its influence on mixture performance, however, is marginal. From an erosion product standpoint, using the semi-immersion method, chemical erosion predominates in the immersion zone, while both chemical and physical erosion are observed in the alternate wet–dry zone. Employing a 0–1 scoring method, Water Reducer 3 (with chain extender) scores 20 points, whereas Water Reducer 3#–1 (without chain extender) scores 4 points. Taking into consideration all factors, the chain extender demonstrates excellent adaptability to ordinary concrete. To validate the effectiveness of the 0–1 scoring method, it is applied to assess fly ash and slag double-blended concrete. Water Reducer 3 (with chain extender) scores 13 points, while Water Reducer 3–1 (without chain extender) scores 10 points. Taking all aspects into consideration, the chain extender component exhibits commendable adaptability to fly ash and slag double-blended concrete. [ABSTRACT FROM AUTHOR]

Fine-particle pollution associated with high sulfate and secondary organic aerosol (SOA) contents still occurs in winter, despite considerable reductions in precursor emissions in China. The chemical mechanisms involved are consistently acknowledged to be linked with aerosol water but remain poorly understood. Here, we present findings demonstrating that the synergistic effect of elevated aerosol water content and particles originating from fossil fuel combustion significantly enhanced the rapid formation of sulfate and SOAs under high humidity conditions during winter in northern China. The presence of high aerosol water content promoted the aging process of particles containing elemental carbon (EC) and facilitated the formation of SOAs. Evidence from single particles reveals an increased potential for SOA formation from primary organic aerosols (POAs) originating from fossil fuel combustion, in the presence of increasing aerosol water. Under conditions of relative humidity exceeding 85%, the multiphase oxidation of SO2 by in-particle nitrite/nitrous acid, generated through reactions involving aged EC-containing and iron-rich particles, as well as aqueous-phase formation of hydroxymethanesulfonate (HMS), led to a substantial increase in sulfate production. This study emphasizes the critical role of aerosol water in the aerosol chemistry concerning sulfate and SOAs, highlighting the urgent necessity to mitigate primary emissions from fossil fuel combustion. [ABSTRACT FROM AUTHOR]

Sulphate (SO42−) is a main component of PM2.5 in China. The chemical formation mechanisms of sulphate are complex, and many air quality models have been used to analyse these mechanisms. To improve the accuracy of Weather Research Forecast-Chemistry (WRF-Chem) on sulphate, an alternative method is proposed in this paper. Moreover, data assimilation is performed to adjust the chemical reaction rates of sulphate. Based on the original reactions, a new sulphate parameterisation scheme, which includes two hypothetical reactions and six undetermined parameters, was added. Based on the WRF-Chem/DART (Data Assistance Research Testbed) system, the near-ground concentrations of SO42−, SO2, NO2, O3 and particulate matter are assimilated to adjust the six parameters. After adjusting the parameters, the new scheme can effectively solve the underestimation of SO42− and overestimation of SO2. The simulation of SO42− improved as the mean bias changed from −13.1 µg m−3 to 3.5 µg m−3 while SO2 improved from 17.0 µg m−3 to 6.3 µg m−3. The temporal and spatial variation characteristics predicted by the new scheme are consistent with the theoretical research results, indicating that the complex mechanism of sulphate formation could be replaced by the temporal and spatial variation characteristics predicted by the new scheme and that the parameters can be adjusted by data assimilation. Furthermore, the reaction rates of the SO42− parameterisation scheme of the WRF-Chem model are improved in this study, and a new method for improving the accuracy of the air quality model is provided. [ABSTRACT FROM AUTHOR]

Supergene hydrous sulfate minerals form through the oxygenation and weathering of primary sulfides. In the Qinghai–Tibet Plateau region, with an alpine and dry environment, hydrous sulfate minerals oxidized from pyrite-bearing ore bodies provide important clues regarding the mineralization and environment. The Tuolugou sedimentary-exhalative (SEDEX) Co-Au deposit is located in the East Kunlun metallogenic belt of the northern Qinghai–Tibet Plateau in China. In the mining district, pyrite is the prevalent Co-hosting sulfide mineral, and is partially exposed on the surface to weathering and oxidation. Herein, we document the mineral assemblages in the supergene oxidation zone in the Tuolugou deposit, probe the genesis of supergene assemblage, and explore the implications for exploration. Three zones can be recognized in the oxidation zone of the Tuolugou deposit, including the outer zone (natrojarosite), intermediate zone (rozenite and aplowite), and inner zone (roemerite and melanterite). The mechanism of oxidation under aerobic and anaerobic conditions, as well as zoning with different oxidation degrees, are described in detail. Hydrous sulfates such as natrojarosite can be used as possible indicators of the exploration of albitite-related SEDEX deposit in this region. [ABSTRACT FROM AUTHOR]

The problem of scale inhibition in thermal power plants using mine water as circulating cooling water is a major focus of current engineering attention. Mine water in North China is predominantly high sulfate mine water, with mine water in Shanxi mines generally having a sulfate content of over 1000 mg/L. Currently, most thermal power plants blindly follow the previous scale inhibitor with carbonate scale as the main scale inhibition target, which leads to a large amount of sulfate scale in its circulating cooling system, which is difficult to remove after the formation of sulfate scale. On the basis of the experiments, the corresponding scale inhibition laws were studied using the response surface method for the water quality characteristics of high sulfate mine water. The scaling process on the heat exchange surface of the circulating cooling water system was simulated by the hanging sheet deposition method, and the quantitative analysis was carried out by the weight method. Using EDTMPS as an example, the scale inhibition law of sulfate‐type scale inhibitors for this type of mine water was systematically investigated. The experiments showed that the scale inhibition rate (reduction of deposited scale after scale inhibitor dosing) reached a peak of 95.21% at a time of 6.1 h, a solution temperature of 70°C and an EDTMPS dosing rate of 6 mg/L. [ABSTRACT FROM AUTHOR]

The strongly 13C-depleted calcite in the Doushantuo cap dolostones (∼635 Ma) of South China is considered to form via thermochemical or biological oxidation of methane by sulfate in an environment with sulfate concentrations close to that of modern seawater (∼28 mM). Here we demonstrate that the coeval seawater sulfate levels were indeed low (∼1 to 3 mM) because all bulk δ34S values of pyrites are close to and higher than the coeval seawater, with only a few showing a wide in situ δ34S range from 5 to 62‰. Such low sulfate concentrations were initially consumed by sulfate reducing microorganisms to extremely low levels (<∼0.2 mM), and thus Mn-driven anaerobic oxidation of methane (AOM) by sulfate occurred in pore water to produce H 2 S, which was in turn oxidized by Mn oxides back to sulfate. Consequently, with increasing Mn reduction and decreasing sulfate concentrations in pore waters, the produced pyrite shows an increase of in situ δ34S values, and is in association with calcite with more negative δ13C values, and an inherited positive Ce anomaly from Mn oxides. Finally, the pyrite with the highest δ34S value may have co-precipitated with the 13C-depelted calcite (with a nadir of −58‰), and thus show similarly high Mn concentrations (∼20000 μg/g). This is the first report of sulfate-dependent AOM driven by Mn- or Fe- oxides from the entire Precambrian record. Such a previously unrecognized biogeochemical cycling during Marinoan global deglaciation may serve as the mechanism for major methane sink during the Proterozoic and Archean with low sulfate concentrations in the oceans. [ABSTRACT FROM AUTHOR]

A regional online chemical weather model WRF/ CUACE (C hina Meteorological Administration U nified A tmospheric C hemistry E nvironment) is used to assess the contributions of cloud chemistry to the SO2 and sulfate levels in typical regions in China. By comparing with several time series of in-situ cloud chemical observations on Mountain Tai in Shandong Province of China, the CUACE cloud chemistry scheme is found to well reproduce the cloud processing the consumption of H2O2, O3, SO2 and sulfate, and consequently is used in the regional assessment for a heavy pollution episode and monthly average in December 2016. During cloud availability in heavy pollution episode, the sulfate production increases 60–95 % and SO2 reduces over 80 %. And the cloud chemistry mainly affects the middle and lower troposphere below 5 km as well as within the boundary layer, and contributes significantly to SO2 reduction and sulfate increase in east-central China. Among the four typical contaminated regions in China, the Sichuan Basin (SCB) is mostly affected by the cloud chemistry, with the average SO2 abatement about 1–15 ppb and sulfate increase about 10–70 μg/m3, followed by Yangtze River Delta (YRD) where SO2 abatement is about 1–3 ppb and sulfate increase is about 10–30 μg/m3. However, the cloud chemistry contribution to Pearl River Delta (PRD) and North China Plain (NCP) are not significant and weaker than other two regions due to lighter pollution and less water vapor, respectively. In addition, the average contribution of cloud chemistry during the pollution period is distinctly greater than that for all December. This study provides a way to analyze the over-estimate phenomenon of SO2 in many chemical transport models. [ABSTRACT FROM AUTHOR]

The Ediacaran–Cambrian (E–C) transition was a critical period in Earth's history, and it was characterized by variable but potentially significant increases in atmospheric oxygen levels (pO2). Sulfate is an essential oxidant and plays a key role in regulating Earth's surface redox conditions. However, there is uncertainty regarding seawater sulfate levels during the E–C transition. To address this issue, organic carbon (δ13Corg) and pyrite sulfur isotope (δ34Spy) analyses of the Heyu section (the Dengying Formation) in the Sichuan Basin, South China, were carried out. The δ13Corg varies between −36.4‰ and −27.4‰, and δ34Spy ranges from −6.6‰ to 27.3‰. The TOC and pyrite content ranges from 0.13 wt.% to 4.28 wt.% and from 0.01 wt.% to 0.94 wt.%, respectively. The marine sulfate concentration was modeled using a one-dimensional diffusion–advection–reaction model (1D-DAR). The modeling results indicate that the seawater sulfate level remained at a relatively low level of ~2–6 mM. The increased pyrite burial at extensive marine anoxia during the terminal Ediacaran period was likely a driver of such a low sulfate level. [ABSTRACT FROM AUTHOR]

The role of environmental change as a significant force driving biological evolution during the Ediacaran–Cambrian transition remains a subject of extensive debate. In this study, we present high-resolution C-isotope data of organic matter (δ13C org) and multiple S-isotope compositions of pyrite (δ34S py and Δ33S py) obtained from a continuous drill core (ZK1505) in South China, spanning the interval from the Ediacaran to Cambrian Stage 2. Our δ13C org and δ34S py data, combined with published data from four sections deposited across a shelf-to-basin transect, reveal substantial gradient from shallow to deep water in δ13C org and sustained positive δ34S py values in the early Cambrian. The vertical δ13C org gradient suggests chemical stratification of the early Cambrian ocean, characterized by oxic shallow water and anoxic deep water. The sustained positive δ34S py values in the same period suggest low seawater sulfate concentrations. Furthermore, we observed intermittent occurrences of negative Δ33S py values coupled with positive δ34S py , suggesting a dominant deep-water anoxia during early Cambrian in the Yangtze Block. We propose that protracted deep-water anoxia may have contributed to the extinction of the Ediacaran biota and played a significant role in the evolution of Cambrian animals. • Vertical δ13C org gradient reveals chemical stratification of the early Cambrian ocean. • Positive δ34S py may have resulted from low seawater sulfate concentrations in the early Cambrian ocean. • Negative Δ33S py coupled with positive δ34S py suggests a dominant deep-water anoxia. • Deep-water anoxia may have hindered the flourishing of early Cambrian animals on the seafloor. [ABSTRACT FROM AUTHOR]

The marine sulfur cycle is highly sensitive to redox environments at the Earth's surface. Fluctuations in atmospheric p O 2 level or marine redox environments are commonly associated with changes in seawater sulfate concentration, sulfate sulfur (S) and oxygen (O) isotopes. Thus, the marine S cycle through the Earth's ancient past provides a first-order constraint on the redox evolution of the Earth's surface. Reconstructions of the marine S cycle have been approached through analyses of various sulfate-bearing geological materials, such as sedimentary barite, evaporitic sulfate (e.g., gypsum), carbonate associated sulfate (CAS), and phosphate-associated sulfate (PAS) in phosphatic ores. These geological materials have their own pros and cons. In this study, we focus on PAS in Lingula brachiopods, which possess phosphatic shells and have a long evolutionary history since Cambrian times. Biogenic phosphate typically has a higher sulfate concentration than carbonate and phosphate ores, and is less vulnerable to diagenetic alteration. Here, we analyzed modern Lingula shells from the South China Sea and fossil Lingula shells collected from the Late Devonian Xiejingsi Formation of South China. Living and fossil Lingula shells have similar P/S ratios (PO 4 3−/SO 4 2−) of ∼76, and S and O isotopes of PAS (δ34S PAS and δ18O PAS) in each group show limited variations. For living Lingula shells, the mean values of δ34S PAS and δ18O PAS are +15.0 ± 1.5‰ and + 9.8 ± 0.4‰, respectively, which are ∼6‰ lower and comparable to those of modern seawater sulfate compositions (δ34S SW and δ18O SW-SO4), probably due to vital effects. For fossil Lingula shells, δ18O PAS (14.1 ± 0.9‰) is identical to coeval evaporite. The range of δ34S PAS is encompassed by the values of both coeval evaporite and CAS, but the mean value of δ34S PAS (29.5 ± 0.9‰) is higher. Thus, fossil Lingula shells show a good potential for reconstructing δ34S SW and δ18O SW-SO4 values. • Sulfate from modern Lingula shells, with stable P/S ratio, δ34S, and δ18O, can reconstruct δ34S and δ18O of seawater sulfate. • Seawater sulfate δ34S reconstructed by fossil Lingula shells are higher than the δ34S of coeval evaporite and CAS. • Phosphate associated sulfate from Lingula shells might be a more reliable achieve of seawater sulfate than evaporite and CAS. [ABSTRACT FROM AUTHOR]

The Hangenberg mass extinction during the Devonian-Carboniferous (D-C) transition represents one of the largest biodiversity losses of the Phanerozoic, while the underlying cause remains controversial. An improved understanding of the contemporaneous sulfur cycle can provide insights into the latest Devonian environmental changes that potentially affected marine biotas. Here, we report on a high-resolution chemostratigraphic study of the sulfur isotopic composition of carbonate-associated sulfate (CAS) through the D-C transition in the Long'an and Qilinzhai sections of South China. The δ34S CAS profiles exhibit a long-term (i.e., >105 yr) negative excursion from +19.0‰ in the upper Lower Si. praesulcata Zone to +13.0‰ in the middle Upper Si. praesulcata Zone, and terminated with a recovery to 20.3‰ in the lower Si. sulcata – Si. duplicata zones, representing a depositional interval of ∼0.9 Myr. In addition, this long-term negative excursion is punctuated by episodic sharp negative shifts. The negative δ34S CAS excursion coincided with the end-Devonian biotic crisis, a positive shift in carbonate δ13C, and negative shifts in bulk-sediment δ15N values and I/Ca ratios. Increasing organic carbon burial indicated by the positive shift in δ13C precludes decreased pyrite burial as an explanation for the negative shift of δ34S CAS , supported by intensified marine anoxia revealed by the negative shifts in δ15N and I/Ca. We attribute the long-term negative shift in δ34S CAS to enhanced inputs of 34S-depleted riverine sulfate in conjunction with low seawater sulfate concentrations within the semi-restricted Yangtze Sea, whereas the transient negative spikes in δ34S CAS were possibly caused by episodic upwelling and oxidation of H 2 S in expanded oceanic oxygen-minimum zones. In conjunction with the positive shift in δ13C, the negative shift in δ34S CAS supports a significant role for enhanced subaerial weathering in intensifying marine anoxia and triggering the biotic crises that occurred during the latest Devonian, the most likely driver of which was the spread of vascular (especially seed-bearing) land plants. • First analysis of δ34S of carbonate-associated sulfate (CAS) in uppermost Devonian. • Long-term (>105 yr) negative δ34S CAS excursion is attributed to enhanced weathering. • Episodic transient negative δ34S shifts possibly caused by oxidation of rising H 2 S. • Ultimate driver was intensified chemical weathering linked to vascular plant spread. [ABSTRACT FROM AUTHOR]

Except for excessive nutrient input and climate warming, the rapidly rising SO 42- concentration is considered as a crucial contributor to the eutrophication in shallow lakes; however, the driving process and mechanism are still far from clear. In this study, we constructed a series of microcosms with initial SO 42- concentrations of 0, 30, 60, 90, 120, and 150 mg L -1 to simulate the rapid SO 42- increase in Lake Taihu, China, subjected to cyanobacteria blooms. Results showed that the sulfate reduction rate was stimulated by the increase in initial SO 42- concentrations and cyanobacteria-derived organic matter, with the maximal sulfate reduction rate of 39.68 mg (L d) -1 in the treatment of 150 mg L -1 SO 42- concentration. During the sulfate reduction, the produced maximal ∑ S 2- concentration in the overlying water and acid volatile sulfate (AVS) in the sediments were 3.15 mg L -1 and 11.11 mg kg -1 , respectively, and both of them were positively correlated with initial SO 42- concentrations (R2=0.97 ; R2= 0.92). The increasing abundance of sulfate reduction bacteria (SRB) was also linearly correlated with initial SO 42- concentrations (R2=0.96), ranging from 6.65×107 to 1.97×108 copies g -1. However, the Fe 2+ concentrations displayed a negative correlation with initial SO 42- concentrations, and the final Fe 2+ concentrations were 9.68, 7.07, 6.5, 5.57, 4.42, and 3.46 mg L -1 , respectively. As a result, the released total phosphorus (TP) in the overlying water, to promote the eutrophication, was up to 1.4 mg L -1 in the treatment of 150 mg L -1 SO 42- concentration. Therefore, it is necessary to consider the effect of rapidly increasing SO 42- concentrations on the release of endogenous phosphorus and the eutrophication in lakes. [ABSTRACT FROM AUTHOR]

Measurements of chemical compositions in the fog water at Murododaira (36.6°N, 137.6°E, altitude 2450 m), Mt. Tateyama, on the Sea of Japan side of central Japan, were performed mainly in autumn, and the characteristics of chemical climatology before 2010 and after 2017 were compared. Strong acid fogs that were sometimes detected before 2010 were not observed after 2017, and the pH of the fog water increased. Since 2017, the concentration of SO42− in the fog water has decreased significantly, and it has been observed that the fog water tends to be purified. There was no significant difference in the concentrations of ionic components except H+ and SO42− between before 2010 and after 2017. The nssSO42−/NO3− ratio in the fog water was high before 2010 but has decreased in recent years. The large reduction in SO2 emissions in China in the 2010s has had a major impact on the fog water chemistry at Mt. Tateyama. [ABSTRACT FROM AUTHOR]

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A series of dramatic oceanic and atmospheric events occurred in the immediate aftermath of the Marinoan “snowball Earth” meltdown ∼635 My ago. However, at the 10- to 100-ky timescale, the order, rate, duration, and causal-feedback relationships of these individual events remain nebulous. Nonetheless, rapid swings in regional marine sulfate concentrations are predicted to have occurred in the aftermath of a snowball Earth, due to the nonlinear responses of its two major controlling fluxes: oxidative weathering on the continents and pyrite burial in marine sediments. Here, through the application of multiple isotope systems on various carbon and sulfur compounds, we determined extremely 13C-depleted calcite cements in the basal Ediacaran in South China to be the result of microbial sulfate reduction coupled to anaerobic oxidation of methane, which indicates an interval of high sulfate concentrations in some part of the postmeltdown ocean. Regional chemostratigraphy places the 13C-depleted cements at the equivalent of the earliest Ediacaran 17O-depletion episode, thus confining the timing of this peak in sulfate concentrations within ∼50 ky since the onset of the deglaciation. The dearth of similarly 13C-depleted cements in other Proterozoic successions implies that the earliest Ediacaran peak in marine sulfate concentration is a regional and likely transient event. [ABSTRACT FROM AUTHOR]

Thermochemical sulfate reduction (TSR) commonly occurred in the dolostone reservoirs of the Upper Permian Changxing Formation (P3c) in the Yuanba (YB) gas field, Sichuan Basin, yet controversy remains regarding the source of sulfate required for TSR. To trace the source of the sulfate, sulfur and strontium isotopic compositions were measured for three diagenetic celestite (SrSO4) samples found in the P3c dolostone reservoirs in the YB gas field. In addition, the sulfur isotopic compositions of Carbonate-associated sulfates (CAS) from the P3c carbonates and spheroidal pyrites in dolomicrites from the P/T boundary (PTB) in the YB gas field were measured for comparative studies. The results show that the sulfur isotopic compositions of celestites are significantly heavier than those of the contemporaneous seawater, and these celestites have strontium isotopic values consistent with those of the host dolostones and contemporaneous seawater. The −33.68‰ fractionation in average δ34S values between pyrites and celestites indicated that their formation was likely to be related to bacterial sulfate reduction (BSR). During the P/T extinction event that accompanied the end-Permian regression, the reflux of brine directly precipitated 34S-rich celestites in the fractures and vugs of the dolostone reservoirs due to the BSR and the evaporation of seawater. These 34S-rich celesites and associated pore fluids provide a new explanation for the source of sulfate required for the late TSR. [ABSTRACT FROM AUTHOR]

This study addresses the ongoing debate concerning the origin of ambient sulfate in northern China, and provides more evidence for primary sulfate from the perspective of source emission. An extensive field experiment was conducted, involving the collection of size-segregated particulate matter emitted under various coal types and combustion conditions for subsequent analysis. Our findings reveal that residential coal combustion (RCC) emits significant amounts of primary sulfate, constituting approximately 26.48 ± 15.43% of the particulate mass. Moreover, these emissions exhibit a strong association with NH 4 +, leading to the formation of stable ammonium sulfate compounds. The emission of sulfate is intricately linked to both coal quality and combustion conditions. Notably, the oversight of δ34S isotope enrichment in RCC particulate matter, which distinctly differs from the raw coal, introduces uncertainties in the quantitative assessment of sulfate sources and formation pathways. Therefore, more in-depth explorations are necessary to elucidate the precise processes involved in RCC sulfate transformation and to accurately determine its environmental impact. • Increase knowledge of RCC sulfate emission characteristics and influences. • Demonstrate RCC emits stable primary sulfate from multiple evidences. [ABSTRACT FROM AUTHOR]

Bacterial sulfate reduction (BSR) is the interaction between sulfates and organic matter that bacteria participate in during the early diagenetic stage. It is one of the important biogeochemical processes that affect the formation of sulfides and sulfur cycling. Due to the lack of sulfate in the lakes, there is relatively little research on lacustrine bacterial sulfate reduction (LBSR), and related research mainly focuses on marine sedimentation. Marine incursion and volcanic ash may bring sulfate to lakes, providing a possibility for the occurrence of LBSR. The process, main influencing factors, and identification methods of BSR are summarized systematically. Through comprehensive analysis, it is believed that the occurrence depth of LBSR is relatively shallow (about 10 cm). Sulfate concentration, total organic matter, and sulfate reducing bacteria activity are the main controlling factors of BSR. The petrological and geochemical characteristics of the product are commonly used indicators to determine whether BSR occurs. The Jimsar Sag is one of the important shale oil rich areas in China. Taking Jimsar Sag as an example, the identification of LBSR was attempted. Based on the characteristics of framboidal pyrite, columnar calcite, and fine-grained dolomite, comprehensive analysis suggests that LBSR has occurred in the Lucaogou Formation of the Jimsar Sag. BSR has a significant effect on the degradation of organic matter, and TOC is usually lower in areas with higher intensity. Therefore, BSR has impact on the enrichment of organic matter in shale. The relevant research may have reference significance for the enrichment of lacustrine organic matter and shale oil exploration. • The impact of marine incursion and volcanic ash on the sulfate content of lakes is considered. • Lacustrine bacterial sulfate reduction is identified and its intensity is analyzed in Jimsar Sag, the Junggar Basin. • The effects of lacustrine bacterial sulfate reduction on organic matter degradation is analyzed. [ABSTRACT FROM AUTHOR]

Thallium (Tl) is a highly toxic trace metal posing a significant threat to human health. Tl pollution in soils and chronic Tl poisoning related to Tl-rich sulfides weathering in the Lanmuchang mine of southwest Guizhou province, China, have been intensively studied in recent years. And yet, there are few studies on the role of secondary sulfate minerals associated with Tl mobility in this area. The sulfate minerals were characterized by XRD and SEM-EDS. The concentrations of Tl and other elements were determined by ICP-MS. The results show that sulfate minerals are predominantly melanterite, halotrichite, and fibroferrite. The average contents of Tl in rock, sulfate minerals, and soil samples were 156.4, 0.11, and 72.1 µg g−1, respectively. This study suggests that Tl in the mineralized rocks entered soils by pyrite oxidation with less scavenged of the sulfate minerals. The dissolution of the ferric sulfate minerals accelerates pyrite oxidation and maintains soil acidity, and this likely enhances Tl mobility from soil to crops. [ABSTRACT FROM AUTHOR]

Purpose: In the booming electric vehicle market, the demand for refined cobalt is showing a blowout growth. China is the largest cobalt-refiner and cobalt-importer in the world. However, the life cycle inventory and potential environmental impact from cobalt refining in China have not been clearly illustrated. This paper builds a comprehensive inventory to support the data needs of downstream users of cobalt sulfate. A "cradle-to-gate" life cycle assessment was conducted to provide theoretical support to stakeholders. Methods: A life cycle assessment was performed based on ISO 14040 to evaluate the potential environmental impact and recognize the key processes. The system boundary of this study contains four stages of cobalt sulfate production: mining, beneficiation, primary extraction, and refining. Except for the experimental data used in the primary extraction stage, all relevant data are actual operating data. The normalization value was calculated based on the latest released global emission and extraction data. Results and discussion: Normalization results show that the potential impacts of cobalt refining were mainly concentrated in the fossil depletion and freshwater ecotoxicity categories. The beneficiation stage and the refining stage account for 72% and 26% of the total normalization value, respectively. The beneficiation stage needs to consume a lot of chemicals and energy to increase the cobalt content, due to the low grade of cobalt ore in China. Compared with cobalt concentrate, the use of cobalt-containing waste (e.g., cobalt waste from EV batteries) can ease endpoint impact by up to 73%. With the application of the target electricity structure in 2050, the potential impact of China's cobalt sulfate production on global warming, fossil depletion, and particulates formation can be reduced by 24%, 22%, and 26%, respectively. Conclusion: Findings indicate that the chemical inputs and electricity consumption are primary sources of potential environmental impact in China's cobalt sulfate production. Promoting the development of urban mines can reduce excessive consumption of chemicals and energy in the beneficiation stage. The environmental benefits of transforming the electricity structure and using more renewable energy to reduce dependence on coal-based power in the cobalt refining industry were revealed. [ABSTRACT FROM AUTHOR]

In the construction industry, it is imperative to replace natural sand with manufactured sand. The environment in northwest China is very complex and harsh. The application of manufactured sand concrete in such a harsh environment needs scientific and comprehensive research to meet the requirements. However, there is a gap in the study of sulfate freeze-thaw resistance of manufactured sand concrete in the complex environment of Northwest China. Therefore, this study investigated the northwest environment, designed an indoor sulfate freeze-thaw cycle experiment system close to the real environment, and designed a conductive titration method to test the sulfate ion content in hardened concrete. The influence of the freeze-thaw cycle on the diffusion depth of sulfate ions in manufactured sand concrete was studied. Finally, the following conclusions are obtained: In the process of conductometric titration, hydrochloric acid is used as the dissolution solution, Ag 2 O and CO 2 are used as neutralizers, and Ba(NO 3) 2 is used as the titration solution, which can perfectly eliminate the significant influence ions in the test solution, and can accurately test the content of sulfate ions in hardened concrete. The sulfate ion content of concrete at different depths was tested, and it was found that the two sides of sulfate erosion caused by freeze-thaw cycles were mainly reflected in about 100 freeze-thaw cycles. The limit number of freeze-thaw cycles N 0 and the limit diffusion depth X 0 are proposed, and the diffusion equation of manufactured sand concrete under the action of sulfate freeze-thaw cycles is derived. The proposed diffusion parameter v is unique to the concrete, which can well judge the sulfate freeze-thaw resistance of the concrete. When v is closer to 0, it shows that the resistance of concrete to sulfate freeze-thaw erosion is better. For the northwest environment of China, the manufactured sand concrete should ensure v < 6; the environment in Northwest China has a very complex multi-factor erosion environment. It is worth noting that this study is only applicable to laboratory conditions. To improve the accuracy and reference value of experimental research, future research needs to add more comprehensive environmental impact factors and collect actual data in the northwest environment of China for verification. • A detailed conductivity test method for sulfate ion content in hardened concrete was designed. • The diffusion equation of manufactured sand concrete under sulfate freeze-thaw cycles is derived by proposing the limit number of freeze-thaw cycles N 0 and the limit diffusion depth X 0. • The diffusion parameter v proposed by is a new concept, which can be used to judge the key index of sulfate freeze-thaw damage, and is of great significance for evaluating the frost resistance of manufactured sand concrete in the northwest environment of China. [ABSTRACT FROM AUTHOR]

In this study, we designed a sensitivity test using the half number concentration of sulfate in the nucleation calculation process to study the aerosol-cloud interaction (ACI) of sulfate on clouds, precipitation, and monsoon intensity in the summer over the eastern China monsoon region (ECMR) with the National Center for Atmospheric Research Community Atmosphere Model version 5. Numerical experiments show that the ACI of sulfate led to an approximately 30% and 34% increase in the cloud condensation nuclei and cloud droplet number concentrations, respectively. Cloud droplet effective radius below 850 hPa decreased by approximately 4% in the southern ECMR, while the total liquid water path increased by 11%. The change in the indirect radiative forcing due to sulfate at the top of the atmosphere in the ECMR during summer was − 3.74 W·m−2. The decreased radiative forcing caused a surface cooling of 0.32 K and atmospheric cooling of approximately 0.3 K, as well as a 0.17 hPa increase in sea level pressure. These changes decreased the thermal difference between the land and sea and the gradient of the sea-land pressure, leading to a weakening in the East Asian summer monsoon (EASM) and a decrease in the total precipitation rate in the southern ECMR. The cloud lifetime effect has a relatively weaker contribution to summer precipitation, which is dominated by convection. The results show that the ACI of sulfate was one possible reason for the weakening of the EASM in the late 1970s. [ABSTRACT FROM AUTHOR]

The formation mechanism of aerosol sulfate during wintertime haze events in China is still largely unknown. As companions, SO2 and transition metals are mainly emitted from coal combustion. Here, we argue that the transition metal-catalyzed oxidation of SO2 on aerosol surfaces could be the dominant sulfate formation pathway and investigate this hypothesis by integrating chamber experiments, numerical simulations and in-field observations. Our analysis shows that the contribution of the manganese-catalyzed oxidation of SO2 on aerosol surfaces is approximately one to two orders of magnitude larger than previously known routes, and contributes 69.2% ± 5.0% of the particulate sulfur production during haze events. This formation pathway could explain the missing source of sulfate and improve the understanding of atmospheric chemistry and climate change. Sulfate aerosols are an important component of wintertime haze events in China, but their production mechanisms are not well known. Here, the authors show that transition metal-catalyzed oxidation of SO2 on aerosol surfaces could be the dominant sulfate formation pathway in Northern China. [ABSTRACT FROM AUTHOR]

The origins of atmospheric sulfate production have previously been explained by focusing on air quality models and complex chemical reaction processes. Here, we first report direct observations of sulfate production in stack plumes discharged from coal‐fired power plants, industrial boilers, and sintering plants equipped with wet desulfurization systems. Less than one third of the particulate SO42− in plumes is attributed to dust‐SO42− and SO3 measured in stacks. The SO2 aqueous‐phase oxidation process is critical in explaining the unknown sulfate formation in plume droplets with pH values ranging from 2.3 to 2.8. When the rapidly formed sulfate in wet plumes is included, a notable amount of underestimated sulfate (∼0.24 Tg in 2017) is emitted from industrial stacks in China and can partially explain the "missing sulfate" on driving most particle pollution episodes. Policy‐making targeting particulate emissions is suggested to substantially reduce sulfate emissions for further air quality improvement. Plain Language Summary: Sulfate aerosols are well known as an important atmospheric aerosol component, especially during haze periods. Their production pathway remains a mystery, and they are also referred to as missing sulfate. We show that sulfuric acid droplets are readily produced in wet plumes emitted from typical coal‐fired stationary sources. The freshly formed sulfate originates from the condensation and absorption of SO2 and SO3 emitted from stacks when the discharged flue gas cools in ambient air. We discover that the fast‐formed sulfate aerosols in the wet plumes from industrial stacks account for ∼31.4% of the directly emitted sulfate aerosols in China. This study advances our understanding of industrial particulate emissions and their contribution to atmospheric sulfate. Key Points: Acidic droplets with pH <3 formed in wet plumes are emitted from coal‐fired stationary sourcesThe SO42− concentrations in plumes grow explosively and are 2.8∼3.3 times higher than those in stacksSO2 aqueous‐phase oxidation process is critical in sulfate aerosol formation via plume droplets [ABSTRACT FROM AUTHOR]

Cracks will be introduced into mortar specimens and embedded copper sheets to simulate fractured concrete according to the designed 20 mm crack lengths and angles. By taking into consideration the actual environment of a hydro-fluctuation belt for a typical bank slope in the Three Gorges Reservoir Region of the Yangtze River, China, a dry–wet cycle testing program will be designed to study the mechanical properties of the fracture mortar specimens immersed in different sulfate solutions. The failure characteristics and modes of the fracture mortar specimens will be measured and analyzed. The tests results show that the strength initially decreased and then increased with an increasing crack angle from 0° to 90°, and this was the smallest for the specimens with a 45° angle. Deterioration occurred in the specimens subjected to dry–wet cycles in different sulfate solutions. The damage extent is expressed as the change in elasticity. A formula for damage evolution of the fracture specimens will be proposed and the relationship between the deformation properties and damage properties of the specimens will be developed for the combined action of dry–wet cycles and sulfate attack. Based on the proposed damage model, the damage evolution equation and elastic damage constitutive model will be derived under the combined action of dry–wet cycles and sulfate attack, and this damage constitutive relation could be used to the study damage evolution for the fracture mortar specimens under the combined effects of dry–wet cycles and sulfate attack. [ABSTRACT FROM AUTHOR]

Introduction: A significant threat to public health is presented by antibiotic-resistant strains of bacteria, selective pressure on which results from antibiotic use. Colistin is an antibiotic commonly used in veterinary medicine, but also one of last resort in human medicine. Since the 2015 discovery in China of the mcr-1 gene encoding colistin resistance in Enterobacteriaceae, other countries have noted its presence. This study was to find the mcr-1 gene prevalence in E. coli isolated from poultry slaughtered in Poland. Material and Methods: Cloacal swabs were taken from December 2017 to October 2018 from broiler chickens in three regions. The samples (n = 158) were grouped as flocks treated with colistin sulphate (n = 87) and those not treated (n = 71). Resistance to antimicrobials commonly used in poultry was evaluated by minimum inhibitory concentration. The presence of the mcr-1 gene was confirmed by PCR. Results: Isolates containing the mcr-1 gene were yielded by 11.27% of the samples from not treated flocks and 19.54% of those from treated flocks, but no statistically significant difference in the prevalence of the gene was seen between the groups. Conclusion: The results clearly preclude intensification of selective pressure for colistin resistance due to colistin sulphate treatment because they show that the avian gastrointestinal tract was already inhabited by colistin-resistant E. coli by the time the chickens came to the poultry house. [ABSTRACT FROM AUTHOR]

A vast area in China is currently going through severe haze episodes with drastically elevated concentrations of PM 2.5 in winter. Nitrate and sulfate are the main constituents of PM 2.5 , but their formations via NO2 and SO2 oxidation are still not comprehensively understood, especially under different pollution or atmospheric relative humidity (RH) conditions. To elucidate formation pathways of nitrate and sulfate in different polluted cases, hourly samples of PM 2.5 were collected continuously in Beijing during the wintertime of 2016. Three serious pollution cases were identified reasonably during the sampling period, and the secondary formations of nitrate and sulfate were found to make a dominant contribution to atmospheric PM 2.5 under the relatively high RH condition. The significant correlation between NOR, NOR = NO3-/(NO3-+NO2) , and [NO2]2 × [O3] during the nighttime under the RH≥60 % condition indicated that the heterogeneous hydrolysis of N2O5 involving aerosol liquid water was responsible for the nocturnal formation of nitrate at the extremely high RH levels. The more often coincident trend of NOR and [HONO] × [DR] (direct radiation) × [ NO2 ] compared to its occurrence with [Dust] × [ NO2 ] during the daytime under the 30 % < RH < 60 % condition provided convincing evidence that the gas-phase reaction of NO2 with OH played a pivotal role in the diurnal formation of nitrate at moderate RH levels. The extremely high mean values of SOR, SOR = SO42-/(SO42-+SO2) , during the whole day under the RH≥60 % condition could be ascribed to the evident contribution of SO2 aqueous-phase oxidation to the formation of sulfate during the severe pollution episodes. Based on the parameters measured in this study and the known sulfate production rate calculation method, the oxidation pathway of H2O2 rather than NO2 was found to contribute greatly to the aqueous-phase formation of sulfate. [ABSTRACT FROM AUTHOR]

Rapid sulfate formation is recognized as a key characteristic of severe winter haze in China. However, air quality models tend to underestimate sulfate formation during heavy haze periods, and heterogeneous formation pathways have been proposed as promising mechanisms to reduce gaps between observation and model simulation. In this study, we implemented a reactive SO2 uptake mechanism through the SO2+NO2 heterogeneous reactions in the Comprehensive Air Quality Model with Extensions (CAMx) to improve simulation of sulfate formation in the Yangtze River Delta (YRD) region. Parameterization of the SO2+NO2 heterogeneous reactions is based on observations in Beijing and considered both the impact of relative humidity and aerosol pH on sulfate formation. Ammonia is reported to be critical for the formation of secondary inorganic aerosols. Estimation of ammonia emissions is usually associated with large uncertainties and models tend to underestimate ammonia concentrations substantially. Sensitivity tests were conducted to evaluate the influence of the SO2+NO2 heterogeneous reactions as well as ammonia emissions on modeled sulfate concentrations during a period with several heavy haze episodes in the YRD region. Base case model results show large underestimation of sulfate concentrations by 36 % under polluted conditions in the YRD region. Adding the SO2+NO2 heterogeneous reactions or doubling ammonia emissions alone leads to slight model improvement (∼6 %) on simulated sulfate concentrations in the YRD region. However, model performance significantly improved when both the SO2+NO2 heterogeneous reactions and doubled ammonia emissions were included in the simulation: predicted sulfate concentrations during polluted periods increased from 23.1 µ g m -3 in the base scenario to 29.1 µ g m -3 (representing an increase of 26 %). Aerosol pH is crucial for the SO2+NO2 heterogeneous reactions, and our calculated aerosol pH is always acidic and increased by 0.7 with doubled ammonia emissions. Modeling results also show that this reactive SO2 uptake mechanism enhanced sulfate simulations by 1 to 5 µ g m -3 for the majority of the eastern and central parts of China, with more than 20 µ g m -3 increase in sulfate concentrations over the northeastern plain. These findings suggest that the SO2+NO2 heterogeneous reactions could be potentially important for sulfate formation in the YRD region as well as other parts of China. Further studies are needed to constrain the uncertainties associated with the parameterization of the SO2+NO2 heterogeneous reactions based on local data as well as to evaluate this mechanism in other regions. In addition, ammonia emissions were found to be a key driving variable of the spatial patterns of sulfate enhancement due to the new pathway. Substantial efforts are needed to improve the accuracy of the ammonia emission inventory. [ABSTRACT FROM AUTHOR]

Sulfate aerosols have profound impacts on the climate, ecosystem, visibility, and public health, but the sulfate formation pathway remains elusive. In the present study, a source-oriented WRF-Chem model is applied to simulate a persistent air pollution episode from 4 to 15 July 2015 in Beijing–Tianjin–Hebei (BTH), China, to study the contributions of four pathways to sulfate formation. When comparing simulations to measurements in BTH, the index of agreement (IOA) of meteorological parameters, air pollutants, and aerosol species generally exceeds 0.6. On average in BTH, the heterogeneous reaction of SO2 involving aerosol water and the SO2 oxidation by OH constitutes the two most important sulfate sources, with a contribution of about 35 %–38 % and 33 %–36 %, respectively. Primary sulfate emissions account for around 22 %–24 % of the total sulfate concentration. SO2 oxidation by stabilized Criegee intermediates (sCIs) also plays an appreciable role in sulfate formation, with a contribution of around 9 % when an upper limit of the reaction rate constant of sCIs with SO2 (κsCI+SO2=3.9×10-11 cm 3 s -1) and a lower limit of the reaction rate constant of sCIs with H2O (κsCI+H2O=1.97×10-18 cm 3 s -1) are used. Sensitivity studies reveal that there are still large uncertainties in the sulfate contribution of SO2 oxidation by sCIs. The sulfate contribution of the reaction is decreased to less than 3 % when κSCI+SO2 is decreased to 6.0×10-13 cm 3 s -1. Furthermore, when κsCI+H2O is increased to 2.38×10-15 cm 3 s -1 based on the reported ratio of κSCI+H2O to κSCI+SO2 (6.1×10-5), the sulfate contribution becomes insignificant at less than 2 %. Further studies need to be conducted to better determine κsCI+SO2 and κsCI+H2O to evaluate the effects of sCI chemistry on sulfate formation. [ABSTRACT FROM AUTHOR]

The estimated contribution of "primary" combustion sulfate to the total atmospheric sulfate flux is inconsistent, hindering our interpretation of the atmospheric "missing sulfate". We expect combustion sulfate to inherit the characteristic triple oxygen isotope composition of air O 2 to variable degrees. To test the hypothesis, we extracted sulfate from soot samples collected from 48 residential chimneys throughout China. The mean sulfate's Δ′17O 0.5305 and δ18O values are −0.27 ± 0.06‰ and 12.8 ± 3.6‰, respectively, and the Δ′17O 0.5305 and δ18O values correlate negatively and extend to air O 2 's triple oxygen isotope composition as an endmember, suggesting that combustion sulfate is generated dominantly by S(IV) multiphase oxidation via O 2 in the plume, with possible additional pathways through •OH in aqueous films or droplets and NO 2 at soot surface. Oxygen sources (i.e., air O 2 , fuel, ambient moisture) and oxidation kinetics determine the triple oxygen isotope composition of combustion sulfate. The characterization of combustion sulfate's triple isotope composition helps to improve global and regional atmospheric sulfur chemistry models. • Triple oxygen isotope composition of combustion sulfate has an average value of −0.27‰ for the Δ′17O and 12.8‰ for the δ18O. • Oxygen sources (O 2 , fuel, water) and oxidation kinetics determine combustion sulfate's triple oxygen isotope composition. • The "primary" combustion sulfate is in fact "secondary" sulfate formed in chimney conduits and hot plumes. [ABSTRACT FROM AUTHOR]

• Concrete with a recycled aggregate content greater than 50% has a significant deterioration in its antifreeze performance and cannot meet its frost resistance requirements. • The Weibull model can better describe the damage variation of recycled concrete. • When the recycled aggregate content is 100%, it is only 40% of the antifreeze life of ordinary concrete. • It is suggested that the proportion of recycled aggregate should not be more than 30%. To study the frost resistance of recycled concrete in a sulfate-rich environment, we prepared recycled concrete with 0%, 30%, 50%, and 100% recycled aggregate replacement rate. The physical and mechanical properties of the recycled concrete in the coupled action of freeze-thaw cycles and a sulfate environment for different replacement rates of aggregate was then studied. We analyzed the micro-structure and the reaction products of the recycled concrete. We used a two-factor Weibull distribution model to establish the damage equation, then predict the service life of the recycled concrete. The results show that when the replacement rate of recycled aggregate increases, the physical and mechanical properties of the recycled concrete gradually deteriorate in the later stages of the freeze-thaw test. When the number of freeze-thaw cycles increases, ettringite and gypsum are gradually formed due to the reaction with sulfate. The Weibull model accurately describes the damage variation in the recycled concrete. Through the prediction of the service life of the recycled concrete, we found that the durability was reduced. Given our analysis, we found that the proportion of recycled aggregate should not exceed 30% to meet the requirements for durability design of a concrete structure in China (GB/T 50746-2008). [ABSTRACT FROM AUTHOR]

Marine evaporitic sulfates (gypsum and anhydrite) can record ancient seawater sulfur isotopic data; however, these records are scarce and widely dispersed owing to both restricted environments in which they form and their propensity to be eroded. The late Neoproterozoic–early Cambrian transition was a pivotal timeframe in Earth's history, witnessing the early evolution of animal life and major environmental changes. Seawater chemistry changed abruptly during this interval, including significant changes to the sulfur cycle as evidenced by unusually high sulfur isotopic values. This positive sulfur excursion, termed the Yudomski Event, has been reported previously from early and middle Cambrian units in Siberia, Iran, Australia, and India. In this study, we provide the first report of the Yudomski Event in early and middle Cambrian evaporites from the Tarim Basin, northwestern China. Our data support this event having been of global significance. We additionally report early and middle Ordovician sulfur data from China, which constrain the decline of the Yudomski Event to the late Cambrian. [ABSTRACT FROM AUTHOR]

The chemical and stable isotopic compositions (δ34SSO4 and δ18OSO4) of Xijiang River water in southwest China, were measured to determine the extent of rock weathering and associated CO2 consumption rates, and to assess the contamination sources of river water. The SO42− concentration in the river water was in the range of 0.05 to 0.96 mmol L−1 (mean value = 0.32 mmol L−1) and was characterized by δ34SSO4 values ranging from −9.1 to 5.1‰ (mean value = −2.1‰) and δ18OSO4 values ranging from −0.4 to 10.8‰ (mean value = 5.0‰). The δ34SSO4 and δ18OSO4 values ranged from high to low from the upper reaches to the lower reaches in all the river water samples. The results indicate that the oxidation of sulfide and anthropogenic inputs are the dominant processes affecting SO42− sources and S cycling of the Xijiang River during high‐discharge conditions, which are controlled by regional hydrological processes that are affected by natural processes and anthropogenic inputs Core Ideas: The dual isotopes (δ34SSO4 and δ18OSO4) of sulfate indicated S sources.The weathering rates of carbonate and silicate were calculated.The relative contributions of various sources are identified. [ABSTRACT FROM AUTHOR]

• The driving damage mechanism for partially immersed cement mortars was examined. • Lowering the RH would accelerate physical sulfate attacks in drying parts. • An intermediate temperature of 35 °C causes more serious degradation than 20 and 50 °C. Concrete structures in salt lakes of western China and South China Sea deteriorate dramatically because of the aggressive salt, high temperature and low relative humidity (RH). In order to study the deterioration mechanism of cement-based materials in these severe environments, the damage progress of mortar specimens that partially exposed to sulfate solutions and under different ambient RH and temperatures was examined. The results indicate that the driving deterioration mechanism for cement mortars that partially exposed to Na 2 SO 4 solution is physical attacks in drying portions, while it is chemical attacks in immersed portions for cement mortars that partially exposed to MgSO 4 solution. Besides, lowering the ambient RH (e.g., from 80% to 50% and 30%) would promote a narrow but supersaturated evaporation interface zone, which accelerates the salt crystallization and eventually surface scaling. While the relatively high ambient RH (80%) causes a broad diffusion zone where the chemical related expansion and cracking formed. Moreover, an intermediate temperature of 35 °C is proved to produce the most severely deterioration when compared to the temperature of 20 and 50 °C. [ABSTRACT FROM AUTHOR]

Sulfate plays an important role in atmospheric haze in China, which has received considerable attention in recent years. Various types of parameterization methods and heterogeneous oxidation rates of SO 2 have been used in previous studies. However, properly representing heterogeneous sulfate formation in air quality models remains a big challenge. In this study, we quantified the heterogeneous oxidation reaction using experimental results that approximate the haze conditions in China. Firstly, a series of experiments were conducted to investigate the heterogeneous uptake of SO 2 with different relative humidity (RH) levels and the presence of NH 3 and NO 2 on natural dust surfaces. Then the uptake coefficients for heterogeneous oxidation of SO 2 to sulfate at different RH under NH 3 and NO 2 coexistence were parameterized based on the experimental results and implemented in the Community Multiscale Air Quality modeling system (CMAQ). Simulation results suggested that this new parameterization improved model performance by 6.6% in the simulation of wintertime sulfate concentrations for Beijing. The simulated maximum growth rate of SO 4 2− during a heavy pollution period increased from 0.97 μg m−3 h−1 to 10.11 μg m−3 h−1. The heterogeneous oxidation of SO 2 in the presence of NH 3 contributed up to 23% of the sulfate concentration during heavy pollution periods. Image 1 • Uptake coefficients of SO 2 on dust with coexistence of NH 3 and NO 2 were obtained. • New parameterization was proposed based on experimental results under different RHs. • The new parameterization can improve sulfate simulation in wintertime in CMAQ. • Impact of NH 3 on heterogeneous formation of sulfate in wintertime is non-negligible. [ABSTRACT FROM AUTHOR]

Sulfate geoengineering could mitigate global warming via injecting SO2 into the stratosphere. However, its impacts on regional climate might lead to adverse consequences for local agriculture. In this study, we simulated the impacts of sulfate geoengineering on rice yield in China both with sufficient irrigation (irrigated) and without irrigation (rainfed). We used Geoengineering Model Intercomparison Project G4 climates from six climate models to force the ORYZA version 3 crop model to simulate rice yields under sulfate geoengineering scenario. G4 prescribes a sulfate injection to offset the radiative forcing in the Representative Concentration Pathway (RCP) 4.5 scenario. Results indicated that during the last 15 years of G4 sulfate geoengineering (i.e., 2055–2069), the implementation of sulfate geoengineering increases rice yields in most areas in China comparing with that without the implementation of sulfate geoengineering (i.e., RCP4.5), with a yield increase of 5.3 ± 5.7% for irrigated yield and 4.8 ± 7.3% for rainfed yield. After the termination of sulfate geoengineering, the irrigated rice yield in G4 is still significantly higher than that in RCP4.5, but such increase is not significant for rainfed yield. Temperature is always the dominant factor that drives the rice yield change no matter under irrigated or rainfed conditions, but the effect from solar radiation cannot be ignored in southern China. Key Points: G4 sulfate geoengineering is projected to increase irrigated rice yield in China by 5.3 ± 5.7%G4 sulfate geoengineering is projected to increase rainfed rice yield in China by 4.8 ± 7.3%Temperature is the dominant factor driving the rice yield changes [ABSTRACT FROM AUTHOR]

Epiphyton, Renalcis, and Girvanella are ubiquitous genera of calcified cyanobacteria/algae from Early Paleozoic shallow-marine limestones. One genus, Epiphyton, is characterized by a particular dendritic outline, and extensive research has revealed the morphology of calcified remains although little information on cellular structure is known. The mass occurrence of calcified Epiphyton in microbialites from Cambrian Miaolingian, the Mianchi area of North China is preserved as black clots within thrombolites and have dendritic and spherical outlines when viewed with a petrographic microscope. These remains, visible under scanning electron microscope (SEM), also comprise spherical or rectangle capsules. These capsules are made up from external envelopes and internal calcite with numerous pits, which closely resemble modern benthic coccoid cyanobacteria. These pits are between 2 μm and 4 μm in diameter and are interpreted here to represent the remnants of degraded coccoid cells, while the calcite that surrounds these pits is interpreted as calcified thin extracellular polymeric substances (EPS). In contrast, associated capsular envelopes represent thick EPS mineralized by calcium carbonate with an admixture of Al-Mg-Fe silicates. Dendritic ‘thalli’ are typically stacked apically because of the repeated growth and calcification of these capsules. Carbon and oxygen isotope results are interpreted to indicate that both photosynthesis and heterotrophic bacterial metabolism (especially sulfate reducing bacteria) contributed to carbonate precipitation by elevated alkalinity. Epiphyton are therefore here interpreted as colonies of calcified coccoid cyanobacteria, and the carbonate-oversaturated seawater during the Cambrian was conducive to their mineralization. [ABSTRACT FROM AUTHOR]

Dust storms are one of the largest sources of non-exhaust emissions in China, which can adversely affect air quality and human health during long-distance transportation. To study the influence of dust storms on aerosol particle composition, samples of fine aerosol (PM 2.5) were collected before, during, and after the severe dust storm episodes in a coastal city of North China. Then the water-soluble inorganic ions in the filters were analyzed. The results showed that the chemical composition varied significantly in different sampling periods. Before the dust storm periods (Phase 1), the weather was characterized by high relative humidity. NO 3 − was the main water-soluble inorganic ion, accounting for about 1/3 of the total mass of PM 2.5 , which is very different from the situation a few years ago when sulfate was the dominant. The results indicated that the chemical composition of the atmosphere in China has changed significantly after the implementation of strict air pollution control measures. During the severe dust storm periods (within a few hours after the dust invasion, Phase 2), the proportion of Ca2+ in PM 2.5 was high; the sulfate formation was limited due to adiabatic air mass affected by the cold front, and the sulfate content might be mainly from desert soil. However, a small amount of nitrate can be formed during their long-distance transportation. After the dust storm periods (Phase 3), dust plums and local polluted air mass mixed well. The proportion of secondary inorganic ions increased, and nitrate formation was still the main. The changes in the chemical composition from a few years ago during Phase 1 and the sharp changes in different water-soluble inorganic ions during different Phases should be carefully considered to evaluate their implications for air quality and human health. [Display omitted] • Chemical compositions varied significantly during different sampling periods. • Nitrate accounted for one third of PM 2.5 , being the main water-soluble ions during Phase 1. • Sulfate was rarely formed and was mainly from desert soil during Phase 2. • Nitrate can be formed gradually during phase 2. [ABSTRACT FROM AUTHOR]

The adverse respiratory health effects of PM 2.5 have been studied. However, the epidemiological evidence for the association of specific PM 2.5 sources with health outcomes is still limited. This study investigated the association between PM 2.5 components and sources with a biomarker of acute respiratory inflammation (FeNO) in guards. Personal exposure was estimated by microenvironment samplers and FeNO measurements were carried out before, during and after the Victory Day Military Parade in Beijing. Four sources were determined by factor analysis, including urban pollution, dust, alloy steel abrasion and toxic metals. A mixed-effect model was used to estimate the associations of FeNO with PM 2.5 sources and chemical constituents, controlling for age, BMI, smoke activity, physical activity, waist circumference, temperature and relative humidity. In summary, large concentration decreases in PM 2.5 concentration and PM 2.5 chemical constituents were observed in both roadside and indoor environments during the air control periods, immediately followed by statistically significant decreases in FeNO of roadside guards and patrol guards. Besides, statistically significant increases in FeNO were found to be associated with interquartile range (IQR) increases in some pollutants, with an increase of 1.45 ppb (95% CI: 0.69, 2.20), 0.65 ppb (95% CI: 0.13, 1.17), 1.48 ppb (95% CI: 0.60, 2.35), 0.82 ppb (95% CI: 0.44, 1.20), 0.77 ppb (95% CI: 0.42, 1.11) in FeNO for mass, sulfate, BC, Ca 2 + and Sm, respectively. In addition, compared to alloy steel abrasion and toxic metals, urban pollution and dust factors were more associated with acute airway inflammation for highly-exposed populations. [ABSTRACT FROM AUTHOR]

Zhundong coal as a high quality steam coal has not been widely utilized due to severe fouling and slagging problems during combustion. It is crucial to reveal the slagging and fouling mechanisms in a boiler burning Zhundong coal. In this paper, the properties of ash deposits collected from various heat transfer surfaces in a 330 MW boiler were characterized by ICP-OES, SEM−EDX, and XRD. These results were also verified by an experiment burning Zhundong coal in a drop-tube furnace and thermodynamic calculation by the software FactSage. The results indicated the ash deposited on different heat transfer surfaces in 330 MW boiler burning Zhundong coal could be classified into silicates and sulfates based on their elemental and mineral analysis. Further, the ash deposited on the division panel superheater is obviously divided into three layers. In the first layer, wollastonite and sodium silicate are the main minerals with the contents of quartz and feldspar being relatively small. The types of mineral in the second layer are the same with the first layer, but their contents are different from the first layer. Meanwhile, the amount of crystalline phase in the third layer is lower than that of the first and second layer. In addition, the temperature of the flue gas or the tube played an important role in the mechanism of ash deposition. Thermodynamics calculation also shows CaSO 4 can be formed at all temperatures and there only exists CaSiO 3 formed in the range 900–1200 °C. The ash deposits along the flue gas flow attributes to sulfates, silicates and sulfates, respectively. The result of the thermodynamic calculation is in accordance with the experiment results obtained in the drop-tube furnace. [ABSTRACT FROM AUTHOR]

The crystal structure of goldichite KFe(SO4)2⋅4H2O was determined on a single crystal from the Baiyinchang copper deposit, Gansu, China. [P121/c1, a = 10.395(2), b = 10.475(2), c = 9.0875(18) Å, β = 101.65(3)°, V = 969.1(3) Å3, Z = 4]. All non-H atoms were refined with anisotropic displacement parameters and positions of H-atoms were determined by difference Fourier methods and refined from X-ray diffraction data. The crystal structure of goldichite consists of corrugated sheets parallel to the (100) plane by sharing corners between FeO6 octahedra and SO4 tetrahedra. The interstitial potassium atom exhibits a [KO7(H2O)2] nine-fold coordination, which shares edges to form a column parallel to the c-axis and to build a slab with the corrugated sheet. These slabs are linked in the [100] direction through a network of hydrogen bonds. Three types of hydrogen bonds involve links of slabs: Ow(3)-H(3B)···O(1), Ow(6)-H(6B)···O(11) and Ow(9)-H(9B)···O(11). The FTIR spectrum of goldichite shows a strong absorption between ~3384 cm−1 and ~3592 cm−1, which is in accordance with the O-H···O distances derived from structure data. [ABSTRACT FROM AUTHOR]

In order to understand the impacts of regional emission changes and local tourism on sulfur and nitrogen wet deposition in Jiuzhaigou National Nature Reserve of southwestern China, wet deposition was monitored at a background site (Rize) and a tourist-affected site (PE: park entrance) in the reserve during 2015–2016. The observation data were compared between Rize and PE and between 2010–2011 and 2015–2016 monitoring campaigns. Also, the observation data were used in the Positive Matrix Factorization (PMF) model to identify the major sources of sulfur and nitrogen wet deposition. The results show that although local tourism emissions had considerable contributions to NH 4 + , NO 2 − , NO 3 − , and SO 4 2− concentrations in wet deposition ( p < 0.05), most of the annual Volume Weighted Mean (VWM) concentrations of these four ions were likely from emissions outside Jiuzhaigou. Annual wet deposition fluxes of the four ions were also affected more by precipitation and regional emissions than by local emissions. Although annual precipitation was higher at Rize (818 mm) during 2015–2016 than at another background site near Long Lake (LL: 752 mm) during 2010–2011, the annual concentrations and fluxes of SO 4 2− and NO 3 − wet deposition decreased by 77% and 74% for SO 4 2− and by 12% and 19% for NO 3 − , respectively, most likely due to regional emission reductions. Similar large reductions in SO 4 2− and NO 3 − concentrations have been also found in some other sites in southwestern China. In contrast, the annual concentration and flux of NH 4 + wet deposition at Rize during 2015–2016 were 1.4 and 1.2 times of that measured at LL during 2010–2011, respectively. The results of source apportionment analysis and tour bus emission estimates suggest that elevated NH 4 + wet deposition was possibly related to NH 3 emissions from local tour buses, but additional studies on NH 3 emissions from tour buses in the reserve are needed to confirm this. [ABSTRACT FROM AUTHOR]

Mining activity is an increasingly important stressor for freshwater ecosystems. However, the mechanism on how sulfate-rich mine drainage affects freshwater ecosystems is largely unknown, and its potential ecological risk has not been assessed so far. During 2009–2016, water and macroinvertebrate samples from 405 sample sites were collected along the mine drainage gradient from circum-neutral to alkaline waters in Hun-Tai River, Northeastern China. Results of linear regressions showed that sulfate-rich mine drainage was significantly positively correlated with the constituents typically derived from rock weathering (Ca 2 + , Mg 2 + and HCO 3 – + CO 3 2 − ); the diversity of intolerant stream macroinvertebrates exhibited a steep decline along the gradient of sulfate-rich mine drainage. Meanwhile, stressor-response relationships between sulfate-rich mine drainage and macroinvertebrate communities were explored by two complementary statistical approaches in tandem (Threshold Indicator Taxa Analysis and the field-based method developed by USEPA). Results revealed that once stream sulfate concentrations in mine drainage exceeded 35 mg/L, significant decline in the abundance of intolerant macroinvertebrate taxa occurred. An assessment of ecological risk posed by sulfate-rich mine drainage was conducted based on a tiered approach consisting of simple deterministic method (Hazard Quotient, HQ) to probabilistic method (Joint Probability Curve, JPC). Results indicated that sulfate-rich mine drainage posed a potential risk, and 64.62–84.88% of surface waters in Hun-Tai River exist serious risk while 5% threshold (HC 05 ) and 1% threshold (HC 01 ) were set up to protect macroinvertebrates, respectively. This study provided us a better understanding on the impacts of sulfate-rich mine drainage on freshwater ecosystems, and it would be helpful for future catchment management to protect streams from mining activity. [ABSTRACT FROM AUTHOR]

Sulfate and nitrate compounds can greatly increase the hygroscopicity of mineral particles in the atmosphere and consequently alter the particles' physical and chemical properties. Their uptake on long-distance-transported Asian dust particles within mainland China has been reported to be substantial in previous studies, but the production was very inefficient in other studies. We compared these two salts in particles collected from a synoptic-scale, mid-latitude, cyclone-induced dust storm plume at the Tengger Desert (38.79° N, 105.38° E) and in particles collected in a postfrontal dust plume at an urban site in Xi'an (34.22° N, 108.87° E) when a front-associated dust storm from the Tengger Desert arrived there approximately 700 km downwind. The results showed that the sulfate concentration was not considerably different at the two sites, while the nitrate concentration was slightly larger at the urban site than that at the desert site. The estimated nitrate production rate was 4-5 ng µg-1 of mineral dust per day, which was much less than that in polluted urban air. The adiabatic process of the dust-loading air was suggested to be the reason for the absence of sulfate formation, and the uptake of background HNO3 was suggested to be the reason for the small nitrate production. According to our investigation of the published literature, the significant sulfate and nitrate in dust-storm-associated samples within the continental atmosphere reported in previous studies cannot be confirmed as actually produced on desert dust particles; the contribution from locally emitted and urban mineral particles or from soil-derived sulfate was likely substantial because the weather conditions in those studies indicated that the collection of the samples was started before dust arrival, or the air from which the samples were collected was a mixture of desert dust and locally emitted mineral particles. These results suggest that the production of nitrate and sulfate on dust particles following cold fronts is likely limited when the particles move from the desert to populated areas within the continent. For an accurate quantification of sulfate and nitrate formed on long-distance-transported desert dust particles at downwind populated areas in eastern China, dust collection efforts are indispensable to minimize any possible influence by locally emitted particles or at least to ensure that the samples are collected after dust arrival. [ABSTRACT FROM AUTHOR]