The Fe-modi fied sepiolite-supported Mn–Cu mixed oxide(Cux Mny/Fe-Sep) catalysts were prepared using the co-precipitation method.These materials were characterized by means of the XRD,N_2 adsorption–desorption,XPS,H...The Fe-modi fied sepiolite-supported Mn–Cu mixed oxide(Cux Mny/Fe-Sep) catalysts were prepared using the co-precipitation method.These materials were characterized by means of the XRD,N_2 adsorption–desorption,XPS,H_2-TPR,and O_2-TPD techniques,and their catalytic activities for CO and ethyl acetate oxidation were evaluated.The results show that catalytic activities of the Cux Mny/Fe-Sep samples were higher than those of the Cu1/Fe-Sep and Mn2/Fe-Sep samples,and the Mn/Cu molar ratio had a distinct in fluence on catalytic activity of the sample.Among the Cux Mny/Fe-Sep and Cu1Mn2/Sep samples,Cu1Mn2/Fe-Sep performed the best for CO and ethyl acetate oxidation,showing the highest reaction rate and the lowest T50 and T90 of 4.4×10^(-6) mmol·g-1·s-1,110,and 140 °C for CO oxidation,and 1.9×10^(-6) mmol·g-1·s-1,170,and210 °C for ethyl acetate oxidation,respectively.Moreover,the Cu1Mn2/Fe-Sep sample possessed the best lowtemperature reducibility and the lowest temperature of oxygen desorption as well as the highest surface Mn^(4+)/Mn^(3+) and Cu^(2+)/CuO atomic ratios.It is concluded that factors,such as the strong interaction between the Cu or Mn and the Fe-Sep support,good low-temperature reducibility,and good mobility of chemisorbed oxygen species,might account for the excellent catalytic activity of Cu1Mn2/Fe-Sep.展开更多
[Objectives]This study was conducted to evaluate the value of local Brassicaceae potherb resources in Shiyan City.[Methods]Seven species of local Brassicaceae edible plants resources in Shiyan City,including Cardamine...[Objectives]This study was conducted to evaluate the value of local Brassicaceae potherb resources in Shiyan City.[Methods]Seven species of local Brassicaceae edible plants resources in Shiyan City,including Cardamine hirsuta L.,Cardamine flexuosa,Cardamine impatiens L.,Capsella bursa-pastoris(Linn.),Orychophragmus violaceus(L.)O.E.Schulz,Draba nemorosa L.,Rorippa indica(L.)Hiern.,were investigated using sampling method,and their value was evaluated.[Results]①Shiyan City was rich in resources of local Brassicaceae potherbs,mostly of which grew in humid areas.②In the communities of target species,there were 20 species of plants in 19 genera of 15 families in the arbor layer,19 species of plants in 16 genera from 15 families in the shrub layer,and 58 species of plants in 51 genera from 23 families in the herbaceous layer.The tree,shrub and herb species with the highest dominance Populus simonii var.przewalskii,Robinia pseudoacacia and Chrysanthemum indicum.Local Brassicaceae potherbs in Shiyan City have high edible and medicinal value,especially Cardamine,which has strong selenium-rich ability and is worthy of vigorous development.[Conclusions]This study provides scientific basis and reference for the development and utilization of local potherbs of Brassicaceae in this area.展开更多
In order to find suspension culture conditions suitable for Premna microphylla Turea, with the leaves of experimented P. microphylla as a material, em- bryogenic callus induction, subculture, dispersion of embryogenic...In order to find suspension culture conditions suitable for Premna microphylla Turea, with the leaves of experimented P. microphylla as a material, em- bryogenic callus induction, subculture, dispersion of embryogenic callus and suspension culture were performed. The results showed that the calli induced from leaves were different. The medium most suitable for induction of loose embryogenic callus for suspension culture was MS + 0.4 mg/L 2,4-D + 0.4 mg/L NAA + 3% sucrose +0.8% agar. A better cell line could be obtained with cellulase and pectinase for dispersion of P. microphyUa callus. The medium most suitable for sus- pension culture was MS +0.4 mg/L 2,4-D +0.8 mg/L KT +3% sucrose. In this medium, the fresh weight of the suspensian-cultured cells increased by 6.46 times per 7 d. Dark culture was more suitable for cell proliferation. The average contents of pectin and protein were, respectively, 6.57% and 0.12% in the sus- pended ceils of P. microphylla, which had been cultured for 3 weeks under the optimum culture conditions.展开更多
Using 'Luotian chestnut' as the raw material, the content changes of resistant starch and main nutrients in the processed fruit were studied after taken common processing of high-temperature steaming of canned food,...Using 'Luotian chestnut' as the raw material, the content changes of resistant starch and main nutrients in the processed fruit were studied after taken common processing of high-temperature steaming of canned food, sand-mixed frying and cooking without shells, with the aim to find out the effects of different processing methods on the content changes of nutrients in chestnuts. The result showed that there were significant differences in the resistant starch contents by different processing methods. After processing, the retention degree of resistant starch was the lowest using the methods of sand-mixed frying, of 42.42%, while the highest was found in canned chestnut products, of 93.16%. Among the main nutrients, adding water and sugar would reduce content of resistant starch, while increasing the protein content would promote the retention of resistant starch retention. The changes in lipid content had no effect or not a single promoting or weakening effects on the content of resistant starch.展开更多
An evidence-based control strategy for emission reduction of VOC sources can effectively solve the regional PM2.5and O3compound pollution in China.We estimated the anthropogenic VOC emission inventory in China in 2018...An evidence-based control strategy for emission reduction of VOC sources can effectively solve the regional PM2.5and O3compound pollution in China.We estimated the anthropogenic VOC emission inventory in China in 2018 and established a source profile database containing 129 sources based on localized detection and the latest research results.Then,the distribution of the ozone formation potential(OFP)and secondary organic aerosol formation potential(SOAFP)for emission sources was analyzed.Moreover,priority control routes for VOC emission sources were proposed for different periods.Anthropogenic VOC emissions in China reached 27,211.8 Gg in 2018,and small passenger cars,industrial protective coatings,biomass burning,heavy trucks,printing,asphalt paving,oil storage and transportation,coking,and oil refining were the main contributors.Industrial protective coatings,small passenger cars,and biomass burning all contributed significantly to OFP and SOAFP.Priority in emission reduction control should be given to industrial protective coatings,small passenger cars,heavy trucks,coking,printing,asphalt paving,chemical fibers,and basic organic chemical sources over the medium and long term in China.In addition,the priority control route for VOC emission sources should be adjusted according to the variations in VOC emission characteristics and regional differences,so as to obtain the maximum environmental benefits.展开更多
Previous air pollution control strategies didn’t pay enough attention to regional collaboration and the spatial response sensitivities,resulting in limited control effects in China.This study proposed an effective PM...Previous air pollution control strategies didn’t pay enough attention to regional collaboration and the spatial response sensitivities,resulting in limited control effects in China.This study proposed an effective PM_(2.5)and O_(3) control strategy scheme with the integration of Self-Organizing Map(SOM),Genetic Algorithm(GA)and WRF-CAMx,emphasizing regional collaborative control and the strengthening of control in sensitive areas.This scheme embodies the idea of hierarchical management and spatial-temporally differentiated management,with SOM identifying the collaborative subregions,GA providing the optimized subregion-level priority of precursor emission reductions,and WRF-CAMx providing response sensitivities for grid-level priority of precursor emission reductions.With Beijing-Tianjin-Hebei and the surrounding area(BTHSA,“2+26”cities)as the case study area,the optimized strategy required that regions along Taihang Mountains strengthen the emission reductions of all precursors in PM_(2.5)-dominant seasons,and strengthen VOCs reductions but moderate NOx reductions in O_(3)-dominant season.The spatiotemporally differentiated control strategy,without additional emission reduction burdens than the 14th Five-Year Plan proposed,reduced the average annual PM_(2.5)and MDA8 O_(3) concentrations in 28 cities by 3.2%-8.2% and 3.9%-9.7% respectively in comparison with non-differential control strategies,with the most prominent optimization effects occurring in the heavily polluted seasons(6.9%-18.0%for PM_(2.5)and 3.3%-14.2% for MDA8 O_(3),respectively).This study proposed an effective scheme for the collaborative control of PM_(2.5)and O_(3) in BTHSA,and shows important methodological implications for other regions suffering from similar air quality problems.展开更多
A study was conducted on aerosol-radiation interactions over six cities in this region within the 2015–2019 period.WRF-Chem simulations on 2017 showed that based on the six-city average,the aerosol load(PM_(2.5)conce...A study was conducted on aerosol-radiation interactions over six cities in this region within the 2015–2019 period.WRF-Chem simulations on 2017 showed that based on the six-city average,the aerosol load(PM_(2.5)concentrations)of 121.9,49.6,43.3,and 66.3μg/m^(3)in January,April,July,and October,mainly lowered the level of downward shortwave radiation by 38.9,24.0,59.1,and 24.4 W/m~2and reduced the boundary layer height by 79.9,40.8,87.4,and 31.0 m,via scattering and absorbing solar radiation.The sensitivity of meteorological changes to identical aerosol loads varied in the order July>January>October and April.Then,the cooling and stabilizing effects of aerosols further led to increases in PM_(2.5),by23.0,3.4,4.6,and 7.3μg/m^(3)respectively in the four months.The sensitivity of the effect of aerosols on PM_(2.5)was greatest in January rather than in July,contrary to the effect on meteorology.Moreover,a negative linear relation was observed between daily BLH reductions and aerosol loads in fall and winter,and between PM_(2.5)increases and aerosol loads in all seasons.With the PM_(2.5)pollution improvements in this region,the aerosol radiative forcing was effectively reduced.This should result in daily BLH increases of 10–24 m in fall and winter,and the estimates in Beijing agreed well with the corresponding results based on AMDAR data.Additionally,the reduction in aerosol radiation effects brought about daily PM_(2.5)decreases of 1.6-2.8μg/m^(3),accounting for 7.0%–17.7%in PM_(2.5)improvements.展开更多
Continuous aggravated surface O_(3) over North China Plain(NCP)has attracted widely public concern.Herein,we evaluated the effects of changes in aerosols,precursor emissions,and meteorology on O_(3) in summer(June)of ...Continuous aggravated surface O_(3) over North China Plain(NCP)has attracted widely public concern.Herein,we evaluated the effects of changes in aerosols,precursor emissions,and meteorology on O_(3) in summer(June)of 2015–2019 over NCP via 8 scenarios with WRF-Chem model.The simulated mean MDA8 O_(3) in urban areas of 13 major cities in NCP increased by 17.1%∼34.8%,which matched well with the observations(10.8%∼33.1%).Meanwhile,the model could faithfully reproduce the changes in aerosol loads,precursors,and meteorological conditions.A relatively-even O_(3) increase(+1.2%∼+3.9%for 24-h O_(3) and+1.0%∼+3.8%for MDA8 O_(3))was induced by PM_(2.5) dropping,which was consistent with the geographic distribution of regional PM_(2.5) reduction.Meanwhile,the NO_(2) reduction coupled with a nearconstant VOCs led to the elevated VOCs/NOx ratios,and then caused O_(3) rising in the areas under VOCs-limited regimes.Therein,the pronounced increases occurred in Handan,Xingtai,Shijiazhuang,Tangshan,and Langfang(+10.7%∼+13.6%for 24-h O_(3) and+10.2%∼+12.2%forMDA8 O_(3));while the increases in other citieswere 5.7%∼10.5%for 24-h O_(3) and 4.9%∼9.2%for MDA8 O_(3).Besides,the meteorological fluctuations brought about the more noticeable O_(3) increases in northern parts(+12.5%∼+13.5%for 24-h O_(3) and+11.2%∼+12.4%for MDA8 O_(3))than those in southern and central parts(+3.2%∼+9.3%for 24-h O_(3) and+3.7%∼+8.8%for MDA8 O_(3)).The sum of the impacts of the three drivers reached 16.7%∼21.9%,which were comparable to the changes of the observed O_(3).Therefore,exploring reasonable emissionsreduction strategies is essential for the ozone pollution mitigation over this region.展开更多
Sepsis is a life-threatening organ dysfunction caused by the dysregulated response of the host to an infection, and treatments are limited. Recently, a novel selenium source, selenium-enriched Cardamine violifolia(SEC...Sepsis is a life-threatening organ dysfunction caused by the dysregulated response of the host to an infection, and treatments are limited. Recently, a novel selenium source, selenium-enriched Cardamine violifolia(SEC) has attracted much attention due to its anti-inflammatory and antioxidant properties, but little is known about its role in the treatment of sepsis. Here, we found that SEC alleviated LPS-induced intestinal damage, as indicated by improved intestinal morphology, and increased disaccharidase activity and tight junction protein expression. Moreover, SEC ameliorated the LPS-induced release of pro-inflammatory cytokines, as indicated by decreased IL-6 level in the plasma and jejunum. Moreover, SEC improved intestinal antioxidant functions by regulating oxidative stress indicators and selenoproteins. In vitro, TNF-α-challenged IPEC-1 cells were examined and showed that selenium-enriched peptides, which are the main functional components extracted from Cardamine violifolia(CSP), increased cell viability, decreased lactate dehydrogenase activity and improved cell barrier function. Mechanistically, SEC ameliorated LPS/TNF-α-induced perturbations in mitochondrial dynamics in the jejunum and IPEC-1 cells. Moreover, CSPmediated cell barrier function is primarily dependent on the mitochondrial fusion protein MFN2 but not MFN1. Taken together,these results indicate that SEC mitigates sepsis-induced intestinal injury, which is associated with modulating mitochondrial fusion.展开更多
A variety of methods based on air quality models,including tracer methods,the bruteforce method(BFM),decoupled direct method(DDM),high-order decoupled direct method(HDDM),response surface models(RSMs)and so on forth,h...A variety of methods based on air quality models,including tracer methods,the bruteforce method(BFM),decoupled direct method(DDM),high-order decoupled direct method(HDDM),response surface models(RSMs)and so on forth,have been widely used to study the transport of air pollutants.These methods have good applicability for the transport of air pollutants with simple formation mechanisms.However,differences in research conclusions on secondary pollutants with obvious nonlinear characteristics have been reported.For example,the tracer method is suitable for the study of simpli?ed scenarios,while HDDM and RSMs are more suitable for the study for nonlinear pollutants.Multiple observation techniques,including conventional air pollutant observation,lidar observation,air sounding balloons,vehicle-mounted and ship-borne technology,aerial surveys,and remote sensing observations,have been utilized to investigate air pollutant transport characteristics with time resolution as high as 1 sec.In addition,based on a multi-regional input-output model combined with emission inventories,the transfer of air pollutant emissions can be evaluated and applied to study the air pollutant transport characteristics.Observational technologies have advantages in temporal resolution and accuracy,while modeling technologies are more?exible in spatial resolution and research plan setting.In order to accurately quantify the transport characteristics of pollutants,it is necessary to develop a research method for interactive veri?cation of observation and simulation.Quantitative evaluation of the transport of air pollutants from different angles can provide a scienti?c basis for regional joint prevention and control.展开更多
This study represents the first quantitative evaluation of pollution transport budget within the boundary layer of typical cities in the Beijing-Tianjin-Hebei (BTH) region from the perspective of horizontal and vertic...This study represents the first quantitative evaluation of pollution transport budget within the boundary layer of typical cities in the Beijing-Tianjin-Hebei (BTH) region from the perspective of horizontal and vertical exchanges and further discusses the impact of the atmospheric boundary layer (ABL)-free troposphere (FT) exchange on concentration of fine particulate matter (PM_(2.5)) within the ABL during heavy pollution.From the perspective of the transport flux balance relationship,differences in pollution transport characteristics between the two cities is mainly reflected in the ABL-FT exchange effect.The FT mainly flowed into the ABL in BJ,while in SJZ,the outflow from the ABL to the FT was more intense.Combined with an analysis of vertical wind profile distribution,BJ was found to be more susceptible to the influence of northwest cold high prevailing in winter,while sinking of strong cold air allowed the FT flowing into the ABL influence the vertical exchange over BJ.In addition,we selected a typical pollution event for targeted analysis to understand mechanistic details of the influence of ABL-FT exchange on the pollution event.These results showed that ABL-FT interaction played an important role in PM_(2.5)concentration within the ABL during heavy pollution.Especially in the early stage of heavy pollution,FT transport contributed as much as 82.74% of PM_(2.5)within the ABL.These findings are significant for improving our understanding of pollution transport characteristics within the boundary layer and the effect of ABL-FT exchange on air quality.展开更多
This study estimates the detailed chemical profiles of China's anthropogenic volatile organic com- pounds (VOCs) emissions for the period of 2005-2020. The chemical profiles of VOCs for seven activity sectors are c...This study estimates the detailed chemical profiles of China's anthropogenic volatile organic com- pounds (VOCs) emissions for the period of 2005-2020. The chemical profiles of VOCs for seven activity sectors are calculated, based on which the Photochemical Ozone Creation Potential (POCP) of VOCs for these sectors is evaluated. At the national level, the VOCs species emitted in 2005 include alkanes, alkenes and alkynes, aromatic compounds, alcohols, ketones, aldehydes, esters, ethers and halocarbons, accounting for 26.4wt.%, 29.2wt.%, 21.3 wt.%, 4.7 wt.%, 5.4 wt.%, 1.7 wt.%, 2.1 wt.%, 0.7 wt. % and 2.2wt.% of total emissions, respectively. And during 2005-2020, their mass proportions would respec- tively grow or decrease by - 34.7%, -48.6%, 108.5%, 6.9%, -32.7%, 7.3%, 65.3%, 100.5%, and 55.4%. This change would bring about a 13% reduction of POCP for national VOCs emissions in the future. Thus, although the national VOCs emissions are expected to increase by 33% over the whole period, its ozone formation potential is estimated to rise only by 14%. Large discrepancies are found in VOCs speciation emissions among provinces. Compared to western provinces, the eastern provinces with a more developed economy would emit unsaturated hydrocarbons and benzene with lower mix ratios, and aromatic compounds except benzene, oxidized hydrocar- bons and halocarbons with higher mix ratios. Such differences lead to lower POCP of VOCs emitted in eastern provinces, and higher POCP of VOCs emitted in western provinces. However, due to the large VOCs emissions from Chinese eastern region, the ozone forma- tion potential of VOCs emission in eastern provinces would be much higher than those in western provinces by about 156%-235%.展开更多
In this study, the characteristics of fine particles before and after wet flue gas desulfurization(WFGD) in three coal-fired heating boilers in northern China were investigated by using a dilution-based emission sampl...In this study, the characteristics of fine particles before and after wet flue gas desulfurization(WFGD) in three coal-fired heating boilers in northern China were investigated by using a dilution-based emission sampling experimental system. The influences of the WFGD process on the mass and number concentrations as well as the chemical composition of fine particles were analyzed. The removal efficiency of desulfurization processes on particulate matter mass was 30.06%–56.25% for the three study units. The WFGD had a great influence on the size distributions of particle mass concentration and number concentration. A significant increase in the number and mass concentration of particles in the size range of 0.094–0.946 μm was observed. The watersoluble ion content accounted for a very large proportion of PM_(2.5) mass, and its proportion in PM_(2.5) increased from 28.39%–41.08% to 48.96%–61.21% after the WFGD process for the three units. The desulfurizing process also drastically increased the proportion of cation component(Ca^(2+) for unit A, Mg^(2+) for unit B, and Na+for unit C) and the proportion of SO_4^(2-) in PM_(2.5), and it increased the CE/AE values of PM_(2.5) from 0.82–0.98 to 0.93–1.27 for the three study units.展开更多
Beijing Capital International Airport(ZBAA) is the world's second busiest airport. In this study, the emissions of air pollutants from aircraft and other sources at ZBAA in 2015 were estimated using an improved met...Beijing Capital International Airport(ZBAA) is the world's second busiest airport. In this study, the emissions of air pollutants from aircraft and other sources at ZBAA in 2015 were estimated using an improved method, which considered the mixing layer height calculated based on aircraft meteorological data relay(AMDAR), instead of using the height(915 m)recommended by ICAO. The yearly emissions of NOx, CO, VOCs, SO2, and PM2.5 at the airport were 8.76 × 10^3, 4.43 × 10^3, 5.43 × 10^2, 4.80 × 10^2, and 1.49 × 10^2 ton/year, respectively. The spatial–temporal distribution of aircraft emissions was systematically analyzed to understand the emission characteristics of aircraft. The results indicated that NOxwas mainly emitted during the take-off and climb phases, accounting for 20.5% and 55.5% of the total emissions. CO and HC were mainly emitted during the taxi phase, accounting for 91.6%and 92.2% of the total emissions. Because the mixing layer height was high in summer, the emissions of aircraft were at the highest level throughout the year. Based on the detailed emissions inventory, four seasons simulation using WRF-CMAQ model was performed over the domain surrounding the airport. The results indicated that the contribution to PM2.5 was relatively high in winter; the average impact was about 1.15 μg/m3 within a radius of1 km around the airport. Meanwhile, the near surroundings and southwest areas of the airport are the most sensitive to PM2.5.展开更多
The objective of this paper is to propose a hybrid approach for the source apportionment of primary and secondary species of PM2.5 in the city of Tangshan. The receptor-based PMF (Positive Matrix Factorization) is i...The objective of this paper is to propose a hybrid approach for the source apportionment of primary and secondary species of PM2.5 in the city of Tangshan. The receptor-based PMF (Positive Matrix Factorization) is integrated with the emission inventory (El) to form the first hybrid method for the source apportionment of the primary species. The hybrid CAMx-PSAT-CP (Comprehensive Air Quality Model with Extensions - Particulate Source App.ortionment Technology - Chemical Profile)approach is then proposed and used for the source apportionment of the secondary species. The PM2.5 sources identified for Tangshan included the soil dust, the metallurgical industry, power plants, coal- fired boilers, vehicles, cement production, and other sources. It is indicated that the PM2.5 pollution is a regional issue. Among all the identified sources, the metallurgy industry was the biggest contribution source.to PM2.5, followed by coal-fired boilers, vehicles and soil dust. The other-source category plays a crucial role for PM2.5, particularly for the formation of secondary species and aerosols, and these other sources include non-specified sources such as agricultural activities, biomass combustion, residential emissions, etc. The source apportionment results could help the local authorities make sound policies and regulations to better protect the citizens from the local and regional PM2.5 pollution. The study also highlights the strength of utilizing the proposed hybrid approaches in the identification of PM2.5 sources. The techniques used in this study show considerable promise for further application to other regions as well as to identify other source categories of PM2.5.展开更多
SO_4^(2-) and NO_3^- are important chemical components of fine particulate matter(PM_(2.5)),especially during haze periods.This study selected two haze episodes in Beijing,China with similar meteorological conditions....SO_4^(2-) and NO_3^- are important chemical components of fine particulate matter(PM_(2.5)),especially during haze periods.This study selected two haze episodes in Beijing,China with similar meteorological conditions.A monitoring-modeling approach was developed to estimate the secondary conversion ratios of sulfur and nitrogen based on monitored and simulated concentrations.Measurements showed that in Episode 1(24th–25th October,2014),the concentrations(proportions)of SO_4^(2-) and NO_3^- reached 35.1μg/m^3(14.9%) and 55.0μg/m^3(22.9%),while they reached 14.4μg/m^3(9.3%) and 59.1μg/m^3(38.1%)in Episode 2(26th–27th October,2017).A modeling system was applied to apportion Beijing's SO_4^(2-) and NO_3^- in primary and secondary SO_4^(2-)/NO_3^- emitted from local and regional sources.Thus,secondary conversion contributions considering the local and regional level were defined.The former primarily focused on Beijing atmospheric oxidation ability and the latter mainly considered the existence form of Beijing SO_4^(2-)/NO_3^- under the regional transport impacts.Finally,secondary oxidation ratios were estimated through combining secondary conversion contribution coefficients for simulated and monitored concentrations.At regional level,sulfur oxidation ratios in polluted(clean)days during two sampling periods were0.57–0.72(0.07–0.52)and 0.74–0.80(0.08–0.61),nitrogen oxidation ratios were 0.20–0.29(0.05–0.15)and 0.34–0.38(0.02–0.29),indicating that atmospheric oxidation was enhanced when considering regional transport through 2014–2017.At the local level,sulfur oxidation ratios were 0.66–0.71(0.04–0.48)in haze(clean)days,while nitrogen oxidation ratios were0.16–0.29(0.02–0.16).The atmospheric oxidation ability markedly increased in PM_(2.5)pollution days,but changed only slightly between the two periods.展开更多
A field measurement campaign for ozone and ozone precursors (VOCs and NOx) was conducted in summer 2011 around a petroleum refinery in the Beijing rural region. Three observation sites were arranged, one at southwes...A field measurement campaign for ozone and ozone precursors (VOCs and NOx) was conducted in summer 2011 around a petroleum refinery in the Beijing rural region. Three observation sites were arranged, one at southwest of the refinery as the background, and two at northeast of the refinery as the downwind receptors. Monitoring data revealed the presence of serious surface 03 pollution with the characteristics of high average daily mean and maximum concentrations (64.0 and 145.4 ppbV in no-rain days, respectively) and multi-peak diurnal variation. For NOx, the average hourly concentrations of NO2 and NO were in the range of 20.546.1 and 1.8-6.4 ppbV, respectively. For VOC measurement, a total of 51 compounds were detected. Normally, TVOCs at the background site was only dozens of ppbC, while TVOCs at the downwind sites reached several hundreds of ppbC. By subtracting the VOC concentrations at background, chemical profiles of VOC emission from the refinery were obtained, mainly including alkanes (60.0% ± 4.3%), alkenes (21.1% ± 5.5%) and aromatics (18.9% ±3.9%). Moreover, some differences in chemical profiles for the same measurement hours were observed between the downwind sites; the volume ratios of alkanes with low reactivity and those of alkenes with high reactivity respectively showed an increasing trend and a decreasing trend. Finally, based on temporal and spatial variations of VOC mixing ratios, their photochemical degradations and dispersion degradations were estimated to be 0.15-0.27 and 0.42-0.62, respectively, by the photochemical age calculation method, indicating stronger photochemical reactions around the refinery.展开更多
In this study, an analysis framework based on the regular monitoring data was proposed for investigating the annual/inter-annual air quality variation and the contributions from different factors(i.e., seasons, pollut...In this study, an analysis framework based on the regular monitoring data was proposed for investigating the annual/inter-annual air quality variation and the contributions from different factors(i.e., seasons, pollution periods and airflow directions), through a case study in Beijing from 2013 to 2016. The results showed that the annual mean concentrations(MC) of PM_(2.5), SO_2, NO_2 and CO had decreased with annual mean ratios of 7.5%, 28.6%, 4.6%and 15.5% from 2013 to 2016, respectively. Among seasons, the MC in winter contributed the largest fractions(25.8%~46.4%) to the annual MC, and the change of MC in summer contributed most to the inter-annual MC variation(IMCV) of PM_(2.5) and NO2. For different pollution periods, gradually increase of frequency of S-1(PM_(2.5), 0~ 75 μg/m^3) made S-1 become the largest contributor(28.8%) to the MC of PM_(2.5) in 2016, it had a negative contribution(-13.1%) to the IMCV of PM_(2.5); obvious decreases of frequencies of heavily polluted and severely polluted dominated(44.7% and 39.5%) the IMCV of PM_(2.5). For different airflow directions, the MC of pollutants under the south airflow had the most significant decrease(22.5%~62.5%), and those decrease contributed most to the IMCV of PM_(2.5)(143.3%),SO2(72.0%), NO_2(55.5%) and CO(190.3%); the west airflow had negative influences to the IMCV of PM_(2.5), NO_2 and CO. The framework is helpful for further analysis and utilization of the large amounts of monitoring data; and the analysis results can provide scientific supports for the formulation or adjustment of further air pollution mitigation policy.展开更多
基金Supported by the National Natural Science Foundation of China(21277008,20777005)the Natural Science Foundation of Beijing(8082008)
文摘The Fe-modi fied sepiolite-supported Mn–Cu mixed oxide(Cux Mny/Fe-Sep) catalysts were prepared using the co-precipitation method.These materials were characterized by means of the XRD,N_2 adsorption–desorption,XPS,H_2-TPR,and O_2-TPD techniques,and their catalytic activities for CO and ethyl acetate oxidation were evaluated.The results show that catalytic activities of the Cux Mny/Fe-Sep samples were higher than those of the Cu1/Fe-Sep and Mn2/Fe-Sep samples,and the Mn/Cu molar ratio had a distinct in fluence on catalytic activity of the sample.Among the Cux Mny/Fe-Sep and Cu1Mn2/Sep samples,Cu1Mn2/Fe-Sep performed the best for CO and ethyl acetate oxidation,showing the highest reaction rate and the lowest T50 and T90 of 4.4×10^(-6) mmol·g-1·s-1,110,and 140 °C for CO oxidation,and 1.9×10^(-6) mmol·g-1·s-1,170,and210 °C for ethyl acetate oxidation,respectively.Moreover,the Cu1Mn2/Fe-Sep sample possessed the best lowtemperature reducibility and the lowest temperature of oxygen desorption as well as the highest surface Mn^(4+)/Mn^(3+) and Cu^(2+)/CuO atomic ratios.It is concluded that factors,such as the strong interaction between the Cu or Mn and the Fe-Sep support,good low-temperature reducibility,and good mobility of chemisorbed oxygen species,might account for the excellent catalytic activity of Cu1Mn2/Fe-Sep.
基金Hubei Provincial Technological Innovation Special Major Project(2019ABA113)Wuhan Polytechnic University-Deyuan Health Industry Group Academician Expert Workstation Horizontal Project(whpu-2019-cg-138,whpu-2018-cg-041,whpu-2018-cg-140).
文摘[Objectives]This study was conducted to evaluate the value of local Brassicaceae potherb resources in Shiyan City.[Methods]Seven species of local Brassicaceae edible plants resources in Shiyan City,including Cardamine hirsuta L.,Cardamine flexuosa,Cardamine impatiens L.,Capsella bursa-pastoris(Linn.),Orychophragmus violaceus(L.)O.E.Schulz,Draba nemorosa L.,Rorippa indica(L.)Hiern.,were investigated using sampling method,and their value was evaluated.[Results]①Shiyan City was rich in resources of local Brassicaceae potherbs,mostly of which grew in humid areas.②In the communities of target species,there were 20 species of plants in 19 genera of 15 families in the arbor layer,19 species of plants in 16 genera from 15 families in the shrub layer,and 58 species of plants in 51 genera from 23 families in the herbaceous layer.The tree,shrub and herb species with the highest dominance Populus simonii var.przewalskii,Robinia pseudoacacia and Chrysanthemum indicum.Local Brassicaceae potherbs in Shiyan City have high edible and medicinal value,especially Cardamine,which has strong selenium-rich ability and is worthy of vigorous development.[Conclusions]This study provides scientific basis and reference for the development and utilization of local potherbs of Brassicaceae in this area.
基金Supported by Nature Science Foundation of Hubei Province(2008CDZ085)
文摘In order to find suspension culture conditions suitable for Premna microphylla Turea, with the leaves of experimented P. microphylla as a material, em- bryogenic callus induction, subculture, dispersion of embryogenic callus and suspension culture were performed. The results showed that the calli induced from leaves were different. The medium most suitable for induction of loose embryogenic callus for suspension culture was MS + 0.4 mg/L 2,4-D + 0.4 mg/L NAA + 3% sucrose +0.8% agar. A better cell line could be obtained with cellulase and pectinase for dispersion of P. microphyUa callus. The medium most suitable for sus- pension culture was MS +0.4 mg/L 2,4-D +0.8 mg/L KT +3% sucrose. In this medium, the fresh weight of the suspensian-cultured cells increased by 6.46 times per 7 d. Dark culture was more suitable for cell proliferation. The average contents of pectin and protein were, respectively, 6.57% and 0.12% in the sus- pended ceils of P. microphylla, which had been cultured for 3 weeks under the optimum culture conditions.
基金Supported by the Project for the Scientific and Technological Innovation Team of the Outstanding Middle-aged and Young of Hubei Provincial Institution of Higher Learning(T201619)the Project for the Scientific and Technological Innovation Team of Huanggang Normal University(201613303)
文摘Using 'Luotian chestnut' as the raw material, the content changes of resistant starch and main nutrients in the processed fruit were studied after taken common processing of high-temperature steaming of canned food, sand-mixed frying and cooking without shells, with the aim to find out the effects of different processing methods on the content changes of nutrients in chestnuts. The result showed that there were significant differences in the resistant starch contents by different processing methods. After processing, the retention degree of resistant starch was the lowest using the methods of sand-mixed frying, of 42.42%, while the highest was found in canned chestnut products, of 93.16%. Among the main nutrients, adding water and sugar would reduce content of resistant starch, while increasing the protein content would promote the retention of resistant starch retention. The changes in lipid content had no effect or not a single promoting or weakening effects on the content of resistant starch.
基金financially supported by the National Natural Science Foundation of China (No.51638001)National Joint Center for Air Pollution Prevention and Control (No.DQGG202010)。
文摘An evidence-based control strategy for emission reduction of VOC sources can effectively solve the regional PM2.5and O3compound pollution in China.We estimated the anthropogenic VOC emission inventory in China in 2018 and established a source profile database containing 129 sources based on localized detection and the latest research results.Then,the distribution of the ozone formation potential(OFP)and secondary organic aerosol formation potential(SOAFP)for emission sources was analyzed.Moreover,priority control routes for VOC emission sources were proposed for different periods.Anthropogenic VOC emissions in China reached 27,211.8 Gg in 2018,and small passenger cars,industrial protective coatings,biomass burning,heavy trucks,printing,asphalt paving,oil storage and transportation,coking,and oil refining were the main contributors.Industrial protective coatings,small passenger cars,and biomass burning all contributed significantly to OFP and SOAFP.Priority in emission reduction control should be given to industrial protective coatings,small passenger cars,heavy trucks,coking,printing,asphalt paving,chemical fibers,and basic organic chemical sources over the medium and long term in China.In addition,the priority control route for VOC emission sources should be adjusted according to the variations in VOC emission characteristics and regional differences,so as to obtain the maximum environmental benefits.
基金supported by the National Natural Science Foundation of China(Nos.51638001,52000005)。
文摘Previous air pollution control strategies didn’t pay enough attention to regional collaboration and the spatial response sensitivities,resulting in limited control effects in China.This study proposed an effective PM_(2.5)and O_(3) control strategy scheme with the integration of Self-Organizing Map(SOM),Genetic Algorithm(GA)and WRF-CAMx,emphasizing regional collaborative control and the strengthening of control in sensitive areas.This scheme embodies the idea of hierarchical management and spatial-temporally differentiated management,with SOM identifying the collaborative subregions,GA providing the optimized subregion-level priority of precursor emission reductions,and WRF-CAMx providing response sensitivities for grid-level priority of precursor emission reductions.With Beijing-Tianjin-Hebei and the surrounding area(BTHSA,“2+26”cities)as the case study area,the optimized strategy required that regions along Taihang Mountains strengthen the emission reductions of all precursors in PM_(2.5)-dominant seasons,and strengthen VOCs reductions but moderate NOx reductions in O_(3)-dominant season.The spatiotemporally differentiated control strategy,without additional emission reduction burdens than the 14th Five-Year Plan proposed,reduced the average annual PM_(2.5)and MDA8 O_(3) concentrations in 28 cities by 3.2%-8.2% and 3.9%-9.7% respectively in comparison with non-differential control strategies,with the most prominent optimization effects occurring in the heavily polluted seasons(6.9%-18.0%for PM_(2.5)and 3.3%-14.2% for MDA8 O_(3),respectively).This study proposed an effective scheme for the collaborative control of PM_(2.5)and O_(3) in BTHSA,and shows important methodological implications for other regions suffering from similar air quality problems.
基金funded by the National Natural Science Foundation of China (Nos.51978010 and 52022005)。
文摘A study was conducted on aerosol-radiation interactions over six cities in this region within the 2015–2019 period.WRF-Chem simulations on 2017 showed that based on the six-city average,the aerosol load(PM_(2.5)concentrations)of 121.9,49.6,43.3,and 66.3μg/m^(3)in January,April,July,and October,mainly lowered the level of downward shortwave radiation by 38.9,24.0,59.1,and 24.4 W/m~2and reduced the boundary layer height by 79.9,40.8,87.4,and 31.0 m,via scattering and absorbing solar radiation.The sensitivity of meteorological changes to identical aerosol loads varied in the order July>January>October and April.Then,the cooling and stabilizing effects of aerosols further led to increases in PM_(2.5),by23.0,3.4,4.6,and 7.3μg/m^(3)respectively in the four months.The sensitivity of the effect of aerosols on PM_(2.5)was greatest in January rather than in July,contrary to the effect on meteorology.Moreover,a negative linear relation was observed between daily BLH reductions and aerosol loads in fall and winter,and between PM_(2.5)increases and aerosol loads in all seasons.With the PM_(2.5)pollution improvements in this region,the aerosol radiative forcing was effectively reduced.This should result in daily BLH increases of 10–24 m in fall and winter,and the estimates in Beijing agreed well with the corresponding results based on AMDAR data.Additionally,the reduction in aerosol radiation effects brought about daily PM_(2.5)decreases of 1.6-2.8μg/m^(3),accounting for 7.0%–17.7%in PM_(2.5)improvements.
基金supported by the National Natural Science Foundation of China(Nos.51978010,52022005).
文摘Continuous aggravated surface O_(3) over North China Plain(NCP)has attracted widely public concern.Herein,we evaluated the effects of changes in aerosols,precursor emissions,and meteorology on O_(3) in summer(June)of 2015–2019 over NCP via 8 scenarios with WRF-Chem model.The simulated mean MDA8 O_(3) in urban areas of 13 major cities in NCP increased by 17.1%∼34.8%,which matched well with the observations(10.8%∼33.1%).Meanwhile,the model could faithfully reproduce the changes in aerosol loads,precursors,and meteorological conditions.A relatively-even O_(3) increase(+1.2%∼+3.9%for 24-h O_(3) and+1.0%∼+3.8%for MDA8 O_(3))was induced by PM_(2.5) dropping,which was consistent with the geographic distribution of regional PM_(2.5) reduction.Meanwhile,the NO_(2) reduction coupled with a nearconstant VOCs led to the elevated VOCs/NOx ratios,and then caused O_(3) rising in the areas under VOCs-limited regimes.Therein,the pronounced increases occurred in Handan,Xingtai,Shijiazhuang,Tangshan,and Langfang(+10.7%∼+13.6%for 24-h O_(3) and+10.2%∼+12.2%forMDA8 O_(3));while the increases in other citieswere 5.7%∼10.5%for 24-h O_(3) and 4.9%∼9.2%for MDA8 O_(3).Besides,the meteorological fluctuations brought about the more noticeable O_(3) increases in northern parts(+12.5%∼+13.5%for 24-h O_(3) and+11.2%∼+12.4%for MDA8 O_(3))than those in southern and central parts(+3.2%∼+9.3%for 24-h O_(3) and+3.7%∼+8.8%for MDA8 O_(3)).The sum of the impacts of the three drivers reached 16.7%∼21.9%,which were comparable to the changes of the observed O_(3).Therefore,exploring reasonable emissionsreduction strategies is essential for the ozone pollution mitigation over this region.
基金supported by the National Natural Science Foundation of China (U22A20517, 32272906 and 32102566)the Project of Wuhan Science and Technology Bureau (2022020801010391)。
文摘Sepsis is a life-threatening organ dysfunction caused by the dysregulated response of the host to an infection, and treatments are limited. Recently, a novel selenium source, selenium-enriched Cardamine violifolia(SEC) has attracted much attention due to its anti-inflammatory and antioxidant properties, but little is known about its role in the treatment of sepsis. Here, we found that SEC alleviated LPS-induced intestinal damage, as indicated by improved intestinal morphology, and increased disaccharidase activity and tight junction protein expression. Moreover, SEC ameliorated the LPS-induced release of pro-inflammatory cytokines, as indicated by decreased IL-6 level in the plasma and jejunum. Moreover, SEC improved intestinal antioxidant functions by regulating oxidative stress indicators and selenoproteins. In vitro, TNF-α-challenged IPEC-1 cells were examined and showed that selenium-enriched peptides, which are the main functional components extracted from Cardamine violifolia(CSP), increased cell viability, decreased lactate dehydrogenase activity and improved cell barrier function. Mechanistically, SEC ameliorated LPS/TNF-α-induced perturbations in mitochondrial dynamics in the jejunum and IPEC-1 cells. Moreover, CSPmediated cell barrier function is primarily dependent on the mitochondrial fusion protein MFN2 but not MFN1. Taken together,these results indicate that SEC mitigates sepsis-induced intestinal injury, which is associated with modulating mitochondrial fusion.
基金supported by the National Key R&D Program of China(No.2018YFC0213200)。
文摘A variety of methods based on air quality models,including tracer methods,the bruteforce method(BFM),decoupled direct method(DDM),high-order decoupled direct method(HDDM),response surface models(RSMs)and so on forth,have been widely used to study the transport of air pollutants.These methods have good applicability for the transport of air pollutants with simple formation mechanisms.However,differences in research conclusions on secondary pollutants with obvious nonlinear characteristics have been reported.For example,the tracer method is suitable for the study of simpli?ed scenarios,while HDDM and RSMs are more suitable for the study for nonlinear pollutants.Multiple observation techniques,including conventional air pollutant observation,lidar observation,air sounding balloons,vehicle-mounted and ship-borne technology,aerial surveys,and remote sensing observations,have been utilized to investigate air pollutant transport characteristics with time resolution as high as 1 sec.In addition,based on a multi-regional input-output model combined with emission inventories,the transfer of air pollutant emissions can be evaluated and applied to study the air pollutant transport characteristics.Observational technologies have advantages in temporal resolution and accuracy,while modeling technologies are more?exible in spatial resolution and research plan setting.In order to accurately quantify the transport characteristics of pollutants,it is necessary to develop a research method for interactive veri?cation of observation and simulation.Quantitative evaluation of the transport of air pollutants from different angles can provide a scienti?c basis for regional joint prevention and control.
基金supported by the National Key Research and Development Program of China (No.2018YFC0213206)the National Natural Science Foundation of China (Nos. 52000005, 51638001)。
文摘This study represents the first quantitative evaluation of pollution transport budget within the boundary layer of typical cities in the Beijing-Tianjin-Hebei (BTH) region from the perspective of horizontal and vertical exchanges and further discusses the impact of the atmospheric boundary layer (ABL)-free troposphere (FT) exchange on concentration of fine particulate matter (PM_(2.5)) within the ABL during heavy pollution.From the perspective of the transport flux balance relationship,differences in pollution transport characteristics between the two cities is mainly reflected in the ABL-FT exchange effect.The FT mainly flowed into the ABL in BJ,while in SJZ,the outflow from the ABL to the FT was more intense.Combined with an analysis of vertical wind profile distribution,BJ was found to be more susceptible to the influence of northwest cold high prevailing in winter,while sinking of strong cold air allowed the FT flowing into the ABL influence the vertical exchange over BJ.In addition,we selected a typical pollution event for targeted analysis to understand mechanistic details of the influence of ABL-FT exchange on the pollution event.These results showed that ABL-FT interaction played an important role in PM_(2.5)concentration within the ABL during heavy pollution.Especially in the early stage of heavy pollution,FT transport contributed as much as 82.74% of PM_(2.5)within the ABL.These findings are significant for improving our understanding of pollution transport characteristics within the boundary layer and the effect of ABL-FT exchange on air quality.
文摘This study estimates the detailed chemical profiles of China's anthropogenic volatile organic com- pounds (VOCs) emissions for the period of 2005-2020. The chemical profiles of VOCs for seven activity sectors are calculated, based on which the Photochemical Ozone Creation Potential (POCP) of VOCs for these sectors is evaluated. At the national level, the VOCs species emitted in 2005 include alkanes, alkenes and alkynes, aromatic compounds, alcohols, ketones, aldehydes, esters, ethers and halocarbons, accounting for 26.4wt.%, 29.2wt.%, 21.3 wt.%, 4.7 wt.%, 5.4 wt.%, 1.7 wt.%, 2.1 wt.%, 0.7 wt. % and 2.2wt.% of total emissions, respectively. And during 2005-2020, their mass proportions would respec- tively grow or decrease by - 34.7%, -48.6%, 108.5%, 6.9%, -32.7%, 7.3%, 65.3%, 100.5%, and 55.4%. This change would bring about a 13% reduction of POCP for national VOCs emissions in the future. Thus, although the national VOCs emissions are expected to increase by 33% over the whole period, its ozone formation potential is estimated to rise only by 14%. Large discrepancies are found in VOCs speciation emissions among provinces. Compared to western provinces, the eastern provinces with a more developed economy would emit unsaturated hydrocarbons and benzene with lower mix ratios, and aromatic compounds except benzene, oxidized hydrocar- bons and halocarbons with higher mix ratios. Such differences lead to lower POCP of VOCs emitted in eastern provinces, and higher POCP of VOCs emitted in western provinces. However, due to the large VOCs emissions from Chinese eastern region, the ozone forma- tion potential of VOCs emission in eastern provinces would be much higher than those in western provinces by about 156%-235%.
基金supported by the National Key R&D Program of China(No.2017YFC0209905)the National Natural Science Foundation of China(Nos.91544232&51638001)+2 种基金the National Key Technology Research and Development Program of the Ministry of Science and Technology of China(Nos.2013BAC17B01,2014BAC23B00)the Ministry of Environmental Protection Special Funds for Scientific Research on Public Causes(No.201409006)the fund support from Beijing Municipal Commission of Science and Technology(Nos.D161100004416001,Z161100004516013)
文摘In this study, the characteristics of fine particles before and after wet flue gas desulfurization(WFGD) in three coal-fired heating boilers in northern China were investigated by using a dilution-based emission sampling experimental system. The influences of the WFGD process on the mass and number concentrations as well as the chemical composition of fine particles were analyzed. The removal efficiency of desulfurization processes on particulate matter mass was 30.06%–56.25% for the three study units. The WFGD had a great influence on the size distributions of particle mass concentration and number concentration. A significant increase in the number and mass concentration of particles in the size range of 0.094–0.946 μm was observed. The watersoluble ion content accounted for a very large proportion of PM_(2.5) mass, and its proportion in PM_(2.5) increased from 28.39%–41.08% to 48.96%–61.21% after the WFGD process for the three units. The desulfurizing process also drastically increased the proportion of cation component(Ca^(2+) for unit A, Mg^(2+) for unit B, and Na+for unit C) and the proportion of SO_4^(2-) in PM_(2.5), and it increased the CE/AE values of PM_(2.5) from 0.82–0.98 to 0.93–1.27 for the three study units.
基金supported by the Ministry of Science and Technology of China(2016YFC0202705)the National Natural Science Foundation of China(Nos.91544232,51638001)the fund support from Beijing Municipal Commission of Science and Technology(Nos.Z161100004516013,Z171100002217002)
文摘Beijing Capital International Airport(ZBAA) is the world's second busiest airport. In this study, the emissions of air pollutants from aircraft and other sources at ZBAA in 2015 were estimated using an improved method, which considered the mixing layer height calculated based on aircraft meteorological data relay(AMDAR), instead of using the height(915 m)recommended by ICAO. The yearly emissions of NOx, CO, VOCs, SO2, and PM2.5 at the airport were 8.76 × 10^3, 4.43 × 10^3, 5.43 × 10^2, 4.80 × 10^2, and 1.49 × 10^2 ton/year, respectively. The spatial–temporal distribution of aircraft emissions was systematically analyzed to understand the emission characteristics of aircraft. The results indicated that NOxwas mainly emitted during the take-off and climb phases, accounting for 20.5% and 55.5% of the total emissions. CO and HC were mainly emitted during the taxi phase, accounting for 91.6%and 92.2% of the total emissions. Because the mixing layer height was high in summer, the emissions of aircraft were at the highest level throughout the year. Based on the detailed emissions inventory, four seasons simulation using WRF-CMAQ model was performed over the domain surrounding the airport. The results indicated that the contribution to PM2.5 was relatively high in winter; the average impact was about 1.15 μg/m3 within a radius of1 km around the airport. Meanwhile, the near surroundings and southwest areas of the airport are the most sensitive to PM2.5.
文摘The objective of this paper is to propose a hybrid approach for the source apportionment of primary and secondary species of PM2.5 in the city of Tangshan. The receptor-based PMF (Positive Matrix Factorization) is integrated with the emission inventory (El) to form the first hybrid method for the source apportionment of the primary species. The hybrid CAMx-PSAT-CP (Comprehensive Air Quality Model with Extensions - Particulate Source App.ortionment Technology - Chemical Profile)approach is then proposed and used for the source apportionment of the secondary species. The PM2.5 sources identified for Tangshan included the soil dust, the metallurgical industry, power plants, coal- fired boilers, vehicles, cement production, and other sources. It is indicated that the PM2.5 pollution is a regional issue. Among all the identified sources, the metallurgy industry was the biggest contribution source.to PM2.5, followed by coal-fired boilers, vehicles and soil dust. The other-source category plays a crucial role for PM2.5, particularly for the formation of secondary species and aerosols, and these other sources include non-specified sources such as agricultural activities, biomass combustion, residential emissions, etc. The source apportionment results could help the local authorities make sound policies and regulations to better protect the citizens from the local and regional PM2.5 pollution. The study also highlights the strength of utilizing the proposed hybrid approaches in the identification of PM2.5 sources. The techniques used in this study show considerable promise for further application to other regions as well as to identify other source categories of PM2.5.
基金supported by the National Key R&D Program of China (No. 2016YFC0202705)the National Natural Science Foundation of China (Nos. 51638001 and 51478017)the funding support from Beijing Municipal Commission of Science and Technology (Nos. Z161100004516013 and Z171100002217002)
文摘SO_4^(2-) and NO_3^- are important chemical components of fine particulate matter(PM_(2.5)),especially during haze periods.This study selected two haze episodes in Beijing,China with similar meteorological conditions.A monitoring-modeling approach was developed to estimate the secondary conversion ratios of sulfur and nitrogen based on monitored and simulated concentrations.Measurements showed that in Episode 1(24th–25th October,2014),the concentrations(proportions)of SO_4^(2-) and NO_3^- reached 35.1μg/m^3(14.9%) and 55.0μg/m^3(22.9%),while they reached 14.4μg/m^3(9.3%) and 59.1μg/m^3(38.1%)in Episode 2(26th–27th October,2017).A modeling system was applied to apportion Beijing's SO_4^(2-) and NO_3^- in primary and secondary SO_4^(2-)/NO_3^- emitted from local and regional sources.Thus,secondary conversion contributions considering the local and regional level were defined.The former primarily focused on Beijing atmospheric oxidation ability and the latter mainly considered the existence form of Beijing SO_4^(2-)/NO_3^- under the regional transport impacts.Finally,secondary oxidation ratios were estimated through combining secondary conversion contribution coefficients for simulated and monitored concentrations.At regional level,sulfur oxidation ratios in polluted(clean)days during two sampling periods were0.57–0.72(0.07–0.52)and 0.74–0.80(0.08–0.61),nitrogen oxidation ratios were 0.20–0.29(0.05–0.15)and 0.34–0.38(0.02–0.29),indicating that atmospheric oxidation was enhanced when considering regional transport through 2014–2017.At the local level,sulfur oxidation ratios were 0.66–0.71(0.04–0.48)in haze(clean)days,while nitrogen oxidation ratios were0.16–0.29(0.02–0.16).The atmospheric oxidation ability markedly increased in PM_(2.5)pollution days,but changed only slightly between the two periods.
基金supported by the National Natural Science Foundation of China (No. 51108006)Ph.D. Programs Foundation of the Ministry of Education of China (No. 20111103120008)the State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex
文摘A field measurement campaign for ozone and ozone precursors (VOCs and NOx) was conducted in summer 2011 around a petroleum refinery in the Beijing rural region. Three observation sites were arranged, one at southwest of the refinery as the background, and two at northeast of the refinery as the downwind receptors. Monitoring data revealed the presence of serious surface 03 pollution with the characteristics of high average daily mean and maximum concentrations (64.0 and 145.4 ppbV in no-rain days, respectively) and multi-peak diurnal variation. For NOx, the average hourly concentrations of NO2 and NO were in the range of 20.546.1 and 1.8-6.4 ppbV, respectively. For VOC measurement, a total of 51 compounds were detected. Normally, TVOCs at the background site was only dozens of ppbC, while TVOCs at the downwind sites reached several hundreds of ppbC. By subtracting the VOC concentrations at background, chemical profiles of VOC emission from the refinery were obtained, mainly including alkanes (60.0% ± 4.3%), alkenes (21.1% ± 5.5%) and aromatics (18.9% ±3.9%). Moreover, some differences in chemical profiles for the same measurement hours were observed between the downwind sites; the volume ratios of alkanes with low reactivity and those of alkenes with high reactivity respectively showed an increasing trend and a decreasing trend. Finally, based on temporal and spatial variations of VOC mixing ratios, their photochemical degradations and dispersion degradations were estimated to be 0.15-0.27 and 0.42-0.62, respectively, by the photochemical age calculation method, indicating stronger photochemical reactions around the refinery.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 21277008 and 20777005) and Natural Science Foundation of Beijing (Grant No. 8082008).
基金financially supported by the National Key R&D Program of China(2017YFC 0209905)the Natural Sciences Foundation of China(No.51878012,51638001)+1 种基金the project supported by Beijing Municipal Education Commission of Science and Technology(No.KM201610005019)the New Talent Program of Beijing University of Technology(No.2017-RX(1)-10)
文摘In this study, an analysis framework based on the regular monitoring data was proposed for investigating the annual/inter-annual air quality variation and the contributions from different factors(i.e., seasons, pollution periods and airflow directions), through a case study in Beijing from 2013 to 2016. The results showed that the annual mean concentrations(MC) of PM_(2.5), SO_2, NO_2 and CO had decreased with annual mean ratios of 7.5%, 28.6%, 4.6%and 15.5% from 2013 to 2016, respectively. Among seasons, the MC in winter contributed the largest fractions(25.8%~46.4%) to the annual MC, and the change of MC in summer contributed most to the inter-annual MC variation(IMCV) of PM_(2.5) and NO2. For different pollution periods, gradually increase of frequency of S-1(PM_(2.5), 0~ 75 μg/m^3) made S-1 become the largest contributor(28.8%) to the MC of PM_(2.5) in 2016, it had a negative contribution(-13.1%) to the IMCV of PM_(2.5); obvious decreases of frequencies of heavily polluted and severely polluted dominated(44.7% and 39.5%) the IMCV of PM_(2.5). For different airflow directions, the MC of pollutants under the south airflow had the most significant decrease(22.5%~62.5%), and those decrease contributed most to the IMCV of PM_(2.5)(143.3%),SO2(72.0%), NO_2(55.5%) and CO(190.3%); the west airflow had negative influences to the IMCV of PM_(2.5), NO_2 and CO. The framework is helpful for further analysis and utilization of the large amounts of monitoring data; and the analysis results can provide scientific supports for the formulation or adjustment of further air pollution mitigation policy.