DsrMKJOP is the terminal reductase complex in anaerobic sulfate respiration.

Microbial dissimilatory sulfate reduction (DSR) is a key process in the Earth biogeochemical sulfur cycle. In spite of its importance to the sulfur and carbon cycles, industrial processes, and human health, it is still not clear how reduction of sulfate to sulfide is coupled to energy conservation. A central step in the pathway is the reduction of sulfite by the DsrAB dissimilatory sulfite reductase, which leads to the production of a DsrC-trisulfide. A membrane-bound complex, DsrMKJOP, is present in most organisms that have DsrAB and DsrC, and its involvement in energy conservation has been inferred from sequence analysis, but its precise function was so far not determined. Here, we present studies revealing that the DsrMKJOP complex of the sulfate reducer Archaeoglobus fulgidus works as a menadiol:DsrC-trisulfide oxidoreductase. Our results reveal a close interaction between the DsrC-trisulfide and the DsrMKJOP complex and show that electrons from the quinone pool reduce consecutively the DsrM hemes b, the DsrK noncubane [4Fe-4S]3+/2+ catalytic center, and finally the DsrC-trisulfide with concomitant release of sulfide. These results clarify the role of this widespread respiratory membrane complex and support the suggestion that DsrMKJOP contributes to energy conservation upon reduction of the DsrC-trisulfide in the last step of DSR.

Generation of zero-valent sulfur from dissimilatory sulfate reduction in sulfate-reducing microorganisms.

Dissimilatory sulfate reduction (DSR) mediated by sulfate-reducing microorganisms (SRMs) plays a pivotal role in global sulfur, carbon, oxygen, and iron cycles since at least 3.5 billion y ago. The canonical DSR pathway is believed to be sulfate reduction to sulfide. Herein, we report a DSR pathway in phylogenetically diverse SRMs through which zero-valent sulfur (ZVS) is directly generated. We identified that approximately 9% of sulfate reduction was directed toward ZVS with S8 as a predominant product, and the ratio of sulfate-to-ZVS could be changed with SRMs' growth conditions, particularly the medium salinity. Further coculturing experiments and metadata analyses revealed that DSR-derived ZVS supported the growth of various ZVS-metabolizing microorganisms, highlighting this pathway as an essential component of the sulfur biogeochemical cycle.

The triple oxygen isotope composition of marine sulfate and 130 million years of microbial control.

The triple oxygen isotope composition (Δ'17O) of sulfate minerals is widely used to constrain ancient atmospheric pO2/pCO2 and rates of gross primary production. The utility of this tool is based on a model that sulfate oxygen carries an isotope fingerprint of tropospheric O2 incorporated through oxidative weathering of reduced sulfur minerals, particularly pyrite. Work to date has targeted Proterozoic environments (2.5 billion to 0.542 billion years ago) where large isotope anomalies persist; younger timescale records, which would ground ancient environmental interpretation in what we know from modern Earth, are lacking. Here we present a high-resolution record of the [Formula: see text]O and Δ'17O in marine sulfate for the last 130 million years of Earth history. This record carries a Δ'17O close to 0o, suggesting that the marine sulfate reservoir is under strict control by biogeochemical cycling (namely, microbial sulfate reduction), as these reactions follow mass-dependent fractionation. We identify no discernible contribution from atmospheric oxygen on this timescale. We interpret a steady fractional contribution of microbial sulfur cycling (terrestrial and marine) over the last 100 million years, even as global weathering rates are thought to vary considerably.

Sulfur assimilation using gaseous carbonyl sulfide by the soil fungus Trichoderma harzianum.

Fungi have the capacity to assimilate a diverse range of both inorganic and organic sulfur compounds. It has been recognized that all sulfur sources taken up by fungi are in soluble forms. In this study, we present evidence that fungi can utilize gaseous carbonyl sulfide (COS) for the assimilation of a sulfur compound. We found that the filamentous fungus Trichoderma harzianum strain THIF08, which has constitutively high COS-degrading activity, was able to grow with COS as the sole sulfur source. Cultivation with 34S-labeled COS revealed that sulfur atom from COS was incorporated into intracellular metabolites such as glutathione and ergothioneine. COS degradation by strain THIF08, in which as much of the moisture derived from the agar medium as possible was removed, indicated that gaseous COS was taken up directly into the cell. Escherichia coli transformed with a COS hydrolase (COSase) gene, which is clade D of the ß-class carbonic anhydrase subfamily enzyme with high specificity for COS but low activity for CO2 hydration, showed that the COSase is involved in COS assimilation. Comparison of sulfur metabolites of strain THIF08 revealed a higher relative abundance of reduced sulfur compounds under the COS-supplemented condition than the sulfate-supplemented condition, suggesting that sulfur assimilation is more energetically efficient with COS than with sulfate because there is no redox change of sulfur. Phylogenetic analysis of the genes encoding COSase, which are distributed in a wide range of fungal taxa, suggests that the common ancestor of Ascomycota, Basidiomycota, and Mucoromycota acquired COSase at about 790-670 Ma.IMPORTANCEThe biological assimilation of gaseous CO2 and N2 involves essential processes known as carbon fixation and nitrogen fixation, respectively. In this study, we found that the fungus Trichoderma harzianum strain THIF08 can grow with gaseous carbonyl sulfide (COS), the most abundant and ubiquitous gaseous sulfur compound, as a sulfur source. When the fungus grew in these conditions, COS was assimilated into sulfur metabolites, and the key enzyme of this assimilation process is COS hydrolase (COSase), which specifically degrades COS. Moreover, the pathway was more energy efficient than the typical sulfate assimilation pathway. COSase genes are widely distributed in Ascomycota, Basidiomycota, and Mucoromycota and also occur in some Chytridiomycota, indicating that COS assimilation is widespread in fungi. Phylogenetic analysis of these genes revealed that the acquisition of COSase in filamentous fungi was estimated to have occurred at about 790-670 Ma, around the time that filamentous fungi transitioned to a terrestrial environment.

Restricted internal diffusion weakens transpiration-photosynthesis coupling during heatwaves: Evidence from leaf carbonyl sulphide exchange.

Increasingly frequent and intense heatwaves threaten ecosystem health in a warming climate. However, plant responses to heatwaves are poorly understood. A key uncertainty concerns the intensification of transpiration when heatwaves suppress photosynthesis, known as transpiration-photosynthesis decoupling. Field observations of such decoupling are scarce, and the underlying physiological mechanisms remain elusive. Here, we use carbonyl sulphide (COS) as a leaf gas exchange tracer to examine potential mechanisms leading to transpiration-photosynthesis decoupling on a coast live oak in a southern California woodland in spring 2013. We found that heatwaves suppressed both photosynthesis and leaf COS uptake but increased transpiration or sustained it at non-heatwave levels throughout the day. Despite statistically significant decoupling between transpiration and photosynthesis, stomatal sensitivity to environmental factors did not change during heatwaves. Instead, midday photosynthesis during heatwaves was restricted by internal diffusion, as indicated by the lower internal conductance to COS. Thus, increased evaporative demand and nonstomatal limitation to photosynthesis act jointly to decouple transpiration from photosynthesis without altering stomatal sensitivity. Decoupling offered limited potential cooling benefits, questioning its effectiveness for leaf thermoregulation in xeric ecosystems. We suggest that adding COS to leaf and ecosystem flux measurements helps elucidate diverse physiological mechanisms underlying transpiration-photosynthesis decoupling.

Glycosidase-activated H2S donorsto enhance chemotherapy efficacy.

Hydrogen sulfide (H2S) plays a critical role in cancer biology. Herein, we developed a series of glycosidase-triggered hydrogen sulfide (H2S) donors by connecting sugar moieties (including glucose, galactose and mannose) to COS donors via a self-immolative spacer. In the presence of corresponding glycosidases, H2S was gradually released from these donors in PBS buffer with releasing efficiencies from 36 to 67 %. H2S release was also detected by H2S probe WSP-1 after treatment HepG2 cells with Man1. Cytotoxicities of these glycosylated H2S donors were evaluated against HepG2 by MTT assay. Among them, Man1 and Man2 exhibited an obvious reduction of cell viability in HepG2 cells, with cell viability as 37.6 % for 80 µM of Man. Consistently, significant apoptosis was observed in HepG2 cells after treatment with Man1 and Man2. Finally, We evaluated the potential of Man1 for combination therapy with doxorubicin. A synergistic effect was observed between Man1 and Doxorubicin in HepG2 and Hela cells. All these results indicated glycosidase-activated H2S donorshave promising potential for cancer therapy.

Cu/Biochar Bifunctional Catalytic Removal of COS and H2S:H2O Dissociation and CuO Anchoring Enhanced by Pyridine N.

Economic and environmentally friendly strategies are needed to promote the bifunctional catalytic removal of carbonyl sulfide (COS) by hydrolysis and hydrogen sulfide (H2S) by oxidation. N doping is considered to be an effective strategy, but the essential and intrinsic role of N dopants in catalysts is still not well understood. Herein, the conjugation of urea and biochar during Cu/biochar annealing produced pyridine N, which increased the combined COS/H2S capacity of the catalyst from 260.7 to 374.8 mg·g-1 and enhanced the turnover frequency of H2S from 2.50 × 10-4 to 5.35 × 10-4 s-1. The nucleophilic nature of pyridine N enhances the moderate basic sites of the catalyst, enabling the attack of protons and strong H2O dissociation. Moreover, pyridine N also forms cavity sites that anchor CuO, improving Cu dispersion and generating more reactive oxygen species. By providing original insight into the pyridine N-induced bifunctional catalytic removal of COS/H2S in a slightly oxygenated and humid atmosphere, this study offers valuable guidance for further C═S and C-S bond-breaking in the degradation of sulfur-containing pollutants.

Elucidating the Mechanism on the Transition-Metal Ion-Synergetic-Catalyzed Oxidation of SO2 with Implications for Sulfate Formation in Beijing Haze.

Currently, atmospheric sulfate aerosols cannot be predicted reliably by numerical models because the pathways and kinetics of sulfate formation are unclear. Here, we systematically investigated the synergetic catalyzing role of transition-metal ions (TMIs, Fe3+/Mn2+) in the oxidation of SO2 by O2 on aerosols using chamber experiments. Our results showed that the synergetic effect of TMIs is critically dependent on aerosol pH due to the solubility of Fe(III) species sensitive to the aqueous phase acidity, which is effective only under pH < 3 conditions. The sulfate formation rate on aerosols is 2 orders of magnitude larger than that in bulk solution and increases significantly on smaller aerosols, suggesting that such a synergetic-catalyzed oxidation occurs on the aerosol surface. The kinetic reaction rate can be described as R = k*[H+]-2.95[Mn(II)][Fe(III)][S(IV)] (pH ≤ 3.0). We found that TMI-synergetic-catalyzed oxidation is the dominant pathway of sulfate formation in Beijing when haze particles are very acidic, while heterogeneous oxidation of SO2 by NO2 is the most important pathway when haze particles are weakly acidic. Our work for the first time clarified the role and kinetics of TMI-synergetic-catalyzed oxidation of SO2 by O2 in haze periods, which can be parameterized into models for future studies of sulfate formation.

Single Droplet Tweezer Revealing the Reaction Mechanism of Mn(II)-Catalyzed SO2 Oxidation.

Sulfate aerosol is one of the major components of secondary fine particulate matter in urban haze that has crucial impacts on the social economy and public health. Among the atmospheric sulfate sources, Mn(II)-catalyzed SO2 oxidation on aerosol surfaces has been regarded as a dominating one. In this work, we measured the reaction kinetics of Mn(II)-catalyzed SO2 oxidation in single droplets using an aerosol optical tweezer. We show that the SO2 oxidation occurs at the Mn(II)-active sites on the aerosol surface, per a piecewise kinetic formulation, one that is characterized by a threshold surface Mn(II) concentration and gaseous SO2 concentration. When the surface Mn(II) concentration is lower than the threshold value, the reaction rate is first order with respect to both Mn(II) and SO2, agreeing with our traditional knowledge. But when surface Mn(II) concentration is above the threshold, the reaction rate becomes independent of Mn(II) concentration, and the reaction order with respect to SO2 becomes greater than unity. The measured reaction rate can serve as a tool to estimate sulfate formation based on field observation, and our established parametrization corrects these calculations. This framework for reaction kinetics and parametrization holds promising potential for generalization to various heterogeneous reaction pathways.

Chalcogen Noncovalent Interactions between Diazines and Sulfur Oxides in Supramolecular Circular Chains.

The noncovalent chalcogen interaction between SO2/SO3 and diazines was studied through a dispersion-corrected DFT Kohn-Sham molecular orbital together with quantitative energy decomposition analyses. For this, supramolecular circular chains of up to 12 molecules were built with the aim of checking the capability of diazine molecules to detect SO2/SO3 compounds within the atmosphere. Trends in the interaction energies with the increasing number of molecules are mainly determined by the Pauli steric repulsion involved in these σ-hole/π-hole interactions. But more importantly, despite the assumed electrostatic nature of the involved interactions, the covalent component also plays a determinant role in its strength in the involved chalcogen bonds. Noticeably, π-hole interactions are supported by the charge transfer from diazines to SO2/SO3 molecules. Interaction energies in these supramolecular complexes are not only determined by the S···N bond lengths but attractive electrostatic and orbital interactions also determine the trends. These results should allow us to establish the fundamental characteristics of chalcogen bonding based on its strength and nature, which is of relevance for the capture of sulfur oxides.

Long-term exposure to fine particulate matter constituents in relation to chronic kidney disease: evidence from a large population-based study in China.

The effects of long-term exposure to fine particulate matter (PM2.5) constituents on chronic kidney disease (CKD) are not fully known. This study sought to examine the association between long-term exposure to major PM2.5 constituents and CKD and look for potential constituents contributing substantially to CKD. This study included 81,137 adults from the 2018 to 2019 baseline survey of China Multi-Ethnic Cohort. CKD was defined by the estimated glomerular filtration rate. Exposure concentration data of 7 major PM2.5 constituents were assessed by satellite remote sensing. Logistic regression models were used to estimate the effect of each PM2.5 constituent exposure on CKD. The weighted quantile sum regression was used to estimate the effect of mixed exposure to all constituents. PM2.5 constituents had positive correlations with CKD (per standard deviation increase), with ORs (95% CIs) of 1.20 (1.02-1.41) for black carbon, 1.27 (1.07-1.51) for ammonium, 1.29 (1.08-1.55) for nitrate, 1.20 (1.01-1.43) for organic matter, 1.25 (1.06-1.46) for sulfate, 1.30 (1.11-1.54) for soil particles, and 1.63 (1.39-1.91) for sea salt. Mixed exposure to all constituents was positively associated with CKD (1.68, 1.32-2.11). Sea salt was the constituent with the largest weight (0.36), which suggested its importance in the PM2.5-CKD association, followed by nitrate (0.32), organic matter (0.18), soil particles (0.10), ammonium (0.03), BC (0.01). Sulfate had the least weight (< 0.01). Long-term exposure to PM2.5 sea salt and nitrate may contribute more than other constituents in increasing CKD risk, providing new evidence and insights for PM2.5-CKD mechanism research and air pollution control strategy.

Catalytic co-combustion of biomass and brown coal in a fluidized bed: Economic and environmental benefits.

The work is devoted to the study of combustion of brown coal, pine sawdust, and their mixtures in a fluidized bed of catalyst at 600-750°Ð¡. It is shown that an increase in the content of sawdust in a mixture with brown coal leads to an increase in the burnout degree of solid fuel from 94.4% to 99.9%, while the emission of greenhouse gases in the form of CO2 CO and NOx is reduced (CO2 from the biomass is not included in the balance). The high content of alkaline earth metal oxides (CaO and MgO) in the mineral part of brown coal, sawdust, and their mixtures eliminates the emission of sulfur oxides and the slagging of heat-exchange surfaces during the combustion in a fluidized bed of catalyst. The optimal temperature, when the highest burnout degree of the above fuels is achieved in the combustion is 750°Ð¡. It is also shown that the increase in temperature and the content of sawdust in the composition of the fuel mixtures has a positive effect on the economic and environmental process indicators.

Fluorosulfate as a Latent Sulfate in Peptides and Proteins.

Sulfation widely exists in the eukaryotic proteome. However, understanding the biological functions of sulfation in peptides and proteins has been hampered by the lack of methods to control its spatial or temporal distribution in the proteome. Herein, we report that fluorosulfate can serve as a latent precursor of sulfate in peptides and proteins, which can be efficiently converted to sulfate by hydroxamic acid reagents under physiologically relevant conditions. Photocaging the hydroxamic acid reagents further allowed for the light-controlled activation of functional sulfopeptides. This work provides a valuable tool for probing the functional roles of sulfation in peptides and proteins.

Exposomic Biomonitoring of Polyphenols by Non-Targeted Analysis and Suspect Screening.

Polyphenols, prevalent in plants and fungi, are investigated intensively in nutritional and clinical settings because of their beneficial bioactive properties. Due to their complexity, analysis with untargeted approaches is favorable, which typically use high-resolution mass spectrometry (HRMS) rather than low-resolution mass spectrometry (LRMS). Here, the advantages of HRMS were evaluated by thoroughly testing untargeted techniques and available online resources. By applying data-dependent acquisition on real-life urine samples, 27 features were annotated with spectral libraries, 88 with in silico fragmentation, and 113 by MS1 matching with PhytoHub, an online database containing >2000 polyphenols. Moreover, other exogenous and endogenous molecules were screened to measure chemical exposure and potential metabolic effects using the Exposome-Explorer database, further annotating 144 features. Additional polyphenol-related features were explored using various non-targeted analysis techniques including MassQL for glucuronide and sulfate neutral losses, and MetaboAnalyst for statistical analysis. As HRMS typically suffers a sensitivity loss compared to state-of-the-art LRMS used in targeted workflows, the gap between the two instrumental approaches was quantified in three spiked human matrices (urine, serum, plasma) as well as real-life urine samples. Both instruments showed feasible sensitivity, with median limits of detection in the spiked samples being 10-18 ng/mL for HRMS and 4.8-5.8 ng/mL for LRMS. The results demonstrate that, despite its intrinsic limitations, HRMS can readily be used for comprehensively investigating human polyphenol exposure. In the future, this work is expected to allow for linking human health effects with exposure patterns and toxicological mixture effects with other xenobiotics.

Efficient NOx Reduction against Alkali Poisoning over a Self-Protection Armor by Fabricating Surface Ce2(SO4)3 Species: Comparison to Commercial Vanadia Catalysts.

Resolving severe deactivation by alkali metals for selective catalytic reduction of NOx with NH3 (NH3-SCR) is challenging. Herein, surface Ce2(SO4)3 species as a self-protection armor originally exhibited antipoisoning of potassium over ceria-based catalysts. The self-protection armor was also effective for other alkali (Na), alkali-earth (Ca), and heavy (Pb) metals, considerably resolving the deactivation of ceria-based SCR catalysts in practical applications. The catalytic activity tests indicated that the presence of ∼0.8 wt % potassium did not deactivate sulfated CeO2 catalysts, yet commercial V2O5-WO3/TiO2 catalysts almost lost the NOx conversions. Potassium preferably bonded with surface sulfates to form K2SO4 accompanied with the majority of surface Ce2(SO4)3 over sulfated CeO2 catalysts, but preferably coupled with active vanadia to generate inactive KVO3 species over V2O5-WO3/TiO2 catalysts. Such an active Ce2(SO4)3 species facilitated the adsorption and reactivity of NH3 and NOx, enabling ceria catalysts to maintain high catalytic efficiency in the presence of potassium. Conversely, the introduction of potassium into V2O5-WO3/TiO2 catalysts caused a considerable loss of surface acidity, hindering catalyst reactivity during the SCR reaction. The self-protection armor of Ce2(SO4)3 species may open a promising pathway to develop efficient ceria-based SCR catalysts with strong antipoisoning ability.

Strengthening Fe(II)/Fe(III) Dynamic Cycling by Surface Sulfation to Achieve Efficient Electrochemical Uranium Extraction at Ultralow Cell Voltage.

Electrochemically mediated Fe(II)/Fe(III) redox-coupled uranium extraction can efficiently reduce the cell voltage of electrochemical uranium extraction (EUE). How to regulate the surface structure to enhance the uranium acyl ion adsorption capacity and strengthen the Fe(II)/Fe(III) redox cycle process is crucial for EUE. In this work, we developed surface sulfated nanoreduced iron (S-NRI) for EUE and exhibited improved properties for EUE at an ultralow cell voltage (-0.1 V). Compared with a nanoreduced iron (NRI) adsorbent, S-NRI displayed faster electrochemical extraction kinetics properties and higher extraction efficiency and capacity for uranium. In a more complex seawater electrolyte containing uranyl ion concentration ranging from 1 to 20 ppm, the removal efficiency could reach almost ∼100% after EUE for 24 h. At a higher 50 ppm uranium acyl ion concentration in a seawater electrolyte, S-NRI exhibited higher extraction capacity (755.03 mg/g), which is better than 528.53 mg/g of NRI at a cell voltage of -0.1 V. Outstanding EUE property could be attributed to the fact that sulfate species (M-SO42-) on the S-NRI surface not only enhanced selective adsorption of uranyl ions but also strengthened the Fe(II)/Fe(III) redox cycle, which accelerated electron transfer between Fe(II) and U(VI), promoted the regeneration of Fe(II) active sites, and finally enhanced the EUE property.

Insight into the Mechanism and Kinetics of the Heterogeneous Reaction between SO2 and NO2 on Diesel Black Carbon under Light Irradiation.

The heterogeneous oxidation of SO2 by NO2 has been extensively proposed as an important pathway of sulfate production during haze events in China. However, the kinetics and mechanism of oxidation of SO2 by NO2 on the surface of complex particles remain poorly understood. Here, we systematically explore the mechanism and kinetics of the reaction between SO2 and NO2 on diesel black carbon (DBC) under light irradiation. The experimental results prove that DBC photochemistry can not only significantly promote the heterogeneous reduction of NO2 to produce HONO via transferring photoinduced electrons but also indirectly promote OH radical formation. These reduction products of NO2 as well as NO2 itself greatly promote the heterogeneous oxidation of SO2 on DBC. NO2 oxidation, HONO oxidation, and the surface photo-oxidation process are proven to be three major surface oxidation pathways of SO2. The kinetics results indicate that the surface photooxidation pathway accounts for the majority of the total SO2 uptake (∼63%), followed by the HONO oxidation pathway (∼27%) and direct oxidation by NO2 (∼10%). This work highlights the significant synergistic roles of DBC, NO2, and light irradiation in enhancing the atmospheric oxidation capacity and promoting the heterogeneous formation of sulfate.

Oxalate-Promoted SO2 Uptake and Oxidation on Iron Minerals: Implications for Secondary Sulfate Aerosol Formation.

Mineral dust serves as a significant source of sulfate aerosols by mediating heterogeneous sulfur dioxide (SO2) oxidation in the atmosphere. Given that a considerable proportion of small organic acids are deposited onto mineral dust via long-range transportation, understanding their impact on atmospheric SO2 transformation and sulfate formation is of great importance. This study investigates the effect of oxalate on heterogeneous SO2 uptake and oxidation phenomenon by in situ FTIR, theoretical calculation, and continuous stream experiments, exploiting hematite (Fe2O3) as an environmental indicator. The results highlight the critical role of naturally deposited oxalate in mononuclear monodentate coordinating surface Fe atoms of Fe2O3 that enhances the activation of O2 for oxidizing SO2 into sulfate. Meanwhile, oxalate increases the hygroscopicity of Fe2O3, facilitating H2O dissociation into reactive hydroxyl groups and further augmenting the SO2 uptake capacity of Fe2O3. More importantly, other conventional iron minerals, such as goethite and magnetite, as well as authentic iron-containing mineral dust, exhibit similar oxalate-promoted sulfate accumulation behaviors. Our findings suggest that oxalate-assisted SO2 oxidation on iron minerals is one of the important contributors to secondary sulfate aerosols, especially during the nighttime with high relative humidity.

Sialylation and Sulfation of Anionic Glycoconjugates Are Common in the Extracellular Polymeric Substances of Both Aerobic and Anaerobic Granular Sludges.

Anaerobic and aerobic granular sludge processes are widely applied in wastewater treatment. In these systems, microorganisms grow in dense aggregates due to the production of extracellular polymeric substances (EPS). This study investigates the sialylation and sulfation of anionic glyconconjugates in anaerobic and aerobic granular sludges collected from full-scale wastewater treatment processes. Size exclusion chromatography revealed a wide molecular weight distribution (3.5 to >5500 kDa) of the alkaline-extracted EPS. The high-molecular weight fraction (>5500 kDa), comprising 16.9-27.4% of EPS, was dominant with glycoconjugates. Mass spectrometry analysis and quantification assays identified nonulosonic acids (NulOs, e.g., bacterial sialic acids) and sulfated groups contributing to the negative charge in all EPS fractions. NulOs were predominantly present in the high-molecular weight fraction (47.2-84.3% of all detected NulOs), while sulfated glycoconjugates were distributed across the molecular weight fractions. Microorganisms, closely related to genera found in the granular sludge communities, contained genes responsible for NulO and sulfate group synthesis or transfer. The similar distribution patterns of sialylation and sulfation of the anionic glycoconjugates in the EPS samples indicate that these two glycoconjugate modifications commonly occur in the EPS of aerobic and anaerobic granular sludges.

Ionic Strength Enhances the Multiphase Oxidation Rate of Sulfur Dioxide by Ozone in Aqueous Aerosols: Implications for Sulfate Production in the Marine Atmosphere.

Multiphase oxidation of sulfur dioxide (SO2) by ozone (O3) in alkaline sea salt aerosols is an important source of sulfate aerosols in the marine atmosphere. However, a recently reported low pH of fresh supermicron sea spray aerosols (mainly sea salt) would argue against the importance of this mechanism. Here, we investigated the impact of ionic strength on the kinetics of multiphase oxidation of SO2 by O3 in proxies of aqueous acidified sea salt aerosols with buffered pH of ∼4.0 via well-controlled flow tube experiments. We find that the sulfate formation rate for the O3 oxidation pathway proceeds 7.9 to 233 times faster under high ionic strength conditions of 2-14 mol kg-1 compared to the dilute bulk solutions. The ionic strength effect is likely to sustain the importance of multiphase oxidation of SO2 by O3 in sea salt aerosols in the marine atmosphere. Our results indicate that atmospheric models should consider the ionic strength effects on the multiphase oxidation of SO2 by O3 in sea salt aerosols to improve the predictions of the sulfate formation rate and the sulfate aerosol budget in the marine atmosphere.