Black carbon(BC)reduces the photolysis coefficient by absorbing solar radiation,thereby affecting the concentration of ozone(O_(3))near the ground.The influence of BC on O_(3)has thus received much attention.In this s...Black carbon(BC)reduces the photolysis coefficient by absorbing solar radiation,thereby affecting the concentration of ozone(O_(3))near the ground.The influence of BC on O_(3)has thus received much attention.In this study,Mie scattering and the tropospheric Ultraviolet and Visible radiation model are used to analyze the effect of BC optical properties on radiation.Combined with data of O_(3)precursors in Nanjing in 2014,an EKMA curve is drawn,and the variations in O_(3)concentration are further investigated using a zero-dimensional box mechanism model(NCAR MM).When O_(3)precursors are unchanged,radiation and O_(3)show a highly similar tendency in response to changing BC optical properties(R=0.997).With the increase of modal radius,the attenuation of fresh BC to radiation and O_(3)first trends upward before decreasing.In the mixing process,the attenuation of BC to radiation and O_(3)presents an upward tendency with the increase of relative humidity but decreases rapidly before increasing slowly with increasing thickness of coating.In addition,mass concentration is another major factor.When the BC to PM_(2.5)ratio increases to 5%in Nanjing,the radiation decreases by approximately 0.13%-3.71%while O_(3)decreases by approximately 8.13%-13.11%.The radiative effect of BC not only reduces O_(3)concentration but also changes the EKMA curve.Compared with the NO_(x)control area,radiation has a significant influence on the VOCs control area.When aerosol optical depth(AOD)increases by 17.15%,the NO_(x)to VOCs ratio decreases by 8.27%,and part of the original NO_(x)control area is transferred to the VOCs control area.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
Chemical composition, hourly counts, and sizes of atmospheric carbonaceous particles were measured to investigate their mixing state on clear and hazy days. 823,122 carbonaceous particles with sizes 0.2-2.0μm was ana...Chemical composition, hourly counts, and sizes of atmospheric carbonaceous particles were measured to investigate their mixing state on clear and hazy days. 823,122 carbonaceous particles with sizes 0.2-2.0μm was analyzed using a single-particle aerosol mass spectrometer from 1st to 17th January 2013. Particle types included biomass/biofuel burning particles (biomass), element carbon (EC-dominant) particles that were also mixed with biomass/biofuel burning species (EC-biomass) or secondary species (EC-secondary), organic carbon (OC), internally mixed OC and EC (OCEC), ammonium-containing (ammo- nium) and sodium-containing (sodium) particles. On clear days the top ranked carbonaceous particle types were biomass (48.2%), EC-biomass (15.7%), OCEC (11.1%), and sodium (9.6%), while on hazy days they were biomass (37.3%), EC-biomass (17,6%), EC-secondary (16.6%), and sodium (12.7%). The fractions of EC-secondary, ammonium (10%), and sodium particle types were elevated on hazy days. Numbers of EC-secondary particles were more than four times those on clear days (4.1%). Thus, carbonaceous particles mixed with ammonium, nitrate and sulfate during aging and transport, enhancing their light extinction effects and hygroscopic growth under high relative humidity on hazy days, further reducing visibility. Our real-time single-particle data showed that changes to mixing state had a significant impact on light extinction during haze events in Nanjing.展开更多
We conducted measurements of black carbon (BC) aerosol in Jiaxing, China during autumn from September 26 to November 30, 2013. We investigated temporal and diurnal variations of BC, and its cor relations with meteor...We conducted measurements of black carbon (BC) aerosol in Jiaxing, China during autumn from September 26 to November 30, 2013. We investigated temporal and diurnal variations of BC, and its cor relations with meteorological parameters and other major pollutants. Results showed that hourly mass concentrations of BC ranged from 0.2 to 22.0 μg/m3, with an average of 5.1 μg/ms. The diurnal variation of BC exhibited a bimodal distribution, with peaks at 07:00 and 18:00. The morning peak was larger than the evening peak. The mass percentages of BC in PM2.s and PM10 were 7.1%and 4.8g, respectively. The absorption coefficient of BC was calculated to be 44.4 Mm-1, which accounted for 11.1% of the total aerosol extinction. BC was mainly emitted from local sources in southwestern Jiaxing where BC concentrations were generally greater than 11μg/m3 during the measurement period. Correlation analysis indicated that the main sources of BC were motor vehicle exhaust, and domestic and industrial combustion.展开更多
基金This work was supported by grants from the National Key Research and Development Program of China(Grant No.2017YFC0210003)the National Natural Science Foundation of China(Grant No.42075177)the Qing Lan Project.
文摘Black carbon(BC)reduces the photolysis coefficient by absorbing solar radiation,thereby affecting the concentration of ozone(O_(3))near the ground.The influence of BC on O_(3)has thus received much attention.In this study,Mie scattering and the tropospheric Ultraviolet and Visible radiation model are used to analyze the effect of BC optical properties on radiation.Combined with data of O_(3)precursors in Nanjing in 2014,an EKMA curve is drawn,and the variations in O_(3)concentration are further investigated using a zero-dimensional box mechanism model(NCAR MM).When O_(3)precursors are unchanged,radiation and O_(3)show a highly similar tendency in response to changing BC optical properties(R=0.997).With the increase of modal radius,the attenuation of fresh BC to radiation and O_(3)first trends upward before decreasing.In the mixing process,the attenuation of BC to radiation and O_(3)presents an upward tendency with the increase of relative humidity but decreases rapidly before increasing slowly with increasing thickness of coating.In addition,mass concentration is another major factor.When the BC to PM_(2.5)ratio increases to 5%in Nanjing,the radiation decreases by approximately 0.13%-3.71%while O_(3)decreases by approximately 8.13%-13.11%.The radiative effect of BC not only reduces O_(3)concentration but also changes the EKMA curve.Compared with the NO_(x)control area,radiation has a significant influence on the VOCs control area.When aerosol optical depth(AOD)increases by 17.15%,the NO_(x)to VOCs ratio decreases by 8.27%,and part of the original NO_(x)control area is transferred to the VOCs control area.
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supported by grants from the National Natural Science Foundation of China(41275143 and 41305135)the Special Fund for Public Welfare Industrial(Meteorology) Research of China(GYHY201206011)+3 种基金the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province(12KJA170003)the Chinese Academy of Sciences Strategic Priority Research Program(XDB05020206)the project of Jiangsu provincial "333" and Six Talent Peaksthe project Funded by the Priority Academic Program Development(PAPD) of Jiangsu Higher Education Institutions
文摘Chemical composition, hourly counts, and sizes of atmospheric carbonaceous particles were measured to investigate their mixing state on clear and hazy days. 823,122 carbonaceous particles with sizes 0.2-2.0μm was analyzed using a single-particle aerosol mass spectrometer from 1st to 17th January 2013. Particle types included biomass/biofuel burning particles (biomass), element carbon (EC-dominant) particles that were also mixed with biomass/biofuel burning species (EC-biomass) or secondary species (EC-secondary), organic carbon (OC), internally mixed OC and EC (OCEC), ammonium-containing (ammo- nium) and sodium-containing (sodium) particles. On clear days the top ranked carbonaceous particle types were biomass (48.2%), EC-biomass (15.7%), OCEC (11.1%), and sodium (9.6%), while on hazy days they were biomass (37.3%), EC-biomass (17,6%), EC-secondary (16.6%), and sodium (12.7%). The fractions of EC-secondary, ammonium (10%), and sodium particle types were elevated on hazy days. Numbers of EC-secondary particles were more than four times those on clear days (4.1%). Thus, carbonaceous particles mixed with ammonium, nitrate and sulfate during aging and transport, enhancing their light extinction effects and hygroscopic growth under high relative humidity on hazy days, further reducing visibility. Our real-time single-particle data showed that changes to mixing state had a significant impact on light extinction during haze events in Nanjing.
基金funded by the National Natural Science Foundation of China(Grant No.41305135)the Natural Science Foundation of Zhejiang Province(Grant No.LQ13D050001)the Chinese Academy of Sciences Strategic Priority Research Program (Grant No.XDB05020206)
文摘We conducted measurements of black carbon (BC) aerosol in Jiaxing, China during autumn from September 26 to November 30, 2013. We investigated temporal and diurnal variations of BC, and its cor relations with meteorological parameters and other major pollutants. Results showed that hourly mass concentrations of BC ranged from 0.2 to 22.0 μg/m3, with an average of 5.1 μg/ms. The diurnal variation of BC exhibited a bimodal distribution, with peaks at 07:00 and 18:00. The morning peak was larger than the evening peak. The mass percentages of BC in PM2.s and PM10 were 7.1%and 4.8g, respectively. The absorption coefficient of BC was calculated to be 44.4 Mm-1, which accounted for 11.1% of the total aerosol extinction. BC was mainly emitted from local sources in southwestern Jiaxing where BC concentrations were generally greater than 11μg/m3 during the measurement period. Correlation analysis indicated that the main sources of BC were motor vehicle exhaust, and domestic and industrial combustion.