Sulfate Precipitation Research Articles

Selective Removal of Sulfate from Water by Precipitation with a Rigid Bis-amidinium Compound.

A simple, readily prepared biphenyl bis-amidinium compound (1⋅Cl2 ) is able to selectively precipitate sulfate from water. The precipitant is effective at concentrations as low as 1 mM and shows complete selectivity against monovalent anions, and high selectivity even against CO3 2- and HPO4 2- . It is highly effective (>90 % sulfate removed) in both seawater and highly acidic conditions relevant to mining waste-streams. X-ray crystallography reveals that 1⋅SO4 forms a tightly packed, anhydrous, structure where each sulfate anion receives eight hydrogen bonds from amidinium N-H hydrogen bond donors.

Winchcombe: An example of rapid terrestrial alteration of a CM chondrite

AbstractWinchcombe is a CM chondrite that fell in England on February 28, 2021. Its rapid retrieval was well characterized. Within two polished sections of Winchcombe, terrestrial phases were observed. Calcite and calcium sulfates were found in a sample recovered from a field on March 6, 2021, and halite was observed on a sample months after its recovery from a driveway on March 2, 2021. These terrestrial phases were characterized by scanning electron microscopy, Raman spectroscopy, and transmission electron microscopy. Calcite veins crosscut the fusion crust and therefore postdate it. The calcite likely precipitated in the damp environment (sheep field) where the meteorite lay for six days prior to its retrieval. The sulfates occur on the edges of the sample and were identified as three minerals: gypsum, bassanite, and anhydrite. Given that the sulfates occur only on the sample's edges, including on top of the fusion crust, they formed after Winchcombe fell. Sulfate precipitation is attributed to the damp fall environment, likely resulted from sulfide‐derived H2S reacting with calcite within the meteorite. Halite occurs as euhedral crystals only on the surface of a polished section and exclusively in areas relatively enriched in sodium. It was likely produced by the interaction of the polished rock slice with the humid laboratory air over a period of months. The sulfates, fusion crust calcite, and halite all post‐date Winchcombe's entry into the Earth's atmosphere and showcase how rapidly meteorite falls can be terrestrially altered.

Application of hydrocyclone in chemical precipitation

ABSTRACT This study demonstrates the use of hydrocyclone as a thickener to precipitate sulfate ions from wastewater. Simulated wastewater containing different concentrations of sodium sulfate (100–400 mg L−1) dissolved in distilled water was prepared. Lime was added as the precipitating agent. Different flow rates of the feed (3–11 L min−1) were used for two split ratios (0.1, 0.9). The results showed that increasing inlet flow rate, initial concentration, and split ratio enhanced the separation by concentrating sulfate ions in the underflow. Design Of Experiments was performed to determine the most effective factor on the response (underflow concentration) and to assign the optimum operating conditions. The effect was in the order: inlet flow rate, initial concentration, and split ratio. The quadratics of the factors also affected the separation in the order (inlet flow rate)2, (inlet flow rate) × (split ratio), (inlet flow rate) × (initial concentration). The optimum (maximum) value of the underflow concentration of sulfate ions was 856.538 mg L−1 at the optimum operating conditions (11 L min−1 inlet flow rate, 400 mg L−1 initial concentration, and 0.9 split ratio). The experimental value at the optimum operating conditions was 932 mg L−1 including 8% error. The process was applied on a real wastewater taken from a tile factory. The results confirmed the experimental results in that the pollutant was concentrated in the underflow. It was concluded that using hydrocyclone as a thickener was feasible to separate sulfate ions from wastewater. Also, the separation using hydrocyclone could be integrated with another technique such as electrocoagulation or ion exchange to recover sulfur as an attempt toward sustainable development requisites.

Chemical Composition and Deposition Characteristics of Precipitation into a Typical Temperate Forest in Northeastern China

The chemical compositions and deposition characteristics of atmospheric precipitation affect the structure and function of forest ecosystems and reflect regional air quality. Although northeastern China constitutes a vital forested area, few relevant studies reveal the chemical composition and the nitrogen (N) and sulphur (S) deposition characteristics within precipitation. In this study, we monitor precipitation chemistry during 2018–2020 at a rural forested site in northeastern China (the Qingyuan site) and compare it with those from background sites (Mondy in Russia and Ochiishi in Japan) and highly anthropogenically influenced areas (Beijing). The precipitation pH range was 4.7–8.0 (volume-weighted average 6.2). The average concentration of total ions in precipitation was 459 μmol L−1, representing a moderate pollution level. Nitrate (NO3−, 73 μmol L−1) and ammonium (NH4+, 133 μmol L−1) were the major anions and cations in the precipitation. Total inorganic nitrogen (TIN) deposition was 12.3–15.9 kg N ha−1 year−1 (NH4+-N deposition accounted for 54–67%), lower than the average level in China (19.4 kg N ha−1 year−1). Annual precipitation sulphate (SO42−) deposition was 4.9–6.7 kg S ha−1 year−1. Seventy-two percent of the precipitation ions at our site originated from human activities. This work has revealed that N and S deposition is an important ion deposition component in atmospheric precipitation in the study of temperate forests in northeastern China. Nitrogen deposition, as a source of vital nutrients in the forest ecosystem, may promote forest growth and, thereby, forest carbon sequestration.

Development of gold Immunochromatographic assay strip based on specific polyclonal antibodies against capsid protein for rapid detection of porcine circovirus 2 in Zhejiang province, China

BackgroundThe existing detection methods for porcine circovirus type 2 (PCV2) specific antibodies in serum cannot determine the infection status, thus it is necessary to establish a method for detecting PCV2 antigen. The capsid protein (CAP) of PCV2, as a major structural protein that plays a significant role in viral replication and in inducing host’s immune response, is an ideal target antigen to monitor PCV2 infection. Therefore, a gold immunochromatographic assay (GICA) for rapid detection of PCV2 antigen based on the polyclonal antibodies (PAbs) against PCV2-CAP will be developed.ResultsThe truncated CAP protein (dCAP) was used to immunize rabbits to generate anti-serum. After preliminary purification by caprylic acid/ammonium sulfate precipitation (CAAS), specific PAbs were purified by affinity chromatography column coupled with dCAP and its titer was about two-fold higher than preliminary purified PAbs. Colloidal gold-PAbs conjugate was synthesized under the optimum conditions. The specific anti-dCAP PAbs and goat anti-rabbit antibody (GAR) were then sprayed onto nitrocellulose (NC) membrane as a test line (TL) and a control line (CL), respectively. The visual limit detection (vLOD) of the GICA strips was 5 ng/mL. Specificity assay indicated that the GICA strips had specifically detected PCV2 and was not reactive for porcine epidemic diarrhea virus (PEDV), pseudorabies virus (PRV), porcine reproductive and respiratory syndrome virus (PRRSV) or classic swine fever virus (CSFV). A total of 36 porcine serum samples were detected by this GICA and commercial enzyme-linked immunosorbent assay (ELISA) Kit, 9 positive samples were found by the developed strip with the rate of 25.0% comparing with 11 positive samples detected by the commercially ELISA Kit which positive rate was 30.5%, and the receiver operating characteristic (ROC) curve revealed that the relative sensitivity and specificity of this GICA strip were 72.7 and 96.0%, respectively, with an area of 87.2%.ConclusionsThis study established an efficient detection method with high sensitivity and specificity for the clinical diagnosis of PCV2 antigen, that will facilitate a rapid and convenient way to evaluate the infection status of vaccinated pigs.

Catalysis in Lithium-Sulfur Cathodes for Improved Performance and Stability

Among next generation batteries, lithium-sulfur batteries are expected to be first battery to find a commercial route in the next few years. The sulfur cathodes in lithium-sulfur batteries provide both a lower cost and high capacity (1675 mAh/g) in comparison to intercalation cathode materials [1]. Despite these upsides, this conversion reaction type battery suffers from few problems that hinders their adoption. Some of these problems include the sluggish reaction kinetics, low sulfur utilization, rapid capacity loss due to various sulfur loss phenomena, and low Coulombic efficiency [2]. The use of electrocatalysts was shown to significantly boost the polysulfides redox reactions and improves the battery performance [3]. Transition metals, especially platinum group metal (PGM) based catalysts are proven to effectively boost the reaction rate of polysulfides conversion during cycling due to their high electrocatalytic activity [4], [5]. However, catalyst incorporation in conversion reaction batteries systems often would lead to side reactions and strategies on how to incorporate them into the battery system have to be developed.In this work, platinum group metal (PGM) nanocatalysts were implemented in lithium-sulfur cathodes using a process that is tailored to effectively improve catalyst dispersion and to provide controlled catalyst electrolyte contact. The nanocatalysts were loaded in carbon nanotube at variable low contents 0.1 – 5 wt% (Figure 1a) and were used in cathodes with sulfur loading up to 70 wt%. Using standard lithium-sulfur electrolyte based on 1 mol/kg LiTFSI in DOL:DME (v:v = 1:1) with lean electrolyte condition, batteries based on 2032 type coin cells and multilayer pouch cells were studied. The batteries' performance was studied for their impedance growth using electrochemical impedance spectroscopy, the redox performance using cycling voltammetry, and for their sulfur utilization/sulfur loss/Coulombic efficiency using galvanostatic charge-discharge cycling. These cathodes were shown to have improved redox performance in the batteries, improved sulfur utilization, and maintained stable capacity even at high sulfur loadings of 4-5 mg/cm2. Comparison of performance of nanocatalyst-containing batteries versus control batteries show improved first cycle capacity and stabilized capacity retention in the early cycling life of the battery (Figure 1b). Elucidating the underlying phenomena of the stabilization is studied in detail revealing reduced sulfur precipitation and shuttle effects. Higher C-rate performance of up to 1C revealed similar observations of stabilization.

Pore-Water Geochemical Gradients of Sulfate, Calcium, Magnesium, and Iodide Correlated With Underlying Gas Hydrate Potential: A Case Study of the Shenhu Area, South China Sea

Geochemical profiles in pore water of marine sediments have been considered as, important indicators of gas hydrate occurrence. In the gas hydrate area around the world, the decrease of sulfate, calcium, and magnesium concentrations with depth mainly results directly or indirectly from the anaerobic oxidation of methane (AOM). The ubiquitous abnormally high concentration gradients of iodide in the research area reflect the large methane-generating potential of the area. Thus, we explore the feasibility of using gradients of sulfate, iodide, and authigenic carbonate precipitation as indicators for gas hydrate in the regional exploration of gas hydrate formation. We test the criterion in the gas hydrate zone in the South China Sea (SCS) for the recognition of gas hydrate by using the gradients of sulfate, calcium plus magnesium, and iodide. Contour maps of pore-water gradients from expeditions in the study area are used to correlate the key gradients to underlying gas hydrate occurrence. The results show that the largest potential gas hydrate indicated by the contour maps of the indicators are well consistent with the discovery of GMGS1 and GMGS3 expedition. It implies the possible applicability of this geochemical method in gas hydrate exploration. Also, we identify a promising area in the South China Sea for future gas hydrate investigations. It is the first collective application of the gradients of sulfate, calcium plus magnesium, and iodide to a gas hydrate terrane, especially to a large area of the SCS. We believe that the result of this research will benefit the future exploration of gas hydrate and will arouse a lot of interest from other researchers.

Solvothermal DMSO-mediated synthesis of the S/AgI micro-/nano-structures and its application as photocatalytic and biological agents

S/AgI microstructures were produced by solvothermal DMSO-mediated synthesis using two methods of sulfur precipitation: at room temperature (method 1) and by water (method 2). The samples were obtained with different percentages of AgI: 10, 30 and 50 %. Microstructures were investigated with help of XRD, Raman spectroscopy and SEM/EDS (elemental mapping). XRD and Raman spectroscopy confirmed the presence of sulfur and AgI. EDS elemental mapping revealed that samples were composed of large grains of sulfur covered by smaller grains of AgI. The obtained SEM micrographs revealed that the 1st method gave larger grains of sulfur in comparison with the 2nd method. Testing of the microstructures as photocatalysits showed the low activity; as the prepared samples were able to degrade no more than 7 % of the molecules of Orange II. Significant biological activity was detected only for S/AgI (2) 50 % sample, as it was able to suppress test strains of S. aureus ATCC ВАА-39, P.aeruginosa ATCC 9027 and Erwinia amylovora at MBC/MFC 5000 µg/mL, and E. coli ATCC 8739 at 2500 µg/mL.

"Production of Equine Anti-Daboia Siamensis Immunoglobulin F(ab’)2 Fragments with Ammonium Sulphate and Caprylic Acid Precipitation and by Multimode Chromatography"

"Production of Equine Anti-Daboia Siamensis Immunoglobulin F(ab’)2 Fragments with Ammonium Sulphate and Caprylic Acid Precipitation and by Multimode Chromatography"

Polysulfide Speciation and Migration in Catholyte Lithium-Sulfur Cells.

Semi‐liquid catholyte Lithium−Sulfur (Li−S) cells have shown to be a promising path to realize high energy density energy storage devices. In general, Li−S cells rely on the conversion of elemental sulfur to soluble polysulfide species. In the case of catholyte cells, the active material is added through polysulfide species dissolved in the electrolyte. Herein, we use operando Raman spectroscopy to track the speciation and migration of polysulfides in the catholyte to shed light on the processes taking place. Combined with ex‐situ surface and electrochemical analysis we show that the migration of polysulfides is central in order to maximize the performance in terms of capacity (active material utilization) as well as interphase stability on the Li‐metal anode during cycling. More specifically we show that using a catholyte where the polysulfides have the dual roles of active material and conducting species, e. g. no traditional Li‐salt (such as LiTFSI) is present, results in a higher mobility and faster migration of polysulfides. We also reveal how the formation of long chain polysulfides in the catholyte is delayed during charge as a result of rapid formation and migration of shorter chain species, beneficial for reaching higher capacities. However, the depletion of ionic species during the last stage of charge, due to the conversion to and precipitation of elemental sulfur on the cathode support, results in polarization of the cell before full conversion can be achieved.

Flowpath influence on stream acid events in tropical urban streams in Singapore

AbstractWe investigated processes contributing to periodic acidification events in headwater streams of Nee Soon Forest Catchment (NSFC) in Singapore by monitoring hydrochemical changes in response to rainfall inputs. Stream chemistry response to most rainfall events was characterized by decreases in pH from means ranging from 5.1 to 5.3 to below 4.8–5.0 and corresponding increases in specific electrical conductivity from baseflow values of 15–30 to 50–80 μS cm−1, indicative of low‐total dissolved solids in stormflow. The decreases in pH in the streams, which are typically acidic year‐round, were related to occasional highly acidic rainfall inputs (pH ~4.05) and likely the flushing of organic acids into the stream by shallow subsurface flow interacting with surface litter and/or organic‐rich soil horizons. The interaction of rainwater runoff with organic matter in the soil matrix possibly alters the chemical composition of stormflow, influencing pH. Decomposition of instream organic matter also reduces stream water pH. Leaching experiments revealed that the overland flow passing through organic matter and A horizon material has the potential to lower stream water pH by approximately a half unit or more, in part, by flushing nitrates that were produced by microbial decomposition of organic matter and/or precipitated sulphur that enterred the forest by wet or dry atmospheric deposition. The observed periodic acid events are a natural phenomenon in the stream system in this urban environment because of naturally acidic rainfall and granitic soils with low buffering potential. However, acid events are likely amplified in frequency and magnitude by anthropogenic pollution emissions of sulphur and nitrogen species (e.g., SO2and NOx) from local and regional sources that lower rainfall pH. Although, acid runoff events are typically short‐lived (<12–24 h), further longitudinal monitoring and experimental studies are needed to investigate the long‐term implications on sensitive taxa in the NSFC streams. Finally, understanding the flow pathways of stormflow water in the nested system was critical for deciphering the mechanisms driving stream acid events at the site.

Trends in the content of acidifying and eutrophying compounds in atmospheric precipitation in an urbanized area

The trends in changing the content of sulfur and nitrogen in atmospheric precipitation in the territory of Minsk over an 18-year period are characterized on the basis of the analysis of the monitoring results of the chemical composition of atmospheric precipitation at the experimental site. A downtrend in the sulfur and nitrogen content combined with an uptrend in the precipitation acidity was identified. An average decrease (trend) in the content of sulfur in atmospheric precipitation for 2002–2019 was 0.019 mg S/dm3/year, of oxidized nitrogen – 0.008 mg/dm3, of reduced nitrogen – 0.019 mg/dm3. Over an 18-year period, the changes in the content of sulfur and nitrogen in atmospheric precipitation decreased the deposition of sulfur on average by 31.3 kg/km2/year, of oxidized nitrogen – by 15.4 kg/km2/year, of reduced nitrogen – by 25.6 kg/km2/year. It is shown that for the period from 2005 to 2012, the acidification potential of the natural environment decreased parallel to the reduction of the sulfur and nitrogen deposition; in the subsequent period, the trend of the acidification potential basically follows the trend of the precipitation of the main cations. It is revealed that the rates of average reduction in the content of oxidized sulfur and oxidized nitrogen in atmospheric precipitation in Minsk for the period from 2002 to 2017 are comparable to the rates of reduction of these compounds at the stations of the EMEP Program in Europe, and exceed those for reduced nitrogen.

Laboratory-Based Bacterial Weathering of the Merensky Reef and Its Impact on Platinum Group Mineral Migration

Abstract Weathering of the Merensky reef was enhanced under laboratory conditions by Fe- and S-oxidizing bacteria: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum ferrooxidans. These bacteria preferentially colonized pyrrhotite and pyrite, versus pentlandite and chalcopyrite (all of which were common within the rock substrate), promoting weathering. Weathering of base metal sulfides resulted in the precipitation of Fe oxides, Fe phosphate, and elemental sulfur as secondary minerals. Fe pyroxene weathered readily under acidic conditions and resulted in mineral dissolution, while other silicates (orthopyroxene and plagio-clase) precipitated Fe phosphate spherules or coatings on their surface. The deterioration of the platinum group metal (PGM) matrix (base metal sulfides and silicates) and the occurrence of a platinum grain associated with platinum nanoparticles observed in the biotic thin sections demonstrate that biogeochemical acid weathering is an important step in the active release of intact PGM grains. A platinum grain embedded in secondary Fe oxides/phosphate that had settled by gravity within the weathering solution demonstrates that secondary minerals that formed during weathering of PGM-hosting minerals also represent targets in PGM exploration by trapping and potentially slowing PGM migration. Dispersion halos surrounding or occurring downstream from PGM occurrences will likely produce two physical target classes—i.e., grains and colloids—under surficial weathering conditions.

Climatology of transport and deposition of atmospheric substances of different intensity on the southern Primorye territory by using the meteorological reanalysis data and observations at EANET monitoring station

Abstract The article presents an analysis of air masses and precipitation transport to the area of EANET monitoring station in Russian Primorsky Krai (Primorskaya) during the warm seasons (June–October) for the period 2013–2018. The relative contributions of chemical compounds transfer from marine or continental regions were defined. The probability of sulfate and nitrate concentration values in precipitation was calculated separately in line with backward trajectory sectors. Obtained information is used for estimating contributions of marine and continental sources into wet deposition fluxes onto the Russian Far East areas.

Multiple sulfur isotopes signature of Thermochemical Sulfate Reduction (TSR): Insights from Alpine Triassic evaporites

The sulfur cycle is driven by redox processes, among which sulfate reduction is of primary importance. Sulfate is reduced to sulfide either abiotically by Thermochemical Sulfate Reduction (TSR) or biotically by Microbial Sulfate Reduction (MSR). Although these two processes occur at different temperature regimes (>100°C and <80°C, respectively), they generate similar by-products (e.g., sulfides, elemental sulfur). The 34S/32S ratio is often used as the sole criterion to identify the origin of reduced sulfur compounds, but overlaps prevent unambiguous conclusions. Contrary to MSR, the multiple sulfur isotopic signatures (δ33S, δ34S, δ36S) of natural TSR remains uncharacterized. Here, we performed multiple sulfur isotopes analyses of sulfates, sulfides, and elemental sulfur from six sites in the Alpine Triassic evaporites formation to better constrain the isotopic signatures of TSR. Unlike MSR, TSR can induce slight negative deviations (Δ33S down to −0.08‰) relative to the initial sulfate Δ33S value, which significantly discriminates between these two processes. Isotopic equilibria between anhydrite and either elemental sulfur or sulfides (pyrite or chalcopyrite) were verified according to their mass-fractionation exponents (θ33/34=0.5140 and 0.5170, respectively). Using sulfate-elemental sulfur (Δ34SSO42−-S8) or sulfate-sulfide (Δ34SSO42−-S2−) fractionation pairs and respective fractionation factors (α34) for samples that fulfilled the criteria of isotopic equilibrium, we determined the precipitation temperatures of elemental sulfur and sulfides (pyrite or chalcopyrite) to be 194 ± 14°C and 293–488°C, respectively. Interestingly, the obtained temperature of elemental sulfur precipitation corresponds exactly to the solid-liquid phase transition of native sulfur. Using Δ33S vs. δ34S and Δ33S vs. Δ36S diagrams, we are able to fully explain the isotopic signatures of disequilibrium sulfides by the mixing of sulfate with either elemental or organic sulfur in the aqueous fluid. Mixing curves allow the determination of the relative proportions of sulfate and organic and elemental sulfur, the latter being formed by the recombination of polysulfides during cooling. It appears that the sulfides' signatures are best explained by a 33% contribution of polysulfides (i.e., elemental sulfur signatures), consistent with the relative proportion of dissolved polysulfides previously measured in fluid inclusions from this formation at >200°C. Finally, no sulfur mass independent fractionation (S-MIF) is observed in this evaporitic formation, consistent with the TSR signature generated both at equilibrium and by mixing. This implies that TSR does not generate S-MIFs. Our results thus provide multiple sulfur isotopes signatures of TSR, which may be used to reliably identify this process in variable geological settings.

Heavy Metal Recovery from Waste CRT Funnel Glasses by the Combined Process of Rapid phase-separation and Mechanochemical Extraction

An innovative and sustainable method of extracting heavy metal oxides (PbO, BaO, and SrO) from a cathode ray tube (CRT) funnel glass was developed. Funnel glass was first remelted with 20 wt % B2O3 at 1000 °C for 30 min in air atmosphere. Most of the heavy metal oxides (PbO, BaO, and SrO) were quickly migrated from the funnel glass to the B2O3-rich phase. Then, heavy metal oxides were recovered efficiently from phase separation product by a sustainable wet ball-milling process (replaced the traditional strong acid) using ethylene diamine tetraacetic acid (EDTA) as extraction reagent at room temperature. Mechanical activation caused the rapid dissolution of the B2O3-rich phase in water. Thus, heavy metal cations (Pb2+, Ba2+, and Sr2+) could be extracted as a metal-EDTA, and the solid residue was high silica glass powder (silica purity >92 wt %). The extraction rates of Pb, Ba, and Sr were 95.74%, 93.57%, and 94.76% when only milling for 5 min and reached 99.35%, 98.07%, and 96.40% for 60 min under optimum conditions: EDTA adding amount, 2 g; rotational speed, 500 rpm; and water/solid ratio, 0.8, respectively. Heavy metal ions could be recovered by sulfate precipitation, and the soluble metal-EDTA could be transformed into solid EDTA when pH < 3. Thus, this paper provides a sustainable method for detoxification and reutilization of heavy metals containing silicate waste.

Effect of Basicity on the Sulfur Precipitation and Occurrence State in Kambara Reactor Desulfurization Slag

Kambara Reactor (KR) desulfurization slag used as slag-making material for converter smelting can promote early slag melting in the initial stage and improve the efficiency of dephosphorization. However, its direct utilization as a slagging material can increase the sulfur content in molten steel since KR desulfurization slag contains 1~2.5% sulfur. Therefore, this research focuses on the effect of basicity on the precipitation behavior and occurrence state of sulfur in KR desulfurization slag in order to provide an academic reference for the subsequent removal of sulfur from slag through an oxidizing atmosphere. The solidification process of slag was simulated by the Factsage8.0. The slag samples were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM), and the amount of CaS grains was analyzed using Image-ProPlus6.0 software. The thermodynamic calculation showed that the crystallization temperature of CaS in the molten slag gradually decreased with the increase in basicity, and the CaS crystals in the molten slag mainly existed in the matrix phase and at the silicate grain boundaries. A large number of CaS grains were precipitated along the silicate grain boundary in low-basicity (R = 2.5 and 3.0) slags and fewer CaS grains were precipitated along the silicate grain boundary, while the CaS grain density in the matrix phase was higher in the high-basicity (R = 3.5, 4.0, 4.5) slag. With the increase in basicity, the number of CaS grains gradually decreased, and the CaS grain sizes in slag sample increased gradually. The sulfur in the synthetic slag was in the form of CaS crystals and the amorphous phase, and the content of amorphous sulfur gradually increased with increasing basicity.

Geochemical proxies for water-soil interactions in the hyperarid Atacama Desert, Chile

The Atacama Desert is the oldest and driest non-polar desert on Earth. Millions of years of hyperaridity enabled salt accumulations through atmospheric deposition. These salts can serve as proxies to decipher the interaction between water and soil as well as to understand the habitability with changing environmental settings. Therefore, we investigated four soil profiles regarding their mineralogy, salt abundance, and sulfate stable isotopic composition. The profiles were located along an elevation transect in the hyperarid region southeast of Antofagasta, Chile. The two lower sites situated on the distal parts of inactive alluvial fan deposits were subject to occasional fog occurrences. The upper steeper-sloped sites experienced no fog but are subject to minimal erosion. In all soil profiles, sulfates are the dominant salts showing a downward transition from gypsum to anhydrite that is accompanied by an increase of highly soluble salts and a decrease of sulfate δ34S and δ18O values. These trends are consistent with downward directed water infiltration during rare rain events causing salt dissolution followed by precipitation within the deeper soil column. This conclusion is also supported by our Rayleigh fractionation model. We attribute the presence of anhydrite at > 40 cm depth to the cooccurrence of nitrate and chloride salts, which decreases water activity during sulfate precipitation and therefore drives anhydrite formation. Along the elevation transect, the total salt inventories of each profile show a trend for nitrates and chlorides concentration decreasing with elevation. This observation together with the sulfate stable isotopes indicates a fog-independent source and suggests remobilization of soluble salts through enhanced washout from hillslopes to alluvial fans. These findings are essential for assessing the long-term regional habitability of hyperarid environments and have also relevance for Mars.

Interrelation between sulphur and conductive materials and its impact on ammonium and organic pollutants removal in electroactive wetlands

This investigation is the first of its kind to evaluate the interrelation of sulphate (SO42-) with conductive materials as well as their individual and synergetic effects on the removal of ammonium and organic pollutants in electroactive wetlands, also known as constructed wetland (CW) - microbial fuel cell (MFC). The role of MFC components in CW was investigated to treat the sulphate containing wastewater under a long-term operation without any toxicity build-up in the system. A comparative study was also performed between CW-MFC and CW, where sulphate containing wastewater (S-replete) and without sulphate wastewater (S-deplete) was assessed. The S-replete showed high NH4+ removal than the S-deplete, and the requesnce of removal was: CW-MFC-replete>CW-MFC-deplete>CW-replete>CW-deplete. The chemical oxygen demand (COD) removal was high in the case of CW-MFC-replete, and the sequence of removal was CW-MFC-replete>CW-MFC-deplete>CW-deplete>CW-replete. X-ray photon spectroscopic study indicates 0.84% sulphur accumulation in CW-MFC-replete and 2.49% in CW-replete, indicating high sulphur precipitation in CW without the MFC component. The high relative abundance of class Deltaproteobacteria (7.3%) in CW-MFC-replete along with increased microbial diversity (Shannon index=3.5) rationalise the symbiosis of sulphate reducing/oxidising microbes and its impact on the treatment performance and electrochemical activity.

Pectin Degradation in Fruit Juices by Pectinase from Meyerozyma sp. VITPCT75 Isolated from Phyllanthus emblica

This study aimed to identify and characterize a pectinase-producing novel yeast from the fermented juice of Phyllanthus emblica and apply the enzyme for fruit juice clarification. Among the five pectinase-producing yeasts, isolate-1 exhibited the highest pectinase activity and was further used in this study. Based on morphological, physiological, and 18SrRNAanalyses, isolate-1 was recognized as a new strain sharing 99% sequence homology with other Meyerozyma strains and was thus designated as Meyerozyma sp. VITPCT75. The strain produced pectinase optimally at a temperature and pH of 25oC and 7, respectively. Maximum pectinase production was observed after 4-days incubation. The enzyme exhibited optimum activity at the temperature of 25 °C and pH 7.0. The enzyme was more stable at a temperature and pH of 20 °C and 7, respectively. Storage stability studies revealed that the enzyme was stable at -20 °C. The cell-free supernatant was partially purified using ammonium sulfate and solvent precipitation. Acetone at a concentration of 20% assured an adequate partial purification. The molecular weight of pectinase was determined as 6 kDa. The enzymatic metal ion preference-related studies revealed that Ca²z, Kz, Cu²z, Fe²z, and Ba²z ions enhanced, Ni²z ions moderately inhibited, and Mn²z ions intensely inhibited the enzymatic activity. Neither Na+ and Mg2+ ions nor EDTA affected the enzyme activity. When subjected to fruit juice clarification, the enzyme significantly reduced the viscosity of the juice.