Regional ozone （O3） pollution has drawn increasing attention in China over the recent decade, but the contributions from urban pollution and biogenic emissions have not been clearly elucidated. To better understand ...Regional ozone （O3） pollution has drawn increasing attention in China over the recent decade, but the contributions from urban pollution and biogenic emissions have not been clearly elucidated. To better understand the formation of the regional O3 problem in the North China Plain （NCP）, intensive field measurements of O3 and related parameters were conducted at a rural site downwind of Ji＇nan, the capital city of Shandong province, in the summer of 2013. Markedly severe 03 pollution was recorded, with the 03 mixing ratios exceeding the Chinese national ambient air quality standard on 28 days （a frequency of 78%） and with a maximum hourly value of 198 ppbv. Extensive regional transport of well-processed urban plumes to the site was identified. An observation-constrained chemical box model was deployed to evaluate in situ photochemical O3 production on two episodes. The results show that the in situ formation accounted for approximately 46% of the observed O3 accumulation, while the remainder （54%） was contributed by regional transport of the O3-laden urban plumes. The in situ ozone production was in a mixed controlled regime that reducing either NOx or VOCs would lead to a reduction of ozone formation. Biogenic VOCs played an important role in the local ozone formation. This study demonstrates the significant mixed effects of both anthropogenic pollution from urban zones and biogenic emission in rural areas on the regional 03 pollution in the NCP region, and may have general applicability in facilitating the understanding of the formation of secondary pollution over China.展开更多
Surface ozone(O_(3))has become a critical pollutant impeding air quality improvement in many Chinese megacities.Chengdu is a megacity located in Sichuan Basin in southwest China,where O_(3)pollution occurs frequently ...Surface ozone(O_(3))has become a critical pollutant impeding air quality improvement in many Chinese megacities.Chengdu is a megacity located in Sichuan Basin in southwest China,where O_(3)pollution occurs frequently in both spring and summer.In order to understand the elevated O_(3)during spring in Chengdu,we conducted sampling campaign at three sites during O_(3)pollution episodes in April.Volatile organic compounds(VOCs)compositions at each site were similar,and oxygenated VOCs(OVOCs)concentrations accounted for the highest proportion(35%-45%),followed by alkanes,alkens(including acetylene),halohydrocarbons,and aromatics.The sensitivity of O_(3)to its precursors was analyzed using an observation based box model.The relative incremental reactivity of OVOCs was larger than other precursors,suggesting that they also played the dominant role in O_(3)formation.Furthermore,the positive matrix factorization model was used to identify the dominant emission sources and to evaluate their contribution to VOCs in the city.The main sources of VOCs in spring were from combustion(27.75%),industrial manufacturing(24.17%),vehicle exhaust(20.35%),and solvent utilization(18.35%).Discussions on VOCs and NO_(x)reduction schemes suggested that Chengdu was typical in the VOC-limited regime,and VOC emission reduction would help to prevent and control O_(3).The analysis of emission reduction scenarios based on VOCs sources showed that the emission reduction ratio of VOCs to NO_(2)needs to reach more than 3 in order to achieve O_(3)prevention.Emission reduction from vehicular exhaust source and solvent utilization source may be more effective.展开更多
基金funded by the Taishan Scholar Grand (No. ts20120552)the National Natural Science Foundation of China (No. 41375126)+2 种基金supported by the National Natural Science Foundation of China (No. 41675118)the Qilu Youth Talent Programme of Shandong Universitythe Jiangsu Collaborative Innovation Center for Climate Change
文摘Regional ozone （O3） pollution has drawn increasing attention in China over the recent decade, but the contributions from urban pollution and biogenic emissions have not been clearly elucidated. To better understand the formation of the regional O3 problem in the North China Plain （NCP）, intensive field measurements of O3 and related parameters were conducted at a rural site downwind of Ji＇nan, the capital city of Shandong province, in the summer of 2013. Markedly severe 03 pollution was recorded, with the 03 mixing ratios exceeding the Chinese national ambient air quality standard on 28 days （a frequency of 78%） and with a maximum hourly value of 198 ppbv. Extensive regional transport of well-processed urban plumes to the site was identified. An observation-constrained chemical box model was deployed to evaluate in situ photochemical O3 production on two episodes. The results show that the in situ formation accounted for approximately 46% of the observed O3 accumulation, while the remainder （54%） was contributed by regional transport of the O3-laden urban plumes. The in situ ozone production was in a mixed controlled regime that reducing either NOx or VOCs would lead to a reduction of ozone formation. Biogenic VOCs played an important role in the local ozone formation. This study demonstrates the significant mixed effects of both anthropogenic pollution from urban zones and biogenic emission in rural areas on the regional 03 pollution in the NCP region, and may have general applicability in facilitating the understanding of the formation of secondary pollution over China.
基金supported by the National Natural Science Foundation of China(No.21906108)the Fundamental Research Funds for the Central Universities(No.YJ201937)Chengdu Science and Technology Bureau(No.2020-YF09-00051-SN)
文摘Surface ozone(O_(3))has become a critical pollutant impeding air quality improvement in many Chinese megacities.Chengdu is a megacity located in Sichuan Basin in southwest China,where O_(3)pollution occurs frequently in both spring and summer.In order to understand the elevated O_(3)during spring in Chengdu,we conducted sampling campaign at three sites during O_(3)pollution episodes in April.Volatile organic compounds(VOCs)compositions at each site were similar,and oxygenated VOCs(OVOCs)concentrations accounted for the highest proportion(35%-45%),followed by alkanes,alkens(including acetylene),halohydrocarbons,and aromatics.The sensitivity of O_(3)to its precursors was analyzed using an observation based box model.The relative incremental reactivity of OVOCs was larger than other precursors,suggesting that they also played the dominant role in O_(3)formation.Furthermore,the positive matrix factorization model was used to identify the dominant emission sources and to evaluate their contribution to VOCs in the city.The main sources of VOCs in spring were from combustion(27.75%),industrial manufacturing(24.17%),vehicle exhaust(20.35%),and solvent utilization(18.35%).Discussions on VOCs and NO_(x)reduction schemes suggested that Chengdu was typical in the VOC-limited regime,and VOC emission reduction would help to prevent and control O_(3).The analysis of emission reduction scenarios based on VOCs sources showed that the emission reduction ratio of VOCs to NO_(2)needs to reach more than 3 in order to achieve O_(3)prevention.Emission reduction from vehicular exhaust source and solvent utilization source may be more effective.
