Major Gaseous Pollutants Research Articles

Spatial Distributions of Gaseous Air Pollutants Including Particulate Matter in the Narsingdi City of Dhaka Division

ABSTRACT This study summarizes the concentration of major gaseous air pollutants in Narsingdi city of Dhaka division. To accomplish this study, we investigate fifteen sampling stations (Velanagar, Railway Station, Boro Bazar, Ghoradia, Brahmondi, Shaheprotap, Launch Terminal, Satirpara, Bus Terminal, Silmandi, Gangpar Bridge, Panchdona, Shekherchar and Anandi) of the study area. In this study we measured six gaseous air pollutantstogether with PM2.5 and PM10 during the month September, 2022 using air quality meter Aeroqual (Series500). Highest concentration of PM2.5 was detected 58 µg/m3 at Boro Bazar whereas highest concentration ofPM10 was 165 µg/m3 was at Anandi of the study area where emission from vehile, construction activities and waste burning are predominant. Moreover, in this study we found statistically significant correlation with CH4 and CO2 (r = 0.679, p > 0.01), PM2.5 and PM10 (r = 0.630, p > 0.05) indicating their sources of emission might be similar including fossil fuel burning in vehicles, industrial emissions and road dust. Furthermore, we calculated AQI value based on PM2.5 concentration and highest AQI (152) value was observed in Boro Bazarof the study area followed by Bus Terminal (129), Gangpar Bridge (117), Anandi (112), Ghoradia (102), Brahmondi (89), Panchdona (84), Satirpara (83), Shaherpotap (82), Silmandi (80), Railway Station (78), Madhabdi (78), Shekherchar (76), Launch Terminal (76), Velanagar (59) and were very much compatiblewith US consulate, Bangladesh published data.

Comparative Analysis of Air Quality Index in Relation to Crop Residue Burning and Industrial Pollution in Punjab

The stubble burning is considered as the major air pollution contributor during the month of October and November, in Northern parts of India. Due to the fact that it corresponds with the burning seasons, the terrible haze seen over India in the winter has been connected to stubble burning (October-November). The situation is more critical in Punjab as the farmers have adopted extensive Rice-Wheat cropping system which leads to accumulation of stubble at large scale. The major gaseous pollutants generated due to stubble burning and industrial pollution are carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NO2), sulfur oxides (SO2), and methane (CH4) as well as particulate matters (PM10 and PM2.5) causing serious issues to human health and the environment. Present study was planned to determine the impact of stubble burning on air quality parameter among industrial, moderately industrial and non-industrial area. It was reported that concentrations of particulate matters PM2.5 and PM10 in air was increasing with increasing in burning events in all the districts studied. Whereas increasing trend of NH3 and NO2 concentration in Ludhiana and NH3 in Bathinda district may be due the impact of crop residue burning along with industrial pollution. If managed properly, crop stubbles might offer farmers significant economic rewards and safeguard the environment from serious contamination. Present results showed that burning of rice crop residue significantly contributes to air pollution in Punjab.

Short-term effects of ambient gaseous air pollution on blood platelet mitochondrial DNA methylation and myocardial ischemia

BackgroundThe potential effects of short-term exposure to major ambient gaseous pollutants (ozone: O3, carbon monoxide: CO, and sulfur dioxide: SO2) on platelet mitochondrial DNA (mtDNA) methylation have been uncertain and no studies have examined whether platelet mtDNA methylation levels could modify the associations between ambient gaseous pollutants and the risks of ST-segment depression (STDE) and T-wave inversion events (TIE), two indicators of myocardial ischemia. MethodsThis study used data from a randomized, double-blind, placebo-controlled intervention study with a standardized 24-hour exposure protocol among 110 participants in Beijing. Absolute changes in platelet mtDNA methylation (ACmtDNAm) levels were determined by two repeated measurements on platelet mtDNA methylation levels in blood samples collected before and after the 24-hour exposure period. A multivariable linear regression model and a generalized linear model with a Poisson link function were used to investigate the associations of ambient gaseous pollutants with platelet mtDNA methylation levels, STDE, and TIE, respectively. ResultsShort-term O3 exposure was significantly associated with decreased ACmtDNAm at ATP6_P1 but increased ACmtDNAm at mt12sRNA, MT-COX1, and MT-COX1_P2; short-term CO and SO2 exposures were significantly associated with decreased ACmtDNAm at D-loop, MT-COX3- and ATP-related genes. Moreover, short-term O3 exposure was significantly associated with increased risks of STDE and TIE, and ACmtDNAm at MT-COX1 and MT-COX1_P2 modified the association between short-term O3 exposure and STDE events. L-Arg supplementation attenuated the effects of ambient gaseous pollutants, particularly O3, on ACmtDNAm and STDE. ConclusionsPlatelet mtDNA methylation levels are promising biomarkers of short-term exposure to ambient gaseous air pollution, and are likely implicated in the mechanism behind the association of ambient O3 pollution with adverse cardiovascular effects. L-Arg supplementation showed the potential to mitigate the adverse effects of ambient O3 pollution.

Zeolite-based materials eliminating nitrogen oxides (NOx) and volatile organic compounds (VOCs): advances and future perspectives

Advances and future perspectives of zeolite-based materials in adsorption and catalytic conversion of NOx and VOCs were reported.

Numerical and experimental investigation of co-combustion of chicken manure and lignite blends in a CFBB with novel compact combustion chamber

Increasing worldwide demand for chicken and chicken products has led to increased production of chicken manure. Therefore, chicken manure has an important application potential in the energy industry. This study aims to dispose of chicken manure, which is harmful to soil and groundwater, for thermal energy purposes and to reduce the emissions of lignite coal. For this purpose, it concerns the design and manufacture of a Circulating Fluidized Bed Boiler (CFBB) with a novel combustion chamber for burning chicken manure (CM) and lignite (L) fuels and their mixtures. The combustion behaviors and contaminating emissions of the mentioned fuels in such a CFBB are investigated experimentally and numerically. Emissions of major gaseous pollutants, including CO, SO2 and NO, and the temperature distribution throughout the combustion chamber are measured during the tests. Experimental results show that increasing the amount of CM in the mixture increases CO and reduces SO2. For this condition, NO emission either increases or decreases. According to the numerical results, the temperature of the combustion chamber decreases with the increase of the CM fraction. In the CFBB, the CO emission decreases in the CM fraction up to 25 %, while it increases in the CM fraction above 25 %. For increasing CM fraction, NO emission decreases in the cyclone while it increases in the evaporator. In the experimental and numerical results, the CO2 emission for the L, CM and CM fractions are observed to be equivalent to each other. In conclusion, this study clearly shows that in situ burning of chicken manure or lignite and chicken manure mixtures reduces lignite emissions and meets the heat requirement and disposal of waste in chicken processing plants.

Comparison of the heterogeneous reaction of NO2 on the surface of clay minerals and desert dust particles

Mineral particles in air could provide atmospheric chemical reaction interface for gaseous substances and participate in atmospheric chemical reaction process, and affecting the status and levels of gaseous pollutants in air. However, differences of the heterogenous reaction on the surface minerals particles are not very clear. Considering main mineral composition of ambient particles was from dust emission, therefore, typical clay minerals (chlorite, illite) and desert particles (Taklimakan Desert) were selected to analysize chemical reaction of NO2, one of major gaseous pollutants, on mineral particles by using of In-situ DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) under different condition. And In situ near-ambient pressure X-ray photoelectron spectroscopy (In situ NAP-XPS) was employed to investigate iron (one of the major metals) species variation on the surface of mineral dust particles during the heterogeneous reactions. Our data show that humidity controlled by deuterium oxide (D2O) has a greater effect on chemical reactions compared to light and temperature. Under dry conditions, the amount of heterogeneous reaction products of NO2 on the particles shows Xiaotang dust > chlorite > illite > Tazhong dust regardless of dark or light conditions. In contrast, under humidity conditions, the order of nitrate product quantity under moderate conditions was chlorite > illite > Xiaotang dust > Tazhong dust. In situ NAP-XPS results demonstrate that specie variation of the Fe could promote the heterogenous reactions. These data could provide useful information for understanding the formation mechanism of nitrate aerosols and removal of nitrogen oxides in the atmosphere.

Recent progress in performance optimization of Cu-SSZ-13 catalyst for selective catalytic reduction of NO x.

Nitrogen oxides (NO x ), which are the major gaseous pollutants emitted by mobile sources, especially diesel engines, contribute to many environmental issues and harm human health. Selective catalytic reduction of NO x with NH3 (NH3-SCR) is proved to be one of the most efficient techniques for reducing NO x emission. Recently, Cu-SSZ-13 catalyst has been recognized as a promising candidate for NH3-SCR catalyst for reducing diesel engine NO x emissions due to its wide active temperature window and excellent hydrothermal stability. Despite being commercialized as an advanced selective catalytic reduction catalyst, Cu-SSZ-13 catalyst still confronts the challenges of low-temperature activity and hydrothermal aging to meet the increasing demands on catalytic performance and lifetime. Therefore, numerous studies have been dedicated to the improvement of NH3-SCR performance for Cu-SSZ-13 catalyst. In this review, the recent progress in NH3-SCR performance optimization of Cu-SSZ-13 catalysts is summarized following three aspects: 1) modifying the Cu active sites; 2) introducing the heteroatoms or metal oxides; 3) regulating the morphology. Meanwhile, future perspectives and opportunities of Cu-SSZ-13 catalysts in reducing diesel engine NO x emissions are discussed.

IMPACT OF FOREST FIRE EMISSIONS ON AIR QUALITY OVER WESTERN HIMALAYA REGION

Abstract. Emissions from forest fires give out huge amounts of greenhouse gases into the atmosphere degrading the surrounding air quality. Climate change results in prolonged summer days and less precipitation thus increasing fuel accumulation facilitating recurring forest fires in the Western Himalayan regions. Most of the forest fire cases are human ignited that damaging the forest irreparably. This study attempts to analyse the impact of the forest fire events on the tropospheric concentrations of five major gaseous pollutants aerosols, Carbon Monoxide (CO), Nitrogen Dioxide (NO2), Sulphur Dioxide (SO2) and Formaldehyde (HCHO). A clear increase in daily average of the air pollutants considered in the study was observed as the number of forest fires were also increasing. The gases responded inversely with precipitation. Precipitation washed away majority of the air pollutants. The high-resolution air quality data were retrieved from the Google Earth Engine platform using Sentinel 5 Precursor datasets, daily active fire points from the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument of Suomi National Polar-orbiting Partnership (SNPP) and daily precipitation data from CHIRPS Daily Version 2.0 Final. Four out of five gases i.e., CO, aerosols, NO2, HCHO pollutants gave moderate to high correlation values with the forest fire incidences. Air pollutants responded inversely with the precipitation pattern.

Application of an improved gas-constrained source apportionment method using data fused fields: A case study in North Carolina, USA

A number of studies have found differing associations of disease outcomes with PM2.5 components (or species) and sources (e.g., biomass burning, diesel vehicles and gasoline vehicles). Here, a unique method of fusing daily chemical transport model (Community Multiscale Air Quality Modeling) results with observations has been utilized to generate spatiotemporal fields of the concentrations of major gaseous pollutants (CO, NO2, NOx, O3, and SO2), total PM2.5 mass, and speciated PM2.5 (including crustal elements) over North Carolina for 2002–2010. The fused results are then used in chemical mass balance source apportionment model, CMBGC-Iteration, which uses both gas constraint and particulate matter concentrations to quantify source impacts. The method, as applied to North Carolina, quantifies the impacts of ten source categories and provides estimates of source contributions to PM2.5 concentrations. The ten source categories include both primary sources (diesel vehicles, gasoline vehicles, dust, biomass burning, coal-fired power plants and sea salt) and secondary components (ammonium sulfate, ammonium bisulfate, ammonium nitrate and secondary organic carbon). The results show a steady decrease in anthropogenic source impacts, especially from diesel vehicles and coal-fired power plants. Secondary pollutant components accounted for approximately 70% of PM2.5 mass. This study demonstrates an ability to provide spatiotemporal fields of both PM components and source impacts using a chemical transport model fused with observation data, linked to a receptor-based source apportionment method, to develop spatiotemporal fields of multiple pollutants.

Superior photocatalytic degradation performance for gaseous toluene by 3D g-C3N4-reduced graphene oxide gels

Abstract Volatile organic compounds (VOCs) are major gaseous pollutants and one of the main causes of environmental problem, which can be extremely harmful to human health. Previous research has shown that photocatalytic oxidation is regarded as a promising technology to remove VOCs. However, for the time being, the photocatalytic performance in the field of removing VOCs by multiple reported photocatalysts cannot meet the demand of the practice. In this study, we have successfully synthesized a series of 3D gel composites with g-C3N4 (GC) and graphite oxide as precursors by a simple hydrothermal and freeze-drying method, which shows good photocatalytic degradation performance for gas toluene as model VOCs. The highest photocatalytic degradation ratio for gaseous toluene is about 86% in 180 min, which is about 3 times that of pure GC. The reason for the results is due to the strong adsorption capacity and very fast electrical conductivity of three dimensional (3D) reduced graphene oxide (RGO). This study implies that the 3D GC-RGO gels have potential usefulness for removing VOCs to meet the demand of the practice.

Cutting Oxygen Production-Related Greenhouse Gas Emissions by Improved Compression Heat Management in a Cryogenic Air Separation Unit.

Oxygen production in cryogenic air separation units is related to a significant carbon footprint and its supply in the medicinal sphere became critical during the recent COVID-19 crisis. An improved unit design was proposed, utilizing a part of waste heat produced during air pre-cooling and intercooling via absorption coolers, to reduce power consumption. Variable ambient air humidity impact on compressed air dryers’ regeneration was also considered. A steady-state process simulation of a model 500 t h−1 inlet cryogenic air separation unit was performed in Aspen Plus® V11. Comparison of a model without and with absorption coolers yielded an achievable reduction in power consumption for air compression and air dryer regeneration by 6 to 9% (23 to 33 GWh year−1) and a favorable simple payback period of 4 to 10 years, both depending on air pressure loss in additional heat exchangers to be installed. The resulting specific oxygen production decrease amounted to EUR 2–4.2 t−1. Emissions of major gaseous pollutants from power production were both calculated by an in-house developed thermal power plant model and adopted from literature. A power consumption cut was translated into the following annual greenhouse gas emission reduction: CO2 16 to 30 kilotons, CO 0.3 to 2.3 tons, SOx 4.7 to 187 tons and NOx 11 to 56 tons, depending on applied fossil fuel-based emission factors. Considering a more renewable energy sources-containing energy mix, annual greenhouse gas emissions decreased by 50 to over 80%, varying for individual pollutants.

Cardiorespiratory Effects of Indoor Ozone Exposure Associated with Changes in Metabolic Profiles among Children: A Repeated-Measure Panel Study

SummaryOzone is one of the major gaseous pollutants associated with short-term adverse cardiopulmonary effects, even at concentrations below the current indoor air quality limits. However, the underlying biological mechanisms of cardiorespiratory changes with exposure to ozone remain unclear. To further explore molecular linkages between indoor ozone exposure and relevant cardiorespiratory effects, a repeated-measure panel study including 46 schoolchildren was conducted and real-time exposure measurements including ozone were performed inside classrooms every weekday during the study period. Repeated health measurements and urine sample collection were conducted in each participant. Ultra-high-performance liquid chromatography/tandem mass spectrometry and meet-in-metabolite approach were used in metabolomics analysis. Methods including mixed-effect models were adopted to identify metabolites associated with ozone exposure or health indices. Nine metabolites were found to be associated with ozone after mixed-effect model analysis, which are mainly involved in amino acid and bile acid metabolism. Boys may have a greater decrease in bile acid and RNA related metabolites. Four of the nine ozone-related metabolites were also associated with cardiorespiratory function indices. Furthermore, 26.67% of the positive association between ozone and heart rate was mediated by cholestane-3,7,12,25-tetrol-3-glucuronide. Exposure to ozone below the current indoor standards was associated with the deteriorated cardiovascular function by disturbing bile acid and endogenous nitric oxide-related oxidation and inflammation, and associated with the exacerbated airway inflammation by reducing GPx-related anti-oxidation. The results provide metabolic evidence of the cardiorespiratory effects of indoor ozone exposure. Indoor ozone pollution should be controlled further, and more attention should be paid to preventing its adverse health effects, especially in children.

NO X and SO X Flue Gas Treatment System Based on Sulfur-Enriched Organic Oil in Water Emulsion.

Nitrogen (NOX) and sulfur (SOX) oxides, the major gaseous pollutants emitted from fossil fuel combustion, have significant health and environmental concerns. Environmental regulations limit these pollutant emissions to tolerable levels. Currently, these pollutants are treated by flue gas desulfurization (SOX removal) and selective catalytic reduction (NOX removal) processes. However, these technologies require large footprints, use expensive catalysts, and operate under high working temperatures. A new catalyst is reported herein, based on sulfur-enriched oil emulsified with water, where the active catalytic species are sulfur-based oxides. The catalyst has been developed using O2 as the oxidation reagent in a low-temperature wet scrubber rather than H2O2 or O3 that are presently used. The catalytically oxidized pollutants are converted to produce ammonium fertilizers by NH4OH addition. As a result of treatment with this novel catalyst, we observed reductions in emissions of SOX and NOX of >85% and 23%, respectively. The catalyst production and the wet scrubbing process are discussed in detail.

Recent advances in simultaneous removal of SO2 and NOx from exhaust gases: Removal process, mechanism and kinetics

• Oxidation, reduction, adsorption/absorption and microbial approaches are summarized. • Removal processes are divided into gas-gas, gas-liquid and gas-solid reactions. • Removal process, mechanism, and kinetics of pathways are systematically reviewed. • Effects of catalyzers and reaction conditions on removal efficiency are analyzed. • Challenges and potential breakthroughs in future de-SO 2 and de-NO x are discussed. SO 2 and NO x , major gaseous pollutants in exhaust gas, can exert adverse effects on human health and environmental disaster. Therefore, numerous desulfurization (de-SO 2 ) and denitrification (de-NO x ) technologies have been designed to reduce SO 2 and NO x emissions. Compared to traditional multi-step removal processes, simultaneous removal of SO 2 and NO x has been attracting significant attention recently. This paper timely reviewed available literature focused on simultaneous de-SO 2 and de-NO x methods, which are classified into four pathways as oxidation, reduction, adsorption/absorption and microbial purification. The removal process, basic mechanism and kinetics of each pathway are systematically reviewed in consideration of reactants, catalyzers, temperatures and atmosphere. Moreover, the main challenges and potential breakthroughs in developing novel simultaneous de-SO 2 and de-NO x methods are critically discussed to provide a roadmap for prospective research activities. Therefore, this review provides a deeper insight in understanding the mechanisms of de-SO 2 and de-NO x , and then helps to develop innovative simultaneous removal methods or improve the efficiency of available abatement methods.

The burden of sulfur dioxide pollution on years of life lost from chronic obstructive pulmonary disease: A nationwide analysis in China

BackgroundSulfur dioxide (SO2) is one of the major gaseous pollutants in China and other developing countries. Few multicity studies have been done to examine the short-term effect of SO2 on cause-specific years of life lost (YLL). This study was designed to investigate the burden of chronic obstructive pulmonary disease (COPD) associated with SO2 exposure. MethodsA 5-year time-series study was conducted in 48 Chinese cities from 2013 to 2017. Generalized additive models were first used to estimate the city-specific relationship. Then, random-effects meta-analyses were applied to pool the estimates. Furthermore, the roles of potential modifiers and the related economic loss estimated by the method of value per statistical life year were also evaluated. ResultsThe annual mean concentration of SO2 was 27.1 μg/m3. A 10 μg/m3 increase in 4-day moving average (lag03) of SO2 concentration was associated with 0.83% (95% CI: 0.13%, 1.53%) relative increment in YLL from COPD, and relevant percent change of mortality was 0.78% (95% CI: 0.16%, 1.41%). Moreover, a significantly higher effect was observed in the warm season, particularly in the south region. SO2 exposure was estimated to account for 1.89% of the total economic loss due to YLL from COPD. ConclusionsOur findings showed a positive association between short-term exposure to SO2 and YLL from COPD and highlighted the importance of continuous control of SO2 pollution to reduce corresponding attributable disease burden.

Evaluation of Contribution of Major Gaseous Pollutants in India with Implications on Health Scenario

Life is the most essential entity in the World. What kind of world are we envisioning where we cannot breathe well due to pollution?One can have adverse consequences of being exposed to polluted air.Serious air contamination occurrences were watched often in north India, particularly at capital, Delhi. Dehradun, a capital of Uttarakhand, was amongst the 30th most polluted cities as ranked by World Health Organisation (WHO). SO2 and NO2 are one of the contributing pollutants which are harmful to health. In this paper, the levels of both the pollutants are considered for various locations of Delhi and Dehradun, to knowwhothe major player is SO2 or NO2.

Experimental study and empirical modeling of CO and NO behaviors in a fluidized-bed combustor firing pelletized biomass fuels

The combustion and emission characteristics were studied in a fluidized-bed combustor burning pellets of five biomass feedstocks: cassava rhizome, eucalyptus bark, rubberwood sawdust, rice husk, and teak sawdust. During combustion tests with an individual pelletized fuel, the heat input to the combustor was ~ 200 kWth, with excess air varied from 20 to 80%. Temperature and gas concentrations were monitored along the combustor height and also at stack to quantify the major gaseous emissions and combustion efficiency of the reactor for the selected fuels and operating conditions. Experimental data revealed a good/fair similarity of the relative axial profiles of temperature, CO, and NO inside the combustor for different fuels fired at variable excess air. Empirical models for predicting the relative axial profiles of the temperature and major gaseous pollutants were derived via regression analysis of experimental data. Using the models, these variables can be predicted at any level in the combustor with an acceptable uncertainty for specified operating parameters. To meet the domestic emission standards for CO and NO, the selected biomass fuels should be fired at excess air of ~ 40%. Under these operating conditions, high (99.2–99.8%) combustion efficiency can be achieved during fluidized-bed combustion of the selected fuels.

Impact of anthropogenic emissions on biogenic secondary organic aerosol: observation in the Pearl River Delta, southern China

Abstract. Secondary organic aerosol (SOA) formation from biogenic precursors is affected by anthropogenic emissions, which are not well understood in polluted areas. In this study, we accomplished a year-round campaign at nine sites in polluted areas located in the Pearl River Delta (PRD) region during 2015. We measured typical biogenic SOA (BSOA) tracers from isoprene, monoterpenes, and β-caryophyllene, as well as major gaseous and particulate pollutants and investigated the impact of anthropogenic pollutants on BSOA formation. The concentrations of BSOA tracers were in the range of 45.4 to 109 ng m−3 with the majority composed of products from monoterpenes (SOAM, 47.2±9.29 ng m−3), isoprene (SOAI, 23.1±10.8 ng m−3), and β-caryophyllene (SOAC, 3.85±1.75 ng m−3). We found that atmospheric oxidants, Ox (O3 plus NO2), and sulfate correlated well with later-generation SOAM tracers, but this was not the case for first-generation SOAM products. This suggested that high Ox and sulfate levels could promote the formation of later-generation SOAM products, which probably led to the relatively aged SOAM that we observed in the PRD. For the SOAI tracers, both 2-methylglyceric acid (NO/NO2-channel product) and the ratio of 2-methylglyceric acid to 2-methyltetrols (HO2-channel products) exhibit NOx dependence, indicating the significant impact of NOx on SOAI formation pathways. The SOAC tracer was elevated in winter at all sites and was positively correlated with levoglucosan, Ox, and sulfate. Thus, the unexpected increase in SOAC in wintertime might be highly associated with the enhancement of biomass burning, O3 chemistry, and the sulfate component in the PRD. The BSOAs that were estimated using the SOA tracer approach showed the highest concentration in fall and the lowest concentration in spring with an annual average concentration of 1.68±0.40 µg m−3. SOAM dominated the BSOA mass all year round. We also found that BSOA correlated well with sulfate and Ox. This implied a significant effect from anthropogenic pollutants on BSOA formation and highlighted that we could reduce BSOA by controlling the anthropogenic emissions of sulfate and Ox precursors in polluted regions.

Adsorption of NH3 onto vacancy-defected Ti2CO2 monolayer by first-principles calculations

Ammonia is one of the major gaseous pollutants and can cause serious diseases to human being and animals. In this paper, density functional theory is used to investigate the adsorption of NH3 on pristine Ti2CO2 (PT) and C-vacancy defected Ti2CO2 (CVT) monolayers. Different possible adsorption sites have been considered. The results indicate that the possible configurations are all exothermic because of the negative adsorption energy. The adsorption with N atom of NH3 molecule on the top site of Ti atom is chemisorbed for PT and CVT monolayers, with the adsorption energy of −1.024 eV and −0.879 eV, respectively. The strong interactions between NH3 and PT, NH3 and CVT are confirmed by the analysis of charge transfer, adsorption energy, and charge density distribution. However, the very strong adsorption of NH3 on PT monolayer results in the difficulty of desorption. The introduction of C vacancy results in the closing of the band gap, and CVT and TT-CVT (the N atom of NH3 molecule vertical to CVT on the top site over Ti) monolayers are all metallic. The electronic properties of PT and CVT monolayers have little change after the adsorption of NH3 molecules. TT-CVT monolayer is suitable as a gas sensor for NH3 detection because of short recovery time and significant resistivity.

Source-specific Fine Particulate Using Spatiotemporal Concentration Fields Developed using Chemical Transport Modelling and Data Assimilation

OPS 47: Increasing spatiotemporal resolution in assessment of exposure to outdoor air pollutants, Room 412, Floor 4, August 27, 2019, 4:30 PM - 5:30 PM A number of studies have found differing associations of disease outcomes with PM2.5 components (or species), and sources (e.g., biomass burning, diesel vehicle and gasoline vehicle). Here, a unique data fusion method has been utilized to generate spatiotemporal fields of major gaseous pollutants and PM2.5 components (e.g., ozone, NO2, SO2, total PM2.5 mass and speciated PM2.5 including crustal metals) over North Carolina for 2002-2010. In a prior study, the PM2.5 total mass field was used as part of the CATHGEN study of associations between PM2.5 and disease associated with cardiac heart disease patients. Here, we extend the exposure method for further health analyses. The method fuses daily CMAQ model observations with observations to develop accurate spatiotemporal maps of pollutant concentrations. Those results are then used in an advanced chemical mass balance source apportionment model, CMBGC-Iteration that uses both gas and particulate matter concentrations to quantify source impacts. The method, as applied to North Carolina, quantifies the impacts of nine source categories and estimate source contributions of total PM2.5 mass. The nine source categories include sources of both primary (diesel vehicle, gasoline vehicle, suspended dust, biomass burning, and coal combustion sources) and secondary components (ammonium sulfate, ammonium bisulfate, ammonium nitrate and secondary organic carbon). The results show the dramatic decrease in source impacts, e.g., sulfate, primarily from coal-burning, and from mobile sources. Secondary organic aerosol, e.g., from biogenic emissions, is becoming more dominant over the state. This study highlights an advantage of using a chemical transport model to develop spatiotemporal fields of pollutants, i.e., the ability to assess PM components and their sources.