Low SO2 Research Articles

Why is the Indo-Gangetic Plain the region with the largest NH<sub>3</sub> column in the globe during pre-monsoon and monsoon seasons?

Abstract. Satellite observations show a global maximum in ammonia (NH3) over the Indo-Gangetic Plain (IGP), with a peak from June to August. However, it has never been explained explicitly. In this study, we investigated the causes of high NH3 loading over the IGP during the pre-monsoon and monsoon seasons using WRF-Chem (Weather Research and Forecasting model coupled to chemistry). The IGP has relatively high NH3 emission fluxes (0.4 t km−2 month−1) due to intensive agricultural activities and high air temperature from June to August. Additionally, low sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions and high air temperature limit the gas-to-particle conversion of NH3, particularly for ammonium nitrate formation. Moreover, the barrier effects of the Himalayas in combination with the surface convergence weaken the horizontal diffusion of NH3. The high NH3 loading over the IGP mainly results from the low gas-to-particle partitioning of NH3 caused by low SO2 and NOx emissions. It contrasts to those in the North China Plain, where high SO2 and NOx emissions promote the conversion of gaseous NH3 into particulate ammonium.

Recent developments in reduction of sulphur emissions from selected Waterberg coal samples used in South African power plants

Sulphur content in the coal is the most notorious environmental contaminant, which produces sulphur dioxide (SO2) during combustion. In this study, the sulphur content of the parent coal samples reduced through biodesulphurization treatment and its influence on the SO2 emissions concentration in a power plant was monitored. Coal samples were screened to a particle size fraction of – 0.85 mm, – 2.30 + 1.00 mm, – 4.60 + 2.30 mm and +4.60 mm prior to biodesulphurization treatment. Data used in this study comprised of average 2 daily interval sulphur content and SO2 emissions concentrations for the period 0 to 20 Days. The finer fraction of – 0.85 mm showed a significant reduction of sulphur content from 1.45 wt% to 0.50 wt% which translate to SO2 emissions concentration reduction from 3716 mg/Nm3 to 1280 mg/Nm3. However, when the temperature was increased from 23 ± 3 °C to 30 ± 2 °C, further reduction of SO2 emissions to 1023 mg/Nm3 was realized. Biodesulphurization treatment demonstrated to lower SO2 emissions by 72.4% and reduce ash content by some 33%. Moreover, pyrite was observed in vitrinite and inertinite, both syngenetically and epigenetically. The current study offers the possibility of reducing SO2 emissions in South African power plants through biodesulphurization treatment.

Characterization of outdoor air pollution from solid fuel combustion in Xuanwei and Fuyuan, a rural region of China

Outdoor air pollution is a growing public health concern, particularly in urban settings. However, there are limited epidemiological data on outdoor air pollution in rural areas with substantial levels of air pollution attributed to solid fuel burning for household cooking and heating. Xuanwei and Fuyuan are rural counties in China where the domestic combustion of locally sourced bituminous (“smoky”) coal has been associated with the highest lung cancer rates in China. We previously assessed indoor and personal air pollution exposures in this area; however, the influence of indoor coal combustion and household ventilation on outdoor air pollution has not been assessed. Therefore, we measured outdoor fine particulate matter (PM2.5), species of polycyclic aromatic hydrocarbons (PAHs) including naphthalene (NAP) and the known carcinogen benzo(a)pyrene (BaP), sulfur dioxide (SO2), and nitrogen dioxide (NO2) over two consecutive 24-h sampling periods in 29 villages. Just over half of the villages were revisited two to nine months after the initial sampling period to repeat all measurements. The overall geometric mean (GM) of outdoor PM2.5, BaP, NAP, and NO2 were 45.3 µg/m3, 9.7 ng/m3, 707.7 ng/m3, and 91.5 µg/m3, respectively. Using linear mixed effects models, we found that burning smoky coal was associated with higher outdoor BaP concentrations [GM ratio (GMR) = 2.79] and lower outdoor SO2 detection rates (GMR = 0.43), compared to areas burning smokeless coal. Areas with predominantly ventilated stoves (> 50% of stoves) had higher outdoor BaP (GMR = 1.49) compared to areas with fewer ventilated stoves. These results show that outdoor air pollution in a rural region of China was associated with the type of coal used for cooking and heating indoors and the presence of stove ventilation. Our findings suggest that efforts of household stove improvement to reduce indoor air pollution have resulted in higher outdoor air pollution levels. Further reducing adverse health effects in rural villages from household coal combustion will require the use of cleaner fuel types.

Investigation on optimal active layer thickness and pore size in dual-layer NH3-SCR monolith for low SO2 oxidation by numerical simulation

Nitrogen oxides (NOx) and sulfur dioxide (SO2) are common gaseous pollutants in the flue gas of stationary resources, such as thermal power plants. The undesired oxidation of SO2 on the catalytic monolith for Selective Catalytic Reduction (SCR) with ammonia will cause deposition of ammonium bisulfate, corrosion and extra pressure drop to downstream devices. A dual-layer model of catalytic monolith was established in this work to thoroughly investigate the effects of active layer thickness on SCR reaction and SO2 oxidation under various operating parameters. Besides, the influences of different sizes of nanopore in catalyst on both reactions are discussed. Thus, optimal parameters and suggestions were given for the design of SCR catalytic monolith with low SO2 oxidation.

First Measurements of Gas Flux with a Low-Cost Smartphone Sensor-Based UV Camera on the Volcanoes of Northern Chile

UV cameras have been used for over a decade in order to remotely sense SO2 emission rates from active volcanoes, and to thereby enhance our understanding of processes related to active and passive degassing. Whilst SO2 column density retrievals can be more accurate/sophisticated using alternative techniques (e.g., Differential Optical Absorption Spectrometer (DOAS), Correlation Spectrometer (COSPEC)), due to their higher spectral resolutions, UV cameras provide the advantage of high time-resolution emission rates, a much greater spatial resolution, and the ability to simultaneously retrieve plume speeds. Nevertheless, the relatively high costs have limited their uptake to a limited number of research groups and volcanic observatories across the planet. One recent intervention in this regard has been the introduction of the PiCam UV camera, which has considerably lowered instrumental cost. Here we present the first data obtained with the PiCam system from seven persistently degassing volcanoes in northern Chile, demonstrating robust field operation in challenging conditions and over an extended period of time, hence adding credence to the potential of these units for more widespread dissemination to the international volcanic gas measurement community. Small and weak plumes, as well as strongly degassing plumes were measured at distances ranging 0.6–10.8 km from the sources, resulting in a wide range of SO2 emission rates, varying from 3.8 ± 1.8 to 361 ± 31.6 td−1. Our acquired data are discussed with reference to previously reported emission rates from other ground-based remotely sensed techniques at the same volcanoes, in particular considering: resolution of single plume emissions in multi-plume volcanoes, light dilution, plume geometry, seasonal effects, and the applied plume speed measurement methodology. The main internal/external factors that influence positive/negative PiCam measurements include camera shake, light dilution, and the performance of the OpenCV and control points post processing methods. A simple reprocessing method is presented in order to correct the camera shake. Finally, volcanoes were separated into two distinct groups: low and moderate SO2 emission rates systems. These groups correlate positively with their volcanological characteristics, especially with the fluid compositions from fumaroles.

Manganese Ore-based Wet Flue-Gas Desulfurization: A Review

The removal of SO2 from flue gases is necessary for eliminating haze and controlling acid rain. However, developing the traditional wet and dry flue-gas desulfurization (FGD) is challenging due to the disposal issue of several byproducts. Manganese (Mn) orebased wet FGD possesses many advantages, including good desulfurization property, low cost, and high economic benefit. The environment friendliness and reusability of MnSO4 provide new ideas and methods in the future research direction of FGD. This review summarizes the background information of Mn ore slurry desulfurization, the desulfurization mechanism, the technological process, and the desulfurization devices. The role of operating parameters, such as temperature, liquid/solid ratio, pH, SO2 concentration, and particle size, in the desulfurization efficiency and manganese leaching rate are also discussed. The temperature (20°C-80°C) has exerted little effect on the desulfurization efficiency, whereas a low pH value is beneficial for SO2 removal. Moreover, a low inlet SO2 concentration and small particle size are beneficial for SO2 removal. The control and digestion techniques related to the byproduct (manganese dithionate) are also presented, along with the future development direction of Mn ore-based wet FGD in different industries.

Maternal arterial blood gas values during delivery: Effect of mode of delivery, maternal characteristics, obstetric interventions and correlation to fetal umbilical cord blood

Obstetricians routinely use biochemical parameters from non-pregnant women to assess the condition of the laboring mother. However, it is well known that pregnancy leads to significant physiological changes in most organ systems. The aim of this study was to determine normal values for maternal arterial blood gases during vaginal deliveries as compared with control values from planned cesarean sections. We also wanted to elucidate the effect of various maternal characteristics, mode of delivery and obstetric interventions on blood gas values. We carried out a randomly selected, prospective-observational cohort study of 250 women undergoing vaginal delivery and 58 women undergoing planned cesarean section at the Department of Obstetrics and Gynecology, Skåne University Hospital, Malmö, Sweden. We found significant differences for gestational age, parity, umbilical venous blood pH, pCO2 and lactate values between the two study groups (P<.005). Significantly lower pH, pCO2 , pO2 and sO2 were found in mothers delivering vaginally. Higher base deficit, hemoglobin, bilirubin, potassium, glucose and lactate were found in vaginal deliveries than in planned cesarean sections (P<.02). Maternal body mass index (BMI), smoking and hypertension were not significantly correlated to acid base parameters in women with vaginal deliveries. On the other hand, multiple regression showed significant associations for the use of epidural anesthesia on maternal pH (P<.05) and pO2 (P<.01); and synthetic oxytocin on pCO2 (P=.08), glucose (P<.00) and lactate (P<.02) levels in maternal arterial blood. Maternal arterial pH, pCO2 and lactate values correlated significantly to values in venous umbilical cord blood (P<.000). Maternal arterial blood gas parameters varied significantly according to mode of delivery, the use of epidural anesthesia and synthetic oxytocin.

Muscle cooling modulates tissue oxidative and biochemical responses but not energy metabolism during exercise.

This study investigated whether muscle cooling and its associated effects on skeletal muscle oxidative responses, blood gases, and hormonal concentrations influenced energy metabolism during cycling. Twelve healthy participants (Males: seven; Females: five) performed two steady-state exercise sessions at 70% of ventilatory threshold on a cycle ergometer. Participants completed one session with pre-exercise leg cooling until muscle temperature (Tm) decreased by 6°C (LCO), and a separate session without cooling (CON). They exercised until Tm returned to baseline and for an additional 30min. Cardiovascular, respiratory, metabolic, hemodynamic variables, and skeletal muscle tissue oxidative responses were assessed continuously. Venous blood samples were collected to assess blood gases, and hormones. Heart rate, stroke volume, and cardiac output all increased across time but were not different between conditions. V̇O2 was greater in LCO when muscle temperature was restored until the end of exercise (p < 0.05). Cycling in the LCO condition induced lower oxygen availability, tissue oxygenation, blood pH, sO2%, and pO2 (p < 0.05). Insulin concentrations were also higher in LCO vs. CON (p < 0.05). Importantly, stoichiometric equations from respiratory gases indicated no differences in fat and CHO oxidation between conditions. The present study demonstrated that despite muscle cooling and the associated oxidative and biochemical changes, energy metabolism remained unaltered during cycling. Whether lower local and systemic oxygen availability is counteracted via a cold-induced activation of lipid metabolism pathways needs to be further investigated.

Detecting hemodynamic changes in the foot vessels of diabetic patients by photoacoustic tomography.

Limb perfusion monitoring is critical for diabetes mellitus (DM) patients as they are vulnerable to vascular complications due to prolonged hyperglycemia. However, current clinical approaches are ineffective in vascular imaging and in assessing vascular function in lower limbs. In this work, a concave ultrasound transducer array-based photoacoustic tomography (PAT) system was used to image the foot dorsal section of a subject, and a total of seven DM patients and seven healthy volunteers were enrolled in this study. Hemodynamic changes in foot vessels during vascular occlusion as well as oxygen saturation (SO2 ) in rest were analyzed for both groups. The results obtained showed that DM patients have a unique peripheral hemodynamic response to occlusion and a lower level SO2 , compared to that for healthy subjects. This suggests that PAT has the potential to detect vascular dysfunction in DM patients and to measure the effect of treatment.

Impact of Ignition Technique on Pollutants Emission during the Combustion of Selected Solid Biofuels

Nowadays, heating using wood, briquettes, or pellets is a curious replacement to fossil fuels such as coal, oil, or gas. Unfortunately, the combustion of biofuels, especially in low-power boilers with unstable operating conditions, releases a lot of gas pollutants (e.g., carbon monoxide (CO), nitric oxide (NO), and various organic compounds) that are usually generated due to the incomplete product combustion. The combustion of biofuel in grate boilers with top-down ignition is a new approach, popular in society (mainly used for coal fuels), which improves the combustion process and reduces the amount of pollutants emitted. This study evaluated the impact of ignition techniques on the emission level of gas pollutants during the combustion of wood logs, briquettes, and pellets of pine in grate-based charging boilers. The combination of top ignition mode with pinewood logs allowed us to achieve a reduction of 6% in CO and sulfur dioxide (SO2) emission into the atmosphere. However, the combination of top-down ignition mode with pellets and briquettes produced, in fully operational conditions, 1- to 18-fold higher levels of CO and SO2 respectively, than bottom-up ignition, after an initial period of low level CO and SO2 emissions. During the tests (mainly with ignition from top), substantial emissions of NO were observed of up to 400 mg·m−3 at 10% O2. Therefore, further research is required to decrease emission related to the content of nitrogen in biomass. In this respect, research of impact on the combustion temperature of such emissions is needed.

Promotional role of Mo on Ce0.3FeOx catalyst towards enhanced NH3-SCR catalytic performance and SO2 resistance

The SO2 resistance of low temperature NH3-SCR in non-electric power industries has always been the bottleneck of this technology. Herein, a series of Mo-modified Ce0.3FeOx catalysts (MoaCe0.3FeOx) were synthesized by an easy to scale-up, environment-friendly two-step solid interface reaction and applied to the treatment of flue gas from the glass industry. Incorporation of Mo into Ce0.3FeOx catalyst could not only remarkably expand the operation temperature window in both low and high temperature regions, but also maintain high catalytic activity (>85% NOx conversion) under 65 h long stability test conditions even with the coexistence of H2O and SO2. The two-step interface reaction over MoaCe0.3FeOx provided an increased specific surface area and more amorphous structure, forming highly dispersed MoO3 species on the surface of the catalyst which serves as a sacrificial site to react with SO2. The process of redox reaction has been greatly improved due to the facilitated electron transfer between Fe2+ and Ce4+ as well as more oxygen vacancies and active oxygen. The enhanced presence of NH4+ could react with gaseous NO species via Eley–Rideal (E–R) mechanism due to the lack of nitrate species (greatly inhibited) while the NH4NO3 was not generated during the reaction which is responsible for excellent low temperature SCR performance as well as high N2 selectivity. Furthermore, less sulfate species and no bulk sulfate were formed, which indicated that the doping of Mo could effectively reduce the basic sites and delay the irreversible deactivation as well as reduce catalyst sulphation. The above features provide a strategy for design and development of non-vanadium-based catalysts with low temperature SO2 resistance in non-electric power industries with high NOx emission concentrations.

The fumarolic CO2 output from Pico do Fogo volcano (Cape Verde)

The Pico do Fogo volcano, in the Cape Verde Archipelago off the western coasts of Africa, has been the most active volcano in the Macaronesia region in the Central Atlantic, with at least 27 eruptions during the last 500 years. Between eruptions fumarolic activity has been persisting in its summit crater, but limited information exists for the chemistry and output of these gas emissions. Here, we use the results acquired during a field survey in February 2019 to quantify the quiescent summit fumaroles' volatile output for the first time. By combining measurements of the fumarole compositions (using both a portable Multi-GAS and direct sampling of the hottest fumarole) and of the SO2 flux (using near-vent UV Camera recording), we quantify a daily output of 1060±340 tons CO2, 780±320 tons H2O, 6.2±2.4 tons H2S, 1.4±0.4 tons SO2 and 0.05±0.022 tons H2. We show that the fumarolic CO2 output from Pico do Fogo exceeds (i) the time-averaged CO2 release during 2015-type recurrent eruptions and (ii) is larger than current diffuse soil degassing of CO2 on Fogo Island. When compared to worldwide volcanoes in quiescent hydrothermal-stage, Pico do Fogo is found to rank among the strongest CO2 emitters. Its substantial CO2 discharge implies a continuous deep supply of magmatic gas from the volcano’s plumbing system (verified by the low but measurable SO2 flux), that becomes partially affected by water condensation and sulphur scrubbing in fumarolic conduits prior to gas exit. Variable removal of magmatic H2O and S accounts for both spatial chemical heterogeneities in the fumarolic field and its CO2- enriched mean composition, that we infer at 64.1±9.2 mol. % H2O, 35.6±9.1 mol. % CO 0.26±0.14 mol. % total Sulfur (S ), and 0.04±0.02 mol. % H2.

Thermal-oxidative aging mechanism of asphalt binder based on isothermal thermal analysis at the SARA level

To better understand the thermal-oxidative aging mechanism of asphalt binder at the component level, a new isothermal agingmethod was developed to discuss thermal behaviors of saturates, aromatics, resins and asphaltenes (SARA) fractions. Volatile constituents released from SARA fractions were identified and the changes in chemical compositions, morphology and elements of SARA fractions were characterized before and after the thermal-oxidative aging. Results indicate that the mass losses of saturates and resins are 2.1% and 0.7%, respectively. However, the aromatics and asphaltenes masses are increased by 2.0% and 5.2%, respectively. Also, endothermic reactions occur in saturates and aromatics, and endothermic and exothermic reactions are basically equivalent in resins, and exothermic reactions occur in asphaltenes. Further, CO, CO2, CH4 and light oxygen-containingcompounds are released during the aging of SARA fractions, and short-chain alkanes are generated in saturates. Low molecular hydrocarbons, CO2, and SO2 are emitted, and more aromatic ring products are generated in aromatics. Carboxylic acids, small molecular unsaturated hydrocarbons and SO2 are volatilized, and fused aromatic rings, alcohols and ethers are produced in resins. Unsaturated hydrocarbons are released, and the molecular polymerization becomes obvious in asphaltenes. Additionally, after the isothermal aging, pores or bulges are left in saturates, and obvious folds and pores appear on aromatics. Cluster whiskers, lumps and disordered lamellar layers are observed on resins, and resins and asphaltenes become loose, dry and rough. C element content is increased, but O element content is decreased. Finally, various volatiles are released from SARA fractions at different aging stages. The thermal-oxidative aging of asphalt binder consists of the volatilization of light components and the oxidation of side chains in benzene methyls and aliphatic hydrocarbons, leading to the content changes of SARA fractions in asphalt binder.

Insight into the Effect of the Continuous Testing and Aging on the so2 Sensing Characteristics of a YSZ (Yttria-stabilized Zirconia)-Based Sensor Utilizing ZnGa2O4 and Pt Electrodes

Insight into the Effect of the Continuous Testing and Aging on the so2 Sensing Characteristics of a YSZ (Yttria-stabilized Zirconia)-Based Sensor Utilizing ZnGa2O4 and Pt Electrodes

Insights into the bioenergy potential of jackfruit wastes considering their physicochemical properties, bioenergy indicators, combustion behaviors, and emission characteristics

Around 2.96 million tons of potential feedstocks are generated annually in the form of jackfruit waste, including peels (JP) and seeds (JS). This study assessed the suitability of JP and JS as new feedstocks for combustion and their preliminary potential for bioenergy considering their physicochemical properties, bioenergy indicators, combustion behaviors and emission characteristics. The jackfruit wastes presented attractive features for direct application in combustion, such as their composition of 75.1–81.3 wt.% of volatile solids, 40.8–41.8 wt.% carbon content, a higher heating value of 16.3–17.2 MJ kg−1, and negligible amounts of nitrogen and sulfur. Their ash contents varied from 5.6 wt.% to 6.7 wt.%, similar to that of other biomass fuels. The bioenergy yield obtained for JP and JS were 2.5 TJ ha−1 yr−1 and 0.9 TJ ha−1 yr−1 (dry basis), respectively, which exceed that of well-known bioenergy crops. The use of jackfruit residues as raw material for bioenergy can be highly feasible, given the low CO, CO2 and SO2 emissions, and a considerable equivalence with reference fuels. Combustion properties of JS and JP revealed a favorable burning performance. In conclusion, the highlights of this study provide useful information for the valorization and large-scale application of jackfruit wastes and contribute to their establishment as sustainable and renewable sources of bioenergy.

Novel shielding and synergy effects of Mn-Ce oxides confined in mesoporous zeolite for low temperature selective catalytic reduction of NOx with enhanced SO2/H2O tolerance

Nitrogen oxides (NOx) are a primary source of air pollutants from combustion of fossil fuels. Though Mn-Ce based catalysts exhibit superior low temperature activities, their water and SO2 tolerance is inferior to other metal oxide catalysts, due to their strong water adsorption and sulfate species formation tendency at low reaction temperatures. Herein, a confinement strategy was adopted to design and synthesize a novel Mn-Ce based catalyst for selective catalytic reduction of NOx with NH3. The confined MnCeOx catalyst was assembled with a simple one pot method, using a mesoporous zeolite (ZSM-5) as the shell and Mn-Ce oxides as the active core (MnCeOx@Z5). Owing to the zeolite shell’s shielding effect and the synergy between the alumina-silica zeolite shell’s acidic properties and the mixed oxide cores’ redox properties, the novel MnCeOx@Z5 catalyst displayed enhanced water and SO2 resistance as compared to the MnCeOx supported on ZSM-5 (MnCeOx/Z5) and its precursor (MnCeOx@Al-SiO2). Evidently, the zeolite sheath hinders sulfate species formation, and this phenomenon was further investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy (In situ DRIFTS). The novel shielding and acid-redox synergy effect/strategy adopted in this work can be applied to design other high performance deNOx catalysts for air pollution control.

Changes in air quality during the lockdown in Barcelona (Spain) one month into the SARS-CoV-2 epidemic

Lockdown measures came into force in Spain from March 14th, two weeks after the start of the SARS-CoV-2 epidemic, to reduce the epidemic curve. Our study aims to describe changes in air pollution levels during the lockdown measures in the city of Barcelona (NE Spain), by studying the time evolution of atmospheric pollutants recorded at the urban background and traffic air quality monitoring stations. After two weeks of lockdown, urban air pollution markedly decreased but with substantial differences among pollutants. The most significant reduction was estimated for BC and NO2 (−45 to −51%), pollutants mainly related to traffic emissions. A lower reduction was observed for PM10 (−28 to −31.0%). By contrast, O3 levels increased (+33 to +57% of the 8 h daily maxima), probably due to lower titration of O3 by NO and the decrease of NOx in a VOC-limited environment. Relevant differences in the meteorology of these two periods were also evidenced. The low reduction for PM10 is probably related to a significant regional contribution and the prevailing secondary origin of fine aerosols, but an in-depth evaluation has to be carried out to interpret this lower decrease. There is no defined trend for the low SO2 levels, probably due to the preferential reduction in emissions from the least polluting ships. A reduction of most pollutants to minimal concentrations are expected for the forthcoming weeks because of the more restrictive actions implemented for a total lockdown, which entered into force on March 30th. There are still open questions on why PM10 levels were much less reduced than BC and NO2 and on what is the proportion of the abatement of pollution directly related to the lockdown, without meteorological interferences.

Changes in PM2.5 sensitivity to NO x and NH3 emissions due to a large decrease in SO2 emissions from 2013 to 2018

The authors evaluated and compared the behavior of PM2.5 with respect to NOx and NH3 emission changes in high (the year 2013) and low (the year 2018) SO2 emission cases. Two groups of simulations were conducted based on anthropogenic emissions from China in 2013 and 2018, respectively. In each group of simulations, a respective 25% reduction in NOx and NH3 emissions were assumed. A sensitivity factor (β) was defined as the relative change in PM2.5 concentration due to 1% change in NOx or NH3 emissions. In the high SO2 emissions case, PM2.5 was more sensitive to NH3 (0.31) emissions change than NOx (0.21). Due to the significant decrease in SO2 emissions from the high to low SO2 emissions case, the sensitivity of PM2.5 to NOx increased to 0.33, while its sensitivity to NH3 decreased to 0.22. The result implies that now and in the future, PM2.5 is/will be less sensitive to NH3 emissions change, while NOx emissions control is more effective in reducing the surface PM2.5 concentration. Seasonally, in the low SO2 emissions case, the sensitivities of PM2.5 to NOx and NH3 in winter were higher than those in summer, indicating that to deal with severe winter haze more attention should be paid to the emissions control of inorganic PM2.5 precursors, especially NOx.

An unexpected catalyst dominates formation and radiative forcing of regional haze

Although regional haze adversely affects human health and possibly counteracts global warming from increasing levels of greenhouse gases, the formation and radiative forcing of regional haze on climate remain uncertain. By combining field measurements, laboratory experiments, and model simulations, we show a remarkable role of black carbon (BC) particles in driving the formation and trend of regional haze. Our analysis of long-term measurements in China indicates declined frequency of heavy haze events along with significantly reduced SO2, but negligibly alleviated haze severity. Also, no improving trend exists for moderate haze events. Our complementary laboratory experiments demonstrate that SO2 oxidation is efficiently catalyzed on BC particles in the presence of NO2 and NH3, even at low SO2 and intermediate relative humidity levels. Inclusion of the BC reaction accounts for about 90-100% and 30-50% of the sulfate production during moderate and heavy haze events, respectively. Calculations using a radiative transfer model and accounting for the sulfate formation on BC yield an invariant radiative forcing of nearly zero W m-2 on the top of the atmosphere throughout haze development, indicating small net climatic cooling/warming but large surface cooling, atmospheric heating, and air stagnation. This BC catalytic chemistry facilitates haze development and explains the observed trends of regional haze in China. Our results imply that reduction of SO2 alone is insufficient in mitigating haze occurrence and highlight the necessity of accurate representation of the BC chemical and radiative properties in predicting the formation and assessing the impacts of regional haze.

An update on biomarkers of 7-ketocholesterol, lysosphingomyelin, bile acid-408 and glucosylsphingosine for Niemann-Pick disease type C

Effective purification of low concentration SO2 at cathode air stream side is essential for Proton exchange membrane fuel cells performance in the real-world application. Amino modification porous material is the effective purification media. The modifier distribution along the pore channels is one of the most influencing parameters that determine the purification performance. Amino-modified porous resins are synthesized to assess the mechanism of modifier distribution along the pore channel. Modifier concentration, modification time, modification temperature, and intersolubility between solvent and modifier are found to significantly affect the modifier distribution. Increased modifier concentration within a relatively low range (0–200 g/L) is favorable to grafting modifier in external pore channel. However, no more significant modifier grafting was found for higher modifier concentration due to the higher solvent viscosity and lower modifier diffusion. Increased modification time leads to more amino groups grafted in deep pore channel. However, after the modification time is longer than 6 h, the modifier no longer diffuses into deeper pore channel due to the diffusion limitation. Solvent property significantly affects the modifier solubility and the swelling degree of porous resin. Larger intersolubility between solvent and modifier enhances the modifier diffusion into pore channel.