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1
Jančauskas, Adolfas, and Kęstutis Buinevičius. "Combination of Primary Measures on Flue Gas Emissions in Grate-Firing Biofuel Boiler." Energies 14, no. 4 (February 3, 2021): 793. http://dx.doi.org/10.3390/en14040793.
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Increasingly stringent limits for NOx and SO2 emission are forcing the investigation of new reduction methods. This study was conducted to determine the combination of primary measures, i.e., flue gas recirculation (FGR) and excess air effects on sulfur, nitrogen and hydrocarbon emissions, in boiler flue gas. Experimental research was performed using an experimental, small-scale (20 kW) model of an industrial biofuel boiler. During combustion of sunflower seed hulls at different FGR ratios and incomplete combustion regimes, the composition of flue gas (NO, NO2, N2O, HCN, NH3, SO2, SO3, H2S, CO, and CxHy) was compared, allowing an explanation of the determinants of emission concentration changes to be provided. Increasing the flue gas recirculation ratio in the primary air had a positive effect on reducing NOX and CO with certain organic compounds. However, an opposite effect on SO2 was observed. NOX and SO2 concentrations were found to be approximately 500 mg/m3 and 150 mg/m3 under a regular combustion regime. When the FGR ratio of 50% NOX concentration decreased by 110 mg/m3, the SO2 concentration increased by 60 mg/m3. The incomplete combustion regime reduced NOX concentration by 70 mg/m3, whereas SO2 concentration increased by 100 mg/m3. The influence of primary measures presented an unclear relationship to hydrocarbon emissions, with concentrations not exceeding 18 mg/m3.
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Yao, X., N. T. Lau, C. K. Chan, and M. Fang. "The use of tunnel concentration profile data to determine the ratio of NO<sub>2</sub>/NO<sub>x</sub> directly emitted from vehicles." Atmospheric Chemistry and Physics Discussions 5, no. 6 (December 13, 2005): 12723–40. http://dx.doi.org/10.5194/acpd-5-12723-2005.
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Abstract. Recently, it is reported that primary vehicular NO2/NOx ratio to be 10–30% and primary vehicular NO2 has raised much interest and concern in the control of NO2 in urban areas. In this study, primary vehicular NO2/NOx ratio in Hong Kong was investigated based on intensive long tunnel (3.7–4 km in length) experiments where concentration profiles of air pollutants along the entire lengths of the tunnels were obtained. Long tunnels were selected because of the inherent low O3 concentrations in the partially enclosed environment. In addition the concentrations of pollutants from vehicles are high. Thus, the NO2 measured inside long tunnels would be more representative of the primary NO2 emitted by vehicles and contribution due to atmospheric transformation would be limited. This dataset was supported by a long-term on-road air quality dataset (June 2002–August 2003). Both datasets were obtained using the Mobile Real-time Air Monitoring Platform (MAP). The primary on-road vehicular NO2/NOx ratio was less than 2%, detected in the mid sections of tunnels investigated, where O3 concentration was at a minimum. In sections of the tunnels (entrance and exit) where O3 concentrations were relatively high, the NO2/NOx ratio could be as high as 19%. Long-term (annual average) on-road air quality data in open air yielded NO2/NOx ratios up to 28%. Thus, it is apparent that directly emitted NO2 from vehicles is not significant in atmospheric NO2 concentration. A simple model was used to segregate the contribution of background NO2 and transformed NO2 measured in vehicle plumes.
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Chang, C. C., M. Shao, C. C. K. Chou, S. C. Liu, J. L. Wang, K. Z. Lee, C. H. Lai, T. Zhu, and P. H. Lin. "Biogenic isoprene and implications for oxidant levels in Beijing during the 2008 Olympic Games." Atmospheric Chemistry and Physics Discussions 13, no. 10 (October 9, 2013): 25939–67. http://dx.doi.org/10.5194/acpd-13-25939-2013.
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Abstract. As the host of the 2008 Summer Olympic Games, Beijing implemented a series of stringent, short-term air quality control measures to reduce the emissions of anthropogenic air pollutants. Large reductions in the daily average concentrations of primary pollutants, e.g., non-methane hydrocarbons (NMHCs) and nitrogen oxides (NOx) of approximately 50% were observed at the air quality observatory of Peking University. Nevertheless, high levels of ozone were present during the control period. Although anthropogenic precursors were greatly reduced, the meteorological conditions in summer, including high temperature and light flux, are conducive to the production of large amounts of biogenic isoprene, which is extremely reactive. The diurnal pattern of isoprene showed daily maximum mixing ratios of 0.83 ppbv at noon and a minimum at night, reflecting its primarily biogenic properties. Using the ratio of isoprene to vehicle exhaust tracers, approximately 92% of the daytime isoprene was estimated from biogenic sources, and only 8% was attributed to vehicular emissions. In terms of OH reactivity and the ozone formation potential (OFP), biogenic isoprene with its midday surge can contribute approximately 20% of the total OFPs and 40–50% of the total OH reactivities of the 65 measured NMHCs during the midday hours. The discrepancy between decreased precursor levels and the observed high ozone was most likely caused by a combination of many factors. The changes in the partition among the components of oxidation products (O3, NO2 and NOz) and the contribution of air pollutants from regional sources outside Beijing should be two primary reasons. Furthermore, the influences of biogenic isoprene as well as the non-linearity of O3-VOC-NOx chemistry are other major concerns that can reduce the effectiveness of the control measures for decreasing ozone formation. Although anthropogenic precursors were greatly reduced during the Olympic Games, sufficient biogenic isoprene and moderate NOx were still present in the conditions of high radiation flux and temperature during midday and early afternoon, which can still contribute a significant fraction of midday and early afternoon O3.
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Bian, Yahui, Zhijiong Huang, Jiamin Ou, Zhuangmin Zhong, Yuanqian Xu, Zhiwei Zhang, Xiao Xiao, et al. "Evolution of anthropogenic air pollutant emissions in Guangdong Province, China, from 2006 to 2015." Atmospheric Chemistry and Physics 19, no. 18 (September 20, 2019): 11701–19. http://dx.doi.org/10.5194/acp-19-11701-2019.
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Abstract. Guangdong Province (GD), one of the most prosperous and populous regions in China, still experiences haze events and growing ozone pollution in spite of the substantial air-quality improvement in recent years. Integrated control of fine particulate matter (PM2.5) and ozone in GD calls for a systematic review of historical emissions. In this study, emission trends, spatial variations, source-contribution variations, and reduction potentials of sulfur dioxide (SO2), nitrogen oxides (NOx), PM2.5, inhalable particles (PM10), carbon monoxide (CO), ammonia (NH3), and volatile organic compounds (VOCs) in GD from 2006 to 2015 were first examined using a dynamic methodology, taking into account economic development, technology penetration, and emission controls. The relative change rates of anthropogenic emissions in GD during 2006–2015 are −48 % for SO2, −0.5 % for NOx, −16 % for PM2.5, −22 % for PM10, 13 % for CO, 3 % for NH3, and 13 % for VOCs. The declines of SO2, NOx, PM2.5, and PM10 emissions in the whole province mainly resulted from the stringent emission control in the Pearl River delta (PRD) region, where most previous control measures were focused, especially on power plants (SO2 and NOx), industrial combustion (SO2, PM2.5, PM10), on-road mobile sources (NOx), and dust sources (PM2.5 and PM10). Emissions from other areas (non-PRD, NPRD), nevertheless, remain relatively stable due to the lax control measures and rapidly growing energy consumption. In addition, emission leaks of SO2 and NOx from industries are observed from PRD to NPRD in 2010 and 2011. As a result, emissions in NPRD are increasingly important in GD, particularly those from industrial combustion. The contribution of NPRD to the total SO2 emissions in GD, for example, increased from 27 % in 2006 to 48 % in 2015. On-road mobile sources and solvent use are the two key sources that should receive more effective control measures in GD. Current control-driven emission reductions from on-road mobile sources are neutralized by the substantial growth of the vehicle population, while VOC emissions in GD steadily increase due to the growth of solvent use and the absence of effective control measures. Besides, future work could focus on power plants and industrial combustion in GD and industrial process sources in NPRD, which still have large emission reduction potentials. The historical emission inventory developed in this study not only helps to understand the emission evolution in GD, but also provides robust data to quantify the impact of emission and meteorology variations on air quality and unveil the primary cause of significant air-quality change in GD in the recent decade.
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Alam, Mohammed S., Leigh R. Crilley, James D. Lee, Louisa J. Kramer, Christian Pfrang, Mónica Vázquez-Moreno, Milagros Ródenas, Amalia Muñoz, and William J. Bloss. "Interference from alkenes in chemiluminescent NO<sub><i>x</i></sub> measurements." Atmospheric Measurement Techniques 13, no. 11 (November 10, 2020): 5977–91. http://dx.doi.org/10.5194/amt-13-5977-2020.
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Abstract. Nitrogen oxides (NOx=NO+NO2) are critical intermediates in atmospheric chemistry and air pollution. NOx levels control the cycling and hence abundance of the primary atmospheric oxidants OH and NO3 and regulate the ozone production which results from the degradation of volatile organic compounds (VOCs) in the presence of sunlight. They are also atmospheric pollutants, and NO2 is commonly included in air quality objectives and regulations. NOx levels also affect the production of the nitrate component of secondary aerosol particles and other pollutants, such as the lachrymator peroxyacetyl nitrate (PAN). The accurate measurement of NO and NO2 is therefore crucial for air quality monitoring and understanding atmospheric composition. The most commonly used approach for the measurement of NO is the chemiluminescent detection of electronically excited NO2 (NO2∗) formed from the NO + O3 reaction within the NOx analyser. Alkenes, ubiquitous in the atmosphere from biogenic and anthropogenic sources, also react with ozone to produce chemiluminescence and thus may contribute to the measured NOx signal. Their ozonolysis reaction may also be sufficiently rapid that their abundance in conventional instrument background cycles, which also utilises the reaction with ozone, differs from that in the measurement cycle such that the background subtraction is incomplete, and an interference effect results. This interference has been noted previously, and indeed, the effect has been used to measure both alkenes and ozone in the atmosphere. Here we report the results of a systematic investigation of the response of a selection of commercial NOx monitors to a series of alkenes. These NOx monitors range from systems used for routine air quality monitoring to atmospheric research instrumentation. The species-investigated range was from short-chain alkenes, such as ethene, to the biogenic monoterpenes. Experiments were performed in the European PHOtoREactor (EUPHORE) to ensure common calibration and samples for the monitors and to unequivocally confirm the alkene levels present (via Fourier transform infrared spectroscopy – FTIR). The instrument interference responses ranged from negligible levels up to 11 %, depending upon the alkene present and conditions used (e.g. the presence of co-reactants and differing humidity). Such interferences may be of substantial importance for the interpretation of ambient NOx data, particularly for high VOC, low NOx environments such as forests or indoor environments where alkene abundance from personal care and cleaning products may be significant.
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Xue, Yifeng, Shihao Zhang, Zhen Zhou, Kun Wang, Kaiyun Liu, Xiaoyan Wang, Aijun Shi, Kangli Xu, and Hezhong Tian. "Spatio-Temporal Variations of Multiple Primary Air Pollutants Emissions in Beijing of China, 2006–2015." Atmosphere 10, no. 9 (August 26, 2019): 494. http://dx.doi.org/10.3390/atmos10090494.
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Air pollution in Beijing, China has attracted continuous worldwide public attention along with the rapid urbanization of the city. By implementing a set of air pollution mitigation measures, the air quality of Beijing has been gradually improved in recent years. In this study, the intrinsic factors leading to air quality improvement in Beijing are studied via a quantitative evaluation of the temporal and spatial changes in emissions of primary air pollutants over the past ten years. Based on detailed activity levels of each economic sector and a localized database containing source and pollutant specific emission factors, an integrated emissions inventory of primary air pollutants discharged from various sources between 2006 and 2015 is established. With the implementation of phased air pollution mitigation measures, and the Clean Air Action Plan, the original coal-dominated energy structure in Beijing has undergone tremendous changes, resulting in the substantial reduction of multiple air pollutants. The total of emissions of six major atmospheric pollutants (PM10, PM2.5, SO2, NOX, VOCs and NH3) in Beijing decreased by 35% in 2015 compared to 2006—this noticeable decrease was well consistent with the declining trend of ambient concentration of criterion air pollutants (SO2, PM10, PM2.5 and NO2) and air quality improvement, thus showing a good correlation between the emission of air pollutants and the outcome of air quality. SO2 emission declined the most, at about 71.7%, which was related to the vigorous promotion of combustion source control, such as the shutdown of coal-fired facilities and domestic stoves and transition to clean energy, like natural gas or electricity. Emissions of PM decreased considerably (by 48%) due to energy structure optimization, industrial structure adjustments, and end-of-pipe PM source control. In general, NOX, NH3, and VOCs decreased relatively slightly, by 25%, 14%, and 2%, respectively, and accordingly, they represented the limiting factors for improving air quality and the key points of air pollution mitigation in Beijing for the future.
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Chou, C. C. K., C. Y. Tsai, C. C. Chang, P. H. Lin, S. C. Liu, and T. Zhu. "Photochemical production of ozone in Beijing during the 2008 Olympic Games." Atmospheric Chemistry and Physics Discussions 11, no. 6 (June 10, 2011): 16553–84. http://dx.doi.org/10.5194/acpd-11-16553-2011.
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Abstract. As a part of the CAREBeijing-2008 campaign, observations of O3, oxides of nitrogen (NOx and NOy), CO, and hydrocarbons (NMHCs) were carried out at the air quality observatory of the Peking University in Beijing, China during August 2008, including the period of the 29th Summer Olympic Games. The measurements were compared to those of the CAREBeijing-2006 campaign to evaluate the effectiveness of the air pollution control measures, which were conducted for improving the air quality in Beijing during the Olympics. The results indicate that significant reduction in the emissions of primary air pollutants had been achieved; the monthly averages of NOx, NOy, CO, and NMHCs reduced by 42.2, 56.5, 27.8, and 49.7 %, respectively. In contrast to the primary pollutants, the averaged mixing ratio of O3 increased by 42.2 %. Nevertheless, it was revealed that the ambient levels of total oxidants (Ox=O3+NO2+1.5NOz) and NOz reduced by 21.3 and 77.4 %, respectively. The contradictions between O3 and Ox were further examined in two case studies. Ozone production rates of 30–70 ppbv hr−1 and OPEx of ~8 mole mole−1 were observed on a clear-sky day in spite of the reduced levels of precursors. In that case, it was found that the concentrations of O3 increased with the increasing NO2/NO ratio, whereas the NOz concentrations leveled off when NO2/NO>8. Consequently, the ratio of O3 to NOz increased to above 10, indicating the shift from VOC-sensitive regime to NOx-sensitive regime. However, in the other case, it was found that the O3 production was inhibited significantly due to substantial reduction in the ambient levels of NMHCs. According to the observations, it was suggested that the O3/Ox production rates in Beijing should have been reduced for the reduction in the emissions of precursors during the Olympic period; however, the nighttime O3 levels were increased for decline in the NO-O3 titration, and the midday O3 peak levels were elevated for the shift in the photochemical regime and the inhibition of NOz formation.
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Tsai, Jiun-Horng, Ming-Ye Lee, and Hung-Lung Chiang. "Effectiveness of SOx, NOx, and Primary Particulate Matter Control Strategies in the Improvement of Ambient PM Concentration in Taiwan." Atmosphere 12, no. 4 (April 6, 2021): 460. http://dx.doi.org/10.3390/atmos12040460.
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The Community Multiscale Air Quality (CMAQ) measurement was employed for evaluating the effectiveness of fine particulate matter control strategies in Taiwan. There are three scenarios as follows: (I) the 2014 baseline year emission, (II) 2020 emissions reduced via the Clean Air Act (CAA), and (III) other emissions reduced stringently via the Clean Air Act. Based on the Taiwan Emission Data System (TEDs) 8.1, established in 2014, the emission of particulate matter 2.5 (PM2.5) was 73.5 thousand tons y−1, that of SOx was 121.3 thousand tons y−1, and that of NOx was 404.4 thousand tons y−1 in Taiwan. The CMAQ model simulation indicated that the PM2.5 concentration was 21.9 μg m−3. This could be underestimated by 24% in comparison with data from the ambient air quality monitoring stations of the Taiwan Environmental Protection Administration (TEPA). The results of the simulation of the PM2.5 concentration showed high PM2.5 concentrations in central and southwestern Taiwan, especially in Taichung and Kaohsiung. Compared to scenario I, the average annual concentrations of PM2.5 for scenario II and scenario III showed reductions of 20.1% and 28.8%, respectively. From the results derived from the simulation, it can be seen that control of NOx emissions may improve daily airborne PM2.5 concentrations in Taiwan significantly and control of directly emitted PM2.5 emissions may improve airborne PM2.5 concentrations each month. Nevertheless, the results reveal that the preliminary control plan could not achievethe air quality standard. Therefore, the efficacy and effectiveness of the control measures must be considered to better reduce emissions in the future.
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Zhang, Gen, Honghui Xu, Hongli Wang, Likun Xue, Jianjun He, Wanyun Xu, Bing Qi, et al. "Exploring the inconsistent variations in atmospheric primary and secondary pollutants during the 2016 G20 summit in Hangzhou, China: implications from observations and models." Atmospheric Chemistry and Physics 20, no. 9 (May 7, 2020): 5391–403. http://dx.doi.org/10.5194/acp-20-5391-2020.
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Abstract. Complex aerosol and photochemical pollution (ozone and peroxyacetyl nitrate, PAN) frequently occur in eastern China, and mitigation strategies to effectively alleviate both kinds of pollution are urgently needed. Although the effectiveness of powerful control measures implemented by the Chinese State Council has been comprehensively evaluated in terms of reducing atmospheric primary pollutants, the effectiveness in mitigating photochemical pollution is less assessed and therefore the underlying mechanisms are still poorly understood. The stringent emission controls implemented from 24 August to 6 September 2016 during the summit for the Group of Twenty (G20) provide us a unique opportunity to address this issue. Surface concentrations of atmospheric O3, PAN, and their precursors including volatile organic compounds (VOCs) and nitrogen dioxides (NOx), in addition to the other trace gases and particulate matter, were measured at the National Reference Climatological Station (NRCS) (30.22∘ N, 120.17∘ E, 41.7 m a.s.l) in urban Hangzhou. We found significant decreases in atmospheric PAN, NOx, total VOCs, PM2.5, and sulfur dioxide (SO2) under the unfavorable meteorological conditions during G20 (DG20) relative to the adjacent period before and after G20 (BG20 and AG20), indicating that the powerful control measures were effective in reducing the pollutant emissions in Hangzhou. Unlike with the other pollutants, daily maximum 8 h average (DMA8) O3 exhibited a slight increase and then decrease from BG20 to AG20, which was mainly attributed to the variation in the solar irradiation intensity and regional transport in addition to the contribution from the implementation of stringent control measures. Results from an observation-based chemical model (OBM) indicated that acetaldehyde and methylglyoxal (MGLY) were the most important second-generation precursors of PAN, accounting for 37.3 %–51.6 % and 22.8 %–29.5 % of the total production rates including the reactions of OVOCs, propagation of other radicals, and other minor sources. Moreover, we confirmed the production of PAN and O3 was sensitive to VOCs throughout the whole period, specifically dominated by aromatics in BG20 and DG20 but by alkenes in AG20. These findings suggested that reducing emissions of aromatics, alkenes, and alkanes would mitigate photochemical pollution including PAN and O3. Source appointment results attributed the reductions of VOC source and ozone formation potentials (OFPs) during G20 to the effective emission controls on traffic (vehicle exhaust) and industrial processes (solvent utilization and industrial manufacturing). However, fuel combustion and biogenic emissions both weakened such an effect with a sizable contribution to the VOC mixing ratios (18.8 % and 20.9 %) and OFPs (25.6 % and 17.8 %), especially during the latter part of G20 (G20 II) when anthropogenic VOCs were substantially reduced. This study highlights the effectiveness of stringent emission controls in relation to traffic and industrial sources, but a coordinated program related to controlling fuel combustion and biogenic emissions is also required to address secondary pollution.
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Liu, Yiming, and Tao Wang. "Worsening urban ozone pollution in China from 2013 to 2017 – Part 2: The effects of emission changes and implications for multi-pollutant control." Atmospheric Chemistry and Physics 20, no. 11 (June 3, 2020): 6323–37. http://dx.doi.org/10.5194/acp-20-6323-2020.
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Abstract. The Chinese government launched the Air Pollution Prevention and Control Action Plan in 2013, and various stringent measures have since been implemented, which have resulted in significant decreases in emissions and ambient concentrations of primary pollutants such as SO2, NOx, and particulate matter (PM). However, surface ozone (O3) concentrations have still been increasing in urban areas across the country. In a previous analysis, we examined in detail the roles of meteorological variation during 2013–2017 in the summertime surface O3 trend in various regions of China. In this study, we evaluated the effect of changes in multi-pollutant emissions from anthropogenic activities on O3 levels during the same period by using an up-to-date regional chemical transport model (WRF-CMAQ) driven by an interannual anthropogenic emission inventory. The Community Multiscale Air Quality (CMAQ) model was improved with regard to heterogeneous reactions of reactive gases on aerosol surfaces, which led to better model performance in reproducing the ambient concentrations of those gases. The model simulations showed that the maximum daily 8 h average (MDA8) O3 mixing ratio in urban areas increased by 0.46 ppbv per year (ppbv a−1) (p=0.001) from 2013 to 2017. In contrast, a slight decrease in MDA8 O3 by 0.17 ppbv a−1 (p=0.005) in rural areas was predicted, mainly attributable to the NOx emission reduction. The effects of changes in individual pollutant emissions on O3 were also simulated. The reduction of NOx emission increased the O3 levels in urban areas due to the nonlinear NOx and volatile organic compound (VOC) chemistry and decreasing aerosol effects; the slight increase in VOC emissions enhanced the O3 levels; the reduction of PM emissions increased the O3 levels by enhancing the photolysis rates and reducing the loss of reactive gases on aerosol surfaces; and the reduction of SO2 emissions resulted in a drastic decrease in sulfate concentrations, which increased O3 through aerosol effects. In contrast to the unfavorable effect of the above changes in pollutant emissions on efforts to reduce surface O3, the reduction of CO emissions did help to decrease the O3 level in recent years. The dominant cause of increasing O3 due to changes in anthropogenic emissions varied geographically. In Beijing, NOx and PM emission reductions were the two largest causes of the O3 increase; in Shanghai, the reduction of NOx and increase in VOC emissions were the two major causes; in Guangzhou, NOx reduction was the primary cause; in Chengdu, the PM and SO2 emission decreases contributed most to the O3 increase. Regarding the effects of decreasing concentrations of aerosols, the drop in heterogeneous uptake of reactive gases – mainly HO2 and O3 – was found to be more important than the increase in photolysis rates. The adverse effect of the reductions of NOx, SO2, and PM emissions on O3 abatement in Beijing, Shanghai, Guangzhou, and Chengdu would have been avoided if the anthropogenic VOCs emission had been reduced by 24 %, 23 %, 20 %, and 16 %, respectively, from 2013 to 2017. Our analysis revealed that the NOx reduction in recent years has helped to contain the total O3 production in China. However, to reduce O3 levels in major urban and industrial areas, VOC emission controls should be added to the current NOx-SO2-PM policy.
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Chou, C. C. K., C. Y. Tsai, C. C. Chang, P. H. Lin, S. C. Liu, and T. Zhu. "Photochemical production of ozone in Beijing during the 2008 Olympic Games." Atmospheric Chemistry and Physics 11, no. 18 (September 23, 2011): 9825–37. http://dx.doi.org/10.5194/acp-11-9825-2011.
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Abstract. As a part of the CAREBeijing-2008 campaign, observations of O3, oxides of nitrogen (NOx and NOy), CO, and hydrocarbons (NMHCs) were carried out at the air quality observatory of the Peking University in Beijing, China during August 2008, including the period of the 29th Summer Olympic Games. The measurements were compared with those of the CAREBeijing-2006 campaign to evaluate the effectiveness of the air pollution control measures, which were conducted for improving the air quality in Beijing during the Olympics. The results indicate that significant reduction in the emissions of primary air pollutants had been achieved; the monthly averaged mixing ratios of NOx, NOy, CO, and NMHCs decreased by 42.2, 56.5, 27.8, and 49.7 %, respectively. In contrast to the primary pollutants, the averaged mixing ratio of O3 increased by 42.2 %. Nevertheless, it was revealed that the ambient levels of total oxidant (Ox = O3+NO2+1.5 NOz) and NOz were reduced by 21.3 and 77.4 %, respectively. The contradictions between O3 and Ox were further examined in two case studies. Ozone production rates of 30–70 ppbv h−1 and OPEx of ~8 mole mole−1 were observed on a clear-sky day in spite of the reduced levels of precursors. In that case, it was found that the mixing ratio of O3 increased with the increasing NO2/NO ratio, whereas the NOz mixing ratio leveled off when NO2/NO>8. Consequently, the ratio of O3 to NOz increased to above 10, indicating the shift from VOC-sensitive regime to NOx-sensitive regime. However, in the other case, it was found that the O3 production was inhibited significantly due to substantial reduction in the NMHCs. According to the observations, it was suggested that the O3 and/or Ox production rates in Beijing should have been reduced as a result of the reduction in the emissions of precursors during the Olympic period. However, the nighttime O3 levels increased due to a decline in the NO-O3 titration, and the midday O3 peak levels were elevated because of the shift in the photochemical regime and the inhibition of NOz formation.
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Salazar, Cristian, Anna I. Kurbatova, and Milana E. Kupriyanova. "Quito’s coronavirus curfew: Escalating tropospheric ozone pollution." E3S Web of Conferences 211 (2020): 04008. http://dx.doi.org/10.1051/e3sconf/202021104008.
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The effect of the curfew due to the pandemic of Covid-19 virus on the levels of air pollution in the historic center of Quito was evaluated with a focus on tropospheric ozone (O3). During the curfew period the daily O3 mean concentration increased by 96%, 109% and 95% in comparison to the concentrations for the same period in the years 2017, 2018 and 2019. This increase is mainly explained by considerable reduction in NOx emissions, thus there was little titration of ozone accumulated in the city environment due to its shallow boundary layer by NO, reaching its maximum concentration at midday. Among studied pollutants that influence O3 formation (CO, NO2, PM2.5) during the curfew the contaminant that showed the greatest reduction in the mean concentration compared to three previous years was NO2, followed by CO and PM2.5. The daily O3 8-hour mean concentrations during the curfew both on weekdays and weekends were lower than the limit values. These results are relevant for designing abatement policies of secondary pollutants such as O3 under strict measures of control of primary pollutant emissions.
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ALMEIDA, José Claudino, Andrea MOREIRA, Lino MOREIRA, and Graciela ARBILLA. "PRIMARY EMISSION RATIOS OBTAINED FROM THE MONITORING OF CRITERIA POLLUTANTS IN REBOUÇAS TUNNEL, RIO DE JANEIRO, BRAZIL." Periódico Tchê Química 05, no. 9 (January 20, 2008): 13–18. http://dx.doi.org/10.52571/ptq.v5.n09.2008.janeiro/2_pgs_13_18.pdf.
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Meassurements of pollutants concentrations in tunnels can reflect the actual characteristics of mobile sources in order to provide a control strategy to reduce emissions and secondary pollutants formation. Concentration levels of CO, NOx, SO2 and PM10 (particulate matter less than 10 m in diameter) were recorded inside Rebouças Tunnel, in a continuous monitoring station installed at about 1,500 m from the entrance. The reported data are the hourly average values through the year of 2002, bracketed only for the weekdays, weekends excluded. In terms of typical day cycles, the highest concentration levels occur close to traffic peaks and the criteria pollutants show good overall correlation levels with CO, as expected, given their common combustion-bound origin. CO hourly averages ranged from 10 to 50 ppm and the average CO/NO ratio (on a ppm basis) was 0.011, in good agreement with preliminary data for other locations in Brazil. NO concentration levels ranged from less than 1 ppm to about 4 ppm and this form is by far the dominant for nitrogen oxides (NOx) found in the tunnel, accounting for more than 90% of the sum of NO plus NO2. Sulfur oxides (measured as SO2 ) and inhalable particles concentrations ranged from 55 to 140 ppb and about 60 to 250 µg m-3 , respectively, for the composite annual profiles.
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Werle, Sebastian. "Nitrogen Oxides Emission Reduction using Sewage Sludge Gasification Gas Reburning Process / Obniżenie Emisji Tlenków Azotu Przy Użyciu Procesu Reburningu Gazem Ze Zgazowania Osadów Ściekowych." Ecological Chemistry and Engineering S 22, no. 1 (March 1, 2015): 83–94. http://dx.doi.org/10.1515/eces-2015-0005.
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Abstract Nitrogen oxides can be formed in various combustion systems. Strategies for the control of NOx emissions in hard coal boilers include the primary (during the combustion) and secondary measures (after combustion). Reburning is the one of the most attractive techniques for reducing NOx emissions. In the last several years, reburning technology has been widely studied but almost only in power engineering big load boilers. Nevertheless, NOx emission is an issue that needs to be considered for small capacity boilers as nitrogen oxides resulting from the combustion of any fossil fuels contribute to the formation of acid rain and photochemical smog, which are significant causes of air pollution. Poland is among the largest coal producing country in Europe. Due to this fact, coal fired boilers are very popular in power engineering and also in the municipal sector. Simultaneously, Poland is characterized by the lack of sewage sludge thermal treatment installation. Gasification is considered as a one of the most perspective method of thermal utilization any carbon-containing material. Syngas, which is the main product of gasification, can be used as a supplemental fuel to reduce the consumption of main fuel in boilers, and it has the potential to reduce NOx emissions. The paper proposes to link those two Polish features so the aim of the work is an experimental investigation of the reburning process of sewage sludge gasification gas in a small capacity domestic coal-fired boiler. The results obtained show how the addition of the reburning fuel influences on NOx reduction efficiency
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Zhao, Y., J. Zhang, and C. P. Nielsen. "The effects of recent control policies on trends in emissions of anthropogenic atmospheric pollutants and CO<sub>2</sub> in China." Atmospheric Chemistry and Physics Discussions 12, no. 9 (September 21, 2012): 24985–5036. http://dx.doi.org/10.5194/acpd-12-24985-2012.
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Abstract. To examine the effects of China's national policies of energy conservation and emission control during 2005–2010, inter-annual emission trends of gaseous pollutants, primary aerosols, and CO2 are estimated with a bottom-up framework. The control measures led to improved energy efficiency and/or increased penetration of emission control devices at power plants and other important industrial sources, yielding reduced emission factors for all evaluated species except NOx. The national emissions of anthropogenic SO2, CO, and total primary PM (particulate matter) in 2010 are estimated to have been 89%, 108%, and 86% of those in 2005, respectively, suggesting successful emission control of those species despite fast growth of the economy and energy consumption during the period. The emissions of NOx and CO2, however, are estimated to have increased by 48% and 43%, respectively, indicating that they remain largely determined by the growth of energy use, industrial production, and vehicle populations. Based on application of a Monte-Carlo framework, estimated uncertainties of SO2 and PM emissions increased from 2005 to 2010, resulting mainly from weakly understood average SO2 removal efficiency in flue gas desulfurization (FGD) systems in the power sector, and unclear changes in the penetration levels of dust collectors at industrial sources, respectively. While emission trends determined by bottom-up methods can be generally verified by observations from both ground stations and satellites, clear discrepancies exist for given regions and seasons, indicating a need for more accurate spatial and time distributions of emissions. Limitations of current emission control polices are analyzed based on the estimated emission trends. Compared with control of total PM, there are fewer gains in control of fine particles and carbonaceous aerosols, the PM forms most responsible for damages to public health and effects on radiative forcing. A decrease of alkaline base cations as primary PM that is much faster than that of SO2 may have raised the acidification risks to ecosystems, indicating further control of acid precursors is required. Moreover, with relatively strict controls in developed urban areas, air pollution challenges have been expanding to less-developed neighboring regions. There is a great need in the future for multi-pollutant control strategies that combine recognition of diverse environmental impacts both in urban and rural areas with emission abatement of multiple species in concert.
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Zhao, Y., J. Zhang, and C. P. Nielsen. "The effects of recent control policies on trends in emissions of anthropogenic atmospheric pollutants and CO<sub>2</sub> in China." Atmospheric Chemistry and Physics 13, no. 2 (January 16, 2013): 487–508. http://dx.doi.org/10.5194/acp-13-487-2013.
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Abstract. To examine the effects of China's national policies of energy conservation and emission control during 2005–2010, inter-annual emission trends of gaseous pollutants, primary aerosols, and CO2 are estimated with a bottom-up framework. The control measures led to improved energy efficiency and/or increased penetration of emission control devices at power plants and other important industrial sources, yielding reduced emission factors for all evaluated species except NOx. The national emissions of anthropogenic SO2, CO, and total primary PM (particulate matter) in 2010 are estimated to have been 89%, 108%, and 87% of those in 2005, respectively, suggesting successful emission control of those species despite fast growth of the economy and energy consumption during the period. The emissions of NOx and CO2, however, are estimated to have increased by 47% and 43%, respectively, indicating that they remain largely determined by the growth of energy use, industrial production, and vehicle populations. Based on application of a Monte-Carlo framework, estimated uncertainties of SO2 and PM emissions increased from 2005 to 2010, resulting mainly from poorly understood average SO2 removal efficiency in flue gas desulfurization (FGD) systems in the power sector, and unclear changes in the penetration levels of dust collectors at industrial sources, respectively. While emission trends determined by bottom-up methods can be generally verified by observations from both ground stations and satellites, clear discrepancies exist for given regions and seasons, indicating a need for more accurate spatial and time distributions of emissions. Limitations of current emission control polices are analyzed based on the estimated emission trends. Compared with control of total PM, there are fewer gains in control of fine particles and carbonaceous aerosols, the PM components most responsible for damages to public health and effects on radiative forcing. A much faster decrease of alkaline base cations in primary PM than that of SO2 may have raised the acidification risks to ecosystems, indicating further control of acid precursors is required. Moreover, with relatively strict controls in developed urban areas, air pollution challenges have been expanding to less-developed neighboring regions. There is a great need in the future for multi-pollutant control strategies that combine recognition of diverse environmental impacts both in urban and rural areas with emission abatement of multiple species in concert.
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Xue, Yifeng, Xizi Cao, Yi Ai, Kangli Xu, and Yichen Zhang. "Primary Air Pollutants Emissions Variation Characteristics and Future Control Strategies for Transportation Sector in Beijing, China." Sustainability 12, no. 10 (May 18, 2020): 4111. http://dx.doi.org/10.3390/su12104111.
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Air pollutant emissions from vehicles, railways, and aircraft for freight and passenger transportation are major sources of air pollution, and strongly impact the air quality of Beijing, China. To better understand the variation characteristics of these emissions, we used the emission factor method to quantitatively determine the air pollutant emissions from the transportation sector. The emission intensity of different modes of transportation was estimated, and measures are proposed to prevent and control air pollutants emitted from the transportation sector. The results showed that air pollutant emissions from the transportation sector have been decreasing year by year as a result of the reduction in emissions from motor vehicles, benefiting from the structural adjustment of motor vehicles. A comparison of the emission intensity of primary air pollutants from different modes of transportation showed that the emission level of railway transportation was much lower than that of road transportation. However, Beijing relies heavily on road transportation, with road freight transportation accounting for 96% of freight transportation, whereas the proportion of railway transportation was low. Primary air pollutants from the transportation sector contributed significantly to the total emissions in Beijing. The proportion of NOX emissions increased from 54% in 2013 to 58% in 2018. To reduce air pollutant emissions from the transportation sector, further adjustments and optimization of the structure of transportation in Beijing are needed. As for the control of motor vehicle pollutant emissions, vehicle composition must be adjusted and the development of clean energy must be promoted, as well as the replacement of diesel vehicles with electric vehicles for passenger and freight transportation.
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Wang, Wen Yong, and Gao Ping Fu. "The Research of Source and Composition of Dust Haze in Chengdu and its Control Countermeasures." Advanced Materials Research 726-731 (August 2013): 2066–73. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.2066.
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In this thesis, on the basis of detailed survey and actual measurement of the emissions of fine particulate matters (PM2.5) and PM2.5 precursors (SO2, NOx and VOC) in Chengdu City, the source composition of PM2.5 in the atmospheric air of Chengdu City is simulated by taking the mode of Community Multiscale Air Quality (CMAQ); meanwhile, with reference to the source analysis results of the other units, the key objects of dust haze (PM2.5) pollution, namely fugitive dust, industrial pollution sources and motor vehicle exhaust, can be controlled. Therefore, four main measures for controlling the dust haze (PM2.5) pollution are put forward: the first is to deeply control the particulate matters emitted by the industrial enterprises and install the desulfurization and denitrification devices to reduce the emissions of PM2.5 primary particulate matters and precursors; the second is to reduce the emissions of motor vehicle exhaust, nitrogen oxides and VOC; the third is to strengthen the control of fugitive dust; and the fourth is to implement joint prevention and joint control system among the cities.
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Dunlea, E. J., S. C. Herndon, D. D. Nelson, R. M. Volkamer, F. San Martini, P. M. Sheehy, M. S. Zahniser, et al. "Evaluation of nitrogen dioxide chemiluminescence monitors in a polluted urban environment." Atmospheric Chemistry and Physics Discussions 7, no. 1 (January 16, 2007): 569–604. http://dx.doi.org/10.5194/acpd-7-569-2007.
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Abstract. Data from a recent field campaign in Mexico City are used to evaluate the performance of the EPA Federal Reference Method for monitoring ambient concentrations of NO2. Measurements of NO2 from standard chemiluminescence monitors equipped with molybdenum oxide converters are compared with those from Tunable Infrared Laser Differential Absorption Spectroscopy (TILDAS) and Differential Optical Absorption Spectroscopy (DOAS) instruments. A significant interference in the chemiluminescence measurement is shown to account for up to 50% of ambient NO2 concentration during afternoon hours. As expected, this interference correlates well with non-NOx reactive nitrogen species (NOz as well as with ambient O3 concentrations, indicating a photochemical source for the interfering species. A combination of ambient gas phase nitric acid and alkyl and multifunctional alkyl nitrates is deduced to be the primary cause of the interference. Observations at four locations at varying proximities to emission sources indicate that the percentage contribution of HNO3 to the interference decreases with time as the air parcel ages. Alkyl and multifunctional alkyl nitrate concentrations are calculated to be reach concentrations as high as several ppb inside the city, on par with the highest values previously observed in other urban locations. Averaged over the MCMA-2003 field campaign, the CL NOx monitor interference resulted in an average measured NO2 concentration up to 22% greater than that from co-located spectroscopic measurements. Thus, this interference has the potential to initiate regulatory action in areas that are close to non-attainment and may mislead atmospheric photochemical models used to assess control strategies for photochemical oxidants.
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Li, Rong, Xin Mei, Liangfu Chen, Lili Wang, Zifeng Wang, and Yingying Jing. "Long-Term (2005–2017) View of Atmospheric Pollutants in Central China Using Multiple Satellite Observations." Remote Sensing 12, no. 6 (March 24, 2020): 1041. http://dx.doi.org/10.3390/rs12061041.
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The air quality in China has experienced dramatic changes during the last few decades. To improve understanding of distribution, variations, and main influence factors of air pollution in central China, long-term multiple satellite observations from moderate resolution imaging spectroradiometer (MODIS) and ozone monitoring instrument (OMI) are used to characterize particle pollution and their primary gaseous precursors, sulfur dioxide (SO2), and nitrogen dioxide (NO2) in Hubei province during 2005–2017. Unlike other regions in eastern China, particle and gaseous pollutants exhibit distinct spatial and temporal patterns in central China due to differences in emission sources and control measures. OMI SO2 of the whole Hubei region reached the highest value of ~0.2 Dobson unit (DU) in 2007 and then declined by more than 90% to near background levels. By contrast, OMI NO2 grew from ~3.2 to 5.9 × 1015 molecules cm−2 during 2005–2011 and deceased to ~3.9 × 1015 molecules cm−2 in 2017. Unlike the steadily declining SO2, variations of OMI NO2 flattened out in 2016 and increased ~0.5 × 1015 molecules cm−2 during 2017. As result, MODIS AOD at 550 nm increased from 0.55 to the peak value of 0.7 during 2005–2011 and then decreased continuously to 0.38 by 2017. MODIS AOD and OMI SO2 has a high correlation (R > 0.8), indicating that annual variations of SO2 can explain most changes of AOD. The air pollution in central China has notable seasonal variations, which is heaviest in winter and light in summer. While air quality in eastern Hubei is dominated by gaseous pollution such as O3 and NOx, particle pollutants are mainly concentrated in central Hubei. The high consistency with ground measurements demonstrates that satellite observation can well capture variations of air pollution in regional scales. The increasing ozone (O3) and NO2 since 2016 suggests that more control measures should be made to reduce O3-related emissions. To improve the air quality in regional scale, it is necessary to monitor the dynamic emission sources with satellite observations at a finer resolution.
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Liu, H., X. M. Wang, J. M. Pang, and K. B. He. "Feasibility and difficulties on China new air quality standard compliance: PRD case of PM<sub>2.5</sub> and ozone from 2010 to 2025." Atmospheric Chemistry and Physics Discussions 13, no. 8 (August 12, 2013): 20923–59. http://dx.doi.org/10.5194/acpd-13-20923-2013.
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Abstract. Improving the air quality in China is a long and arduous task. Although China has made very aggressive plan on pollutants control, the difficulties to achieve the new air quality goals are still significant. In north, PM2.5 and PM10 are still far beyond the standards. In south, O3 goal is much challenged. A lot of cities are making their city implementation plan (CIP) for new air quality goals. In this study, a southern city, Guangzhou, is selected to analyze the feasibility and difficulties on new air quality standard compliance, as well as the CIP evaluation. A comprehensive study of air quality status in Guangzhou and surrounding area is conducted based on 22 sites monitoring data of O3, PM2.5 and PM10. The monthly non-attainment rates for O3 vary in 7–25% from May to November. The city average PM2.5 concentration is 41 μg m–3 in Guangzhou in 2010, which needs to be reduced by at least 15% to achieve the target of 35 μg m–3. The PM2.5 high violate months are from November to March. Guangzhou CIP was then evaluated with PM2.5 and O3 placed in a core position. The emission amount of NOx, PM10, PM2.5 and VOC in 2025 would be controlled to 600, 420, 200 and 860 thousand tons respectively. Analysis of air quality using the MM5-STEM model suggests that the long-term control measures would achieve the PM2.5 and PM10 goals successfully by 2025. The PM2.5 annual average concentration would be reduced to 20.8 μg m–3 in 2025. The O3 non-attainment rate would increase from 7.1% in 2010 to 12.9% in 2025 and become the most primary atmospheric environmental problem. Guangzhou needs very strong control on VOCs to reduce its ozone. The VOC / NOx reduction ratio should reach at least 2 : 1 (in California, it is about 3 : 1), instead of the current plan of 0.7 : 1. The evaporative emissions control from vehicle non-tailpipe emission and solvent usage should be enhanced and regional ozone transport must be taken into account.
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Yaghi, Asma, John R. Bend, Christopher D. Webb, Darryl C. Zeldin, Sean Weicker, Sanjay Mehta, and David G. McCormack. "Excess nitric oxide decreases cytochrome P-450 2J4 content and P-450-dependent arachidonic acid metabolism in lungs of rats with acute pneumonia." American Journal of Physiology-Lung Cellular and Molecular Physiology 286, no. 6 (June 2004): L1260—L1267. http://dx.doi.org/10.1152/ajplung.00273.2003.
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Recently, we demonstrated that pulmonary CYP2J4 content, a prominent source of EETs and HETEs formation in rat lungs, is reduced in pneumonia. Therefore, the purpose of this study was to determine the role of iNOS-derived NO in reduced pulmonary CYP2J4 protein content and decreased CYP metabolites in pneumonia. Rats were randomized to control, control plus 1400W (iNOS inhibitor), pneumonia, and pneumonia plus 1400W groups. Pseudomonas organisms were injected into lungs of pneumonia rats. At 40 h after surgery, rats were treated with either saline or 1400W for 4 h before death. Venous plasma samples were obtained for measuring nitrites/nitrates (NOx). There was no significant effect of 1400W on blood pressure measured in control or pneumonia rats, whereas 1400W reduced the elevated plasma NOx levels in pneumonia rats by half. CYP primary metabolites of AA formed at significantly lower rates in pulmonary microsomes from pneumonia rats compared with control rats. Treatment of pneumonia rats with 1400W resulted in a significant increase in the rate of formation of pulmonary EETs and ω-terminal HETEs compared with untreated pneumonia rats. The reduction in CYP2J4 protein content in pneumonia lung microsomes was also partially prevented by 1400W. Therefore, excess NO from iNOS decreases the pulmonary production of EETs and ω-HETEs in acute pneumonia. Inhibition of iNOS restores CYP2J4 protein content and CYP activity in acute pneumonia, indicating an important NO-CYP interaction in pulmonary responses to infection. We speculate CYP2J4 and its AA metabolites are involved in the modulation of pulmonary function in health and disease.
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Li, Meng, Qiang Zhang, Bo Zheng, Dan Tong, Yu Lei, Fei Liu, Chaopeng Hong, et al. "Persistent growth of anthropogenic non-methane volatile organic compound (NMVOC) emissions in China during 1990–2017: drivers, speciation and ozone formation potential." Atmospheric Chemistry and Physics 19, no. 13 (July 12, 2019): 8897–913. http://dx.doi.org/10.5194/acp-19-8897-2019.
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Abstract. Non-methane volatile organic compounds (NMVOCs) are important ozone and secondary organic aerosol precursors and play important roles in tropospheric chemistry. In this work, we estimated the total and speciated NMVOC emissions from China's anthropogenic sources during 1990–2017 by using a bottom-up emission inventory framework and investigated the main drivers behind the trends. We found that anthropogenic NMVOC emissions in China have been increasing continuously since 1990 due to the dramatic growth in activity rates and absence of effective control measures. We estimated that anthropogenic NMVOC emissions in China increased from 9.76 Tg in 1990 to 28.5 Tg in 2017, mainly driven by the persistent growth from the industry sector and solvent use. Meanwhile, emissions from the residential and transportation sectors declined after 2005, partly offsetting the total emission increase. During 1990–2017, mass-based emissions of alkanes, alkenes, alkynes, aromatics, oxygenated volatile organic compounds (OVOCs) and other species increased by 274 %, 88 %, 4 %, 387 %, 91 % and 231 %, respectively. Following the growth in total NMVOC emissions, the corresponding ozone formation potential (OFP) increased from 38.2 Tg of O3 in 1990 to 99.7 Tg of O3 in 2017. We estimated that aromatics accounted for the largest share (43 %) of the total OFP, followed by alkenes (37 %) and OVOCs (10 %). Growth in China's NMVOC emissions was mainly driven by the transportation sector before 2000, while industry and solvent use dominated the emission growth during 2000–2010. Since 2010, although emissions from the industry sector and solvent use kept growing, strict control measures on transportation and fuel transition in residential stoves have successfully slowed down the increasing trend, especially after the implementation of China's clean air action since 2013. However, compared to large emission decreases in other major air pollutants in China (e.g., SO2, NOx and primary PM) during 2013–2017, the relatively flat trend in NMVOC emissions and OFP revealed the absence of effective control measures, which might have contributed to the increase in ozone during the same period. Given their high contributions to emissions and OFP, tailored control measures for solvent use and industrial sources should be developed, and multi-pollutant control strategies should be designed to mitigate both PM2.5 and ozone pollution simultaneously.
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Davis, N. T., V. G. McDonell, and G. S. Samuelsen. "Effects of Cycle Operating Conditions on Combustor Performance." Journal of Engineering for Gas Turbines and Power 119, no. 1 (January 1, 1997): 45–49. http://dx.doi.org/10.1115/1.2815560.
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To mitigate the environmental impact of next-generation gas turbine combustors, the emission performance at each condition throughout the load duty cycle must be optimized. Achieving this with a single combustor geometry may not be possible. Rather, the mixing processes and airflow splits must likely be modified as a function of load in order to (1) abate the emission of oxides of nitrogen, (2) maintain combustion efficiency, and (3) preclude lean blow-out over the entire duty cycle. The present study employs a model combustor to evaluate combustor performance as a function of load and explore the application of variable geometry to optimize performance at each condition. A parametric variation of flow splits is conducted at each load condition by independently adjusting the primary jet area and swirler choke area. The resultant impact on combustor performance is measured and quantified in terms of a cost function. The cost function is defined to increase with improving combustor performance (e.g., improving combustion efficiency and/or declining NOx emissions). Cycle operating conditions are found to alter the response mappings of efficiency and NOx. As a result, the optimal configuration of the combustor changes as the load is varied over the duty cycle. The results provide guidance on the application of active control.
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Feitelberg, A. S., and M. A. Lacey. "The GE Rich-Quench-Lean Gas Turbine Combustor." Journal of Engineering for Gas Turbines and Power 120, no. 3 (July 1, 1998): 502–8. http://dx.doi.org/10.1115/1.2818173.
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The General Electric Company has developed and successfully tested a full-scale, F-class (2550°F combustor exit temperature), rich-quench-lean (RQL) gas turbine combustor, designated RQL2, for low heating value (LHV) fuel and integrated gasification combined cycle applications. Although the primary objective of this effort was to develop an RQL combustor with lower conversion of fuel bound nitrogen to NOx than a conventional gas turbine combustor, the RQL2 design can be readily adapted to natural gas and liquid fuel combustion. RQL2 is the culmination of a 5 year research and development effort that began with natural gas tests of a 2” diameter perforated plate combustor and included LHV fuel tests of RQL1, a reduced scale (6” diameter) gas turbine combustor. The RQL2 combustor includes a 14” diameter converging rich stage liner, an impingement cooled 7” diameter radially-stratified-quench stage, and a backward facing step at the entrance to a 10” diameter film cooled lean stage. The rich stage combustor liner has a novel double-walled structure with narrow circumferential cooling channels to maintain metal wall temperatures within design limits. Provisions were made to allow independent control of the air supplied to the rich and quench/lean stages. RQL2 has been fired for almost 100 hours with LHV fuel supplied by a pilot scale coal gasification and high temperature desulfurization system. At the optimum rich stage equivalence ration NOx emissions were about 50 ppmv (on a dry, 15 percent O2 basis), more than a factor of 3 lower than expected from a conventional diffusion flame combustor burning the same fuel. With 4600 ppmv NH3 in the LHV fuel, this corresponds to a conversion of NH3 to NOx of about 5 percent. As conditions were shifted away from the optimum, RQL2 NOx emissions gradually increased until they were comparable to a standard combustor. A chemical kinetic model of RQL2, constructed from a series of ideal chemical reactors, matched the measured NOx emissions fairly well. The CO emissions were between 5 and 30 ppmv (on a dry, 15 percent O2 basis) under all conditions.
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Piersanti, Antonio, Ilaria D’Elia, Maurizio Gualtieri, Gino Briganti, Andrea Cappelletti, Gabriele Zanini, and Luisella Ciancarella. "The Italian National Air Pollution Control Programme: Air Quality, Health Impact and Cost Assessment." Atmosphere 12, no. 2 (February 1, 2021): 196. http://dx.doi.org/10.3390/atmos12020196.
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Air pollution is the primary environmental cause of death globally. To improve air quality and reduce health impacts, the National Emission Ceilings Directive requires Member States of the European Union to provide National Air Pollution Control Programmes, including emission reduction measures aimed to achieve binding commitments for the years 2020 and 2030. Integrated assessment models are pivotal to assess the reduction of pollutants concentrations determined by measures implemented or foreseen for emission reduction. Here we discuss scenarios elaborated for year 2030 in the Italian National Air Pollution Control Programme, considering 2010 as reference year. The two scenarios, “With Measures” and “With Additional Measures”, show a significant reduction of the pollutants concentration, namely PM2.5, NO2 and O3. The scenarios are here also used to provide an integrated approach for calculating the effect of the program on health impacts (mortality) and related costs. Avoidable attributable cases and associated costs are here reported at both the national and regional level and provide a significant framework to assess air-pollution reduction measures with an integrated approach. The procedure proposed may be therefore further developed and applied to assess the overall positive benefits (environmental, health and economic) determined by air-pollution control plans or other integrated policies targeting air quality, energy and climate goals.
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Dunlea, E. J., S. C. Herndon, D. D. Nelson, R. M. Volkamer, F. San Martini, P. M. Sheehy, M. S. Zahniser, et al. "Evaluation of nitrogen dioxide chemiluminescence monitors in a polluted urban environment." Atmospheric Chemistry and Physics 7, no. 10 (May 23, 2007): 2691–704. http://dx.doi.org/10.5194/acp-7-2691-2007.
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Abstract. Data from a recent field campaign in Mexico City are used to evaluate the performance of the EPA Federal Reference Method for monitoring the ambient concentrations of NO2. Measurements of NO2 from standard chemiluminescence monitors equipped with molybdenum oxide converters are compared with those from Tunable Infrared Laser Differential Absorption Spectroscopy (TILDAS) and Differential Optical Absorption Spectroscopy (DOAS) instruments. A significant interference in the chemiluminescence measurement is shown to account for up to 50% of ambient NO2 concentration during afternoon hours. As expected, this interference correlates well with non-NOx reactive nitrogen species (NOz) as well as with ambient O3 concentrations, indicating a photochemical source for the interfering species. A combination of ambient gas phase nitric acid and alkyl and multifunctional alkyl nitrates is deduced to be the primary cause of the interference. Observations at four locations at varying proximities to emission sources indicate that the percentage contribution of HNO3 to the interference decreases with time as the air parcel ages. Alkyl and multifunctional alkyl nitrate concentrations are calculated to reach concentrations as high as several ppb inside the city, on par with the highest values previously observed in other urban locations. Averaged over the MCMA-2003 field campaign, the chemiluminescence monitor interference resulted in an average measured NO2 concentration up to 22% greater than that from co-located spectroscopic measurements. Thus, this interference has the potential to initiate regulatory action in areas that are close to non-attainment and may mislead atmospheric photochemical models used to assess control strategies for photochemical oxidants.
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Cravero, Carlo, and Davide De Domenico. "The Use of CFD for the Design and Development of Innovative Configurations in Regenerative Glass Production Furnaces." Energies 12, no. 13 (June 26, 2019): 2455. http://dx.doi.org/10.3390/en12132455.
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The limitation of nitrogen oxides emissions is nowadays a challenge in several engineering fields. Recent European regulations have reduced the maximum NOx emissions and therefore forced the glass production sector to develop emission reduction strategies. Two different systems have been developed within the framework of the European LIFE project and are currently applied to glass regenerative furnaces: the Waste Gas Recirculation (WGR) and the Hybrid Air Staging (HyAS). The above systems are primary NOx reduction strategies because they both operate to control the combustion evolution. Both WGR and HyAS systems have been conceived with the extensive use of Computational Fluid Dynamics (CFD) models: design strategies for both systems have been developed based on the use of CFD and are currently under use by glass furnace designers. In the present work, the CFD procedures routinely used for the design of the above systems are described. The systems effectiveness, due to the harsh conditions in the industrial installation, can be tested with oxygen concentration measurements inside the regenerators. The oxygen concentration is correlated to the flame evolution and therefore to the nitrogen oxides formation. For the above reason, the models have been validated with experimental data from pilot furnaces using measured values of O2 mole fraction. The CFD procedures are described in the paper together with their application to different configurations.
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Zheng, Xu, Qikai Wang, Xiang Yuan, Yingbo Zhou, Hui Chu, Guosheng Wang, Xiangpei Li, et al. "B7-H4 Inhibits the Development of Primary Sjögren’s Syndrome by Regulating Treg Differentiation in NOD/Ltj Mice." Journal of Immunology Research 2020 (September 27, 2020): 1–13. http://dx.doi.org/10.1155/2020/4896727.
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Background. This study is aimed at exploring the role of B7-H4 in the pathogenesis of primary Sjögren’s syndrome (pSS) in NOD/Ltj mouse. Methods. B7-H4 expression in salivary glands was examined by IHC, and lymphocyte infiltration was showed by H&E. Next, anti-B7-H4 mAb or immunoglobulin isotype was injected into NOD/Ltj mice. Cytokine levels were measured by quantitative RT-PCR, and immunoglobulins were measured by ELISA. T cell subsets were analyzed by flow cytometry. Last, we treated NOD/Ltj mice with B7-H4Ig and control Ig. CD4+Foxp3+ T cells were assessed by immunohistochemistry. Two-tailed Student’s t-tests were used to detect the statistical difference in various measures between the two groups. Results. B7-H4 expression was remarkably reduced in salivary glands of NOD/Ltj mice at 15 weeks compared with the NOD/Ltj mice at 8 weeks. Anti-B7-H4 mAb treatment increased lymphocyte infiltration in salivary glands. Inflammatory cytokines including IL-12, IL-18, IL-1α, TNF-α, IFN-α, and BAFF were upregulated markedly in anti-B7-H4 mAb-treated mice compared to IgG isotype-treated mice. Flow cytometry analysis showed that anti-B7-H4 mAb-treated mice had lower levels of CD4+Foxp3+/CD4+ T cells in spleen. Moreover, Foxp3 mRNA levels of salivary glands were diminished in anti-B7-H4 mAb-treated mice. Flow cytometry analysis showed that anti-B7-H4 mAb inhibited CD4+Foxp3+/CD4+ T cell production, while B7-H4Ig would promote naïve CD4+ T into Treg differentiation. Administration with B7-H4Ig displayed significantly decreased lymphocyte infiltration in salivary glands and low levels of total IgM and IgG in serum. Analysis of inflammatory cytokines in salivary glands after B7-H4Ig treatment revealed that the mRNA levels of IL-12, IL-6, IL-18, IL-1α, TNF-α, and IFN-α were significantly downregulated in B7-H4Ig-treated mice compared to control Ig treatment. B7-H4Ig-treated mice had significantly higher levels of CD4+Foxp3+/CD4+ T cells in spleen. IHC in salivary gland revealed that CD4+Foxp3+ T cells of B7-H4Ig treatment mouse were more than control Ig treatment. Conclusions. Our findings implicate that B7-H4 has a protective role for salivary gland epithelial cells (SGECs) and therapeutic potential in the treatment of pSS.
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Wang, T., W. Nie, J. Gao, L. K. Xue, X. M. Gao, X. F. Wang, J. Qiu, et al. "Air quality during the 2008 Beijing Olympics: secondary pollutants and regional impact." Atmospheric Chemistry and Physics Discussions 10, no. 5 (May 12, 2010): 12433–63. http://dx.doi.org/10.5194/acpd-10-12433-2010.
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Abstract. This paper presents the first results of the atmospheric measurements of trace gases and aerosols at three surface sites in and around Beijing before and during the 2008 Olympics. We focus on secondary pollutants including ozone, fine sulfate and nitrate, and the contribution of regional sources in summer 2008. The results reveal different responses of secondary pollutants to the control measures from primary pollutants. Ambient concentrations of vehicle-related nitrogen oxides (NOx) and volatile organic compounds (VOCs) at an urban site dropped by 25% and 20–45% in the first two weeks after full control was put in place, but the levels of ozone, sulfate and nitrate in PM2.5 increased by 16%, 64%, 37%, respectively, compared to the period prior to the full control; wind data and back trajectories indicated the contribution of regional pollution from the North China Plain. Air quality (for both primary and secondary pollutants) improved significantly during the Games, which were also associated with the changes in weather conditions (prolonged rainfall, decreased temperature, and more frequent air masses from clean regions). A comparison of the ozone data at three sites on eight ozone-pollution days, when the air masses were from the southeast-south-southwest sector, showed that regional pollution sources contributed 34%–88% to the peak ozone concentrations in urban Beijing. Ozone production efficiencies at two sites were low (~3 ppbv/ppbv), indicating that ozone formation was being controlled by VOCs. Compared with data collected in 2005 at a downwind site, the concentrations of ozone, sulfur dioxide (SO2), total sulfur (SO2+PM2.5 sulfate), carbon monoxide (CO), reactive aromatics (toluene and xylenes) sharply decreased (by 8–64%) in 2008, but no significant changes were observed for the concentrations of PM2.5, fine sulfate, total odd reactive nitrogen (NOy), and longer lived alkanes and benzene. We suggest that these results indicate the success of the government's efforts in reducing emissions of SO2, CO, and VOCs in Beijing. However, further control of regional emissions is needed for significant reductions of ozone and fine particulate pollution in Beijing.
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Geng, Guannan, Qiang Zhang, Dan Tong, Meng Li, Yixuan Zheng, Siwen Wang, and Kebin He. "Chemical composition of ambient PM<sub>2. 5</sub> over China and relationship to precursor emissions during 2005–2012." Atmospheric Chemistry and Physics 17, no. 14 (July 31, 2017): 9187–203. http://dx.doi.org/10.5194/acp-17-9187-2017.
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Abstract. In this work, we presented the characteristics of PM2. 5 chemical composition over China for the period of 2005–2012 by synthesis of in situ measurement data collected from literatures and satellite-based estimates using aerosol optical depth (AOD) data and the GEOS-Chem chemical transport model. We revealed the spatiotemporal variations in PM2. 5 composition during 2005–2012 and investigated the driving forces behind the variations by examining the changes in precursor emissions using a bottom-up emission inventory. Both in situ observations and satellite-based estimates identified that secondary inorganic aerosols (i.e., sulfate, nitrate, and ammonium; SNA) ranked as the highest fraction of dust-free PM2. 5 concentrations, followed by organic matter (OM) and black carbon (BC). For instance, satellite-based estimates found that SNA, OM, and BC contributed to 59, 33, and 8 %, respectively, of national population-weighted mean dust-free PM2. 5 concentrations during 2005–2012. National population-weighted mean PM2. 5 concentration increased from 63.9 µg m−3 in 2005 to 75.2 µg m−3 in 2007 and subsequently decreased to 66.9 µg m−3 from 2007 to 2012. Variations in PM2. 5 concentrations are mainly driven by the decrease in sulfate and the increase in nitrate. Population-weighted mean sulfate concentration decreased by 2.4 % yr−1 during 2005–2012 (from 14.4 to 12.9 µg m−3), while population-weighted mean nitrate concentration increased by 3.4 % yr−1 during 2005–2012 (from 9.8 to 12.2 µg m−3), largely offsetting the decrease in sulfate concentrations. By examining the emission data from the Multi-resolution Emission Inventory for China (MEIC), we found that the changes in sulfate and nitrate concentrations were in line with the decrease in SO2 emissions and the increase in NOx emissions during the same period. The desulfurization regulation in power plants enforced around 2005 has been the primary contributor to the SO2 emission reduction since 2006. In contrast, growth of energy consumption and lack of control measures for NOx resulted in a persistent increase in NOx emissions until the installation of denitrification devices on power plants late in 2011, which began to take effect in 2012. The results of this work indicate that the synchronized abatement of emissions for multipollutants is necessary for reducing ambient PM2. 5 concentrations over China.
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Sutton, M. A., Y. S. Tang, U. Dragosits, N. Fournier, A. J. Dore, R. I. Smith, K. J. Weston, and D. Fowler. "A Spatial Analysis of Atmospheric Ammonia and Ammonium in the U.K." Scientific World JOURNAL 1 (2001): 275–86. http://dx.doi.org/10.1100/tsw.2001.313.
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As measures are implemented internationally to reduce SO2 and NOx emissions, attention is falling on the contribution of NH3 emissions to acidification, nitrogen eutrophication, and aerosol formation. In the U.K., a monitoring network has been established to measure the spatial distribution and long-term trends in atmospheric gaseous NH3 and aerosol NH4+. At the same time, an atmospheric chemistry and transport model, FRAME, has been developed with a focus on reduced nitrogen (NHx). The monitoring data are important to evaluate the model, while the model is essential for a more detailed spatial assessment. The national network is established with over 80 sampling locations. Measurements of NH3 and NH4+ (at up to 50 sites) have been made using a new low-cost denuder-filterpack system. Additionally, improved passive sampling methods for NH3 have been applied to explore local variability. The measurements confirm the high spatial variability of NH3 (annual means 0.06 to 11 mg NH3 m�3), consistent with its nature as a primary pollutant emitted from ground-level sources, while NH4+, being a slowly formed secondary product, shows much less spatial variability (0.14 to 2.4 mg NH4+ m�3). These features are reproduced in the FRAME model, which provides estimates at a 5-km level. Analysis of the underlying NH3 emission inventory shows that sheep emissions may have been underestimated and nonagricultural sources overestimated relative to emissions from cattle. The combination of model and measurements is applied to estimate spatial patterns of dry deposition to different vegetation types. The combined approach provides the basis to assess NHx responses across the U.K. to international emission controls.
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Liu, Y., B. Yuan, X. Li, M. Shao, S. Lu, Y. Li, C. C. Chang, et al. "Impact of pollution controls in Beijing on atmospheric oxygenated volatile organic compounds (OVOCs) during the 2008 Olympic Games: observation and modeling implications." Atmospheric Chemistry and Physics 15, no. 6 (March 18, 2015): 3045–62. http://dx.doi.org/10.5194/acp-15-3045-2015.
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Abstract. Oxygenated volatile organic compounds (OVOCs) are important products of the photo-oxidation of hydrocarbons. They influence the oxidizing capacity and the ozone-forming potential of the atmosphere. In the summer of 2008, 2 months of emission restrictions were enforced in Beijing to improve air quality during the Olympic Games. Observational evidence reported in related studies that these control measures were efficient in reducing the concentrations of primary anthropogenic pollutants (CO, NOx and non-methane hydrocarbons, i.e., NMHCs) by 30–40%. In this study, the influence of the emission restrictions on ambient levels of OVOCs was explored using a neural network analysis with consideration of meteorological conditions. Statistically significant reductions in formaldehyde (HCHO), acetaldehyde (CH3CHO), methyl ethyl ketone (MEK) and methanol were found to be 12.9, 15.8, 17.1 and 19.6%, respectively, when the restrictions were in place. The effect of emission controls on acetone was not detected in neural network simulations, probably due to pollution transport from surrounding areas outside Beijing. Although the ambient levels of most NMHCs were reduced by ~35% during the full control period, the emission ratios of reactive alkenes and aromatics closely related to automobile sources did not present much difference (< 30%). A zero-dimensional box model based on the Master Chemical Mechanism version 3.2 (MCM3.2) was applied to evaluate how OVOC production responds to the reduced precursors during the emissions control period. On average, secondary HCHO was produced from the oxidation of anthropogenic alkenes (54%), isoprene (30%) and aromatics (15%). The importance of biogenic sources for the total HCHO formation was almost on par with that of anthropogenic alkenes during the daytime. Anthropogenic alkenes and alkanes dominated the photochemical production of other OVOCs such as acetaldehyde, acetone and MEK. The relative changes of modeled HCHO, CH3CHO, methyl vinyl ketone and methacrolein (MVK + MACR) before and during the pollution controlled period were comparable to the estimated reductions in the neural network, reflecting that current mechanisms can largely explain secondary production of those species under urban conditions. However, it is worth noting that the box model overestimated the measured concentrations of aldehydes by a factor of 1.4–1.7 without consideration of loss of aldehydes on aerosols, and simulated MEK was in good agreement with the measurements when primary sources were taken into consideration. These results suggest that the understanding of the OVOCs budget in the box model remains incomplete, and that there is still considerable uncertainty in particular missing sinks (unknown chemical and physical processes) for aldehydes and absence of direct emissions for ketones.
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Wang, T., W. Nie, J. Gao, L. K. Xue, X. M. Gao, X. F. Wang, J. Qiu, et al. "Air quality during the 2008 Beijing Olympics: secondary pollutants and regional impact." Atmospheric Chemistry and Physics 10, no. 16 (August 16, 2010): 7603–15. http://dx.doi.org/10.5194/acp-10-7603-2010.
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Abstract. This paper presents the first results of the measurements of trace gases and aerosols at three surface sites in and outside Beijing before and during the 2008 Olympics. The official air pollution index near the Olympic Stadium and the data from our nearby site revealed an obvious association between air quality and meteorology and different responses of secondary and primary pollutants to the control measures. Ambient concentrations of vehicle-related nitrogen oxides (NOx) and volatile organic compounds (VOCs) at an urban site dropped by 25% and 20–45% in the first two weeks after full control was put in place, but the levels of ozone, sulfate and nitrate in PM2.5 increased by 16%, 64%, 37%, respectively, compared to the period prior to the full control; wind data and back trajectories indicated the contribution of regional pollution from the North China Plain. Air quality (for both primary and secondary pollutants) improved significantly during the Games, which were also associated with the changes in weather conditions (prolonged rainfall, decreased temperature, and more frequent air masses from clean regions). A comparison of the ozone data at three sites on eight ozone-pollution days, when the air masses were from the southeast-south-southwest sector, showed that regional pollution sources contributed >34–88% to the peak ozone concentrations at the urban site in Beijing. Regional sources also contributed significantly to the CO concentrations in urban Beijing. Ozone production efficiencies at two sites were low (~3 ppbv/ppbv), indicating that ozone formation was being controlled by VOCs. Compared with data collected in 2005 at a downwind site, the concentrations of ozone, sulfur dioxide (SO2), total sulfur (SO2+PM2.5 sulfate), carbon monoxide (CO), reactive aromatics (toluene and xylenes) sharply decreased (by 8–64%) in 2008, but no significant changes were observed for the concentrations of PM2.5, fine sulfate, total odd reactive nitrogen (NOy), and longer lived alkanes and benzene. We suggest that these results indicate the success of the government's efforts in reducing emissions of SO2, CO, and VOCs in Beijing, but increased regional emissions during 2005–2008. More stringent control of regional emissions will be needed for significant reductions of ozone and fine particulate pollution in Beijing.
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Liu, Y., B. Yuan, X. Li, M. Shao, S. Lu, Y. Li, C. C. Chang, and T. Zhu. "Impact of pollution controls in Beijing on atmospheric oxygenated volatile organic compounds (OVOCs) during the 2008 Olympic Games: observation and modeling implications." Atmospheric Chemistry and Physics Discussions 14, no. 19 (October 17, 2014): 26127–71. http://dx.doi.org/10.5194/acpd-14-26127-2014.
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Abstract. Oxygenated volatile organic compounds (OVOCs) are important products of the photo-oxidation of hydrocarbons. They influence the oxidizing capacity and the ozone forming potential of the atmosphere. In the summer of 2008 two months' emission restrictions were enforced in Beijing to improve air quality during the Olympic Games. Observation evidence has been reported in related studies that these control measures were efficient in reducing the concentrations of primary anthropogenic pollutants (CO, NOx and non-methane hydrocarbons, i.e. NMHCs) by 30–40%. In this study, the influence of the emission restrictions on ambient levels of OVOCs was explored using a neural network analysis with consideration of meteorological conditions. Statistically significant reductions in formaldehyde (HCHO), acetaldehyde (CH3CHO), methyl ethyl ketone (MEK) and methanol were found to be 12.9, 15.8, 17.1 and 19.6%, respectively, when the restrictions were in place. The effect of emission control on acetone was not detected in neural network simulations, probably due to pollution transport from surrounding areas outside Beijing. Although the ambient levels of most NMHCs were decreased by ~35% during the full control period, the emission ratios of reactive hydrocarbons attributed to vehicular emissions did not present obvious difference. A zero-dimensional box model based on Master Chemical Mechanism version 3.2 (MCM3.2) was applied to evaluate how OVOCs productions respond to the reduced precursors during the emission controlled period. On average, secondary HCHO was produced from the oxidation of anthropogenic alkenes (54%), isoprene (30%) and aromatics (15%). The importance of biogenic source for the total HCHO formation was almost on a par with that of anthropogenic alkenes during the daytime. Anthropogenic alkenes and alkanes dominated the photochemical production of other OVOCs such as acetaldehyde, acetone and MEK. The relative changes of modelled aldehydes, methyl vinyl ketone and methacrolein (MVK + MACR) before and during the pollution controlled period were comparable to the estimated reductions in the neural network, reflecting that current mechanisms can largely explain secondary production of those species under urban conditions. However, it is worthy to notice that the box model overestimated the measured concentrations of aldehydes by a factor of 1.4–1.7, and simulated MEK was in good agreement with the measurements when primary sources were taken into consideration. These results suggest that the understanding of OVOCs budget in the box model remains incomplete, there is still considerable uncertainty in particular missing sinks (unknown chemical reactions and physical dilution processes) for aldehydes and absence of direct emissions for ketones.
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Wang, Hai Ying, Yong Jing Liu, and Di Hua Tang. "Association Study on Air Pollution and Cardiopulmonary Function of Primary and Secondary School Students." Applied Mechanics and Materials 700 (December 2014): 437–41. http://dx.doi.org/10.4028/www.scientific.net/amm.700.437.
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Impact of air pollution on health has become an important social issue. Air pollution is closely related to the morbidity and death rate of cardiopulmonary disease, produces short-term acute and chronic hazards on health, and especially has long-term and profound impact on primary and secondary school students’ constitution. Long-term effects of air pollution on cardiopulmonary function of primary and secondary school students are represented as incidence increase of asthma, decrease of FEV1, MMEF, VO2max, MVV and other indicators and relation to NO, PM2.5 and CO. Students taking exercise in air pollution environment can cause acute cardiopulmonary reactions, such as abnormal changes of MVV, VC, FEV1, FVC and other indicators after exercise, which may relate to O3, PM10, PM2.5, SO2and NO2. Therefore, schools should strengthen the awareness of air pollution in implementing sports, and conduct development of control measures, to ensure the effect of physical exercise.
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Ding, Shenzhen, Xumei Chen, Lei Yu, and Xu Wang. "Arterial Offset Optimization Considering the Delay and Emission of Platoon: A Case Study in Beijing." Sustainability 11, no. 14 (July 17, 2019): 3882. http://dx.doi.org/10.3390/su11143882.
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The effective setting of offsets between intersections on arterial roads can greatly reduce the travel time of vehicles through intersections. However, coordinated control systems of urban arterial roads often do not achieve the desired effect. On the contrary, they are very likely to increase the traffic congestion on arterial roads, resulting in more delays of the platoon with more exhaust emissions, if the coordinated control system does not have effective settings. Meanwhile, taking into account increasing environmental pollution, measures are needed to solve the conflict between environmental and traffic management. Thus, in order to ensure the smooth flow of urban arterial roads while considering the environment, this paper develops a bi-objective offset optimization model, with reducing delays of the platoon on arterial roads as the primary objective, and reducing exhaust emissions as the secondary objective. The proposed bi-objective model is based on the division of platoon operating modes on arterial roads, and more pollutant types, including NOx, HC, and CO, are considered when measuring environmental impact. Further, the modified hierarchical method, combining the branch and bound approach with the introductions of a relaxation coefficient, is employed to solve the model. By introducing a relaxation coefficient, the modified hierarchical method overcomes the defects of the traditional one. Finally, Xi Dajie Road in Beijing was taken as an example. The results showed that the bi-objective offset optimization model, considering both the delays and emissions of the platoon reduced delays by up to 20% and emissions by 7% compared with the existing timing plan. If compared with the offset optimization model considering delays only, such a model increases delays no more than 3% and reduces emissions by 6%.
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Franklin, M. L., D. B. Kittelson, and R. H. Leuer. "The Application of a Thermal Efficiency Maximizing Control Strategy for Ignition Timing and Equivalence Ratio on a Natural Gas-Fueled Hercules G1600." Journal of Engineering for Gas Turbines and Power 118, no. 4 (October 1, 1996): 872–79. http://dx.doi.org/10.1115/1.2817008.
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A two-dimensional optimization process, which simultaneously adjusts the spark timing and equivalence ratio of a lean-burn, natural gas, Hercules G1600 engine, has been demonstrated. First, the three-dimensional surface of thermal efficiency was mapped versus spark timing and equivalence ratio at a single speed and load combination. Then the ability of the control system to find and hold the combination of timing and equivalence ratio that gives the highest thermal efficiency was explored. NOx, CO, and HC maps were also constructed from our experimental data to determine the tradeoffs between efficiency and emissions. The optimization process adds small synchronous disturbances to the spark timing and air flow while the fuel injected per cycle is held constant for four cycles. The engine speed response to these disturbances is used to determine the corrections for spark timing and equivalence ratio. The control process, in effect, uses the engine itself as the primary sensor. The control system can adapt to changes in fuel composition, operating conditions, engine wear, or other factors that may not be easily measured. Although this strategy was previously demonstrated in a Volkswagen 1.7 liter light duty engine (Franklin et al., 1994b), until now it has not been demonstrated in a heavy-duty engine. This paper covers the application of the approach to a Hercules G1600 engine.
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Khajehpour, Hossein, Nima Norouzi, and Maryam Fani. "An Exergetic Model for the Ambient Air Temperature Impacts on the Combined Power Plants and its Management Using the Genetic Algorithm." International Journal of Air-Conditioning and Refrigeration 29, no. 01 (February 26, 2021): 2150008. http://dx.doi.org/10.1142/s2010132521500085.
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4E analysis is used on a Brayton–Rankine combined cycle power plant (CCPP) with a dual pressure heat recovery steam generation (HRSG) system. A multi-objective genetic-based evolutionary optimization has been used to estimate the most optimal exergy efficiency status, exergy cost reduction, carbon emission reduction, and NOx emission reduction. For the validation of the data, the simulation results are compared with the plant’s data. This study investigates the effect of every decisive parameter on the objective performance parameters of the CCPP. The primary estimated results are the emission rates, efficiencies, and the exergoeconomic cost of the system. At the optimum operational state, the exergy efficiency may increase by 10%, while the total emissions may decrease by 14.6%. The conventional technical measures’ effectiveness to improve the combined cycle power plant’s energy performance is applied to the simulated case study. Results have shown that the main source of the exergy destruction in this system is the HRSG and the combustion chamber, and also the overall performance of the plant shows great sensitivity to the ambient air temperature. This fact has shown that climate change and global warming are effective in thermal power plants’ performance. Therefore, the effect of the climate change on the ambient air temperature impact on the power plant and the 4E performance of the simulated combined cycle power plant is also studied. The results show that, due to the global warming effect, the exergy efficiency of the CCPP unit is decreased by over 0.2% in the last two decades, which can be generalized to all thermal electricity generation units throughout the world based on the mean global temperature rise in the last decades.
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AMES, PAUL R. J., JOANA R. BATUCA, ANTONIO CIAMPA, LUIGI IANNACCONE, and JOSE DELGADO ALVES. "Clinical Relevance of Nitric Oxide Metabolites and Nitrative Stress in Thrombotic Primary Antiphospholipid Syndrome." Journal of Rheumatology 37, no. 12 (October 1, 2010): 2523–30. http://dx.doi.org/10.3899/jrheum.100494.
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Objective.To assess the role of nitrite (NO2−), nitrate (NO3−), and nitrative stress in thrombotic primary antiphospholipid syndrome (PAPS).Methods.We investigated 46 patients with PAPS: 21 asymptomatic but persistent carriers of antiphospholipid antibodies (PCaPL), 38 patients with inherited thrombophilia (IT), 33 patients with systemic lupus erythematosus (SLE), and 29 healthy controls (CTR). IgG anticardiolipin (aCL), IgG anti-beta2-glycoprotein I (anti-ß2-GPI), IgG anti-high density lipoprotein (aHDL), IgG anti-apolipoprotein A-I (aApoA-I), crude nitrotyrosine (NT) (an indicator of nitrative stress), and high sensitivity C-reactive protein (CRP) were measured by immunoassays. Plasma nitrite (NO2−), nitrate (NO3−), and total antioxidant capacity (TAC) were measured by colorimetric spectroscopic assays.Results.Average plasma NO2−was lower in PAPS, PCaPL, and IT (p < 0.0001); average NO3−was highest in SLE (p < 0.0001), whereas average NT was higher in PAPS and SLE (p = 0.01). In thrombotic PAPS, IgG aCL titer and number of vascular occlusions negatively predicted NO2−(p = 0.03 and p = 0.001, respectively), whereas arterial occlusions and smoking positively predicted NO3−(p = 0.05 and p = 0.005), and CRP positively predicted NT (p = 0.004). In the PCaPL group IgG aCL negatively predicted NO3−(p = 0.03). In the SLE group IgG aCL negatively predicted NO2−(p = 0.03) and NO3−(p = 0.02).Conclusion.PAPS is characterized by decreased NO2−in relation to type and number of vascular occlusions and to aPL titers. Nitrative stress and low grade inflammation are linked phenomena in PAPS and may have implications for thrombosis and atherosclerosis.
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Gordon, T. D., A. A. Presto, N. T. Nguyen, W. H. Robertson, K. Na, K. N. Sahay, M. Zhang, et al. "Secondary organic aerosol production from diesel vehicle exhaust: impact of aftertreatment, fuel chemistry and driving cycle." Atmospheric Chemistry and Physics Discussions 13, no. 9 (September 16, 2013): 24223–62. http://dx.doi.org/10.5194/acpd-13-24223-2013.
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Abstract. Environmental chamber ("smog chamber") experiments were conducted to investigate secondary organic aerosol (SOA) production from dilute emissions from two medium-duty diesel vehicles (MDDVs) and three heavy-duty diesel vehicles (HDDVs) under urban-like conditions. Some of the vehicles were equipped with emission control aftertreatment devices including diesel particulate filters (DPF), selective catalytic reduction (SCR) and diesel oxidation catalysts (DOC). Experiments were also performed with different fuels (100% biodiesel and low-, medium- or high-aromatic ultralow sulfur diesel) and driving cycles (Unified Cycle, Urban Dynamometer Driving Schedule, and creep+idle). During normal operation, vehicles with a catalyzed DPF emitted very little primary particulate matter (PM). Furthermore, photo-oxidation of dilute emissions from these vehicles produced essentially no SOA (below detection limit). However, significant primary PM emissions and SOA production were measured during active DPF regeneration experiments. Nevertheless, under reasonable assumptions about DPF regeneration frequency, the contribution of regeneration emissions to the total vehicle emissions is negligible, reducing PM trapping efficiency by less than 2%. Therefore, catalyzed DPFs appear to be very effective in reducing both primary and secondary fine particulate matter from diesel vehicles. For both MDDVs and HDDVs without aftertreatment substantial SOA formed in the smog chamber – with the emissions from some vehicles generating twice as much SOA as primary organic aerosol after three hours of oxidation at typical urban VOC : NOx ratios (3:1). Comprehensive organic gas speciation was performed on these emissions, but less than half of the measured SOA could be explained by traditional (speciated) SOA precursors. The remainder presumably originates from the large fraction (~30%) of the non-methane organic gas emissions that could not be speciated using traditional one-dimensional gas-chromatography. The unspeciated organics – likely comprising less volatile species, such as intermediate volatility organic compounds – appear to be important SOA precursors; we estimate that the effective SOA yield (defined as the ratio of SOA mass to reacted precursor mass) was 9 ± 6% if both speciated SOA precursors and unspeciated organics are included in the analysis. SOA production from creep+idle operation was 3–4 times larger than SOA production from the same vehicle operated over the Urban Dynamometer Driving Schedule (UDDS). Fuel properties had little or no effect on primary PM emissions or SOA formation.
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Gordon, T. D., A. A. Presto, N. T. Nguyen, W. H. Robertson, K. Na, K. N. Sahay, M. Zhang, et al. "Secondary organic aerosol production from diesel vehicle exhaust: impact of aftertreatment, fuel chemistry and driving cycle." Atmospheric Chemistry and Physics 14, no. 9 (May 13, 2014): 4643–59. http://dx.doi.org/10.5194/acp-14-4643-2014.
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Abstract. Environmental chamber ("smog chamber") experiments were conducted to investigate secondary organic aerosol (SOA) production from dilute emissions from two medium-duty diesel vehicles (MDDVs) and three heavy-duty diesel vehicles (HDDVs) under urban-like conditions. Some of the vehicles were equipped with emission control aftertreatment devices, including diesel particulate filters (DPFs), selective catalytic reduction (SCR) and diesel oxidation catalysts (DOCs). Experiments were also performed with different fuels (100% biodiesel and low-, medium- or high-aromatic ultralow sulfur diesel) and driving cycles (Unified Cycle,~Urban Dynamometer Driving Schedule, and creep + idle). During normal operation, vehicles with a catalyzed DPF emitted very little primary particulate matter (PM). Furthermore, photooxidation of dilute emissions from these vehicles produced essentially no SOA (below detection limit). However, significant primary PM emissions and SOA production were measured during active DPF regeneration experiments. Nevertheless, under reasonable assumptions about DPF regeneration frequency, the contribution of regeneration emissions to the total vehicle emissions is negligible, reducing PM trapping efficiency by less than 2%. Therefore, catalyzed DPFs appear to be very effective in reducing both primary PM emissions and SOA production from diesel vehicles. For both MDDVs and HDDVs without aftertreatment substantial SOA formed in the smog chamber – with the emissions from some vehicles generating twice as much SOA as primary organic aerosol after 3 h of oxidation at typical urban VOC / NOx ratios (3 : 1). Comprehensive organic gas speciation was performed on these emissions, but less than half of the measured SOA could be explained by traditional (speciated) SOA precursors. The remainder presumably originates from the large fraction (~30%) of the nonmethane organic gas emissions that could not be speciated using traditional one-dimensional gas chromatography. The unspeciated organics – likely comprising less volatile species such as intermediate volatility organic compounds – appear to be important SOA precursors; we estimate that the effective SOA yield (defined as the ratio of SOA mass to reacted precursor mass) was 9 ± 6% if both speciated SOA precursors and unspeciated organics are included in the analysis. SOA production from creep + idle operation was 3–4 times larger than SOA production from the same vehicle operated over the Urban Dynamometer Driving Schedule (UDDS). Fuel properties had little or no effect on primary PM emissions or SOA formation.
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Kaul, Dhananjay K., Trisha Dasgupta, Xiaoqin Zhang, and Mary Fabry. "Hemolytic Rate and Nitric Oxide Bioavailability Modulate the Expression of Hypoxia-Inducible Factor-1α (HIF-1α) in Transgenic Sickle Mice." Blood 112, no. 11 (November 16, 2008): 2501. http://dx.doi.org/10.1182/blood.v112.11.2501.2501.
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Abstract In sickle cell disease (SCD), tissue hypoxia (caused by vaso-occlusive events, abnormal red cell rheology and anemia), intense oxidative stress and persistent hemolysis are three major components that determine pathogenesis. In SCD, ischemic events are likely to activate hypoxia-inducible factor-1α (HIF-1α), a transcription factor that is involved in regulation of several genes including genes for vasoactive molecules. Although tissue ischemia is the primary instigator of HIF-1α activation, the induction, stabilization and degradation of HIF-1α also involves participation of signaling molecules, oxygen sensors (prolyl hydroxylases or PHDs) and redox reactions. Nitric oxide (NO) is a major signaling molecule affecting the activity of PHDs. We hypothesize that increased oxidative stress and reduced NO bioavailability caused by cell-free plasma heme will have a significant effect on HIF-1α expression under in vivo conditions. To this end, we have explored the effect of hemolysis and NO bioavailability on HIF-1α expression: in transgenic-knockout sickle (BERK) mice expressing varying levels of anti-sickling fetal hemoglobin (HbF), and in transgenic sickle (NY1DD) mice subjected to arginine treatment and hypoxia. We used BERK mice expressing different levels of HbF: BERK (HbF <1.0), BERKγM (~20% HbF) and BERKγH (~40% HbF). BERK mice show severe pathology, tissue hypoxia, significant hemolysis, and accumulation of HIF-1α under ambient conditions as determined in the cremaster tissue. Also, BERK mice showed maximal hemolytic rate (measured as plasma heme), and introduction of γ-transgene to elevate HbF levels to 20 and 40% caused significant reductions in plasma heme values as reported (Kaul et al. JCI, 2004). Increasing HbF expression and reducing hemolysis in BERK mice resulted in corresponding increases in NO metabolites (NOx) levels (P<0.05, multiple comparisons by ANOVA). Notably, in BERK mice, HIF-1α expression decreased by almost 50% with increased NOx levels. The present in vivo finding is in contrast with the reported NO-provoked HIF-1α accumulation in vitro under normoxic conditions. Next, we evaluated the effect of NO bioavailability on HIF-1α accumulation under hypoxic conditions. To this end, we treated in C57BL and transgenic sickle (NY1DD) mice with arginine (5% arginine in mouse chow). NY1DD mice show mild pathology but develop severe phenotype under hypoxic conditions. Both groups of mice were treated for 15 days with arginine followed by hypoxia (8% O2) starting day 12 of arginine treatment. Compared with normoxic controls, hypoxia caused marked accumulation of HIF-1α in the cremaster tissue. Importantly, arginine markedly reduced hypoxia-induced HIF-1α activation in NY1DD mice to the control level, indicating that under hypoxic conditions increased NO bioavailability (arginine treatment) is associated with degradation of HIF-1α. Interestingly, arginine-treated NY1DD mice show increased NOx levels, and reduced expression of heme oxygenase-1 (HO-1), a marker of hemolysis, by almost 40%. Taken together, these results provide the first in vivo demonstration that the hemolytic rate and NO bioavailability have a major influence on HIF-1α expression in the mouse models of SCD.
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Huang, X. H. H., Q. J. Bian, P. K. K. Louie, and J. Z. Yu. "Contributions of vehicular carbonaceous aerosols to PM<sub>2.5</sub> in a roadside environment in Hong Kong." Atmospheric Chemistry and Physics 14, no. 17 (September 9, 2014): 9279–93. http://dx.doi.org/10.5194/acp-14-9279-2014.
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Abstract. Hourly measurements of elemental carbon (EC) and organic carbon (OC) were made at Mong Kok, a roadside air quality monitoring station in Hong Kong, for a year, from May 2011 to April 2012. The monthly average EC concentrations were 3.8–4.9 μg C m−3, accounting for 9.2–17.7% of the PM2.5 mass (21.5–49.7 μg m−3). The EC concentrations showed little seasonal variation and peaked twice daily, coinciding with the traffic rush hours of a day. Strong correlations were found between EC and NOx concentrations, especially during the rush hours in the morning, confirming vehicular emissions as the dominant source of EC at this site. The analysis by means of the minimum OC / EC ratio approach to determine the OC / EC ratio representative of primary vehicular emissions yields a value of 0.5 for (OC / EC)vehicle. By applying the derived (OC / EC)vehicle ratio to the data set, the monthly average vehicle-related OC was estimated to account for 17–64% of the measured OC throughout the year. Vehicle-related OC was also estimated using receptor modeling of a combined data set of hourly NOx, OC, EC and volatile organic compounds characteristic of different types of vehicular emissions. The OCvehicle estimations by the two different approaches were in good agreement. When both EC and vehicle-derived organic matter (OM) (assuming an OM-to-OC ratio of 1.4) are considered, vehicular carbonaceous aerosols contributed ~ 7.3 μg m−3 to PM2.5, accounting for ~ 20% of PM2.5 mass (38.3 μg m−3) during winter, when Hong Kong received significant influence of air pollutants transported from outside, and ~ 30% of PM2.5 mass (28.2 μg m−3) during summertime, when local emission sources were dominant. A reduction of 3.8 μg m−3 in vehicular carbonaceous aerosols was estimated during 07:00–11:00 (i.e., rush hours on weekdays) on Sundays and public holidays. This could mainly be attributed to less on-road public transportation (e.g., diesel-powered buses) in comparison with non-holidays. These multiple lines of evidence confirm local vehicular emissions as an important source of PM2.5 in an urban roadside environment and suggest the importance of vehicular emission control in reducing exposure to PM2.5 in busy roadside environments.
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Libby, Peter, and Brendan M. Everett. "Novel Antiatherosclerotic Therapies." Arteriosclerosis, Thrombosis, and Vascular Biology 39, no. 4 (April 2019): 538–45. http://dx.doi.org/10.1161/atvbaha.118.310958.
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Many measures can control lipid risk factors for atherosclerosis. Yet, even with excellent control of dyslipidemia, other sources of risk remain. Hence, we must look beyond lipids to address residual risk. Lifestyle measures should form the foundation of cardiovascular risk control. Many pharmacological interventions targeting oxidation have proven disappointing. A large program tested inhibition of a LpPLA 2 (lipoprotein-associated phospholipase A 2 ), culminating in 2 large-scale clinical trials that did not meet their primary end points. A variety of antioxidants have not shown benefit in clinical trials. Numerous laboratory and clinical studies have inculpated inflammatory pathways in the pathogenesis of atherosclerotic events. The p38 MAPK (mitogen-activated protein kinase) inhibitor losmapimod and an inhibitor of a leukocyte adhesion molecule, P-selectin, did not alter adverse events in trials. Low-dose methotrexate, despite the promising observational studies, did not lower biomarkers of inflammation or alter cardiovascular outcomes in the CIRT (cardiovascular inflammation reduction trial). Four large-scale investigations underway will determine colchicine’s ability to reduce recurrent events in secondary prevention. The CANTOS (Canakinumab Anti-inflammatory Thrombosis Outcomes Study) showed that an antibody that neutralizes IL (interleukin)-1β can reduce recurrent cardiovascular events in secondary prevention. The success of CANTOS points to the pathway that leads from the NLRP3 (NOD-like receptor family, pyrin domain-containing protein 3) inflammasome through IL-1β to IL-6 as an attractive target for further study and clinical development beyond lipid therapies to address the unacceptable burden of risk that remains despite our best current care in secondary prevention.
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Thangaraja, J., K. Anand, and Pramod S. Mehta. "Biodiesel NOx penalty and control measures - a review." Renewable and Sustainable Energy Reviews 61 (August 2016): 1–24. http://dx.doi.org/10.1016/j.rser.2016.03.017.
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Yu, Yue, Zhi-xin Jin, Ji-zu Li, Yu-cheng Wu, and Li Jia. "An Air Pollutant Emission Reduction Path of China’s Power Industry." Atmosphere 11, no. 8 (August 12, 2020): 852. http://dx.doi.org/10.3390/atmos11080852.
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In China, as the major source of energy consumption and air pollutant emissions, the power industry is not only the principal force that bears the responsibility of national emission reduction targets but also a breakthrough that reflects the effectiveness of emission reduction. In this study, based on the integrated MARKAL-EFOM system (TIMES) model and scenario analysis method, a bottom-up energy system optimization model for the power industry was established, and four scenarios with different constraints were set up to predict and analyze the power demand and the energy consumption structure. Emission characteristics, emission reduction characteristics, and emission reduction cost of sulfur dioxide (SO2), nitrogen oxide (NOX), particulate matter 2.5 (PM2.5), and mercury (Hg) were quantitatively studied. Finally, for the environmentally friendly development and optimal adjustment of power production systems in China, the control path in the power industry that is conducive to the emission reduction of air pollutants was obtained, which is of great significance for the ultimate realization of climate friendliness. The results demonstrate that from 2020 to 2050, the power demand of the terminal departments will increase, with the composition significantly changed. The focus of power demand will change from industry to the service industry gradually. If no additional targeted emission reduction or adjustment policies are added in the power industry, the primary energy and air pollutant emissions will increase significantly, putting great pressure on resources and the environment. For the emission reduction of air pollutants, the promotion effect of emission reduction measures, such as the implementation and promotion of non-fossil fuels, is restricted. The power industry can introduce and maximize the best available technologies while optimizing the structure of energy consumption to realize efficient emission reduction of air pollutants and energy conservation. In 2030, emissions will reach peak values with reasonable emission reduction cost. This has the additional effect of abating energy consumption and preventing deterioration of the ecological environment, which is of profound significance for the ultimate realization of climate friendliness.
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Ye, Lexuan, and Yungang Wang. "Long-Term Air Quality Study in Fairbanks, Alaska: Air Pollutant Temporal Variations, Correlations, and PM2.5 Source Apportionment." Atmosphere 11, no. 11 (November 6, 2020): 1203. http://dx.doi.org/10.3390/atmos11111203.
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As one of the most polluted U.S. cities, Fairbanks was reclassified as a “serious” nonattainment area by the Environmental Protection Agency (EPA) in 2017 for its fine particulate matter (PM2.5) pollution. In this study, November 2013–May 2019 observations of criteria air pollutants (NO2, SO2, CO, O3, PM2.5, and inhalable particulate matter (PM10)) and meteorological parameters (temperature, wind speed, and relative humidity) in Fairbanks were used for temporal variation and correlation analysis, with positive matrix factorization (EPA PMF 5.0) adopted for further PM2.5 source identification. All pollutants exhibited obvious seasonal trends under the influence of climatology, topography, and human activity, while abnormal patterns likely resulted from occasional emission events such as wildfires. Primary and secondary pollutants performed distinctively under similar meteorological conditions due to different decisive factors. Identified PM2.5 sources included sulfate (32.7%), wood smoke (19.3%), gasoline (18.3%), nitrate (15.7%), diesel (9.2%), soil (3.8%), and road salt (1.0%). Compared with the 2005–2012 result, sulfate and nitrate contributions had increased, while wood smoke and diesel contributions had decreased, in which emission control measures as well as a change of sampling sites could play an important role. This systematic analysis offers reference for mitigation measures and pollution prediction. Meanwhile, further field investigation is required for conclusion validation and model improvement.
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Hilda Huang, X. H., Q. J. Bian, P. K. K. Louie, and J. Z. Yu. "Contributions of vehicular carbonaceous aerosols to PM<sub>2.5</sub> in a roadside environment in Hong Kong." Atmospheric Chemistry and Physics Discussions 14, no. 1 (January 2, 2014): 57–93. http://dx.doi.org/10.5194/acpd-14-57-2014.
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Abstract. Hourly measurements of elemental carbon (EC) and organic carbon (OC) were made at Mong Kok, a roadside air quality monitoring station in Hong Kong for a year from May 2011 to April 2012. The monthly average EC concentrations were 3.8–4.9 μgC m−3, accounting for 9.2–17.7% of the PM2.5 mass (21.5–49.7 μg m−3). The EC concentrations showed little seasonal variation and peaked twice daily in coincidence with the traffic rush hours of a day. Good correlations were found between EC and NOx concentrations, especially during the rush hours in the morning. In time periods when diesel-powered vehicles dominated the road traffic, the OC / EC ratio was approximately 0.5. The analysis by the minimum OC / EC ratio approach to determine OC / EC ratio representative of primary emissions also yields a value of 0.5, suggesting that it is a reasonable lower limit estimation of (OC / EC)vehicle in representing vehicular emissions. By applying the derived (OC / EC)vehicle ratio to the dataset, the monthly average vehicle-related OC was estimated to account for 16.6–64.0% of the measured OC throughout the year. Vehicle-related OC was also estimated using receptor modeling of a combined dataset of hourly NOx, OC, EC and select volatile organic compounds. The estimations by the two different approaches were in good agreement. When both EC and vehicle-derived organic matter (OM) (assuming an OM-to-OC ratio of 1.4) are considered, vehicular carbonaceous aerosols contributed ~ 7.3 μg m−3 to PM2.5, accounting for ~ 20% of PM2.5 mass (38.3 μg m−3) during winter when Hong Kong was largely influenced by regional transport of air pollutants and ~ 30% of PM2.5 mass (28.2 μg m−3) during summertime when local emission sources were dominant. A reduction of 3.82 μg m−3 in vehicular carbonaceous aerosols was observed during 07:00–11:00 LT (i.e. rush hours on weekdays) on Sundays and public holidays. This could mainly be attributed to less on-road public transportation (e.g. diesel-powered buses) in comparison with non-holidays. These multiple lines of evidence confirm local vehicular emissions as an important source of PM in an urban roadside environment and suggest the importance of vehicular emission control in reducing exposure to PM2.5 in busy roadside environments.
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Martin, Roy C., Adam Gerstenecker, Louis B. Nabors, Daniel C. Marson, and Kristen L. Triebel. "Impairment of medical decisional capacity in relation to Karnofsky Performance Status in adults with malignant brain tumor." Neuro-Oncology Practice 2, no. 1 (December 4, 2014): 13–19. http://dx.doi.org/10.1093/nop/npu030.
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Abstract Background We aimed to investigate the relationship between medical decisional capacity (MDC) and Karnofsky Performance Status (KPS) in adults with malignant brain tumors. Methods Participants were 71 adults with primary (n = 26) or metastatic (n = 45) brain tumors. Testing to determine KPS scores and MDC was performed as close together as possible for each patient. Participants were administered a standardized measure of medical decision-making capacity (Capacity to Consent to Treatment Instrument [CCTI]) to assess 3 treatment consent abilities (ie, appreciation, reasoning, and understanding). Capacity classifications (ie, capable, marginally capable, and incapable) were established using cut scores previously derived from healthy control CCTI performance. Results The majority of participants had KPS scores of 90–100 (n = 39), with the remainder divided between KPS scores of 70–80 (n = 26) and 50–60 (n = 6). Comparisons between persons with KPS scores of 90–100 or 70–80 revealed significant differences on the CCTI consent standards of understanding and appreciation. Participants with KPS ratings of 90–100 achieved 46% capable classifications across all CCTI standards, in contrast with 23% of participants with KPS ratings of 70–80, and 0% of participants with KPS ratings of 50–60. Conclusions A substantial portion of brain-tumor patients with KPS scores reflecting only minimal disability nonetheless demonstrated impairments on standardized measures of MDC. Clinicians working with this adult population should carefully screen for capacity to make clinical treatment decisions regardless of functional/performance status.