Sulfate Oxygen Research Articles

Hydrogen Peroxide-Assisted Alkaline Defluorination of the Fumigant and Potent Greenhouse Gas, Sulfuryl Fluoride: Hydrogen Peroxide as a Nucleophilic Reagent.

Sulfuryl fluoride (SO2F2, SF) is an effective and increasingly popular fumigant for treating buildings and commodities in international trade but has come under scrutiny as a potent greenhouse gas. Passage of vent gases through an alkaline spray has been proposed for scrubbing SF, but base hydrolysis is insufficiently fast and generates equal yields of fluoride and fluorosulfate, the latter of unknown environmental hazard. We report here that alkaline hydrogen peroxide (H2O2) markedly accelerates SF removal and gives nearly quantitative yield of fluoride, with fluorosulfate produced in less than 3.5% yield. The other major products are sulfate, peroxymonosulfate, and oxygen. The oxidation state of S was unchanged. Hydroxyl and superoxide radical scavengers had no effect on the rate. The reaction proceeds by sequential nucleophilic displacement of fluoride by hydroperoxide ion (HO2-) to form a transient diperoxysulfate species that rapidly undergoes intramolecular redox rearrangement to give sulfate and singlet oxygen. Peroxymonosulfate, produced through side reactions, can fully defluorinate SF as well, although more slowly. Two new peaks were detected in the 19F-NMR spectrum corresponding to intermediates. Fluoride can be removed conventionally, and the other products are innocuous or short-lived. Thus, H2O2-assisted alkaline defluorination promises to be an effective method for scrubbing spent SF fumes and preventing SF from reaching the atmosphere. This study highlights the benefits of H2O2 and peroxymonosulfate as nucleophiles in remediation chemistry.

Hydrogenimonas leucolamina sp. nov., a hydrogen- and sulphur-oxidizing mesophilic chemolithoautotroph isolated from a deep-sea hydrothermal vent chimney at the Suiyo Seamount in the Western Pacific Ocean.

A novel mesophilic bacterium, strain SS33T, was isolated from a deep-sea hydrothermal vent chimney at Suiyo Seamount, Izu-Bonin Arc, Western Pacific Ocean. The cells of strain SS33T were motile short rods with a single polar flagellum. The growth of strain SS33T was observed at the temperature range between 33 and 55 °C (optimum growth at 45 °C), at the pH range between 5.0 and 7.1 (optimum growth at pH 6.0) and in the presence of between 2.0 and 4.5% (w/v) NaCl [optimum growth at 3.5% (w/v)]. Strain SS33T was a facultative anaerobic chemolithoautotroph using molecular hydrogen and elemental sulphur as the sole electron donor. Nitrate, nitrous oxide, sulphate, elemental sulphur and molecular oxygen were capable of serving as the sole electron acceptor. Phylogenetic analysis based on 16S rRNA gene sequences placed strain SS33T in the genus Hydrogenimonas belonging to the class Epsilonproteobacteria. The closely related species of strain SS33T were Hydrogenimonas urashimensis SSM-Sur55T (95.96%), Hydrogenimonas thermophila EP1-55-1%T (95.75%) and Hydrogenimonas cancrithermarum ISO32T (95.24%). According to the taxonomic and physiological characteristics, it is proposed that strain SS33T was classified into a novel species of genus Hydrogenimonas, Hydrogenimonas leucolamina sp. nov., with SS33T (=JCM 39184T =KCTC 25253T) as the type strain. Furthermore, the genome comparison of Epsilonproteobacteria revealed that their [NiFe] hydrogenase genes belonging to Group 1b could be divided into two phylogenetic lineages and suggested that the reverse gyrase gene has been lost after division to the genus Hydrogenimonas.

Cobalt-substituted porous calcium copper titanate electrodes for paracetamol degradation by an electro-oxidation/peroxymonosulfate system

Developing cobalt-substituted perovskite electroactive membranes with an efficient Co/Cu combination mode is an important environmental challenge for removing drugs via peroxymonosulfate (PMS) activation. In this work, cobalt (Co)-substituted calcium copper titanatewas synthesized with an easy ball milling process and used as an anode in electro-oxidation in the presence of PMS for paracetamol degradation. The Co-CCTO anode with a Co ratio of 0.5 showed the highest removal efficiency (100 % of 10 ppm paracetamol after 180 min) due to the increase of the active sites and the appearance of the Co2+/Co3+ cycle that accelerates the charge transfer with Co incorporation into the lattice. Scavenger experiments showed that sulfate radicals (SO4̇−), oxygen radicals (O2̇-), hydroxyl radicals (̇OH), and singlet oxygen (1O2) were generated in the electro-oxidation-PMS reaction system and that SO4̇−, 1O2, and O2̇- were the dominant active radicals. The toxicity tests with Vibrio fischeri confirmed paracetamol mineralization and decomposition and the elimination of harmful by-products. It is crucial to explore the substitution of CCTO with different metal dopants in order to optimize the membrane performance and overcome the limitations associated with cobalt substitution.

Effect of pyrite particle size on the denitrification performance of autotrophic or split-mixotrophic bioreactors supported by pyrite/polycaprolactone.

In this study, a pyrite-based autotrophic denitrification (PAD) system, a polycaprolactone (PCL)-supported heterotrophic denitrification (PHD) system, and a pyrite+PCL-based split-mixotrophic denitrification (PPMD) system were constructed. The pyrite particle size was controlled in 1-3, 3-5, or 5-8mm in both the PAD and PPMD systems to investigate the effect of pyrite particle size on the denitrification performance of autotrophic or split-mixotrophic bioreactors. It was found that the PAD system achieved the best denitrification efficiency with an average removal rate of 98.98% in the treatment of 1- to 3-mm particle size, whereas it was only 19.24% in the treatment of 5- to 8-mm particle size. At different phases of the whole experiment, the nitrate removal rates of both the PHD and PPMD systems remained stable at a high level (>94%). Compared with the PAD or PHD system, the PPMD system reduced the concentrations of sulfate and chemical oxygen demand in the final effluent efficiently. The interconnection network diagram explained the intrinsic metabolic pathways of nitrogen, sulfur, and carbon in the three denitrification systems at different phases. In addition, the microbial community analysis showed that the PPMD system was beneficial for the enrichment of Firmicutes. Finally, the impact mechanism of pyrite particle size on the performance of the PPMD system was proposed. PRACTITIONER POINTS: The reduction of pyrite particle size was beneficial for improving the efficiency of the PAD process. The change in particle size had an effect on NO2 --N accumulation in the PAD system. The accumulation of NH4 +-N in the PPMD system increased with the decrease in particle size. The reduction of pyrite particle size increased the production of SO4 2- in the PAD and PPMD systems. The correlations among the effluent indicators of the PAD and PPMD systems could be well explained.

Seasonal variation of surface water quality and streamflow in Rispana: A tributary of Ganges river, India

AbstractTo evaluate the seasonal changes in quality and quantity of river Rispana (a tributary of river Ganges—Dehradun region of India) water quality index (WQI) was calculated at four major locations by using the weighted arithmetic method. Sixteen samples in all were taken throughout the pre‐monsoon (April 2022), monsoon (July 2022), post‐monsoon (November 2022), and the Winter season (January 2023). The major parameters, namely, temperature, dissolved oxygen (DO), pH, electrical conductivity (EC), and total dissolved solids (TDS), E‐coliform, sulphate, total alkalinity (TA), total hardness (TH), and biochemical oxygen demand (BOD) were considered for calculation of WQI. The WQI varied from minimum 44.53 (good) at site 1 – Kairwaan Gaon during monsoon season to maximum 302.69 (unfit for drinking) at site 4 – Mothrowala during the pre‐monsoon period. In 75% samples quality of water was unfit for domestic purpose and the contributing factors are DO, BOD, and Coliform which exceeds permissible limit in all samples. The major factors attributed for decline in the Rispana water quality are discharge of sewage, commercial sites effluent, and urban runoff. Pre‐monsoon, monsoon, post‐monsoon, and winter had average total coliform levels of 1849.6, 2419.6, 2419.6, and 1546.25, respectively, in MPN units. The average value of E‐coli for the four season vary from 1306.8 to 1888.1 MPN. The pollution load (physico‐chemical parameters and bacteriological factors) increases as the river Rispana flows to downstream in urban locations. Streamflow was observed as very lean except monsoon season (~1500 cfs) due to more extraction of Rispana's fresh water in upstream and unplanned changes in its catchment basin; thus establishes an extensive decline in availability of fresh water sources (Domestic use) in downstream Dehradun city area. In monsoon season, more streamflow (rain water influx) maintains the WQI also in good‐moderate category. The land use/land cover – LULC analysis in Rispana basin area, depicted 71% enhancement in urbanization (24.16%–41.55%) takes place in 15 years’ span (2003–2017). The study establishes the potential causes (natural and anthropogenic) for Rispana deterioration and provides a baseline (quality index) for aquatic and ecological rejuvenation of its watershed by executing a proper management strategy with people participation. This work contributes discernments for effective water resource management to address the smart city objectives and sustainable development goal‐SDG:6, urban and municipal authorities must take cognizance for revival of this domestic water resource.

Similarities in Storage and Transport of Sulfate in Forested and Suburban Watersheds, Despite Anthropogenically Elevated Suburban Sulfate

AbstractSulfate is a potential pollutant and important nutrient linked with the nitrogen, carbon, and phosphorus cycles. The importance of different anthropogenic sulfate sources in suburban streams (septic systems, fertilizer, road salt, and infrastructure) is uncertain, and the temporal dynamics of stream export sparsely documented. We study sources and export dynamics of sulfate in suburban and forested headwater catchments. Stream baseflow discharge and sulfate concentrations were strongly positively correlated in both watersheds with the highest values in spring. Suburban concentrations and fluxes (2.48–7.5 mg/L or 25.8–78.1 μM, 16.6 kg/ha/yr) were consistently higher than forested (0.56–2.78 mg/L or 5.8–28.9 μM, 5 kg/ha/yr). Following precipitation, sulfate concentrations in both forested and suburban streams increased to concentrations above pre‐storm values and remained high after peak discharge. These dynamics suggest that both catchments have a large pool of sulfate that can be mobilized under wet conditions. Ridge‐top forest soil samples contained 210 kg/ha stored, extractable sulfate. Current atmospheric sulfate deposition rates (5–7 kg/ha/yr) are approximately in balance with sulfate export in the forested stream. In the suburban watershed, we estimated septic fields contribute up to 11 kg/ha/yr (about half from surfactants) and lawn care up to 4.3 kg/ha/yr and are the most likely sources of elevated stream sulfate. Sulfate sulfur (4.9–5.8‰ forested; 6.1–7.0‰ suburban) and oxygen isotope values (0.7–2.0‰ forested; −0.1–4.1‰ suburban) are consistent with this interpretation, but do not provide strong corroboration due to large variation and overlap in estimated source values.

The investigation of ion association characteristics in lanthanum sulfate solution by the density functional theory and molecular dynamics simulations

The ion association behavior in aqueous lanthanum sulfate solutions was investigated using density functional theory (DFT). The structures and properties of [La(SO4)m·(H2O)n](3–2m) clusters, where m = 1 to 3 and n = 1 to 9, were examined at the PBE0/6-311+G(d, p) level. The results show that Lanthanum sulfate hydrated clusters exist in the aqueous solution's microscopic state of contact ion pairs (CIP). [La(SO4)(H2O)n]+ and [La(SO4)2·(H2O)n]-, and [La(SO4)3·(H2O)n]3- clusters approximately reach the saturation of the first water shell at n = 7 and 6 and 3. [La(SO4)2·(H2O)6]- and [La(SO4)3·(H2O)3]3- clusters have lower binding energy than [LaSO4·(H2O)n]+. This indicates that lanthanum sulfate tends to aggregate in an aqueous solution. Compared to the gas-phase cluster structures, the distance of R(La–O)H2O expands in the PCM solvent model, while R(La–O)SO4 contracts. The hydration energy of LaSO4·(H2O)7, La(SO4)2·(H2O)6, and La(SO4)3·(H2O)3 were −76.5, −54.1 and −332.0 kcal/mol, respectively. The molecular dynamics simulation results show that La is more inclined to coordinate with sulfate's oxygen than water's oxygen, and the coordination number of water around La3+ is 6.075. These results are consistent with the calculated results by DFT.

Arctic Permafrost Thawing Enhances Sulfide Oxidation

AbstractPermafrost degradation is altering biogeochemical processes throughout the Arctic. Thaw‐induced changes in organic matter transformations and mineral weathering reactions are impacting fluxes of inorganic carbon (IC) and alkalinity (ALK) in Arctic rivers. However, the net impact of these changing fluxes on the concentration of carbon dioxide in the atmosphere (pCO2) is relatively unconstrained. Resolving this uncertainty is important as thaw‐driven changes in the fluxes of IC and ALK could produce feedbacks in the global carbon cycle. Enhanced production of sulfuric acid through sulfide oxidation is particularly poorly quantified despite its potential to remove ALK from the ocean‐atmosphere system and increase pCO2, producing a positive feedback leading to more warming and permafrost degradation. In this work, we quantified weathering in the Koyukuk River, a major tributary of the Yukon River draining discontinuous permafrost in central Alaska, based on water and sediment samples collected near the village of Huslia in summer 2018. Using measurements of major ion abundances and sulfate () sulfur (34S/32S) and oxygen (18O/16O) isotope ratios, we employed the MEANDIR inversion model to quantify the relative importance of a suite of weathering processes and their net impact on pCO2. Calculations found that approximately 80% of in mainstem samples derived from sulfide oxidation with the remainder from evaporite dissolution. Moreover, 34S/32S ratios, 13C/12C ratios of dissolved IC, and sulfur X‐ray absorption spectra of mainstem, secondary channel, and floodplain pore fluid and sediment samples revealed modest degrees of microbial sulfate reduction within the floodplain. Weathering fluxes of ALK and IC result in lower values of pCO2 over timescales shorter than carbonate compensation (∼104 yr) and, for mainstem samples, higher values of pCO2 over timescales longer than carbonate compensation but shorter than the residence time of marine (∼107 yr). Furthermore, the absolute concentrations of and Mg2+ in the Koyukuk River, as well as the ratios of and Mg2+ to other dissolved weathering products, have increased over the past 50 years. Through analogy to similar trends in the Yukon River, we interpret these changes as reflecting enhanced sulfide oxidation due to ongoing exposure of previously frozen sediment and changes in the contributions of shallow and deep flow paths to the active channel. Overall, these findings confirm that sulfide oxidation is a substantial outcome of permafrost degradation and that the sulfur cycle responds to permafrost thaw with a timescale‐dependent feedback on warming.

Abiotic aerobic oxidation pathways of stibnite revealed by oxygen and sulfur isotope systematics of sulfate

The environmental threat posed by stibnite is an important geoenvironmental issue of current concern. To better understand stibnite oxidation pathways, aerobic abiotic batch experiments were conducted in aqueous solution with varying δ18OH2O value at initial neutral pH for different lengths of time (15-300 days). The sulfate oxygen and sulfur isotope compositions as well as concentrations of sulfur and antimony species were determined. The sulfur isotope fractionation factor (Δ34SSO4-stibnite) values decreased from 0.8‰ to -2.1‰ during the first 90 days, and increased to 2.6‰ at the 180 days, indicating the dominated intermediate sulfur species such as S2O32−, S0, and H2S (g) involved in Sb2S3 oxidation processes. The incorporation of O into sulfate derived from O2 (∼100%) indicated that the dissociated O2 was only directly adsorbed on the stibnite-S sites in the initial stage (0-90 days). The proportion of O incorporation into sulfate from water (27%-52%) increased in the late stage (90-300 days), which suggested the oxidation mechanism changed to hydroxyl attack on stibnite-S sites promoted by nearby adsorbed O2 on stibnite-Sb sites. The exchange of oxygen between sulfite and water may also contributed to the increase of water derived O into SO42−. The new insight of stibnite oxidation pathway contributes to the understanding of sulfide oxidation mechanism and helps to interpret field data.

Unveiling the Nexus the link between water quality index and phthalic acid ester concentrations in Tigris River

Monitoring water quality in an aquatic system is a crucial objective in pursuing sustainable development, despite the challenges posed by water scarcity and the impact of climate change. The objective of the present study was to examine the water quality of the Tigris River along its course from the point of entry into Baghdad city to its exit, particularly in the presence of Phthalic Acid Esters (PAEs). In both dry and wet seasons and from five sites of the river, nine environmental factors (Turbidity, Total dissolved solids, pH, dissolved oxygen, Chloride, nitrate, phosphate, sulfate, and Biological oxygen demand) and three PAEs (di-n-butyl phthalate (DBP), di-isononyl phthalate (DiNP), and di-2-ethyl hexyl phthalate (DEHP)) were investigated. Results revealed that the river has high levels of turbidity and Total dissolved solids, slightly alkaline, and well-aerated (dissolved oxygen >7 mg/L). Chloride, nitrate, phosphate, and sulfate values varied between seasons, as high values were recorded in the wet season. Biochemical oxygen demand levels were higher during the dry season. The highest value of total PAEs (2.20 μg/L) was observed during the dry season, and the lowest value was in the wet season (1.16 μg/L). The HQ results revealed that the river was ranked as a moderate risk area. However the water quality index and environmental risk index classified the water quality as a poor category, with a high-risk score in the study sites within Baghdad city. Therefore, despite the acceptable limit of PAEs in the river's water (<3 μg/L), its presence is an early alarm to withdraw attention to its environmental risk. These findings highlight the need for appropriate measures to control and remove pollutants to ensure a safe and healthy water supply in the Tigris River.

Carbonate-associated sulfate as an archive of sulfur and oxygen stable isotope composition of seawater sulfate: Evidence from reef carbonate rocks of the southern South China Sea

Carbonate-associated sulfate (CAS) is a useful proxy for the reconstruction of the isotopic composition of ancient seawater sulfate, archiving information on the global sulfur cycle, Earth's surface redox evolution, and biological activity. The CAS proxy is possibly compromised by early diagenetic alteration, which may cause secondary inhomogeneities in the isotopic composition of pore water sulfate achieved in the form of CAS. However, the effects of early diagenesis on the retention of primary δ34S signals of CAS in reef carbonates are not well understood, and it is unknown whether reef carbonate deposits can faithfully record the coeval isotopic composition of marine sulfate. To provide new constraints on the resilience of CAS isotopic signatures of reef carbonate, we have measured and analyzed CAS content and CAS isotopic composition of reef carbonates from the Meiji Atoll (well NK-1) of the South China Sea, representing carbonates affected by meteoric and marine diagenesis including dolomitization. CAS contents were found to decrease rapidly during meteoric and marine diagenesis, with minimum CAS contents caused by prolonged subaerial exposure. Despite low contents, the corresponding δ34SCAS values were found to vary within a narrow range from 21.5 to 24.1‰, compared to values of 20.9 to 22.7‰ of coeval barite, suggesting that the original δ34SCAS values are preserved and largely unaffected by recrystallization. However, δ18OCAS values were found to vary widely, ranging from 7.1‰ to 15.0‰, only recording the same oxygen isotope signal as coeval marine barite for reef carbonates younger than 5 Ma. Our data reveal that reef carbonates can be used as an archive of paleoceanic change, faithfully tracking δ34S changes in coeval seawater regardless of whether reef carbonates underwent recrystallization, including dolomitization. In contrast to sulfur isotopes, the oxygen isotope composition of CAS is more susceptible to alteration during diagenesis. Overall, this study provides new insight for the future reconstruction of the sulfate sulfur and oxygen isotope record of ancient seawater.

Development of biochar supported NiFe2O4 composite for peroxydisulfate (PDS) activation to effectively remove moxifloxacin from wastewater

Waste durian peels derived-biochar (DP-BC) supported magnetic nickel ferrite (NiFe2O4) was successfully synthesized at various composite ratios of 5, 10, 15, 20, 25 and 30% between NiFe2O4 NPs and DP-BC. The nanocomposites (DP-BC@NiFe2O4) were then applied to activate peroxydisulfate (PDS) for the removal of moxifloxacin (MFX) from wastewater. The textural, morphology, and structure properties of the DP-BC@NiFe2O4 were systematically characterized. The initial catalytic activity of DP-BC@NiFe2O4 was assessed through the MFX degradation efficiency in the DP-BC@NiFe2O4/PDS systems. The results showed that the pyrolysis temperature of 350 °C gave the highest removal of MFX in the PDS system activated by DP-BC. Besides, loading 15% of NiFe2O4 onto DP-BC gave the highest degradation efficiency of MFX in the DP-BC@NiFe2O4/PDS system with a MFX removal of 88.6% for 90 min reaction. Based on catalyst's property data and quenching tests using different scavengers, the primary mechanisms of MFX degradation by DP-BC@NiFe2O4/PDS system were through both radical and non-radical pathways thanks to effective formation of reactive oxygen species (ROS), consisting of hydroxyl (*OH), sulfate (⁎SO4−), superoxide (⁎O2) and singlet oxygen (1O2) during catalytic reactions. Among ROS, the singlet oxygen (1O2) participated mainly in MFX degradation. The increased formation of ROS in the DP-BC@NiFe2O4/PDS system was due to enhanced PDS activation by the redox reaction a couple of Fe3/Fe2+ and Ni3+/Ni2+ and electron transfer of DP-BC biochar's abundant oxygen-containing surface functional groups. Therefore, it is confirmed that BC@ NiFe2O4 exhibited good catalytic activity in the activation of PDS to effectively remove MFX from wastewater.

Anthropogenic activities and COVID-19 effects on natural water bodies: Arroyo Seco’s case

Concerns about pollution in Arroyo Seco, an important natural water body in the Monterrey Metropolitan Area, have been reported due to possible wastewater discharges and solid waste mismanagement, turning the river into a potential public health hazard in the context of the COVID-19 pandemic. As a result, a volunteer clean-up campaign denominated “Arroyo Vivo” has been promoted by Distrito Tec and the Campana-Altamira initiative. To aid in the efforts, ammonium, nitrates, nitrites, and sulfate concentrations, total solids, and total organic matter were measured in parallel with SARS-CoV-2 detection and quantification in river water samples. Compared with applicable regulations (NOM-001-SEMARNAT-2021, NOM-127-SSA1-2021), total suspended solid levels (55-365 mg/L) were found above the maximum limit (84 mg/L), while ammonium (0.0175-0.198 mg/L), nitrite (0.0585-0.169 mg/L), nitrate (1.065-3.285 mg/L), sulfate (91.2-111 mg/L), and chemical oxygen demand (16.95-43.1 mg/L) were consistently below the maximum limits (0.50, 0.90, 11.00, 84.00, 400.00, and 100.00 mg/L, respectively), showing that no large-scale wastewater discharges had taken place in Arroyo Seco. However, SARS-CoV-2 genetic material was detected at three sampling sites, indicating some degree of sewage leakage and inadequate management of solid waste containing respiratory fluids of infected patients. While reports indicate that water bodies are not sources of SARS-CoV-2 infection in surrounding populations, it proves that waste disposal policies must be enforced more strictly to ensure water quality and environmental protection towards sustainable development. Nonetheless, continued efforts to screen concerning contaminants are still needed to fully assess the environmental status of the stream and propose relevant public policy.

Heterogeneous sulfide reoxidation buffered oxygen release in the Ediacaran Shuram ocean

Ediacaran (∼635–539 Ma) carbonate rocks record the largest negative carbonate-carbon isotope excursion in Earth history, termed the Shuram Excursion (SE). This event has been attributed to anaerobic oxidation of dissolved organic carbon as a result of enhanced weathering inputs of sulfate to the ocean during the amalgamation of Gondwana. However, the effect of carbon–sulfur cycle interplay on the net redox state of the ocean–atmosphere system remains unclear, impeding our understanding of the co-evolution of life and the environment during the Ediacaran. Here, we generate high-resolution records of paired sulfate sulfur and oxygen isotopes, in addition to phosphorus concentrations, for the SE interval in South Australia (Parachilna Gorge) and South China (Jiulongwan and Xiang’erwan sections, Three Gorges), and we evaluate these data in the context of COPSE biogeochemical model simulations to assess net long-term redox changes. Our results support widespread H2S reoxidation in shelf areas during the SE, which would have buffered the net release of oxygen sourced from the burial of organic carbon and pyrite. Varying degrees of H2S reoxidation on different cratons likely contributed significantly to high spatial heterogeneity in both local oceanic redox state and nutrient availability, which characterized local oxygen-deficient conditions in an overall oxygenated SE shelf ocean, and likely affected the distribution of the Ediacaran Biota. Our study highlights the important role of H2S reoxidation in the coevolution of marine redox conditions and complex life during the critical Ediacaran period.

Changing Sub‐Surface Chemistry Resulting From a 26‐Million‐Year Unconformity: Porewater Chemistry From IODP Site U1553 in the South Pacific

AbstractWhereas changes in pore water chemistry are known to impact carbonate sediment geochemistry, little is known about the impact of long unconformities on carbonate alteration. IODP Site 378‐U1553 on the southern Campbell Plateau, with a 26‐million‐year, erosional unconformity, provides a key location for examining the impact of long‐term unconformities on sub‐surface chemistry and carbonate archives. This study examined 76 interstitial water samples for sulfate sulfur and oxygen isotopes, as well as 28 bulk carbonate samples for carbonate associated sulfate (CAS) sulfur isotopes, to quantify the effects of this unconformity on the sub‐surface redox chemistry of the Site. The current state of the system suggests limited influence of redox processes on the CAS archive. Manganese reduction reaches 30 mbsf, with a decrease in manganese reduction between 20 and 30 mbsf. Below 30 mbsf, the system transitions to iron reduction to a depth of approximately 140 mbsf where sulfate reduction begins. Dissolved sulfate sulfur and oxygen isotope values suggest repeated oxygenation of sulfides. The CAS record from the Site deviates from previously published seawater values. However, the lack of a relationship between the dissolved sulfate and CAS records suggests most of the alteration of the CAS record likely occurred before the unconformity when the carbonate sediments were more reactive. This further supports the CAS record as a relatively robust archive, withstanding most post‐depositional mechanisms of carbonate alteration.

Solvent-dependent hypsochromic shift in the imidazole based complex [Cu(µ2-SO4)(Im)4] and ameliorative effects on breast cancer-induced bone metastases associated oxidative injury in rats

A sulfate-bridged complex [Cu(µ2-SO4)(Im)4] (1) was prepared and structurally characterized, where Im: imidazole. The X-ray structure analysis reveals that 1 crystallizes in the monoclinic system with space group C2/c. The octahedral coordination around the metal center is made up of four distinct imine nitrogen atoms in the equatorial plane, and two sulfate oxygen atoms occupying the axial sites. The covalent linkage between metals via the sulfate group, forming infinite 1D zigzag chains, ensures the entanglement of the structure. These chains, in turn, are further assembled into a 2D network through NH⋯O hydrogen bonding. Thermal analyses underline the high thermal stability of our complex, which starts to decompose at 200 °C. The infrared spectrum confirms the results obtained from the crystallographic analysis. Optical studies reveal the presence of a hypsochromic effect noticed in the absorption and photoluminescence spectra. The synthesized compound was found to reduce both oxidative injury and histopathological features, which are associated with skeletal metastases as a result of malignant Walker 256/B breast cancer cells.

Impacts of phosphorus and nitrogen absence on microbial diversity and sulfate removal in anaerobic batch reactors

Sulfate-rich effluents have been successfully treated in anaerobic reactors using sulfate-reducing bacteria (SRB). Many authors have demonstrated that these systems require nitrogen and phosphorous supplementation to achieve high sulfate removal rates. However, the resource ratio theory assumes that some species can be dominant according to the nutritional relations used or even without external nutrient supplementation. Thus, this study evaluated the SRB communities in batch reactors without external nitrogen and phosphorus sources based on most probable number (MPN) quantification, denaturing gradient gel electrophoresis (DGGE) analyses and sequencing. The sulfate and chemical oxygen demand (COD) removal and kinetic parameters were also determined. After 100 days of operation, the sulfate and COD removal achieved 71.8 ± 10% and 86.5 ± 10%, respectively. The SRB population increased from 8.106 to 4 × 1012 MPN 100 mL−1, and the richness of SRB bands was much higher at the end of the experiment compared to the inoculum. In addition, the sequenced bands from SRB-DGGE showed similarities to Desulfacinum infernum, Desulfobulbus sp, Syntrophobacter and Desulfomicrobium aestuarii-related sequences. Therefore, biological treatment of acid mine drainage wastewater was effective in the absence of nutrients, lowering costs and providing high sulfate removal efficiency.

The influence of submarine hydrothermal systems on seawater sulfate

Seawater sulfate is a major carrier of oxidizing capacity and influences the redox budget of the Earth’s surface on geologic timescales. Records of oxygen and sulfur isotopes in seawater sulfate are used to track changes in sulfate cycling through geologic time. Interpretations of these records are typically based on models that describe the seawater sulfate reservoir as a mass balance between microbial, riverine and sedimentary sulfate fluxes. Here, we investigate the influence of hydrothermal sulfate cycling, which remains an unconstrained but potentially significant additional flux in this mass balance. We find that anhydrite (CaSO4) from eight submarine hydrothermal vent fields is consistently offset from seawater sulfate in δ18O but not Δ’17O or δ34S. Experiments at hydrothermal pressure–temperature conditions indicate that this δ18O offset is driven by oxygen isotope exchange between sulfate and hydrothermal H2O at high temperature. An updated isotope mass balance model shows that a flux of hydrothermal sulfate into seawater, derived from retrograde dissolution of hydrothermal anhydrite, could cause high-temperature oxygen isotope exchange to buffer seawater sulfate δ18O and Δ’17O by as much as 25%. Hydrothermal sulfate preserved in the Troodos Ophiolite (Cretaceous) also records a δ18O and Δ’17O signal of high-temperature oxygen isotope exchange, supporting the conclusion that geologic records of seawater sulfate oxygen isotopes may include a hydrothermal component.

The difference between drainage channels and sewers in rural areas: from sewage quality to bacterial characteristics.

Channels and sewers are commonly used to collect sewage during extensively rural areas. The sewage and bacterial characteristics of rural sewage collection systems can influence their operation and maintenance performance which further affect appropriate system decision. In this study, eight rural sewage collection systems (four each of channels and sewers) were applied to evaluate the sewage quality, bacterial characteristics, and their differences of two kinds of collection systems. The results indicate that significantly distinction existed between the rural sewage collection systems of channels and sewers. Sewage in channels had higher suspended solid (SS) concentration but lower sulfide concentration than that in sewers. The SS, sulfate, and chemical oxygen demand (COD) removal capacity in channels was nearly 3.5, 4.0, and 0.6 times than those in sewers. At least 14 genera and 18 species of bacteria showed significantly distinction between channels and sewers even their main phylum, genus, and species of bacteria communities was Proteobacteria (∼70.3%), Acinetobacter (∼22.3%), and Pseudomonas fragi (∼13.8%), respectively. The structural characteristics and bacterial function caused the difference between channels and sewers. Overall, this study revealed the intrinsic and essential differences of channels and sewers, providing basic and meaningful data for rural sewage collection systems decision.

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.