Low SO2 Research Articles

Depth investigation of the regulation mechanism of SiO2 on the denitrification performance and sulfur resistance of MnCe/Ti SCR catalyst

The “deep peaking” of coal-fired units presents great challenges for SCR catalysts’ de-NOx activity at wide temperatures. Mn-based catalysts have good de-NOx activity at low temperatures, but their poor sulfur resistance is one of the key issues affecting industrial applications. In this study, the effects of SiO2 doping on the denitrification, sulfur resistance, and physicochemical performance of the MnCe/Ti catalyst were investigated. The results showed that SiO2 improved the de-NOx activity of catalysts at high temperatures and enhanced SO2/H2O resistance at wide temperatures. Under short reaction time conditions, the MnCe/Ti0.9Si0.1 catalyst exhibited the highest NO conversion rate at 400 °C, which was 33% higher than that of the MnCe/Ti catalyst. The NO conversion rates of Si-doped MnCe/Ti catalysts increased rapidly to over 85% (65% of the MnCe/Ti catalyst) as the reaction temperature increased from 200 °C to 250 °C under SO2-containing atmosphere due to the promoting effects of SiO2 on the decomposition of ammonium bisulfate. MnCe/Ti0.7Si0.3 catalyst exhibited the optimal sulfur and H2O resistance, with NO conversion rate higher than 85% with 600 min under SO2/H2O-containing atmospheres. SiO2 inhibited the crystallization of anatase TiO2, and increased the specific surface area to 306.60 m2/g. Additionally, the ratios of Mn4+/Mnn+ and Ce3+/Cem+, and the surface adsorbed oxygen and weak-medium acid amount also increased due to the multiple interactions between the TiO2-SiO2 and Mn/Ce, resulting in the higher de-NOx activity. Compared with the MnCe/Ti catalyst, Si-doped MnCe/Ti catalysts have lower SO2(g) adsorption amount and the sulfation of Mn, and higher SO3(a) desorption performance, resulting in better sulfur resistance at wide temperatures.

Evaluation of Ain Shams University Hospitals Clinical Pathway for Pulmonary Artery Banding

Abstract Background Pulmonary artery banding (PAB) remains a useful surgical palliation for small neonates and early infants with excessive pulmonary blood flow who are unable or difficult to withstand an open heart surgery using cardiopulmonary bypass or in developing countries where the facilities not suitable for primary corrective surgery in those infants. Objectives In our current study we aimed to study clinical pathway of cases underwent PAB at ASU hospital pediatric cardiac surgery department with discussion of different causes of mortality and morbidity. Patients and Methods Study done by data collection retrospectively of 50 patients underwent pulmonary artery banding in the period from January 2018 to December 2019 who fulfilling the inclusion criteria with evaluation of different clinical pathways for the outcome mainly morbidities and mortality. Results We found that the major risk factors of mortality in cases underwent PAB in ASU hospitals includes patients diagnosed with TGA, low preoperative so2 ≤85, ventilation is high risk factor for mortality so it is recommended to extubate those patients on table or shortly after discharge to ICU as soon as possible, duration of intubation: the longer the duration of intubation, the higher the mortality, postoperative PG across band ≤45.that indicator for a loose band with still persistent pulmonary overflow, re-intubation, post operative morbidities are highly associated with mortality, 11 out of 12 mortality cases suffered from postoperative complications (91.7 % of mortality cases) that includes poor chest condition, stroke, postoperative convulsions and pulmonary hemorrhage. These morbidities result in prolonged intubation and prolonged ICU stay. Conclusion Pulmonary artery banding is palliative procedure done in infants with pulmonary artery overflow with unprotected pulmonary circulation in variable congenital cardiac diseases (VSD, single ventricle, TGA) as a primary stage for total repair when the infant gain weight and get older, the suitable age for banding is < 6 months.

Effect of additives on sulfur resistance of catalytic filter material during denitrification and synergistic decomposition of 1,2-DCBz.

Modified Mn-Ce/P84 catalytic filter material can be used to achieve high removal efficiency of NOx and 1,2-DCBz in bag-filtering dust precipitator synergistic removal of multiple pollutants. However, the presence of SO2 in the actual industrial flue gas has an adverse impact on the catalytic performance of the catalytic filter material. In this paper, a kind of Mn-Ce catalytic filter material was prepared by the impregnation method, which was modified by Fe, Cu, and Co, respectively. As a result, the sulfur resistance of the catalytic filter material was improved. The change of catalytic activity of the three kinds of modified catalytic filter material at different concentrations was compared in the SO2 flue gas fixed bed system. And the modified catalytic filter materials were characterized by SEM, BET, XPS, XRD, and H2-TPR. When the temperature was over 80 °C, different concentrations of SO2 were injected into the simulated flue gas to test the denitrification activity of the catalytic filter material. The results showed that under the low SO2 concentration of 150 ppm, the denitrification activity and 1,2-DCBz activity of Fe, Co, and Cu-modified filter material were increased, and the sulfur resistance of Fe was better under the flue gas conditions of 300 ppm and 450 ppm SO2. Under the condition of 450 ppm SO2 and 200 °C reaction, 93.4% denitrification efficiency and 96.1% 1,2-DCBz removal efficiency could be achieved by using modified Fe-Mn-Ce catalytic filter material.

Release of Sulfur and Chlorine Gas Species during Combustion and Pyrolysis of Walnut Shells in an Entrained Flow Reactor

The release behavior of sulfur and chlorine compounds into the gas phase of walnut shell particles (WNS) is studied with an entrained flow reactor. Experiments are carried out in nitrogen (N2), carbon dioxide (CO2) atmosphere and under air and oxy-fuel conditions at different temperatures (T = 1000–1300 °C) and stoichiometries (λ = 0.8–1.1). A total of 98.7% of fuel-bound sulfur volatilizes as sulfur dioxide (SO2), carbonyl sulfide (COS) and hydrogen sulfide (H2S) in the gas phase in N2 atmosphere at 1000 °C. As hydrogen chloride (HCl), 37.0% of the chlorine is released at this temperature. In CO2 atmosphere, a similar total release of sulfur and chlorine is observed (1000 °C). With each temperature increment, the release of SO2, H2S and HCl in the gas phase decreases (N2 and CO2 atmosphere). SO2 forms the major sulfur component in both atmospheres. In CO2 atmosphere, higher concentrations of COS were detected than in N2 atmosphere. Air and oxy-fuel combustion conditions show significantly lower SO2, COS and HCl concentrations as in N2 and CO2 atmosphere. No H2S is detected in the gas phase during any of the combustion trials.

Time series analyses based on the joint lagged effect analysis of pollution and meteorological factors of hemorrhagic fever with renal syndrome and the construction of prediction model.

Hemorrhagic fever with renal syndrome (HFRS) is a rodent-related zoonotic disease induced by hantavirus. Previous studies have identified the influence of meteorological factors on the onset of HFRS, but few studies have focused on the stratified analysis of the lagged effects and interactions of pollution and meteorological factors on HFRS. We collected meteorological, contaminant and epidemiological data on cases of HFRS in Shenyang from 2005-2019. A seasonal autoregressive integrated moving average (SARIMA) model was used to predict the incidence of HFRS and compared with Holt-Winters three-parameter exponential smoothing model. A distributed lag nonlinear model (DLNM) with a maximum lag period of 16 days was applied to assess the lag, stratification and extreme effects of pollution and meteorological factors on HFRS cases, followed by a generalized additive model (GAM) to explore the interaction of SO2 and two other meteorological factors on HFRS cases. The SARIMA monthly model has better fit and forecasting power than its own quarterly model and the Holt-Winters model, with an optimal model of (1,1,0) (2,1,0)12. Overall, environmental factors including humidity, wind speed and SO2 were correlated with the onset of HFRS and there was a non-linear exposure-lag-response association. Extremely high SO2 increased the risk of HFRS incidence, with the maximum RR values: 2.583 (95%CI:1.145,5.827). Extremely low windy and low SO2 played a significant protective role on HFRS infection, with the minimum RR values: 0.487 (95%CI:0.260,0.912) and 0.577 (95%CI:0.370,0.898), respectively. Interaction indicated that the risk of HFRS infection reached its highest when increasing daily SO2 and decreasing humidity. The SARIMA model may help to enhance the forecast of monthly HFRS incidence based on a long-range dataset. Our study had shown that environmental factors such as humidity and SO2 have a delayed effect on the occurrence of HFRS and that the effect of humidity can be influenced by SO2 and wind speed. Public health professionals should take greater care in controlling HFRS in low humidity, low windy conditions and 2-3 days after SO2 levels above 200 μg/m3.

Influences analysis of Sb/Si dopant in TiO2 on NH3-SCR activity and low temperature SO2 resistance of V2O5/TiO2 catalysts

The Sb/Si doped TiO2 prepared by sol–gel method were used as supports of V2O5/TiO2 SCR catalysts in order to improve SCR activity and SO2 resistance. The type of dopant atoms changed catalyst physiochemical properties discriminatively. Surface chemical properties of catalysts played more important role in their catalytic performance. Simultaneous enhanced surface acidity and redox capacity leaded to the better SCR activity for V2O5/Sb-TiO2 compared with other catalysts. The low temperature SO2 resistance was improved for the support doped catalysts. The special electronic charge migration brought by surface sulfate species for V2O5/Sb-TiO2 even elevated its SCR activity during SO2 resistance test, which was due to the formation of new acid sites and enhancement of redox performance. Even though NOx conversion for V2O5/Si-TiO2 decreased, the relative stable efficiency was kept at low temperatures with SO2. The results proved hetero atom doping in TiO2 by sol–gel method was a useful method to improve low temperature SO2 resistance of catalysts. By contrast, Sb is a better choice for the development of support doped V2O5/TiO2 SCR catalyst used in a wide temperature range.

Impact of Gaseous Pollutants Reduction on Fine Particulate Matter and Its Secondary Inorganic Aerosols in Beijing–Tianjin–Hebei Region

A reduction in gaseous pollutants is an important method for mitigating PM2.5 concentration in the atmosphere, and the reduction in SO2/NH3/NOx is beneficial to control secondary inorganic aerosols in PM2.5. In this study, the Weather Research and Forecasting model with Chemistry model (WRF-Chem) was applied to study the impact on the PM2.5 and its secondary inorganic aerosols using the scenario simulation method in the Beijing–Tianjin–Hebei (BTH) region. The results showed that the BTH region is characterized by being NH3-rich and having a higher [NH4+]/[SO42−] ratio in southern BTH, with a ratio of more than 6.0. Source contribution to PM2.5 was highest in the 30%_SO2_40%_NH3_40%_NOx scenario, with a contribution ratio of 6.8%, followed by 3.8% contribution in the 30%_SO2_40%_NH3 scenario, and a 3.4% contribution in the 30%_SO2_60%_NH3_60%_NOx scenario. These results indicate that synergistic reduction measures may be suitable for controlling PM2.5 concentrations. A lower sensitivity factor, β value between PM2.5 and NH3 suggests that solely reducing NH3 emissions is not beneficial for the BTH region. However, this study indicates that the sensitivity of NO3− would improve significantly if NH3 emissions are reduced sharply. A slight reduction in NH3 was found to be beneficial for controlling NO3− in medium and small cities, while a significant decrease in NH3 would be more suitable for mega-cities. The study also observed that SO42− and its constituents continued to decrease with a consistent β value of approximately 0.14 in the 30%_SO2_%_NH3 scenario and between 10.5 and 12.8 in the 30%_SO2_%_NH3_%_NOx scenario. These findings suggest that a synergistic reduction in SO2-NH3-NOx emissions may be more effective in reducing PM2.5 concentrations and its secondary inorganic aerosols (SIAs). However, it is important to ensure that the reduction in NH3 and NOx exceeds 60% in low SO2 concentration conditions.

Unveiling the SO2 Resistance Mechanism of a Nanostructured SiO2(x)@Mn Catalyst for Low-Temperature NH3-SCR of NO.

Low N2 selectivity and SO2 resistance of Mn-based catalysts for removal of NOx at low temperatures by NH3-SCR (selective catalytic reduction) technology are the two main intractable problems. Herein, a novel core-shell-structured SiO2@Mn catalyst with greatly improved N2 selectivity and SO2 resistance was synthesized by using manganese carbonate tailings as raw materials. The specific surface area of the SiO2@Mn catalyst increased from 30.7 to 428.2 m2/g, resulting in a significant enhancement in NH3 adsorption capacity due to the interaction between Mn and Si. Moreover, the N2O formation mechanism, the anti-SO2 poisoning mechanism, and the SCR reaction mechanism were proposed. N2O originated from the reaction of NH3 with O2 and the SCR reaction, as well as from the reaction of NH3 with the chemical oxygen of the catalyst. Regarding improving the SO2 resistance, DFT calculations showed that SO2 was observed to preferentially adsorb onto the surface of SiO2, thus preventing the erosion of active sites. Adding amorphous SiO2 can transform the reaction mechanism from Langmuir-Hinshelwood (L-H) to Eley-Rideal (E-R) by adjusting the formation of nitrate species to produce gaseous NO2. This strategy is expected to assist in designing an effective Mn-based catalyst for low-temperature NH3-SCR of NO.

Postharvest control of spotted-wing drosophila and blueberry maggot by low temperature conditions and fumigation with sulfur dioxide

Cold treatment and fumigation are widely applied approaches to disinfest storage pests after harvest of fruits, nuts, grains, and vegetables. Cold conditions can limit the development and survival of spotted-wing drosophila, Drosophila suzukii Matsumura, in fruit and fumigation of blueberries with SO2 may control blueberry maggot, Rhagoletis mendax Curran. In this study, we found that at least 21 d of 0.5 °C was needed for achieving 98.3% reduction in R. mendax making this unsuitable for pre-export disinfestation. The average concentration of SO2 in modified atmosphere packages with slow release SO2 pads was only 2.93 ( ± 0.37) µL L−1 held at 0.5 °C, too low for control of R. mendax. To develop a fruit treatment schedule that controls both pests, we first combined fumigation of 10,000 µL L−1 SO2 and CO2 at 6% v/v for 30 min followed by cold storage at 2 °C for 12 d or − 0.5 °C for 6 d to mimic shipping conditions. With short fumigation and long cold, R. mendax survival was reduced by no more than 4%, whereas D. suzukii was controlled effectively by cold in fumigated and non-fumigated conditions. However, fruit condition was negatively affected by SO2, so lower dosages were explored. 300 and 500 µL L−1 of SO2 with a longer exposure duration were applied at room temperature. These dosages successfully controlled R. mendax without damaging fruit quality. Survival of R. mendax to pupation was reduced by 58% and 61% after 2 d and 3 d fumigation at 22 ⁰C with 300 µL L−1 SO2, respectively. Fumigating infested blueberries at 22 °C with 500 µL L−1 of SO2 reduced pupation by 97% after 2 d and by 100% after 3 d. Fruit quality parameters were not significantly reduced by the low SO2 fumigation regimen on three different blueberry cultivars. Our data indicate that both insect pests can be controlled in harvested blueberries without loss of fruit quality by the combination of fumigation for 3 d at 22 ⁰C with 500 µL L−1 SO2, followed by cold storage. These results can inform export protocols for blueberries as part of a systems approach that combines in-field management and postharvest control programs.

Temporal Variability in Gas Emissions at Bagana Volcano Revealed by Aerial, Ground, and Satellite Observations

AbstractBagana is a remote, highly active volcano, located on Bougainville Island in southeastern Papua New Guinea. The volcano has exhibited sustained and prodigious sulfur dioxide gas emissions in recent decades, accompanied by frequent episodes of lava extrusion. The remote location of Bagana and its persistent activity have made it a valuable case study for satellite observations of active volcanism. This remoteness has also left many features of Bagana relatively unexplored. Here, we present the first measurements of volcanic gas composition, achieved by unoccupied aerial system (UAS) flights through the volcano's summit plume, and a payload comprising a miniaturized MultiGAS. We combine our measurements of the molar CO2/SO2 ratio in the plume with coincident remote sensing measurements (ground‐ and satellite‐based) of SO2 emission rate to compute the first estimate of CO2 flux at Bagana. We report low SO2 and CO2 fluxes at Bagana from our fieldwork in September 2019, ∼320 ± 76 td−1 and ∼320 ± 84 td−1, respectively, which we attribute to the volcano's low level of activity at the time of our visit. We use satellite observations to demonstrate that Bagana's activity and emissions behavior are highly variable and advance the argument that such variability is likely an inherent feature of many volcanoes worldwide and yet is inadequately captured by our extant volcanic gas inventories, which are often biased to sporadic measurements. We argue that there is great value in the use of UAS combined with MultiGAS‐type instruments for remote monitoring of gas emissions from other inaccessible volcanoes.

Relevance and Reliability of Outdoor SO2 Monitoring in Low-Income Countries Using Low-Cost Sensors

In the Western world, the SO2 concentration in ambient air dropped to low levels, but some emission sources (e.g., merchant ships) and some regions (e.g., low-income countries) still emit substantial amounts of SO2. At those locations, SO2 monitoring is critical. However, low-income countries do not have much access to expensive reference instruments. Low-cost gas sensors might be an alternative, but it is unclear how reliable such measurements are. To evaluate the performance of the low-cost alternative, the same SO2 gas sensor has been subjected to three different calibration methods: (1) low-cost calibration performed in the tropical climate of Cuba; (2) high-end calibration performed in Belgium; (3) a field calibration at an air quality measuring station in Belgium. The first two methods showed similar trends, suggesting that the gas sensor can be calibrated with a low-cost method. The field calibration was hampered by the low SO2 concentrations. For the monitoring campaign in Cienfuegos, Cuba, the low-cost SO2 sensor calibrated by the low-cost method appeared to be sufficiently reliable. The reliability of the sensor increases with the increase in SO2 concentration, so it can be used in Cuba instead of Belgium.

Facile Synthesis of Alkaline Ternary Deep Eutectic Solvents: Application for Effective and Reversible SO2 Uptake

Effective capture and recycling of SO2 are of great significance to environmental protection and high-value utilization. Herein, a promising strategy for effective and reversible capture of SO2 was proposed using alkaline ternary deep eutectic solvents (DESs) as absorbents. The absorbents consisting of choline chloride (ChCl), diethylenetriamine (DETA), and ethylene glycol (EG) with different molar ratios show a relatively lower viscosity and higher thermal stability. Here, ChCl/DETA/EG (1:1:2) could take out 0.87 g of SO2/g of solvent at 298.15 K and 1.0 bar. Surprisingly, a SO2 absorption capacity of 0.53 g/g could still be gained under a lower SO2 partial pressure (0.2 bar). Besides, the prepared absorbents also exhibit rapid equilibration time and satisfied reusability, providing a potential alternative strategy for the effective and reversible elimination of SO2.

Health Impacts of Air Pollution in Tianjin

Ambient air pollution is a dominant determinant of health. The health effects and economic losses due to air pollution are very important for decision-making. Since the implementation of the "Air Pollution Prevention and Control Action Plan" and "blue sky defense war" policies, the air quality of Tianjin has changed significantly. Here, the health effects and economic losses attributable to ambient air pollution in Tianjin from 2013 to 2020 wereestimated. For the particulate matter which has complex components, we assessed the inhalation health risks of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in PM2.5. The variation in the concentration of the main components of PM2.5 was also analyzed. The results showed that improved air quality had positive health benefits. The health benefits from SO2 were the highest among the six air pollutants, and 3786 deaths were avoided in 2020 compared to in 2013 due to lower SO2 concentration. The economic losses caused by air pollutants ranged from several billion to ten billion yuan. Among the six air pollutants, particulate matter and ozone had higher health losses in recent years. The health risks of heavy metals and PAHs in PM2.5 showed a decreasing trend. However, Cr(Ⅵ), As, Cd, and Ni in PM2.5in the winter of 2020 still had respiratorysystem carcinogenic risk, whereas there was no health risk of PAHs in PM2.5in 2019-2020. The concentrations of main components of PM2.5 have decreased significantly. In the future, the reduction of health loss caused by air pollution depends on synergy governance of particulate matter and ozone and further research on health effects.

Efficient SO2 capture at ultra-low concentration using a hybrid absorbent of deep eutectic solvent and ethylene glycol

Deep eutectic solvents (DESs) are considered as the highly effective absorbents for sulfur dioxide (SO2) capture. However, the high viscosity of DESs and the resulting slow absorption rate as well as low absorption capacity at low SO2 concentration seriously hinder their industrial application. In this study, DES of N-methyldiethanolamine (MDEA) and imidazole (Im) is simply blended with ethylene glycol (EG) forming a hybrid absorbent, namely MDEA/Im-EG, which exhibits extremely high SO2 capture capacity at low concentration. In particular, SO2 capture capacity in MDEA/Im-EG (molar ratio = 1:1) reaches 0.446 g SO2/g absorbent at 293.2 K with SO2 concentration of 2000 ppm. Moreover, the corresponding desorption enthalpy is only −40.67 kJ/mol. To well understand the results, thermodynamic analysis of SO2 capture is performed and the SO2 capture mechanism is speculated by nuclear magnetic resonance and Fourier transform infrared spectroscopy.

Metschnikowia pulcherrima as biocontrol agent and wine aroma enhancer in combination with a native Saccharomycescerevisiae

One of the main objectives for a sustainable winemaking process is the reduction of the use of sulfur dioxide. In this regard, non-Saccharomyces wine yeasts are proposed as biocontrol agent in different steps of wine production chain. Here, a selected strain of Metschnikowia pulcherrima (DiSVA 269) and a native Saccharomyces cerevisiae low sulfite producer strain (DiSVA 708) were investigated. After preliminary laboratory trials, winemaking process at industrial level showed an effective biocontrol action (reduction of c.a. 1 Log order of wild yeasts) of M. pulcherrima inoculated at prefermentative stage in cold clarification (48 h at 10 °C) and during the subsequent fermentation process. The combination of M. pulcherrima/S. cerevisiae led a distinctive aromatic profile of wines both in laboratory and winery trials with a significant enhancement of ethyl butyrate, ethyl hexanoate, isoamyl acetate and β-phenyl ethanol. Moreover the use of the two selected strains was the best combination to enhance volatile thiols (3-mercaptohexan-1-ol and 3-mercaptoexil acetate) that well correlate with the sensory analysis (tropical fruits). The overall results indicate that the combined use of M. pulcherrima DiSVA 269 and native S. cerevisiae DiSVA 708 led a biocontrol action and an improvement of aromatic and sensorial profile of wine with low SO2 content.

The Application of Non-Thermal Technologies for Wine Processing, Preservation, and Quality Enhancement

Recently, non-thermal wine processing technologies have been proposed as alternatives to conventional winemaking processes, mostly with the aims to improve wine quality, safety, and shelf-life. Winemakers typically rely on sulfites (SO2) to prevent wine oxidation and microbial spoilage, as these processes can negatively affect wine quality and aging potential. However, SO2 can trigger allergic reactions, asthma, and headaches in sensitive consumers, so limitations on their use are needed. In red winemaking, prolonged maceration on skins is required to extract enough phenolic compounds from the wine, which is time-consuming. Consequently, the wine industry is looking for new ways to lower SO2 levels, shorten maceration times, and extend shelf life while retaining wine quality. This review aggregates the information about the novel processing techniques proposed for winemaking, such as high-pressure processing, pulsed electric field, ultrasound, microwave, and irradiation. In general, non-thermal processing techniques have been shown to lead to improvements in wine color characteristics (phenolic and anthocyanin content), wine stability, and wine sensory properties while reducing the need for SO2 additions, shortening the maceration time, and lowering the microbial load, thereby improving the overall quality, safety, and shelf life of the wines.

Blood Gas, Acid-Base and Electrolyte Analysis in Healthy Dromedary Camel Calves up to 21 Days of Life.

The importance of prompt evaluation and care of the newborn is essential for reducing neonatal mortality, which represents a major cause of loss in camelids. This study investigated the blood gases, acid-base and electrolyte profiles in healthy dromedary calves during the first 3 weeks of life, assessing possible associations with age. Twenty-one dromedary camel calves aged 1 to 21 days were sampled, and venous whole blood analyzed through a VETSTAT® analyzer. The following parameters were measured: sodium (Na+), potassium (K+), chloride (Cl-), hydrogen ion concentration (pH), partial pressure carbon dioxide (pCO2), partial pressure oxygen (pO2), total hemoglobin concentration (tHb), hemoglobin oxygen saturation (sO2), total carbon dioxide (tCO2), bicarbonate (HCO3-), base excess (BE) and anion gap (AG). Calves were divided in two groups; younger calves (1-10 d), and older calves (11-21 d). Statistical analysis showed an effect of age, with lower K+ (p < 0.001) and higher Na+ and Cl- (p < 0.05) mean concentrations in the younger calves compared to the older ones, and higher pCO2 and lower sO2 mean concentrations in the older group. These preliminary results firstly described the blood gas, acid-base and electrolyte profiles in the healthy dromedary calf during the first 3 weeks of age, suggesting an effect of age on some parameters.

Rapid determination of free sulfur dioxide in wine and cider by capillary electrophoresis

A novel method for the determination of “true” free sulfur dioxide (SO2) in wine and cider was developed using capillary electrophoresis with direct ultraviolet-visible spectrophotometric detection (CE-UV/vis). Free SO2 was measured in model solutions with different SO2-binding agents present (α-ketoglutarate, pyruvate, acetaldehyde, glucose, fructose, and malvidin-3-glucoside) as well as a variety of white and red wines and ciders. The CE method was compared to three conventional methods for measuring free SO2, the Ripper method, Aeration-Oxidation (AO), and pararosaniline by discrete analyzer (DA). While some statistically significant differences (p<0.05) were found between the four methods in unpigmented model solutions and samples, the values generally agreed. In the presence of anthocyanins in model solution and red wines, free SO2 values found by CE were significantly lower than the other three methods (p<0.05). The difference in values found by Ripper and CE correlated strongly with anthocyanin content (R2 = 0.8854) and even more strongly when accounting for polymeric pigments (R2 = 0.9251). The results in red ciders differed from those in red wines, while the CE measured significantly lower free SO2 values than the other three methods, the difference in free SO2 values measured by CE and Ripper correlated more closely with anthocyanin concentration (R2 = 0.8802) than absorbance due to bleachable pigment (R2 = 0.7770). The CE method was found to be rapid (4 min/injection), sensitive (LOD=0.5 mg/L, LOQ=1.6 mg/L free SO2 in wine, 0.8 and 2.8 mg/L, respectively, in cider), robust, and repeatable (average RSD = 4.9%) and did not suffer from the issue of over-reporting free SO2 in pigmented samples often observed with currently accepted methods.

Secondary aerosol formation drives atmospheric particulate matter pollution over megacities (Beijing and Seoul) in East Asia

Atmospheric particulate matter (PM) pollution in Beijing and Seoul is an urgent concern because of the dense population and the role of the capital city. This study aimed to understand haze formation over East Asia during winter by simultaneously measuring the in situ aerosol chemical composition in the two megacities. During the sampling period, a similar pollution situation characterized by extremely low SO2 (approximately 1 ppbv) and high NOx (approximately 20 ppbv) concentrations and secondary inorganic aerosol (SIA)-dominated PM was found in both cities. Nitrate dominated the inorganic components in the submicron particles in both cities and was more pronounced in Seoul than in Beijing. The enhanced SIA mass concentrations during pollution episodes were observed to be associated with an increased local atmospheric oxidation capacity (indicated by O3+NO2=Ox concentration) and ambient relative humidity under similar stagnant weather conditions. Regarding the thermodynamic equilibrium, abundant aerosol liquid water promoted the partitioning of gaseous HNO3 into its particle phase when pollution events occurred. This result emphasized the importance of local secondary aerosol formation for atmospheric PM pollution in East Asian megacities. The box model simulation of nitrate formation indicated that the homogeneous oxidation of NO2 by OH radicals was the major nitrate formation pathway in both megacities. The downward transport of nitrate from the residual layer also significantly contributed to nitrate concentrations. NOx and volatile organic compounds (VOCs) exhibited a non-linear relationship with nitrate formation. Reducing VOCs concentrations was an efficient approach to mitigate nitrate in both megacities. A reduction of more than 50% in NOx concentrations was required for the effective reduction of nitrate. This study highlighted that Beijing and Seoul were experiencing similar PM pollution situations, and nitrate reduction should be considered to improve their air quality.

Unusually high SO2 emissions and plume height from Piton de la Fournaise volcano during the April 2020 eruption

Piton de la Fournaise volcano, La Réunion, France, erupted between the 2 and 6 April 2020, one of a series of eruptive phases which occur typically two or three times per year. Here, we use back trajectory analysis of satellite data from the TROPOMI instrument to determine that gas emissions during the June 2020 eruption were of unusually high intensity and altitude, producing 34.9 ± 17.4 kt of SO2 and plume heights up to 5 km a.s.l. The early stages of the eruption (2–4 April 2020) were characterised by relatively low SO2 emission rates despite strong low frequency tremor (LFT); the latter phase followed an increase in intensity and explosivity in the early hours of 5 April 2020. This period included lava fountaining, significantly increased SO2 emission rates, increased high frequency tremor (HFT) and decreased LFT. Using the PlumeTraj back trajectory analysis toolkit, we found the peak SO2 emission rate was 284 ± 130 kg/s on the 6 April. The plume altitude peaked at ~ 5 km a.s.l. on 5 April, in the hours following a sudden increase in explosivity, producing one of the tallest eruption columns recorded at Piton de la Fournaise. PlumeTraj allowed us to discriminate each day’s SO2, which otherwise would have led to a mass overestimate due to the plumes remaining visible for more than 24 h. The eruption exhibited a remarkable decoupling and anti-correlation between the intensity of the LFT signal and that of the magma and gas emission rates. LFT intensity peaked during the first phase with low magma and SO2 emissions, but quickly decreased during the second phase, replaced by unusually strong HFT. We conclude that the observation of strong HFT is associated with higher intensity of eruption, degassing, and greater height of neutral buoyancy of the plume, which may provide an alert to the presence of greater hazards produced by higher intensity eruptive activity. This might be particularly useful when direct visual observation is prevented by meteorological conditions. This eruption shows the importance of combining multiple data sets when monitoring volcanoes. Combining gas and seismic data sets allowed for a much more accurate assessment of the eruption than either could have done alone.