Ultraviolet（UV） radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. O...Ultraviolet（UV） radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization＇s measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes.展开更多
Beijing is one of the most polluted cities in the world.In this study,the long-term and continuous measurements of volatile organic compounds （VOCs） in the urban area of Beijing,specifically at Beijing 325 m Meteoro...Beijing is one of the most polluted cities in the world.In this study,the long-term and continuous measurements of volatile organic compounds （VOCs） in the urban area of Beijing,specifically at Beijing 325 m Meteorological Tower,were conducted from 2000 to 2007.The annual record of VOC trends exhibited in two different phases was separated in 2003.Records show that VOC concentrations increased from 2000 to 2003 due to the abrupt increase in vehicle number.Contrarily,since 2003,there had been a decrease in VOCs concentrations as the policy on gasoline and air pollution was implemented.Toluene,benzene,and i-pentane are the chemicals that abound in and are directly related to vehicle activity,such as in vehicle exhaust and gasoline evaporation.Furthermore,records indicate that there had been seasonal variation in VOCs levels in that VOCs level in summer is higher than that in winter.As such,temperature is considered to significantly contribute to VOCs in Beijing.Records also show that VOCs level was high in the morning and during rush hours in the evening.In contrast,VOCs level was low during midday due to photochemical destruction with OH radical and dilution effect.In this study,a particular benzene to toluene ratio range （0.4–1.0） was used as the indicator of air propelled by vehicular exhaust.We also applied the correlation coefficients between BTEX and i-pentane to evaluate evaporation influence to ambient BTEX in the Beijing urban area.展开更多
In this study, we performed a highly time-resolved chemical characterization of nonrefractory submicron particles（NR-PM_1） in Beijing by using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer（HR...In this study, we performed a highly time-resolved chemical characterization of nonrefractory submicron particles（NR-PM_1） in Beijing by using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer（HR-ToF-AMS）. The results showed the average NR-PM_1 mass concentration to be 56.4 ± 58.0 μg/m^3, with a peak at 307.4 μg/m^3. Due to the high frequency of biomass burning in autumn, submicron particles significantly increased in organic content, which accounted for 51% of NR-PM_1 on average. Secondary inorganic aerosols（sulfate ＋ nitrate ＋ ammonium） accounted for 46% of NR-PM_1, of which sulfate,nitrate, and ammonium contributed 15%, 20%, and 11%, respectively. To determine the intrinsic relationships between the organic and inorganic species, we used the positive matrix factorization（PMF） model to merge the high-resolution mass spectra of the organic species and NO＋and NO_2~＋ions. The PMF analysis separated the mixed organic and nitrate（NO＋and NO_2~＋） spectra into four organic factors, including hydrocarbon-like organic aerosol（HOA）, oxygenated organic aerosol（OOA）, cooking organic aerosol（COA）, and biomass burning organic aerosol（BBOA）, as well as one nitrate inorganic aerosol（NIA） factor. COA（33%） and OOA（30%） contributed the most to the total organic aerosol（OA） mass, followed by BBOA（20%） and HOA（17%）. We successfully quantified the mass concentrations of the organic and inorganic nitrates by the NO＋and NO2＋ions signal in the organic and NIA factors. The organic nitrate mass varied from 0.01-6.8 μg/m^3, with an average of 1.0 ±1.1 μg/m^3, and organic nitrate components accounted for 10% of the total nitrate mass in this observation.展开更多
Accurate determination of the atmospheric particulate matter mass concentration and chemical composition is helpful in exploring the causes and sources of atmospheric enthalpy pollution and in evaluating the rationali...Accurate determination of the atmospheric particulate matter mass concentration and chemical composition is helpful in exploring the causes and sources of atmospheric enthalpy pollution and in evaluating the rationality of environmental air quality control strategies.Based on the sampling and chemical composition data of PM2.5 in different key regions of China in the CARE-China observation network,this research analyzes the environmental air quality data released by the China National Environmental Monitoring Centre during the studied period to determine the changes in the particulate matter mass concentration in key regions and the evolution of the corresponding chemical compositions during the implementation of the Action Plan for Prevention and Control of Air Pollution from 2013-2017.The results show the following.(1)The particulate matter mass concentration in China showed a significant downward trend;however,the PM2.5 annual mass concentration in 64%of cities exceeds the New Chinese Ambient Air Quality Standard(CAAQS)GradeⅡ(GB3095-2012).The region to the east of the Taihang Mountains,the Fenhe and Weihe River Plain and the Urumqi-Changji regions in Xinjiang,all have PM2.5 concentration loading that is still high,and heavy haze pollution occurred frequently in the autumn and winter.(2)During the heavy pollution in the autumn and winter,the concentrations of sulfate and organic components decreased significantly.The mean SO42-concentration in PM2.5 decreased by 76%,12%,81%and 38%in Beijing-Tianjin-Hebei(BTH),the Pearl River Delta(PRD),the Sichuan-Chongqing region(SC)and the Fenhe and Weihe River Plain,respectively.The mean organic matter(OM)concentration decreased by 70%,44%,48%and 31%,respectively,and the mean concentration of NH4+decreased by 68%,1.6%,38%and 25%,respectively.The mean elemental carbon(EC)concentration decreased by 84%and 20%in BTH and SC,respectively,and it increased by 61%and 11%in the PRD and Fenhe and Weihe River Plain,respectively.The mean concentration of mineral and unresolved chemical components(MI)dropped by 70%,24%and 13%in BTH,the PRD and the Fenhe and Weihe River Plain,respectively.The change in the PM2.5 chemical composition is consistent with the decrease of the PM2.5mass concentration.(3)In 2015,the mean OM concentration contributions to fine particles and coarse particles were 13-46%and 46-57%,respectively,and the mean MI concentration contributions to fine particles and coarse and particles were 31-60%and 39-73%,respectively;these values are lower than the 2013 values from the key regions,which is the most important factor behind the decrease of the particulate matter mass concentration.From 2013 to 2015,among the chemical components of different particle size fractions,the peak value of the coarse particle size fraction decreased significantly,and the fine particle size fractions of SO42-,NO3-,and NH4+decreased with the decrease of the particulate matter mass concentration in different particle size fractions.The fine-particle size peaks of SO42-,NO3-and NH4+shifted from 0.65-1.1μm to the finer size range of0.43-0.65μm during the same time frame.展开更多
An intensive and persistent regional ozone pollution event occurred over eastern China from 25 June to 5 July 2017.73 out of 96 selected cities,most located in the Beijing-TianjinHebei and the surrounding area(BTHS),s...An intensive and persistent regional ozone pollution event occurred over eastern China from 25 June to 5 July 2017.73 out of 96 selected cities,most located in the Beijing-TianjinHebei and the surrounding area(BTHS),suffered severe ozone pollution.A north-south contrast ozone distribution,with higher ozone(199±33μg/m3)in the BTHS and lower ozone(118±25μg/m^3)in the Yangtze River Delta(YRD),was found to be dominated by the position of the West Pacific Subtropical High(WPSH)and mid-high latitude wave activities.In the BTHS,the positive anomalies of geopotential height at 500 hPa and temperature at the surface indicated favorable meteorological conditions for local ozone formation.Prevailing northwesterly winds in the mid-high troposphere and warm advection induced by weak southerly winds in the low troposphere resulted in low-moderate relative humidity(RH),less total cloud cover(TGC),strong solar radiation and high temperatures.Moreover,southerly winds prevailing over the BTHS aggravated the pollution due to regional transportation of O3 and its precursors.On one hand,the deep sinking motion and inversion layer suppressed the dispersion of pollutants.On the other hand,O3-rich air in the upper layer was maintained at night due to temperature inversion,which facilitated O3 vertical transport to the surface in the next-day morning due to elevated convection.Generally,temperature,UV radiation,and RH showed good correlations with O3 in the BTHS,with rates of 8.51(μg/m^3)/℃(within the temperature range of 20-38℃),59.54(μg/m^3)/(MJ/m^2)and-1.93(μg/m^3)/%,respectively.展开更多
Qualitative and quantitative analyses of derivatized phenols in Beijing and in Xinglong were performed from 2016 to 2017 using gas chromatography-mass spectrometry.The results showed substantially more severe pollutio...Qualitative and quantitative analyses of derivatized phenols in Beijing and in Xinglong were performed from 2016 to 2017 using gas chromatography-mass spectrometry.The results showed substantially more severe pollution in Beijing.Of the 14 compounds detected,the total average concentration was 100 ng/m^3 in Beijing,compared with 11.6 ng/m^3 in Xinglong.More specifically,concentration of nitro-aromatic compounds(NACs)(81.9 ng/m^3 in Beijing and 8.49 ng/m^3 in Xinglong) was the highest,followed by aromatic acids(14.6 ng/m^3 in Beijing and 2.42 ng/m^3 in Xinglong) and aromatic aldehydes(3.62 ng/m^3 in Beijing and 0.681 ng/m^3 in Xinglong).In terms of seasonal variation,the highest concentrations were found for 4-nitrocatechol in winter in Beijing(79.1±63.9 ng/m^3) and 4-nitrophenol in winter in Xinglong(9.72±8.94 ng/m^3).The analysis also revealed diurnal variations across different seasons.Most compounds presented higher concentrations at night in winter because of the decreased boundary layer height and increased heating intensity.While some presented higher levels during the day,which attributed to the photo-oxidation process for summer and more biomass burning activities for autumn.Higher concentrations appeared in winter and autumn than in spring and summer,which resulted from more coal combustions and adverse meteorological conditions.The significant correlations among NACs indicated similar sources of pollution.Higher correlations presented within each subgroup than those between the subgroups.Good correlations between levoglucosan and nitrophenols,nitrocatechols,nitro salicylic acids,with correlation coefficients(r) of 0.66,0.69 and 0.69,respectively,indicating an important role of biomass burning among primary sources.展开更多
We implemented the online coupled WRF-Chem model to reproduce the 2013 January haze event in North China, and evaluated simulated meteorological and chemical fields using multiple observations. The comparisons suggest...We implemented the online coupled WRF-Chem model to reproduce the 2013 January haze event in North China, and evaluated simulated meteorological and chemical fields using multiple observations. The comparisons suggest that temperature and relative humidity （RH） were simulated well （mean biases are 0.2K and 2.7%, respectively）, but wind speeds were overestimated （mean bias is 0.5 m.s -1）. At the Beijing station, sulfur dioxide （SO2） concentrations were overpredicted and sulfhte concentrations were largely underpredicted, which may result from uncertainties in SO2 emissions and missing heterogeneous oxidation in current model. We conducted three parallel experiments to examine the impacts of doubling SO2 emissions and incorporating heterogeneous oxidation of dissolved SO2 by nitrogen dioxide （NO2） on sulfate formation during winter haze. The results suggest that doubling SO2 emissions do not significantly affect sulthte concentrations, but adding heterogeneous oxidation of dissolved SO2 by NO, substantially improve simulations of sulfate and other inorganic aerosols. Although the enhanced SO2 to sulfate conversion in the HetS （heterogeneous oxidation by NO2） case reduces SO2 concentrations, it is still largely overestimated by the model, indicating the overestimations of SO2 concentrations in the North China Plain （NCP） are mostly due to errors in SO2 emission inventory.展开更多
A field campaign was conducted to study the PM2.5 and atmospheric gases and aerosol’s components to evaluate the efficacy of radical measures implemented by the Chinese government to improve air quality during the 20...A field campaign was conducted to study the PM2.5 and atmospheric gases and aerosol’s components to evaluate the efficacy of radical measures implemented by the Chinese government to improve air quality during the 2016 G20 Summit in Hangzhou China.The lower level of PM2.5(32.48±11.03μg/m3)observed during the control period compared to precontrol and post-control periods showed that PM2.5 was alleviated by control policies.Based on the mass concentrations of particulate components,the emissions of PM2.5 from local sources including fossil fuel,coal combustion,industry and construction were effectively reduced,but non-exhaust emission was not reduced as effectively as expected.The accumulation of SNA(SO42-,NO3-,NH4+)was observed during the control period,due to the favourable synoptic weather conditions for photochemical reactions and heterogeneous hydrolysis.Because of transboundary transport during the control period,air masses from remote areas contributed significantly to local PM2.5.Although,secondary organic carbon(OCsec)exhibited more sensitivity than primary organic carbon(OCpri)to control measures,and the increased nitrogen oxidation ratio(NOR)implied the regional transport of aged sec-ondary aerosols to the study area.Overall,the results from various approaches revealed that local pollution sources were kept under control,indicating that the implementation of mitigation measures were helpful in improving the air quality of Hangzhou during G20 summit.To reduce ambient levels of PM2.5 further in Hangzhou,regional control policies may have to be taken so as to reduce the impact of long-range transport of air masses from inland China.展开更多
Particulate matter(PM_(2.5))pollution in high emission regions will affect air quality,human health and climate change on both local and regional scales,and thus attract worldwide attention.In this study,a comprehensi...Particulate matter(PM_(2.5))pollution in high emission regions will affect air quality,human health and climate change on both local and regional scales,and thus attract worldwide attention.In this study,a comprehensive study on PM_(2.5)and its chemical composition were performed in Yuncheng(the most polluted city of Fen-Wei Plain of China)from November28,2020 to January 24,2021.The average concentration of PM_(2.5)was 87.8±52.0μg/m^(3),which were apparently lower than those observed during the same periods of past five years,attributable to the clean air action plan implemented in this region.NO_(3)^(-)and organic carbon(OC)were the dominant particulate components,which on average contributed 22.6%and16.5%to PM_(2.5)2.5,respectively.The fractions of NO_(3)^(-),NH_(4)^(+),OC and trace metals increased while those of crustal materials and elemental carbon decreased with the degradation of PM_(2.5)pollution.Six types of PM_(2.5)sources were identified by the PM_(2.5)F model,including secondary inorganic aerosol(35.3%),coal combustion(28.7%),vehicular emission(20.7%),electroplating industry(8.6%),smelt industry(3.9%)and dust(2.8%).Locations of each identified source were pinpointed based on conditional probability function,potential source contribution function and concentration weighted trajectory,which showed that the geographical distribution of the sources of PM_(2.5)roughly agreed with the areas of high emission.Overall,this study provides valuable information on atmospheric pollution and deems beneficial for policymakers to take informed action to sustainably improve air quality in highly polluted region.展开更多
基金This study was supported by the National Key Research and Development Program of China[grant numbers 2020YFA0607803 and 2019YFA0606800]the National Natural Science Foundation of China[grant number 41975159].
文摘Ultraviolet（UV） radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization＇s measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes.
基金supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No.KZCX2-YW-Q02-03)the Chinese Academy of Sciences Strategic Priority Research Program (No. XDA05100100)+1 种基金the Science and Technology Project of Bejing (No.D09040903670902)the National Natural Science Foundation of China (No. 41021004)
文摘Beijing is one of the most polluted cities in the world.In this study,the long-term and continuous measurements of volatile organic compounds （VOCs） in the urban area of Beijing,specifically at Beijing 325 m Meteorological Tower,were conducted from 2000 to 2007.The annual record of VOC trends exhibited in two different phases was separated in 2003.Records show that VOC concentrations increased from 2000 to 2003 due to the abrupt increase in vehicle number.Contrarily,since 2003,there had been a decrease in VOCs concentrations as the policy on gasoline and air pollution was implemented.Toluene,benzene,and i-pentane are the chemicals that abound in and are directly related to vehicle activity,such as in vehicle exhaust and gasoline evaporation.Furthermore,records indicate that there had been seasonal variation in VOCs levels in that VOCs level in summer is higher than that in winter.As such,temperature is considered to significantly contribute to VOCs in Beijing.Records also show that VOCs level was high in the morning and during rush hours in the evening.In contrast,VOCs level was low during midday due to photochemical destruction with OH radical and dilution effect.In this study,a particular benzene to toluene ratio range （0.4–1.0） was used as the indicator of air propelled by vehicular exhaust.We also applied the correlation coefficients between BTEX and i-pentane to evaluate evaporation influence to ambient BTEX in the Beijing urban area.
基金supported by“Strategic Priority Research Program”of the Chinese Academy of Sciences(No.XDB05020201)the Beijing Natural Science Foundation(No.8142034)
文摘In this study, we performed a highly time-resolved chemical characterization of nonrefractory submicron particles（NR-PM_1） in Beijing by using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer（HR-ToF-AMS）. The results showed the average NR-PM_1 mass concentration to be 56.4 ± 58.0 μg/m^3, with a peak at 307.4 μg/m^3. Due to the high frequency of biomass burning in autumn, submicron particles significantly increased in organic content, which accounted for 51% of NR-PM_1 on average. Secondary inorganic aerosols（sulfate ＋ nitrate ＋ ammonium） accounted for 46% of NR-PM_1, of which sulfate,nitrate, and ammonium contributed 15%, 20%, and 11%, respectively. To determine the intrinsic relationships between the organic and inorganic species, we used the positive matrix factorization（PMF） model to merge the high-resolution mass spectra of the organic species and NO＋and NO_2~＋ions. The PMF analysis separated the mixed organic and nitrate（NO＋and NO_2~＋） spectra into four organic factors, including hydrocarbon-like organic aerosol（HOA）, oxygenated organic aerosol（OOA）, cooking organic aerosol（COA）, and biomass burning organic aerosol（BBOA）, as well as one nitrate inorganic aerosol（NIA） factor. COA（33%） and OOA（30%） contributed the most to the total organic aerosol（OA） mass, followed by BBOA（20%） and HOA（17%）. We successfully quantified the mass concentrations of the organic and inorganic nitrates by the NO＋and NO2＋ions signal in the organic and NIA factors. The organic nitrate mass varied from 0.01-6.8 μg/m^3, with an average of 1.0 ±1.1 μg/m^3, and organic nitrate components accounted for 10% of the total nitrate mass in this observation.
基金supported by the Ministry of Science and Technology National Key Research and Development Program (Grant No. 2017YFC0210000)the Fundamental Heavy Pollution Cause and Governance Research Project (Grant No. DQGG0101)the Beijing Municipal Science and Technology Commission Capital Blue Sky Action and Cultivation Project (Grant No. Z181100005418014)
文摘Accurate determination of the atmospheric particulate matter mass concentration and chemical composition is helpful in exploring the causes and sources of atmospheric enthalpy pollution and in evaluating the rationality of environmental air quality control strategies.Based on the sampling and chemical composition data of PM2.5 in different key regions of China in the CARE-China observation network,this research analyzes the environmental air quality data released by the China National Environmental Monitoring Centre during the studied period to determine the changes in the particulate matter mass concentration in key regions and the evolution of the corresponding chemical compositions during the implementation of the Action Plan for Prevention and Control of Air Pollution from 2013-2017.The results show the following.(1)The particulate matter mass concentration in China showed a significant downward trend;however,the PM2.5 annual mass concentration in 64%of cities exceeds the New Chinese Ambient Air Quality Standard(CAAQS)GradeⅡ(GB3095-2012).The region to the east of the Taihang Mountains,the Fenhe and Weihe River Plain and the Urumqi-Changji regions in Xinjiang,all have PM2.5 concentration loading that is still high,and heavy haze pollution occurred frequently in the autumn and winter.(2)During the heavy pollution in the autumn and winter,the concentrations of sulfate and organic components decreased significantly.The mean SO42-concentration in PM2.5 decreased by 76%,12%,81%and 38%in Beijing-Tianjin-Hebei(BTH),the Pearl River Delta(PRD),the Sichuan-Chongqing region(SC)and the Fenhe and Weihe River Plain,respectively.The mean organic matter(OM)concentration decreased by 70%,44%,48%and 31%,respectively,and the mean concentration of NH4+decreased by 68%,1.6%,38%and 25%,respectively.The mean elemental carbon(EC)concentration decreased by 84%and 20%in BTH and SC,respectively,and it increased by 61%and 11%in the PRD and Fenhe and Weihe River Plain,respectively.The mean concentration of mineral and unresolved chemical components(MI)dropped by 70%,24%and 13%in BTH,the PRD and the Fenhe and Weihe River Plain,respectively.The change in the PM2.5 chemical composition is consistent with the decrease of the PM2.5mass concentration.(3)In 2015,the mean OM concentration contributions to fine particles and coarse particles were 13-46%and 46-57%,respectively,and the mean MI concentration contributions to fine particles and coarse and particles were 31-60%and 39-73%,respectively;these values are lower than the 2013 values from the key regions,which is the most important factor behind the decrease of the particulate matter mass concentration.From 2013 to 2015,among the chemical components of different particle size fractions,the peak value of the coarse particle size fraction decreased significantly,and the fine particle size fractions of SO42-,NO3-,and NH4+decreased with the decrease of the particulate matter mass concentration in different particle size fractions.The fine-particle size peaks of SO42-,NO3-and NH4+shifted from 0.65-1.1μm to the finer size range of0.43-0.65μm during the same time frame.
基金supported by a grant from the National Key R&D Plan(Quantitative Relationship and Regulation Principle between Regional Oxidation Capacity of Atmospheric and Air Quality 2017YFC0210003)the National Natural Science Foundation of China(No.41505133&41775162)+1 种基金the National Research Program for Key Issues in Air Pollution Control(DQGG0101)the Beijing Major Science and Technology Project 510(No.Z181100005418014)。
文摘An intensive and persistent regional ozone pollution event occurred over eastern China from 25 June to 5 July 2017.73 out of 96 selected cities,most located in the Beijing-TianjinHebei and the surrounding area(BTHS),suffered severe ozone pollution.A north-south contrast ozone distribution,with higher ozone(199±33μg/m3)in the BTHS and lower ozone(118±25μg/m^3)in the Yangtze River Delta(YRD),was found to be dominated by the position of the West Pacific Subtropical High(WPSH)and mid-high latitude wave activities.In the BTHS,the positive anomalies of geopotential height at 500 hPa and temperature at the surface indicated favorable meteorological conditions for local ozone formation.Prevailing northwesterly winds in the mid-high troposphere and warm advection induced by weak southerly winds in the low troposphere resulted in low-moderate relative humidity(RH),less total cloud cover(TGC),strong solar radiation and high temperatures.Moreover,southerly winds prevailing over the BTHS aggravated the pollution due to regional transportation of O3 and its precursors.On one hand,the deep sinking motion and inversion layer suppressed the dispersion of pollutants.On the other hand,O3-rich air in the upper layer was maintained at night due to temperature inversion,which facilitated O3 vertical transport to the surface in the next-day morning due to elevated convection.Generally,temperature,UV radiation,and RH showed good correlations with O3 in the BTHS,with rates of 8.51(μg/m^3)/℃(within the temperature range of 20-38℃),59.54(μg/m^3)/(MJ/m^2)and-1.93(μg/m^3)/%,respectively.
基金supported by the National Key R&D Program of China (No:2017YFC0210000)the Ministry of Science and Technology of China (No:2016YFC0202001).
文摘Qualitative and quantitative analyses of derivatized phenols in Beijing and in Xinglong were performed from 2016 to 2017 using gas chromatography-mass spectrometry.The results showed substantially more severe pollution in Beijing.Of the 14 compounds detected,the total average concentration was 100 ng/m^3 in Beijing,compared with 11.6 ng/m^3 in Xinglong.More specifically,concentration of nitro-aromatic compounds(NACs)(81.9 ng/m^3 in Beijing and 8.49 ng/m^3 in Xinglong) was the highest,followed by aromatic acids(14.6 ng/m^3 in Beijing and 2.42 ng/m^3 in Xinglong) and aromatic aldehydes(3.62 ng/m^3 in Beijing and 0.681 ng/m^3 in Xinglong).In terms of seasonal variation,the highest concentrations were found for 4-nitrocatechol in winter in Beijing(79.1±63.9 ng/m^3) and 4-nitrophenol in winter in Xinglong(9.72±8.94 ng/m^3).The analysis also revealed diurnal variations across different seasons.Most compounds presented higher concentrations at night in winter because of the decreased boundary layer height and increased heating intensity.While some presented higher levels during the day,which attributed to the photo-oxidation process for summer and more biomass burning activities for autumn.Higher concentrations appeared in winter and autumn than in spring and summer,which resulted from more coal combustions and adverse meteorological conditions.The significant correlations among NACs indicated similar sources of pollution.Higher correlations presented within each subgroup than those between the subgroups.Good correlations between levoglucosan and nitrophenols,nitrocatechols,nitro salicylic acids,with correlation coefficients(r) of 0.66,0.69 and 0.69,respectively,indicating an important role of biomass burning among primary sources.
文摘We implemented the online coupled WRF-Chem model to reproduce the 2013 January haze event in North China, and evaluated simulated meteorological and chemical fields using multiple observations. The comparisons suggest that temperature and relative humidity （RH） were simulated well （mean biases are 0.2K and 2.7%, respectively）, but wind speeds were overestimated （mean bias is 0.5 m.s -1）. At the Beijing station, sulfur dioxide （SO2） concentrations were overpredicted and sulfhte concentrations were largely underpredicted, which may result from uncertainties in SO2 emissions and missing heterogeneous oxidation in current model. We conducted three parallel experiments to examine the impacts of doubling SO2 emissions and incorporating heterogeneous oxidation of dissolved SO2 by nitrogen dioxide （NO2） on sulfate formation during winter haze. The results suggest that doubling SO2 emissions do not significantly affect sulthte concentrations, but adding heterogeneous oxidation of dissolved SO2 by NO, substantially improve simulations of sulfate and other inorganic aerosols. Although the enhanced SO2 to sulfate conversion in the HetS （heterogeneous oxidation by NO2） case reduces SO2 concentrations, it is still largely overestimated by the model, indicating the overestimations of SO2 concentrations in the North China Plain （NCP） are mostly due to errors in SO2 emission inventory.
基金supported by the Ningbo Innovation Team Project(No.2017C510001)the Ningbo Municipal Bureau of Science and Technology Key Program(Nos.2019C10033,2019C10104)+4 种基金the National Natural Science Foundation of China(No.41975831)the Start-up Research Funding of South-Central University for Nationalities(No.YZZ18018)the Natural Science Foundation of Zhejiang Province(No.LY19D050002)the Provincial Key Laboratory Programme by Zhejiang Provincial Department of Science and Technology(No.2020E10018)。
文摘A field campaign was conducted to study the PM2.5 and atmospheric gases and aerosol’s components to evaluate the efficacy of radical measures implemented by the Chinese government to improve air quality during the 2016 G20 Summit in Hangzhou China.The lower level of PM2.5(32.48±11.03μg/m3)observed during the control period compared to precontrol and post-control periods showed that PM2.5 was alleviated by control policies.Based on the mass concentrations of particulate components,the emissions of PM2.5 from local sources including fossil fuel,coal combustion,industry and construction were effectively reduced,but non-exhaust emission was not reduced as effectively as expected.The accumulation of SNA(SO42-,NO3-,NH4+)was observed during the control period,due to the favourable synoptic weather conditions for photochemical reactions and heterogeneous hydrolysis.Because of transboundary transport during the control period,air masses from remote areas contributed significantly to local PM2.5.Although,secondary organic carbon(OCsec)exhibited more sensitivity than primary organic carbon(OCpri)to control measures,and the increased nitrogen oxidation ratio(NOR)implied the regional transport of aged sec-ondary aerosols to the study area.Overall,the results from various approaches revealed that local pollution sources were kept under control,indicating that the implementation of mitigation measures were helpful in improving the air quality of Hangzhou during G20 summit.To reduce ambient levels of PM2.5 further in Hangzhou,regional control policies may have to be taken so as to reduce the impact of long-range transport of air masses from inland China.
基金supported by the National Key Research and Development Program of China(No.2019YFC0214203)
文摘Particulate matter(PM_(2.5))pollution in high emission regions will affect air quality,human health and climate change on both local and regional scales,and thus attract worldwide attention.In this study,a comprehensive study on PM_(2.5)and its chemical composition were performed in Yuncheng(the most polluted city of Fen-Wei Plain of China)from November28,2020 to January 24,2021.The average concentration of PM_(2.5)was 87.8±52.0μg/m^(3),which were apparently lower than those observed during the same periods of past five years,attributable to the clean air action plan implemented in this region.NO_(3)^(-)and organic carbon(OC)were the dominant particulate components,which on average contributed 22.6%and16.5%to PM_(2.5)2.5,respectively.The fractions of NO_(3)^(-),NH_(4)^(+),OC and trace metals increased while those of crustal materials and elemental carbon decreased with the degradation of PM_(2.5)pollution.Six types of PM_(2.5)sources were identified by the PM_(2.5)F model,including secondary inorganic aerosol(35.3%),coal combustion(28.7%),vehicular emission(20.7%),electroplating industry(8.6%),smelt industry(3.9%)and dust(2.8%).Locations of each identified source were pinpointed based on conditional probability function,potential source contribution function and concentration weighted trajectory,which showed that the geographical distribution of the sources of PM_(2.5)roughly agreed with the areas of high emission.Overall,this study provides valuable information on atmospheric pollution and deems beneficial for policymakers to take informed action to sustainably improve air quality in highly polluted region.
