Tropospheric ozone(O3)is a trace gas of great significance for air quality and climate change.In recent years,due to the extensive implementation of emission reduction policies,the concentration of fine particulate ma...Tropospheric ozone(O3)is a trace gas of great significance for air quality and climate change.In recent years,due to the extensive implementation of emission reduction policies,the concentration of fine particulate matter in many countries has decreased significantly^([1]).In contrast,the global ground-level O3 concentration has increased by approximately 0.25 ppbv/a^([2]).Research shows that developed countries are experiencing a rebound in O3 levels while developing countries are facing more severe O3 pollution problems^([3,4]).Therefore,the prevention and control of O3 pollution is the top priority at this stage and will play a vital role in the longterm improvement of air quality.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
The structure of the boundary layer affects the evolution of ozone(O3), and research into this structure will provide important insights for understanding photochemical pollution.In this study, we conducted a one-mont...The structure of the boundary layer affects the evolution of ozone(O3), and research into this structure will provide important insights for understanding photochemical pollution.In this study, we conducted a one-month observation(from June 15 to July 14, 2016) of the boundary layer meteorological factors as well as O3 and its precursors in Luancheng County,Shijiazhuang(37°53′N, 114°38′E). Our research showed that photochemical pollution in Shijiazhuang is serious, and the mean hourly maximum and mean 8-hr maximum O3 concentrations are 97.9 ± 26.1 and 84.4 ± 22.4 ppbV, respectively. Meteorological factors play a significant role in the formation of O3. High temperatures and southeasterly winds lead to elevated O3 values, and at moderate relative humidity(40%–50%) and medium boundary layer heights(1200–1500 m), O3 production sensitivity occurred in the transitional region between volatile organic compounds(VOC) and nitrogen oxides(NOx) limitations,and the O3 concentration was the highest. The vertical profiles of O3 were also measured by a tethered balloon. The results showed that a large amount of O3 was stored in the residual layer, and the concentration was positively correlated with the O3 concentration measured the previous day. During the daytime of the following day, the contribution of O3 stored in the residual layer to the boundary layer reached 27%± 7% on average.展开更多
Following the implementation of the strictest clean air policies to date in Beijing,the physicochemical characteristics and sources of PM_(2.5) have changed over the past few years.To improve pollution reduction polic...Following the implementation of the strictest clean air policies to date in Beijing,the physicochemical characteristics and sources of PM_(2.5) have changed over the past few years.To improve pollution reduction policies and subsequent air quality further,it is necessary to explore the changes in PM_(2.5) over time.In this study,over one year(2017-2018)field study based on filter sampling(TH-150C;Wuhan Tianhong,China)was conducted in Fengtai District,Beijing,revealed that the annual average PM_(2.5) concentration(64.8±43.1μg/m^3)was significantly lower than in previous years and the highest PM_(2.5) concentration occurred in spring(84.4±59.9μg/m^3).Secondary nitrate was the largest source and accounted for 25.7%of the measured PM_(2.5).Vehicular emission,the second largest source(17.6%),deserves more attention when considering the increase in the number of motor vehicles and its contribution to gaseous pollutants.In addition,the contribution from coal combustion to PM_(2.5) decreased significantly.During weekends,the contribution from EC and NO3−increased whereas the contributions from SO4^2−,OM,and trace elements decreased,compared with weekdays.During the period of residential heating,PM_(2.5) mass decreased by 23.1%,compared with non-heating period,while the contributions from coal combustion and vehicular emission,and related species increased.With the aggravation of pollution,the contribution of vehicular emission and secondary sulfate increased and then decreased,while the contribution of NO3−and secondary nitrate continued to increase,and accounted for 34.0%and 57.5%of the PM_(2.5) during the heavily polluted days,respectively.展开更多
Atmospheric extinction is impacted by the chemical composition of particles.To better understand the chemical composition of PM_(2.5)(particles with diameters of less than 2.5μm)and its relationship with extinction,o...Atmospheric extinction is impacted by the chemical composition of particles.To better understand the chemical composition of PM_(2.5)(particles with diameters of less than 2.5μm)and its relationship with extinction,one-month sampling campaigns were carried out in four different seasons from 2013 to 2014 in Jinan,China.The seasonal average concentrations of PM_(2.5)were 120.9(autumn),156.6(winter),102.5(spring),and 111.8μg/m^(3)(summer).The reconstructed PM_(2.5)chemical composition showed that sulfate,nitrate,chlorine salt,organic matter(OM),mineral dust,elemental carbon(EC)and others accounted for 25%,14%,2%,24%,22%,3%and 10%,respectively.The relationship between the chemical composition of PM_(2.5)and visibility was reconstructed by the IMPROVE method,and ammonium sulfate,ammonium nitrate,OM and EC dominated the visibility.Seven main sources were resolved for PM_(2.5),including secondary particles,coal combustion,biomass burning,industry,motor vehicle exhaust,soil dust and cooking,which accounted for 37%,21%,13%,13%,12%,3%and 1%,respectively.The contributions of different sources to visibility were similar to those to PM_(2.5).With increasing severity of air pollution,the contributions of secondary particles and coal combustion increased,while the contribution of motor vehicle exhaust decreased.The results showed that coal combustion and biomass burning were still the main sources of air pollution in Jinan.展开更多
The thermal internal boundary layer（TIBL） is associated with coastal pollution dispersion,which can result in high concentrations of air pollutants near the surface of the Earth. In this study, boundary layer height...The thermal internal boundary layer（TIBL） is associated with coastal pollution dispersion,which can result in high concentrations of air pollutants near the surface of the Earth. In this study, boundary layer height data which were obtained using a ceilometer were used to assess the effect of the TIBL on atmospheric pollutants in Qinhuangdao, a coastal city in North China.A TIBL formed on 33% of summer days. When a TIBL formed, the sunshine duration was 2.4 hr longer, the wind speed was higher, the wind direction reflected a typical sea breeze, and the boundary layer height was lower from 9：00 LT to 20：00 LT compared to days without a TIBL. If no TIBL formed, the average concentrations of PM2.5 and PM10 decreased with increasing boundary layer height. However, when a TIBL was observed, the average concentrations of PM2.5 and PM10 increased with increasing boundary layer height. Because the air from the sea is clean, PM2.5 and PM10 concentrations reached minimums in the daytime at 16：00 LT. After16：00 LT, the PM2.5 and PM10 concentrations increased rapidly on days when a TIBL formed,which indicated that the TIBL leads to the rapid accumulation of atmospheric pollutants in the evening. Therefore, the maximum concentrations of particulate matters were larger when a TIBL formed compared to when no TIBL was present during the night. These results indicate that it is suitable for outdoor activities in the daytime on days with a TIBL in coastal cities.展开更多
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0604)the National Natural Science Foundation of China(42177081)+1 种基金the Beijing Municipal Natural Science Foundation(8222075)the Youth Cross Team Scientific Research Project of the Chinese Academy of Sciences(JCTD-2021-10)。
文摘Tropospheric ozone(O3)is a trace gas of great significance for air quality and climate change.In recent years,due to the extensive implementation of emission reduction policies,the concentration of fine particulate matter in many countries has decreased significantly^([1]).In contrast,the global ground-level O3 concentration has increased by approximately 0.25 ppbv/a^([2]).Research shows that developed countries are experiencing a rebound in O3 levels while developing countries are facing more severe O3 pollution problems^([3,4]).Therefore,the prevention and control of O3 pollution is the top priority at this stage and will play a vital role in the longterm improvement of air quality.
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 the National Key R&D Program of China(Nos.2017YFC0210000 and 2016YFC0203100)State Key Laboratory of Atmospheric Chemistry,Chinese Meteorological Administration(LAC/CMA)(No.2017A01)+4 种基金the Young Talent Project of the Center for Excellence in Regional Atmospheric Environment,Chinese Academy of Sciences(CAS)(No.CERAE201802)the National Natural Science Foundation of China(Nos.41705113,41877312 and 41675124)the National research program for key issues in air pollution control(No.DQGG0101)Beijing Major Science and Technology Project(No.Z181100005418014)Postgraduate Research and Practice Innovation Program of Jiangsu Province(No.SJCX18_0327)
文摘The structure of the boundary layer affects the evolution of ozone(O3), and research into this structure will provide important insights for understanding photochemical pollution.In this study, we conducted a one-month observation(from June 15 to July 14, 2016) of the boundary layer meteorological factors as well as O3 and its precursors in Luancheng County,Shijiazhuang(37°53′N, 114°38′E). Our research showed that photochemical pollution in Shijiazhuang is serious, and the mean hourly maximum and mean 8-hr maximum O3 concentrations are 97.9 ± 26.1 and 84.4 ± 22.4 ppbV, respectively. Meteorological factors play a significant role in the formation of O3. High temperatures and southeasterly winds lead to elevated O3 values, and at moderate relative humidity(40%–50%) and medium boundary layer heights(1200–1500 m), O3 production sensitivity occurred in the transitional region between volatile organic compounds(VOC) and nitrogen oxides(NOx) limitations,and the O3 concentration was the highest. The vertical profiles of O3 were also measured by a tethered balloon. The results showed that a large amount of O3 was stored in the residual layer, and the concentration was positively correlated with the O3 concentration measured the previous day. During the daytime of the following day, the contribution of O3 stored in the residual layer to the boundary layer reached 27%± 7% on average.
基金the National Natural Science Foundation of China(Nos.41805095,41705113,41877312)the Sichuan Science and Technology Program(Nos.2018SZ0288 and 2019YFS0476)+1 种基金the National Research Program for Key Is-sues in Air Pollution Control(DQGG0101)the Beijing Ma-jor Science and Technology Project(Z181100005418014)。
文摘Following the implementation of the strictest clean air policies to date in Beijing,the physicochemical characteristics and sources of PM_(2.5) have changed over the past few years.To improve pollution reduction policies and subsequent air quality further,it is necessary to explore the changes in PM_(2.5) over time.In this study,over one year(2017-2018)field study based on filter sampling(TH-150C;Wuhan Tianhong,China)was conducted in Fengtai District,Beijing,revealed that the annual average PM_(2.5) concentration(64.8±43.1μg/m^3)was significantly lower than in previous years and the highest PM_(2.5) concentration occurred in spring(84.4±59.9μg/m^3).Secondary nitrate was the largest source and accounted for 25.7%of the measured PM_(2.5).Vehicular emission,the second largest source(17.6%),deserves more attention when considering the increase in the number of motor vehicles and its contribution to gaseous pollutants.In addition,the contribution from coal combustion to PM_(2.5) decreased significantly.During weekends,the contribution from EC and NO3−increased whereas the contributions from SO4^2−,OM,and trace elements decreased,compared with weekdays.During the period of residential heating,PM_(2.5) mass decreased by 23.1%,compared with non-heating period,while the contributions from coal combustion and vehicular emission,and related species increased.With the aggravation of pollution,the contribution of vehicular emission and secondary sulfate increased and then decreased,while the contribution of NO3−and secondary nitrate continued to increase,and accounted for 34.0%and 57.5%of the PM_(2.5) during the heavily polluted days,respectively.
基金supported by the National Key R&D Program of China(No.2017YFC0210000)the National Natural Science Foundation of China(Nos.41705113 and 41877312)+1 种基金the Young Talent Project of the Center for Excellence in Regional Atmospheric Environment CAS(CERAE201802)the Beijing Major Science and Technology Project(No.Z181100005418014)。
文摘Atmospheric extinction is impacted by the chemical composition of particles.To better understand the chemical composition of PM_(2.5)(particles with diameters of less than 2.5μm)and its relationship with extinction,one-month sampling campaigns were carried out in four different seasons from 2013 to 2014 in Jinan,China.The seasonal average concentrations of PM_(2.5)were 120.9(autumn),156.6(winter),102.5(spring),and 111.8μg/m^(3)(summer).The reconstructed PM_(2.5)chemical composition showed that sulfate,nitrate,chlorine salt,organic matter(OM),mineral dust,elemental carbon(EC)and others accounted for 25%,14%,2%,24%,22%,3%and 10%,respectively.The relationship between the chemical composition of PM_(2.5)and visibility was reconstructed by the IMPROVE method,and ammonium sulfate,ammonium nitrate,OM and EC dominated the visibility.Seven main sources were resolved for PM_(2.5),including secondary particles,coal combustion,biomass burning,industry,motor vehicle exhaust,soil dust and cooking,which accounted for 37%,21%,13%,13%,12%,3%and 1%,respectively.The contributions of different sources to visibility were similar to those to PM_(2.5).With increasing severity of air pollution,the contributions of secondary particles and coal combustion increased,while the contribution of motor vehicle exhaust decreased.The results showed that coal combustion and biomass burning were still the main sources of air pollution in Jinan.
基金supported by the National Key R&D Program of China(No.2017YFC 0210000)the National Natural Science Foundation of China(Nos.41230642 and 41705113)the Beijing Municipal Science and Technology Project(No.ZL171100000617002)
文摘The thermal internal boundary layer（TIBL） is associated with coastal pollution dispersion,which can result in high concentrations of air pollutants near the surface of the Earth. In this study, boundary layer height data which were obtained using a ceilometer were used to assess the effect of the TIBL on atmospheric pollutants in Qinhuangdao, a coastal city in North China.A TIBL formed on 33% of summer days. When a TIBL formed, the sunshine duration was 2.4 hr longer, the wind speed was higher, the wind direction reflected a typical sea breeze, and the boundary layer height was lower from 9：00 LT to 20：00 LT compared to days without a TIBL. If no TIBL formed, the average concentrations of PM2.5 and PM10 decreased with increasing boundary layer height. However, when a TIBL was observed, the average concentrations of PM2.5 and PM10 increased with increasing boundary layer height. Because the air from the sea is clean, PM2.5 and PM10 concentrations reached minimums in the daytime at 16：00 LT. After16：00 LT, the PM2.5 and PM10 concentrations increased rapidly on days when a TIBL formed,which indicated that the TIBL leads to the rapid accumulation of atmospheric pollutants in the evening. Therefore, the maximum concentrations of particulate matters were larger when a TIBL formed compared to when no TIBL was present during the night. These results indicate that it is suitable for outdoor activities in the daytime on days with a TIBL in coastal cities.
