High O2 Concentrations Research Articles

Rehabilitación respiratoria oportuna y precoz en pacientes con neumonía COVID 19 en un hospital referencial

SARS-CoV-2 is a beta-coronavirus of the same subgenus as SARS and MERS viruses, they share the same gene binding receptor, angiotensin converting enzyme (ACE2). (1) The spectrum of disease severity is varied, with the mild form being the most frequent (81%), and severe disease present in 14% of cases, with critical presentation being present in 5%, with a mortality of 2.3%.(2) The post-pneumonia respiratory sequela caused by beta-Coronaviruses is diffuse alveolar damage with fibrotic lesions; the pathophysiological mechanism is multifactorial, which involves activation of transforming growth factor beta (TGF-β)(3), IL1, IL6, MCP1 and TNF-α secondary to epithelial injury and subsequent inflammation. In addition, exposure to high O2 concentrations and effects of barotrauma, caused by advanced oxygen/ventilatory support, activate the pro-fibrotic TGF-β pathway, resulting in aberrant repair characterized by exaggerated deposition of fibroblasts, myofibroblasts and collagen. Forty-seven percent and 25% of patients who survive moderate to severe COVID-19 pneumonia have decreased carbon monoxide diffusion and predicted total lung capacity, respectively. (4)

Influence of Fuel Type and Water Content Variation on Pollutant Emission Characteristics of a Biomass Circulating Fluidized Bed Boiler

In general, the biomass raw materials burned by biomass power plants generally have the characteristics of variable fuel types, high moisture content, and high volatile content. In this paper, a 130 t/h biomass circulating fluidized bed (BCFB) model was established on the MWorks platform with Modelica language. The influence of biomass type changes on operation parameters, the corresponding steady-state characteristics, and the dynamic characteristics of the BCFB were carried out. The temperature corresponding to the combustion of pine was overall higher than that of the other fuels, and the flue gas from the combustion of pine had the highest concentration of SO2, up to 520.49 mg/Nm3. The flue gas from the combustion of pure cotton sticks had the highest concentration of NO, up to 254.34 mg/Nm3. The changes of fuel type and moisture content all have a great influence on the operation of BCFBs. The emission of pollutants was not only related to the element content of fuel, but also closely related to the furnace temperature. The fuel moisture content also indirectly affects the pollutant emission concentration and the steam-water system.

Speciation analysis of inorganic selenium in wastewater using a highly selective cellulose-based adsorbent via liquid electrode plasma optical emission spectrometry

Speciation of selenium (Se) is typically carried out using a sophisticated technique such as ICP-MS after preconcentration using an adsorbent; however, the separation and preconcentration of inorganic Se has not been realized in the solutions containing high concentrations of SO42–. A dithiocarbamate-modified cellulose (DMC) was used in this study for the selective extraction and preconcentration of inorganic Se in wastewater, with a portable liquid electrode plasma-optical emission spectrometry (LEP-OES) being employed for quantification. DMC was found to selectively and quantitatively adsorb selenite (SeIV) over a wide range of pH (1.0–8.0); however, less than 3.0% of selenate (SeVI) was adsorbed in a pH range of 3.0–11. Quantitative extraction of SeIV was achieved even in the presence of 3.5 mol L–1 SO42–. The maximum sample volume from which 10 mg of DMC could quantitatively extract SeIV was found to be 500 mL. KOH (0.60 mL, 1.5 mol L–1) was found to quantitatively desorb SeIV retained on the adsorbent and yielded an enrichment factor of 833. The recovery of Se species from synthetic flue-gas desulfurization wastewater containing SeIV and SeVI at concentrations of 5.0 µmol L–1 was 96.2 ± 1.8% and 105.8 ± 1.8%, respectively.

Carbon, Nutrients and Methylmercury in Water from Small Catchments Affected by Various Forest Management Operations

Forest management activities in boreal and hemiboreal environments have been found to increase the concentration of carbon, nutrients, and methylmercury (MeHg) in runoff water, thus contributing to environmental quality issues. We evaluated carbon, nutrient, and MeHg concentrations in water at eight small, forested catchments on organic soils in Latvia, subject to ditch cleaning and beaver dam removal. These management-induced disturbances were classified into a major, minor, or no disturbance classes. The concentrations of dissolved organic carbon and total nitrogen were elevated in disturbed catchments (both major and minor) compared to the catchments with no disturbance. The concentrations of MeHg in the water displayed a clear seasonal variation with higher concentrations in spring and summer, but there were no significant differences in MeHg concentrations between catchments with major, minor, and no disturbances. However, the higher concentrations of SO42− in the disturbed catchments compared to those undisturbed may promote MeHg formation if the conditions become more reduced further downstream. While most former studies of forest management effects on water quality have focused on forest harvest, our research contributes to the currently rather scarce pool of data on the impact of less-studied management operations, such as ditch cleaning and beaver dam removal, on carbon, nutrient, and MeHg concentrations in runoff water.

A reactive molecular dynamics study of HCN oxidation during pressurized oxy-fuel combustion

In the present work, HCN oxidation during pressurized oxy-fuel combustion is studied using reactive molecular dynamics (ReaxFF MD) simulations. The effects of CO2, pressure, and O2 concentration on HCN oxidation are investigated. Under fuel-rich conditions, CO2 reduces the overall oxidation rate of HCN due to the lower diffusion coefficient of O2 in O2/CO2 environment. On the other hand, CO2 increases the amount of OH radicals through the reaction of CO2 + H → CO + OH at high temperatures. Although high pressure reduces the diffusion coefficient of O2, the oxidation rate of HCN still increases with the increase in pressure due to the higher partial pressure of O2. Moreover, NO emissions decrease with the increase in pressure because high pressure promotes the conversion of NO to N2. Furthermore, CO2 reduces the amount of CN, which is an important intermediate for the reduction of NO at high temperatures. Due to this reason, a positive effect of CO2 on the emissions of NO is observed. Additionally, the oxidation rate of HCN increases with the increase in the concentration of O2. Unlike fuel-rich conditions, CO2 exhibits an inhibitory effect on the emissions of NO under high concentration of O2.

Synergistic effects of gaseous pollutants on hospital admissions for cardiovascular disease in Liuzhou, China.

Previous studies demonstrated that short-term exposure to gaseous pollutants (nitrogen dioxide (NO2), sulfur dioxide (SO2), and ozone (O3)) had a greater adverse effect on cardiovascular disease. However, little evidence exists regarding the synergy between gaseous pollutants and cardiovascular disease (CVD). Therefore, we aimed to estimate the effect of individual gaseous pollutants on hospital admissions for CVD and to explore the possible synergistic effects between gaseous pollutants. Daily hospitalization counts for CVD were collected from January 1, 2014, to December 31, 2015. We also collected daily time series on gaseous pollutants from the Environment of the People's Republic of China, including NO2, SO2, and O3. We used distributed lag nonlinear models (DLNMs) to assess the association of individual gaseous pollutants on CVD hospitalization, after controlling for seasonality, day of the week, public holidays, and weather variables. Then, we explored the variability across age and sex groups. In addition, we analyzed the synergistic effects between gaseous pollutants on CVD. Extremely low NO2 and SO2 increase the risk of CVD in all subgroup at lag 7 days. The greatest effect of high concentration of SO2 was observed in male and the elderly (≥ 65 years) at lag 3 days. Greater effects of high concentration of O3 were more pronounced in the young (< 65 years) and female at lag 3 days, while the effect of low concentration of O3 was greater in male and the young (< 65 years) at lag 0 day. We found a synergistic effect between NO2 and SO2 for CVD, as well as between SO2 and O3. The synergistic effects of NO2 and SO2 on CVD were stronger in the elderly (≥ 65) and female. The female was sensitive to synergistic effects of SO2-O3 and NO2-O3. Interestingly, we found that there was a risk of CVD in the susceptible population even for gaseous pollutant concentrations below the National Environmental Quality Standard. The synergy between NO2 and SO2 was significantly associated with cardiovascular disease hospitalization in the elderly (≥ 65). This study provides evidence for the synergistic effect of gaseous pollutants on hospital admissions for cardiovascular disease.

Long-term air pollution exposure and decreased kidney function: A longitudinal cohort study in Bangkok Metropolitan Region, Thailand from 2002 to 2012

BackgroundKidney dysfunction is considered a cardiovascular risk factor. However, few longitudinal studies have examined the effects of air pollution on kidney function. We evaluated associations between long-term air pollution exposure and estimated glomerular filtration rate (eGFR) using data from a cohort of the Electricity Generating Authority of Thailand (EGAT) study in Bangkok Metropolitan Region, Thailand. MethodsThis longitudinal study included 1839 subjects (aged 52–71 years in 2002) from the EGAT1 cohort study during 2002–2012. eGFR, based on creatinine, was measured in 2002, 2007, and 2012. Annual mean concentrations of air pollutants (i.e., particulate matter with an aerodynamic diameter ≤10 μm (PM10), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO)) prior to a measurement of creatinine were assessed with the ordinary kriging method. Mixed-effect linear regression models were used to assess associations between air pollutants and eGFR, while controlling for potential covariates. eGFR values are expressed as percent change per interquartile range (IQR) increments of each pollutant. ResultsLower eGFR was associated with higher concentrations of PM10 (−1.99%, 95% confidence interval (CI): −3.33, −0.63), SO2 (−4.89%, 95%CI: −6.69, −3.07), and CO (−0.97%, 95%CI: −1.96, 0.03). However, after adjusting for temperature, relative humidity, PM10, and SO2, no significant association was observed between CO and eGFR. ConclusionsOur findings support the hypothesis that long-term exposure to high concentrations of PM10 and SO2 is associated with the progression of kidney dysfunction in subjects of the EGAT cohort study.

The taxonomical and functional diversity of three groups of aquatic insects in rheocrene karst springs are affected by different environmental factors

Karst springs represent valuable and often the most threatened habitats in the riverine landscape. Unlike other stream habitats, they have several specifics that determine their insularity in the river continuum, e.g., high seasonal thermal and chemical stability. The presented study aimed to find out the taxonomical and functional richness of three groups of aquatic insects (Ephemeroptera, Plecoptera and Trichoptera) in the Western Carpathians karst springs, as well as uncover the mechanism of the EPT community assembly. Low within-site species richness was generally found, however, there was high between-site diversity and thus high total diversity of the studied groups of benthic invertebrates as well. Species richness of the EPT community was higher in larger and colder springs: those with lower concentrations of CO2 and Fe, as well as higher concentrations of SO42−. Analysis of functional richness, as well as functional dispersion, did not reveal any clear assembly mechanism in the spring EPT community; however, both analyses indicated a higher proportion of environmental filtering there. Unlike the taxonomic richness, the functional richness of the EPT community was significantly higher in small and medium springs with higher water temperatures, as well as in springs with the presence of deadwood. Between-site dissimilarities in the functional composition of EPT were significantly correlated with environmental differences of springs, which determined variables such as spring size and temperature, as well as the concentration of CO2 and SiO2.

SafePod: A respiration chamber to characterise apple fruit response to storage atmospheres

During long-term storage of apples, detection of low O2 stress is used to optimise low O2 storage regimes for dynamic controlled atmosphere (DCA) storage. Monitoring respiratory characteristics, specifically the respiratory quotient (RQ), provides a tool to achieve this. The objectives of this study were to evaluate protocols to monitor response of apple consignments to low O2 using a respiration chamber, the SafePod, designed for use in commercial stores and research laboratories, and to compare the RQ response to changes in chlorophyll fluorescence (CF) yield from the fruit skin as used in DCA-CF.Protocols to identify the lowest oxygen limit (LOL), the O2 concentration below which RQ rises, were tested using ‘Braeburn’ (sensitive to low O2) and ‘Gala’ (less sensitive to low O2). A protocol that allows fruit to acclimatise at each O2 concentration takes several weeks and is therefore not practical for commercial use. A rapid profile without fruit acclimatisation can be completed in 2–3 days. Although this underestimates RQ values, and results in an increase in RQ at a higher O2 concentration than observed for acclimatised fruit, the rapid RQ protocol provides a practical method to compare response of apple consignments between cultivars, orchards and seasons. By the rapid protocol, the LOL of ‘Braeburn’ consignments was near 0.6 kPa and of ‘Gala’ consignments was near 0.2 kPa, consistent with detection of alcoholic taints below the LOL in each case. The RQ response using the SafePod was consistent with increase in CF yield using HarvestWatch™.Fruit respiration rates change through the storage season, including a substantial decrease over the first 2 months after harvest. As RQ response is affected by respiration rate, accurate comparison of consignments depends on profiles being measured at the same stage in the storage season. It is more difficult to determine the LOL by RQ profiling later in the season when respiration rates are lower.

Morphofunctional features of platelets in premature newborns with very low and extremely low body weight

Background. Currently, the development of medicine in the field of perinatology is aimed at improving the quality of medical care for newborns, especially those born prematurely. Premature newborns are most likely to develop hemorrhagic disorders, which often aggravates their condition and determines high morbidity and mortality. On modern hematological analyzers, it has become possible to evaluate a larger number of blood parameters, including platelet parameters, however, there are a small number of studies devoted to the study of platelet parameters in premature newborns. The aim was to study the morphofunctional features of platelets in premature newborns with very low and extremely low body weight. Materials and methods. The study included 78 newborns born at 2534 weeks of gestation, with a body weight of less than 1500 grams. On the 3rd5th day of life, a clinical blood test was performed on the Advia 2120i hematological analyzer (Siemens), with the determination of platelet parameters: PLT, 103 cells/l, PCT, %, PDW, %, Large Plt, 103 cells/l, MPC, g/dl, MRM, pg. Results. In newborns with ELBW, a decrease in the number and granularity of platelets in the blood, an increase in the average dry mass of platelets was found. Newborns with intrauterine growth retardation have a reduced platelet count and reduced thrombocrit. In premature newborns with a gestational age of 2527 weeks, blood circulation of platelets with a reduced volume was established, and in newborns who were born at a gestational age of 3234 weeks with increased granularity. In the absence of antenatal prevention of respiratory distress syndrome in newborns, there is a decrease in thrombocrit, the number of platelets, including large forms in the blood. In premature newborns born in a state of severe asphyxia, a decrease in platelet granularity was noted. The use of high concentrations of O2 in the oxygen-air mixture during respiratory therapy leads to a decrease in the number of platelets in the blood. Conclusions. Factors determining the morphofunctional state of platelets in premature newborns were established: the presence of a full course of antenatal prevention of respiratory distress syndrome of newborns, gestational age, the severity of asphyxia at birth, as well as the concentration of O2 in the oxygen-air mixture used in respiratory therapy. Newborns with ELBW have a reduced platelet count, low-granulated platelets, and an increased average dry platelet mass. Newborns with intrauterine growth retardation have a reduced number of platelets and thrombocrit in the blood. The revealed morphofunctional features of platelets allow us to clarify the nature of changes in the platelet link of hemostasis in premature newborns for the timely prevention of complications during the underlying disease.

Proxies for paleo-oxygenation: A downcore comparison between benthic foraminiferal surface porosity and I/Ca

Benthic foraminiferal surface porosity (the mean percentage of surface area covered by pores; higher porosity: lower oxygenation) and iodine to calcium ratio (I/Ca, higher I/Ca: higher oxygenation) are both promising paleoceanographic proxies that will advance through testing in down-core studies. Here we report the first down-core comparison (~45 kyr) of these proxies for a core from the southern Brazilian margin (26°40.22′ S, 46°26.46′ W, 475 m water depth). Both proxies are most sensitive to low-O2 conditions (<50 μmol/kg), and not well-constrained at higher O2 concentrations. Porosity values are generally low (<15%) and I/Ca ranges between ~4 and ~ 6 μmol/mol throughout the core. The two proxies are overall consistent, suggesting that bottom-water oxygen concentrations at the site remained above 50 μmol/kg during the last 45 kyr. Several non-O2 factors (e.g., iodate reduction rates, water mass mixing, temperature, foraminiferal shell robustness) could influence the proxies and require further investigation.

Hydrogen-Enriched Biogas Premixed Charge Combustion and Emissions in Direct Injection and Indirect Injection Diesel Dual Fueled Engines: A Comparative Study

Abstract This paper presents a comparative study on combustion and emissions of hydrogen-enriched biogas premixed charge direct injection dual-fuel (DIDF) engine and indirect injection dual-fuel (IDIDF) engine. The results show that the IDIDF engine outperforms the DIDF engine in terms of higher indicative engine cycle work (Wi) and lower emissions of CO, soot, and noise, but the disadvantage is higher NOx emission. Under the same fueling condition, the IDIDF engine’s Wi is on average 6% higher than that of the DIDF engine, but the NOx concentration in the combustion products of the IDIDF engine is 1.5 times higher than that of the DIDF engine. The IDIDF engine creates the stratified mixture distribution with higher O2 concentration in the auxiliary combustion chamber, which is favorable for auto-ignition and reduces the ignition delay. The biogas composition affects slightly CO and soot emissions, but significantly affects NOx emission. When the methane composition in biogas increases from 60% to 80%, the soot volume fraction is approximately 0.1 ppm in both types of combustion chambers, the CO concentration varies from 1.4% to 1.8%, and the NOx concentration varies from 3000 to 5000 ppm in the case of IDIDF engine and 2500–4500 ppm in the case of DIDF engine. For both types of dual-fuel engines, when engine speed increases, CO concentration and the soot volume fraction increase, while Wi and NOx concentration decrease.

Spatial Variation of Water Chemistry in Aries River Catchment, Western Romania

This study aims to investigate the quality and vulnerability of surface water (Aries River catchment) in order to identify the impact of past mining activities. For this purpose, the pollution and water quality indices, Piper and Durov plots, as well vulnerability modeling maps were used. The obtained results indicate that the water samples were contaminated with As, Fe, Mn, Pb and have relatively high concentrations of SO42−, HCO3−, TDS, Ca, K, Mg and high values for the electrical conductivity. Possible sources of the high content of chemicals could be the natural processes or the inputs of the mine drainage. Generally, according to the pollution indices, which were correlated to high concentrations of heavy metals, especially with Pb, Fe and Mn, the water samples were characterized by heavy metals pollution. The water quality index classified the studied water samples into five different classes of quality, namely: unsuitable for drinking, poor, medium, good and excellent quality. Similarly, medium, high and very high vulnerability classes were observed. The Durov and Piper plots classified the waters into Mg-HCO3− and Ca-Cl− types. The past and present mining activities clearly change the water chemistry and alter the quality of the Aries River, with the water requiring specific treatments before use.

In vitro toxicity of arsenic rich waters from an abandoned gold mine in northeast Portugal

This is a follow-up study of physicochemical water monitoring data from the abandoned Freixeda gold mine in Portugal, where arsenic (As) has remained above drinking water and irrigation limits over the years. The main objective of the current work was to investigate the toxicological potential of As-containing water on human cell line as an indicator of a potential health risk to humans. Six water samples collected in February 2018 were analysed for arsenic, major anions, cations and trace elements. Toxicity experiments were carried out on the human gastrointestinal cell line Caco-2 with five water samples containing As above 10 μg L−1. The results show that groundwater contains higher amounts of dissolved minerals than surface water, particularly with higher concentrations of SO42−, Fe and HCO3− and also higher As(III), reaching 336 μg L−1 (As(T) = 607 μg L−1). In surface waters As concentration decreased and reached 150 μg L−1, mainly as As(V). Metabolic activity was generally lower in Caco-2 cells exposed to As-containing water samples compared to pure As(III) solution, adapted to As concentrations, while production of reactive oxygen species (ROS) was higher. Short-term exposure to As-contaminated water samples also resulted in increased genotoxicity. This study suggests that mixture of As with various chemical elements in water may have a synergistic effect in promoting cytotoxicity. It is likely that prolonged exposure, as is common in areas with contaminated water, would have even more harmful effects.

P 61. Effects of acute normobaric hypoxia on memory and attention in young adults

Objective. An increasing number of sea-level residents takes part in alpine sports such as trekking or skiing. This has inspired a growing research interest on the effects of high altitude and hypoxic conditions on cognition. The aim of this study was to assess the effects of an acute normobaric hypoxia intervention (90 minutes) on cognition in healthy young adults. Methods . Twenty-five healthy, high-altitude-naive adults (25,8 ± 3,3 years; 15 females) were analysed in a randomized cross-over study. Participants received one acute normobaric hypoxic and one normobaric normoxic intervention separated by at least 2 weeks. Heart frequency and saturation of arterial blood oxygenation (SaO2) were continuously monitored while participants lay down for 120 minutes. After 30 minutes, either normobaric hypoxia (SaO2 of 80-85%) or normobaric normoxia was applied for the following 90 minutes. Cognitive parameters related to working memory and sustained attention (d2-Test, N-Back and Digit Span Test) were collected before and after each intervention session. Results . Normobaric hypoxia led to a significant decrease of SaO2 compared to normobaric normoxia (82,7 ± 4,3% vs. 98,1 ± 0,5%, p < .001). Regarding cognitive parameters, no significant time × group interactions were observed. Post hoc t-tests revealed a significant improvement in the d2-Test in both groups. Conclusion . In contrast to previous studies (Malle et al., 2013; Pilmanis, Balldin & Fischer, 2016; Ochi et al., 2018) our results indicate that acute normobaric hypoxia has no effects on working memory and sustained attention. One potential explanation for the absence of effects is the short duration and/or the rather high O2 concentration of the hypoxic condition. In this regard, Ochi et al. have found dose-dependent effects of hypoxia on cognition with the most pronounced results under the severe condition (5000 m). Future studies are needed that investigate dose-response mechanisms of acute hypoxia on cognition.

Non-planar platinum group metal-free fuel cell cathodes for enhanced oxygen transport and water rejection

Proton exchange membrane fuel cells (PEMFC) with cathodes using platinum group metal-free (PGM-free) catalysts could significantly reduce costs, but the lower volumetric oxygen reduction reaction (ORR) activity requires thick electrodes that suffer from liquid water flooding and increased oxygen transport resistance. To address these challenges, we developed a 3D gas diffusion electrode (GDE) architecture to enhance liquid water removal through the diffusion media and reduce cathode saturation. The cathode features a uniform catalyst layer adjacent to the membrane for high ORR activity and then pillars of the hydrophilic catalyst layer that pass through the microporous layer (MPL), providing a low capillary pressure barrier pathway to the carbon fiber paper layer and channel. The non-planar cathode also increases the interfacial area between the catalyst layer and hydrophobic MPL for a greater fraction of the cathode with high O2 concentration. Our studies included parametric experimental study of the pillar density to identify the optimum pitch between pillars. Our measurements show significant improvements in the mass transport region of the polarization curve with 3D structured electrodes leading to an 8% increase in maximum current density, 19% increase in maximum power density, and 16% increase in current density at 0.67 V with air.

Volcanic controls on the microbial habitability of Mars-analogue hydrothermal environments.

Due to their potential to support chemolithotrophic life, relic hydrothermal systems on Mars are a key target for astrobiological exploration. We analysed water and sediments at six geothermal pools from the rhyolitic Kerlingarfjöll and basaltic Kverkfjöll volcanoes in Iceland, to investigate the localised controls on the habitability of these systems in terms of microbial community function. Our results show that host lithology plays a minor role in pool geochemistry and authigenic mineralogy, with the system geochemistry primarily controlled by deep volcanic processes. We find that by dictating pool water pH and redox conditions, deep volcanic processes are the primary control on microbial community structure and function, with water input from the proximal glacier acting as a secondary control by regulating pool temperatures. Kerlingarfjöll pools have reduced, circum-neutral CO2 -rich waters with authigenic calcite-, pyrite- and kaolinite-bearing sediments. The dominant metabolisms inferred from community profiles obtained by 16S rRNA gene sequencing are methanogenesis, respiration of sulphate and sulphur (S0 ) oxidation. In contrast, Kverkfjöll pools have oxidised, acidic (pH<3) waters with high concentrations of SO42- and high argillic alteration, resulting in Al-phyllosilicate-rich sediments. The prevailing metabolisms here are iron oxidation, sulphur oxidation and nitrification. Where analogous ice-fed hydrothermal systems existed on early Mars, similar volcanic processes would likely have controlled localised metabolic potential and thus habitability. Moreover, such systems offer several habitability advantages, including a localised source of metabolic redox pairs for chemolithotrophic microorganisms and accessible trace metals. Similar pools could have provided transient environments for life on Mars; when paired with surface or near-surface ice, these habitability niches could have persisted into the Amazonian. Additionally, they offer a confined site for biosignature formation and deposition that lends itself well to in situ robotic exploration.

Removal of elemental mercury using magnetic Fe-containing carbon prepared from sludge flocculated with ferrous sulfate by zinc chloride activation

In this work, sewage sludge flocculated with ferrous sulfate (SFS) was treated by one-step pyrolysis and ZnCl2 activation to obtain magnetic Fe-containing carbon, which was used to remove elemental mercury (Hg0) from flue gas. When 30% ZnCl2 was added to SFS (names as SFS-30), sulfides, chloride, magnetic FexOy, as well as a suitable BET surface area were produced during pyrolysis. SFS-30 showed a maximum mercury removal efficiency of 96.1%. The presence of O2 and a low SO2 concentration enhanced Hg0 removal, while H2O vapor and a high concentration of SO2 inhibited it. The addition of ZnCl2 increased the BET surface area as well as the conversion of sulfate to sulfide, which were both beneficial for Hg0 removal. In addition, the generated magnetism during the pyrolysis process assisted in the recovery and utilization of SFS-30 in flue gas. After being magnetically separated from a mixture with fly ash, spent SFS-30 was thermally regenerated and recycled. After 8 Hg0 capture and regeneration cycles, the removal efficiency was not notably degraded, demonstrating that SFS-30 prepared by one-step pyrolysis with ZnCl2 activation can be used for Hg0 removal. The results of this study have guiding significance for practical engineering applications of this material.

Groundwater resources and quality in Syria

The resources of groundwater and its pollution in Syria are identified, and pathways of contaminants to groundwater are described. Then, suggestions for improvement of groundwater quality in Syria are evaluated. Syria is located in a region where water scarcity is dominant. About 87% of all water in Syria is mainly used for irrigation, with almost 60% of this water taken from groundwater resources. The rest is used for domestic and industrial purposes, which account for 9% and 4%, respectively. Due to over-pumping and the increase in the number of unsustainable wells observed in recent decades, groundwater is quantitatively deteriorating. In general, sources of groundwater contamination fall into two main categories: natural and anthropogenic sources. Important sources of natural groundwater pollution include climate effects. About 43% of groundwater has a high concentration of SO4 and/or NaCl. This is specifically dominant in the eastern region of Syria due to the harsh environment where precipitation is relatively low, and evaporation is high. One of the major sources of anthropogenic groundwater contamination is civil war. Most of the damaged regions are located on permeable rocks, which increases the probability of groundwater contamination due to chemical weapons (CW) used. It is vital to manage and control groundwater resources well. With the increase in water contamination and with the absence of poor water management, access to drinking water will be more of a problem than it is now.

Influencing factors of PM2.5 and O3 from 2016 to 2020 based on DLNM and WRF-CMAQ

In this study, distributed lag nonlinear models (DLNM) were built to characterize the non-linear exposure-lag-response relationship between the concentration of PM2.5 and O3 and multiple influencing factors, including basic meteorological elements and precursors. Then, a stratified analysis of different years, seasons, pollution levels, and wind direction was conducted. DLNMs and coupled Weather Research and Forecasting Model-Community Multi-scale Air Quality Model (WRF-CMAQ) were used to evaluate PM2.5 and O3 changes attributed to meteorological conditions and anthropogenic emissions comparing 2020 with 2016. As DLNMs showed, PM2.5 pollution was promoted by low wind speed, high temperature, low humidity, and high concentrations of SO2, NO2, and O3, among which NO2 tended to be the dominant influencing factor. O3 pollution was promoted by low wind speed, high temperature, low humidity, high concentration of PM2.5 and low concentration of NO2, among which temperature tended to be the dominant influencing factor. Moreover, north-south and easterly winds showed the greatest contribution to PM2.5 and O3, respectively. Both DLNMs and CMAQ showed that anthropogenic factors alleviated PM2.5 pollution but aggravated O3 pollution in 2020 in comparison with 2016, so did meteorological factors, but with smaller impacts. And anthropogenic influences were more evident in heavily polluted seasons for both PM2.5 and O3. This research may help understand the influencing factors of PM2.5 and O3 and provide scientific guide for abatement policies. Moreover, the good consistency in the results obtained from DLNMs and CMAQ indicated the reliability of the two models.