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Yuesi Wang - One of the best experts on this subject based on the ideXlab platform.
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seasonal variation and secondary formation of size segregated aerosol water soluble Inorganic Ions in a coast megacity of north china plain
2020Co-Authors: Qing Yao, Zirui Liu, Xiaojuan Huang, Suqin Han, Ziying Cai, Jingle Liu, Tianyi Hao, Jinyun Liu, Yuesi WangAbstract:The aerosol samples of water-soluble Inorganic Ions (WSIs), including SO42−, NO3−, NH4+, Cl−, K+, Na+, Ca2+, and Mg2+ in size-segregated particulate matter (PM), were collected by an Anderson sampler (with 8 nominal cut-sizes ranged from 0.43 to 9.0 μm) in urban Tianjin during 2013–2014. The results showed that particulate matters in the fine mode (PM2.1, Dp < 2.1 μm) comprised large part of mass concentratIons of aerosols, and the water-soluble ionic species in the fine mode were 47.07 ± 14.29 μg m−3 (spring), 67.87 ± 28.74 μg m−3 (summer), 86.60 ± 48.53 μg m−3 (autumn), and 104.16 ± 51.76 μg m−3 (winter), respectively, which accounted for 59.5%, 63.3%, 71.9%, and 71.4% of the PM2.1 mass concentratIons. Secondary pollutants of SO42−, NO3−, and NH4+ (SNA) were the dominant contributors of WSIs, which showed a bimodal size distribution in each season, with the larger peak appeared in the size fraction of 0.65–1.1 μm and the smaller one in 3.3–5.8 μm fraction. SNA concentratIons in lightly polluted days (LPD) and heavily polluted days (HPD) were observably higher than non-polluted days (NPD), especially in the fine mode, with the peak diameter moving from 0.43–0.65 μm on NPD to 0.65–1.1 μm on LPD and HPD. The correlation analysis between NH4+, NO3−, and SO42− suggested that almost all SO42− and NO3− for fine particles had been completely neutralized by NH4+, and primarily existed in the forms of (NH4)2SO4 and NH4NO3. The sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) on LPD and HPD in fine mode were observably higher than those on NPD, especially in the range of 0.65–1.1 μm and 1.1–2.1 μm. Furthermore, SOR and NOR values in the size fraction of 0.43–3.3 μm increase as the RH elevated, especially in 0.43–2.1 μm, where RH was significantly positive correlated with SOR and NOR, indicating the significant contributIons of heterogeneous processes to the secondary formation of SO42− and NO3−. These results suggested an enhanced formation ability of secondary pollutants under high RH in the coast city. Therefore, controlling the precursors of SNA, such as SO2 and NOx, would be more effective to reduce the fine particulate pollution in the coast megacity of Tianjin.
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seasonal variation and source analysis of water soluble Inorganic Ions in fine particulate matter in zhengzhou
2019Co-Authors: Guangxuan Yan, Jingwen Zhang, Haojie Lei, Haiyan Huang, Mingshuang Tang, Zhiguo Cao, Jing Fan, Yuesi WangAbstract:In order to explore the characteristics of PM2.5 concentration and water-soluble Inorganic Ions in Zhengzhou City, a total of 170 PM2.5 samples were collected in the spring, summer, autumn, and winter seasons of 2016, with 30 days continuous sampling during each season. The mass concentration of PM2.5 was analyzed gravimetrically, water-soluble Inorganic Ions were determined by ion chromatography, and principle component analysis was employed for source apportionment. The results showed that the mass concentration of PM2.5 was 150.72μg·m-3 during the sampling period. The mass concentration was highest in winter and lowest in summer, and that of autumn is higher was higher than that of spring. The Ions SO42-, NO3-, and NH4+ were the major WSIs found in PM2.5, accounting for 92.55%, 92.94%, 93.06%, and 93.15% of the total amount of the seven Ions found in spring, summer, autumn, and winter, respectively. The anion-to-cation ratio was 0.886, which indicated that PM2.5 was slightly alkaline in Zhengzhou. Secondary Inorganic species, including NH4+, NO3-, and SO42- were the major components of the water-soluble Ions. These Ions most likely existed in the form of NH4NO3 and (NH4)2SO4 during spring and summer, while they were present as NH4NO3, (NH4)2SO4 and NH4HSO4 in autumn. In addition to these three forms, NH4Cl or other forms may exist in winter. Industrial emissIons, combustion, secondary transformation, soil, and construction dust were the major sources of the water-soluble Ions in PM2.5.
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the impact of relative humidity on the size distribution and chemical processes of major water soluble Inorganic Ions in the megacity of chongqing china
2017Co-Authors: Lu Wang, Meng Gao, Shili Tian, Tianxue Wen, Zirui Liu, Lili Wang, Changsheng Jiang, Yuesi WangAbstract:Abstract To investigate the impacts of relative humidity (RH) on the size distribution and evolution of water-soluble Inorganic Ions (WSIIs) in Chongqing, China, size-resolved aerosols were collected using nine-stage viable Andersen cascade impactors bi-weekly from June 2012 to May 2014. The WSIIs (SO42 −, NO3−, NH4+, K+, Na+, Cl−, Ca2 +, Mg2 + and F−) were analyzed. The SO42 −, NO3− and NH4+ peaks shifted from 0.43–0.65 μm particles at 40–60% RH to 0.65–1.1 μm particles at 70–90% RH. For K+, Na+ and Cl−, the peak concentratIons were in the size range of 0.65–2.1 μm and increased as the RH increased from 40 to 90%. However, the Ca2 +, Mg2 + and F− peaks at all RH levels were mainly concentrated in the coarse mode, and their concentratIons did not increase as regularly as those of SO42 −, NO3− and NH4+. All of the results suggest that RH was likely an important factor in determining the size distributIons of the WSIIs. SO42 −, NO3− and NH4+ increased linearly in all size ranges as a function of RH (40–90%). Additionally, SO42 − presented the highest rate of mass increase at 1.8 μg/m3/10% RH in 1.1
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seasonal variation and secondary formation of size segregated aerosol water soluble Inorganic Ions during pollution episodes in beijing
2016Co-Authors: Xiaojuan Huang, Zirui Liu, Tianxue Wen, Junke Zhang, Yuesi WangAbstract:Abstract Particulate matter (PM) pollution is a serious issue that has aroused great public attention in Beijing. To examine the seasonal characteristics of aerosols in typical pollution episodes, water-soluble Inorganic Ions (SO 4 2 − , NO 3 − , NH 4 + , Cl − , K + , Na + , Ca 2 + and Mg 2 + ) in size-segregated PM collected by an Anderson sampler (equipped with 50% effective cut-off diameters of 9.0, 5.8, 4.7, 3.3, 2.1, 1.1, 0.65, 0.43 μm and an after filter) were investigated in four intensive campaigns from June 2013 to May 2014 in the Beijing urban area. Pronounced seasonal variation of TWSIs in fine particles (aerodynamic diameter less than 2.1 μm) was observed, with the highest concentration in summer (71.5 ± 36.3 μg/m 3 ) and the lowest in spring (28.1 ± 15.2 μg/m 3 ). Different ion species presented different seasonal characteristics of mass concentration and size distribution, reflecting their different dominant sources. As the dominant component, SO 4 2 − , NO 3 − and NH 4 + (SNA) in fine particles appeared to play an important role in the formation of high PM pollution since its contribution to the TWSIs and PM 2.1 mass increased significantly during pollution episodes. Due to the hygroscopic growth and enhanced secondary formation in the droplet mode (0.65–2.1 μm) from clean days to polluted days, the size distribution peak of SNA in the fine mode tended to shift from 0.43–0.65 μm to 0.65–2.1 μm. Relative humidity (RH) and temperature contributed to influence the secondary formation and regulate the size distributIons of sulfates and nitrates. Partial correlation analysis found that high RH would promote the sulfur and nitrogen oxidation rates in the fine mode, while high temperature favored the sulfur oxidation rate in the condensation mode (0.43–0.65 μm) and reduced the nitrogen oxidation rate in the droplet mode (0.65–2.1 μm). The NO 3 − /SO 4 2 − mass ratio in PM 2.1 (73% of the samples) exceeded 1.0, suggesting that vehicle exhaust currently makes a greater contribution to aerosol pollution than stationary sources in Beijing.
Fumo Yang - One of the best experts on this subject based on the ideXlab platform.
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characterization of water soluble Inorganic Ions and their evolution processes during pm2 5 pollution episodes in a small city in southwest china
2019Co-Authors: Baoqing Qiao, Mi Tian, Huanbo Wang, Yang Chen, Leiming Zhang, Guangming Shi, Fumo Yang, Chao Peng, Qiong LuoAbstract:Abstract PM2.5 samples were collected in four segregate one-month periods, each representing one season, for analyzing their contents of water soluble Inorganic Ions (WSIIs) in a small city inside Sichuan Basin. Daily PM2.5 concentratIons ranged from 23.2 to 203.1 μg m−3 with an annual mean of 66.9 ± 33.6 μg m−3. Annual mean concentratIons of WSIIs was 28.8 ± 20.3 μg m−3, accounting for 43.1% of PM2.5. Seasonal mean concentratIons of WSIIs ranged from 17.5 ± 9.3 μg m−3 in summer to 46.5 ± 27.6 μg m−3 in winter. Annual mean mass ratio of NO3−/SO42− was 0.49, demonstrating predominant stationary sources for secondary Inorganic aerosols (SNA, including SO42−, NH4+ and NO3−); whereas annual mean molar ratio of [NH4+]/[NO3−] was 3.5, suggesting dominant agriculture emissIons contributing to the total nitrogen. During a severe and long-lasting (13 days) winter pollution period when mean PM2.5 concentration reached to 132.5 μg m−3, PM2.5 concentration was enhanced by a factor of 2.6 while that of SNA by a factor of 2.9 compared to those before the pollution event, and the fraction of SNA in PM2.5 only increased slightly (from 46.7% to 50.6%). Thus, local accumulation of pollutants under poor diffusion conditIons played a major role causing the extremely high PM2.5 concentration, besides the contributIons from the enhanced SNA formation under specific weather conditIons.
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highly time resolved characterization of water soluble Inorganic Ions in pm2 5 in a humid and acidic mega city in sichuan basin china
2017Co-Authors: Mi Tian, Huanbo Wang, Yang Chen, Leiming Zhang, Guangming Shi, Yuan Liu, Chongzhi Zhai, Jing Wang, Fumo YangAbstract:To investigate the characteristics of water-soluble Inorganic Ions (WSIIs) in Chongqing, a well-known foggy and acid region in southwestern China, hourly real-time concentratIons of five catIons (Na+, K+, NH4+, Ca2+, and Mg2+) and six anIons (F-, Cl-, NO2-, NO3-, PO43-, and SO42-) in PM2.5 during winter (from Dec. 18, 2015 to Mar. 20, 2016) in Chongqing were collected by applying In-situ Gas and Aerosol CompositIons Monitor. The hourly total concentration of WSIIs was 38.5μg/m3 on average, accounting for 57% of PM2.5 mass concentration. Secondary Inorganic aerosols (NH4+, NO3-, and SO42-) were dominant WSIIs, accounting for 91% of WSIIs mass. Compared to ten years ago, SO42- concentratIons were decreased by 31% but NO3- levels were doubled, likely indicative of sharply enhanced contribution to fine particle pollution from mobile sources over stationary sources. NO3- originated from the current fluxes of NH3 and HNO3 onto sulfate particles and/or from in-cloud processes were critical pathways under humid conditIons in the study area. Water content and/or RH might be important factors controlling nitrate formation. Trajectory analysis manifested that aerosol pollutIons in Chongqing were mostly caused by local emissIons.
Zirui Liu - One of the best experts on this subject based on the ideXlab platform.
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seasonal variation and secondary formation of size segregated aerosol water soluble Inorganic Ions in a coast megacity of north china plain
2020Co-Authors: Qing Yao, Zirui Liu, Xiaojuan Huang, Suqin Han, Ziying Cai, Jingle Liu, Tianyi Hao, Jinyun Liu, Yuesi WangAbstract:The aerosol samples of water-soluble Inorganic Ions (WSIs), including SO42−, NO3−, NH4+, Cl−, K+, Na+, Ca2+, and Mg2+ in size-segregated particulate matter (PM), were collected by an Anderson sampler (with 8 nominal cut-sizes ranged from 0.43 to 9.0 μm) in urban Tianjin during 2013–2014. The results showed that particulate matters in the fine mode (PM2.1, Dp < 2.1 μm) comprised large part of mass concentratIons of aerosols, and the water-soluble ionic species in the fine mode were 47.07 ± 14.29 μg m−3 (spring), 67.87 ± 28.74 μg m−3 (summer), 86.60 ± 48.53 μg m−3 (autumn), and 104.16 ± 51.76 μg m−3 (winter), respectively, which accounted for 59.5%, 63.3%, 71.9%, and 71.4% of the PM2.1 mass concentratIons. Secondary pollutants of SO42−, NO3−, and NH4+ (SNA) were the dominant contributors of WSIs, which showed a bimodal size distribution in each season, with the larger peak appeared in the size fraction of 0.65–1.1 μm and the smaller one in 3.3–5.8 μm fraction. SNA concentratIons in lightly polluted days (LPD) and heavily polluted days (HPD) were observably higher than non-polluted days (NPD), especially in the fine mode, with the peak diameter moving from 0.43–0.65 μm on NPD to 0.65–1.1 μm on LPD and HPD. The correlation analysis between NH4+, NO3−, and SO42− suggested that almost all SO42− and NO3− for fine particles had been completely neutralized by NH4+, and primarily existed in the forms of (NH4)2SO4 and NH4NO3. The sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) on LPD and HPD in fine mode were observably higher than those on NPD, especially in the range of 0.65–1.1 μm and 1.1–2.1 μm. Furthermore, SOR and NOR values in the size fraction of 0.43–3.3 μm increase as the RH elevated, especially in 0.43–2.1 μm, where RH was significantly positive correlated with SOR and NOR, indicating the significant contributIons of heterogeneous processes to the secondary formation of SO42− and NO3−. These results suggested an enhanced formation ability of secondary pollutants under high RH in the coast city. Therefore, controlling the precursors of SNA, such as SO2 and NOx, would be more effective to reduce the fine particulate pollution in the coast megacity of Tianjin.
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the impact of relative humidity on the size distribution and chemical processes of major water soluble Inorganic Ions in the megacity of chongqing china
2017Co-Authors: Lu Wang, Meng Gao, Shili Tian, Tianxue Wen, Zirui Liu, Lili Wang, Changsheng Jiang, Yuesi WangAbstract:Abstract To investigate the impacts of relative humidity (RH) on the size distribution and evolution of water-soluble Inorganic Ions (WSIIs) in Chongqing, China, size-resolved aerosols were collected using nine-stage viable Andersen cascade impactors bi-weekly from June 2012 to May 2014. The WSIIs (SO42 −, NO3−, NH4+, K+, Na+, Cl−, Ca2 +, Mg2 + and F−) were analyzed. The SO42 −, NO3− and NH4+ peaks shifted from 0.43–0.65 μm particles at 40–60% RH to 0.65–1.1 μm particles at 70–90% RH. For K+, Na+ and Cl−, the peak concentratIons were in the size range of 0.65–2.1 μm and increased as the RH increased from 40 to 90%. However, the Ca2 +, Mg2 + and F− peaks at all RH levels were mainly concentrated in the coarse mode, and their concentratIons did not increase as regularly as those of SO42 −, NO3− and NH4+. All of the results suggest that RH was likely an important factor in determining the size distributIons of the WSIIs. SO42 −, NO3− and NH4+ increased linearly in all size ranges as a function of RH (40–90%). Additionally, SO42 − presented the highest rate of mass increase at 1.8 μg/m3/10% RH in 1.1
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seasonal variation and secondary formation of size segregated aerosol water soluble Inorganic Ions during pollution episodes in beijing
2016Co-Authors: Xiaojuan Huang, Zirui Liu, Tianxue Wen, Junke Zhang, Yuesi WangAbstract:Abstract Particulate matter (PM) pollution is a serious issue that has aroused great public attention in Beijing. To examine the seasonal characteristics of aerosols in typical pollution episodes, water-soluble Inorganic Ions (SO 4 2 − , NO 3 − , NH 4 + , Cl − , K + , Na + , Ca 2 + and Mg 2 + ) in size-segregated PM collected by an Anderson sampler (equipped with 50% effective cut-off diameters of 9.0, 5.8, 4.7, 3.3, 2.1, 1.1, 0.65, 0.43 μm and an after filter) were investigated in four intensive campaigns from June 2013 to May 2014 in the Beijing urban area. Pronounced seasonal variation of TWSIs in fine particles (aerodynamic diameter less than 2.1 μm) was observed, with the highest concentration in summer (71.5 ± 36.3 μg/m 3 ) and the lowest in spring (28.1 ± 15.2 μg/m 3 ). Different ion species presented different seasonal characteristics of mass concentration and size distribution, reflecting their different dominant sources. As the dominant component, SO 4 2 − , NO 3 − and NH 4 + (SNA) in fine particles appeared to play an important role in the formation of high PM pollution since its contribution to the TWSIs and PM 2.1 mass increased significantly during pollution episodes. Due to the hygroscopic growth and enhanced secondary formation in the droplet mode (0.65–2.1 μm) from clean days to polluted days, the size distribution peak of SNA in the fine mode tended to shift from 0.43–0.65 μm to 0.65–2.1 μm. Relative humidity (RH) and temperature contributed to influence the secondary formation and regulate the size distributIons of sulfates and nitrates. Partial correlation analysis found that high RH would promote the sulfur and nitrogen oxidation rates in the fine mode, while high temperature favored the sulfur oxidation rate in the condensation mode (0.43–0.65 μm) and reduced the nitrogen oxidation rate in the droplet mode (0.65–2.1 μm). The NO 3 − /SO 4 2 − mass ratio in PM 2.1 (73% of the samples) exceeded 1.0, suggesting that vehicle exhaust currently makes a greater contribution to aerosol pollution than stationary sources in Beijing.
Leiming Zhang - One of the best experts on this subject based on the ideXlab platform.
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characterization of water soluble Inorganic Ions and their evolution processes during pm2 5 pollution episodes in a small city in southwest china
2019Co-Authors: Baoqing Qiao, Mi Tian, Huanbo Wang, Yang Chen, Leiming Zhang, Guangming Shi, Fumo Yang, Chao Peng, Qiong LuoAbstract:Abstract PM2.5 samples were collected in four segregate one-month periods, each representing one season, for analyzing their contents of water soluble Inorganic Ions (WSIIs) in a small city inside Sichuan Basin. Daily PM2.5 concentratIons ranged from 23.2 to 203.1 μg m−3 with an annual mean of 66.9 ± 33.6 μg m−3. Annual mean concentratIons of WSIIs was 28.8 ± 20.3 μg m−3, accounting for 43.1% of PM2.5. Seasonal mean concentratIons of WSIIs ranged from 17.5 ± 9.3 μg m−3 in summer to 46.5 ± 27.6 μg m−3 in winter. Annual mean mass ratio of NO3−/SO42− was 0.49, demonstrating predominant stationary sources for secondary Inorganic aerosols (SNA, including SO42−, NH4+ and NO3−); whereas annual mean molar ratio of [NH4+]/[NO3−] was 3.5, suggesting dominant agriculture emissIons contributing to the total nitrogen. During a severe and long-lasting (13 days) winter pollution period when mean PM2.5 concentration reached to 132.5 μg m−3, PM2.5 concentration was enhanced by a factor of 2.6 while that of SNA by a factor of 2.9 compared to those before the pollution event, and the fraction of SNA in PM2.5 only increased slightly (from 46.7% to 50.6%). Thus, local accumulation of pollutants under poor diffusion conditIons played a major role causing the extremely high PM2.5 concentration, besides the contributIons from the enhanced SNA formation under specific weather conditIons.
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highly time resolved characterization of water soluble Inorganic Ions in pm2 5 in a humid and acidic mega city in sichuan basin china
2017Co-Authors: Mi Tian, Huanbo Wang, Yang Chen, Leiming Zhang, Guangming Shi, Yuan Liu, Chongzhi Zhai, Jing Wang, Fumo YangAbstract:To investigate the characteristics of water-soluble Inorganic Ions (WSIIs) in Chongqing, a well-known foggy and acid region in southwestern China, hourly real-time concentratIons of five catIons (Na+, K+, NH4+, Ca2+, and Mg2+) and six anIons (F-, Cl-, NO2-, NO3-, PO43-, and SO42-) in PM2.5 during winter (from Dec. 18, 2015 to Mar. 20, 2016) in Chongqing were collected by applying In-situ Gas and Aerosol CompositIons Monitor. The hourly total concentration of WSIIs was 38.5μg/m3 on average, accounting for 57% of PM2.5 mass concentration. Secondary Inorganic aerosols (NH4+, NO3-, and SO42-) were dominant WSIIs, accounting for 91% of WSIIs mass. Compared to ten years ago, SO42- concentratIons were decreased by 31% but NO3- levels were doubled, likely indicative of sharply enhanced contribution to fine particle pollution from mobile sources over stationary sources. NO3- originated from the current fluxes of NH3 and HNO3 onto sulfate particles and/or from in-cloud processes were critical pathways under humid conditIons in the study area. Water content and/or RH might be important factors controlling nitrate formation. Trajectory analysis manifested that aerosol pollutIons in Chongqing were mostly caused by local emissIons.
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chemical composition sources and deposition fluxes of water soluble Inorganic Ions obtained from precipitation chemistry measurements collected at an urban site in northwest china
2012Co-Authors: Leiming Zhang, Zhenxing Shen, Junji Cao, Jing Tian, Li Liu, Geihui Wang, Zhuzi Zhao, Xin Wang, Renjian ZhangAbstract:Precipitation samples were collected at an urban site in Xi'an, northwest China during March to November in 2009 and were then analyzed to determine the pH and concentratIons of water-soluble Inorganic Ions (Na+, NH4+, K+, Mg2+, Ca2+, SO42−, NO3−, Cl−, and F−) in precipitation. The pH of precipitation ranged from 4.1 to 7.6 for all of the samples with an annual volume-weighted mean of 6.4. While a large portion of the precipitation events were weakly acidic or alkaline, around 30% of the precipitation events in the autumn were strongly acidic. Precipitation events with air masses from the northeast and the southeast were weakly acidic while those with air masses from the northwest and the southwest were alkaline. SO42−, Ca2+, NH4+, and NO3− were dominant Ions in the precipitation, accounting for 37%, 25%, 18%, and 9%, respectively, of the total analyzed Ions. Ca2+ and NH4+ were found to be the major neutralizers of precipitation acidity; however, the contribution of Mg2+, although much lower than those of Ca2+ and NH4+, was important, in many cases, in changing the precipitation from weakly acidic to weakly alkaline. Enrichment factor analysis confirmed that SO42− and NO3− were produced from anthropogenic sources, Ca2+, K+, and 80% Mg2+ were from crustal sources, and Na+, Cl−, and ∼20% of Mg2+ were from marine sources. The annual wet depositIons were estimated to be 3.5 t km−2 per year for sulfur; 2.3 t km−2 per year for nitrogen, of which 0.8 t km−2 per year was oxidized nitrogen and 1.5 t km−2 per year was reduced nitrogen; and 3.0 t km−2 per year for Ca2+.
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characterization of the size segregated water soluble Inorganic Ions at eight canadian rural sites
2008Co-Authors: Leiming Zhang, Robert Vet, A Wiebe, C Mihele, B Sukloff, Elton Chan, M D Moran, S IqbalAbstract:Abstract. Size-segregated water-soluble Inorganic Ions, including particulate sulphate (SO42-), nitrate (NO3-), ammonium (NH4+), chloride (Cl-), and base catIons (K+, Na+, Mg2+, Ca2+), were measured using a Micro-Orifice Uniform Deposit Impactor (MOUDI) during fourteen short-term field campaigns at eight locatIons in both polluted and remote regIons of eastern and central Canada. The size distributIons of SO42- and NH4+ were unimodal, peaking at 0.3–0.6 µm in diameter, during most of the campaigns, although a bimodal distribution was found during one campaign and a trimodal distribution was found during another campaign made at a coastal site. SO42- peaked at slightly larger sizes in the cold seasons (0.5–0.6 µm) compared to the hot seasons (0.3–0.4 µm) due to the higher relative humidity in the cold seasons. The size distributIons of NO3- were unimodal, peaking at 4.0–7.0 µm during the warm-season campaigns, and bimodal, with one peak at 0.3–0.6 µm and another at 4–7 µm during the cold-season campaigns. A unimodal size distribution, peaking at 4–6 µm, was found for Cl-, Na+, Mg2+, and Ca2+ during approximately half of the campaigns and a bimodal distribution, with one peak at 2 µm and the other at 6 µm, was found during the rest of the campaigns. For K+, a bimodal distribution, with one peak at 0.3 µm and the other at 4 µm, was observed during most of the campaigns. Seasonal contrasts in the size-distribution profiles suggest that emission sources and air mass origins were the major factors controlling the size distributIons of the primary aerosols while meteorological conditIons were more important for the secondary aerosols. The dependence of the particle acidity on the particle size from the nucleation mode to the accumulation mode was not consistent from site to site or from season to season. Particles in the accumulation mode were more acidic than those in the nucleation mode when submicron particles were in the state of strong acidity; however, when submicron particles were neutral or weakly acidic, particles in the nucleation mode could sometimes be more acidic. The inconsistency of the dependence of the particle acidity on the particle size should have been caused by the different emission sources of all the related species and the different meteorological conditIons during the different campaigns. The results presented here at least partially explain the controversial phenomenon found in previous studies on this topic.
Xiaojuan Huang - One of the best experts on this subject based on the ideXlab platform.
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seasonal variation and secondary formation of size segregated aerosol water soluble Inorganic Ions in a coast megacity of north china plain
2020Co-Authors: Qing Yao, Zirui Liu, Xiaojuan Huang, Suqin Han, Ziying Cai, Jingle Liu, Tianyi Hao, Jinyun Liu, Yuesi WangAbstract:The aerosol samples of water-soluble Inorganic Ions (WSIs), including SO42−, NO3−, NH4+, Cl−, K+, Na+, Ca2+, and Mg2+ in size-segregated particulate matter (PM), were collected by an Anderson sampler (with 8 nominal cut-sizes ranged from 0.43 to 9.0 μm) in urban Tianjin during 2013–2014. The results showed that particulate matters in the fine mode (PM2.1, Dp < 2.1 μm) comprised large part of mass concentratIons of aerosols, and the water-soluble ionic species in the fine mode were 47.07 ± 14.29 μg m−3 (spring), 67.87 ± 28.74 μg m−3 (summer), 86.60 ± 48.53 μg m−3 (autumn), and 104.16 ± 51.76 μg m−3 (winter), respectively, which accounted for 59.5%, 63.3%, 71.9%, and 71.4% of the PM2.1 mass concentratIons. Secondary pollutants of SO42−, NO3−, and NH4+ (SNA) were the dominant contributors of WSIs, which showed a bimodal size distribution in each season, with the larger peak appeared in the size fraction of 0.65–1.1 μm and the smaller one in 3.3–5.8 μm fraction. SNA concentratIons in lightly polluted days (LPD) and heavily polluted days (HPD) were observably higher than non-polluted days (NPD), especially in the fine mode, with the peak diameter moving from 0.43–0.65 μm on NPD to 0.65–1.1 μm on LPD and HPD. The correlation analysis between NH4+, NO3−, and SO42− suggested that almost all SO42− and NO3− for fine particles had been completely neutralized by NH4+, and primarily existed in the forms of (NH4)2SO4 and NH4NO3. The sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) on LPD and HPD in fine mode were observably higher than those on NPD, especially in the range of 0.65–1.1 μm and 1.1–2.1 μm. Furthermore, SOR and NOR values in the size fraction of 0.43–3.3 μm increase as the RH elevated, especially in 0.43–2.1 μm, where RH was significantly positive correlated with SOR and NOR, indicating the significant contributIons of heterogeneous processes to the secondary formation of SO42− and NO3−. These results suggested an enhanced formation ability of secondary pollutants under high RH in the coast city. Therefore, controlling the precursors of SNA, such as SO2 and NOx, would be more effective to reduce the fine particulate pollution in the coast megacity of Tianjin.
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seasonal variation and secondary formation of size segregated aerosol water soluble Inorganic Ions during pollution episodes in beijing
2016Co-Authors: Xiaojuan Huang, Zirui Liu, Tianxue Wen, Junke Zhang, Yuesi WangAbstract:Abstract Particulate matter (PM) pollution is a serious issue that has aroused great public attention in Beijing. To examine the seasonal characteristics of aerosols in typical pollution episodes, water-soluble Inorganic Ions (SO 4 2 − , NO 3 − , NH 4 + , Cl − , K + , Na + , Ca 2 + and Mg 2 + ) in size-segregated PM collected by an Anderson sampler (equipped with 50% effective cut-off diameters of 9.0, 5.8, 4.7, 3.3, 2.1, 1.1, 0.65, 0.43 μm and an after filter) were investigated in four intensive campaigns from June 2013 to May 2014 in the Beijing urban area. Pronounced seasonal variation of TWSIs in fine particles (aerodynamic diameter less than 2.1 μm) was observed, with the highest concentration in summer (71.5 ± 36.3 μg/m 3 ) and the lowest in spring (28.1 ± 15.2 μg/m 3 ). Different ion species presented different seasonal characteristics of mass concentration and size distribution, reflecting their different dominant sources. As the dominant component, SO 4 2 − , NO 3 − and NH 4 + (SNA) in fine particles appeared to play an important role in the formation of high PM pollution since its contribution to the TWSIs and PM 2.1 mass increased significantly during pollution episodes. Due to the hygroscopic growth and enhanced secondary formation in the droplet mode (0.65–2.1 μm) from clean days to polluted days, the size distribution peak of SNA in the fine mode tended to shift from 0.43–0.65 μm to 0.65–2.1 μm. Relative humidity (RH) and temperature contributed to influence the secondary formation and regulate the size distributIons of sulfates and nitrates. Partial correlation analysis found that high RH would promote the sulfur and nitrogen oxidation rates in the fine mode, while high temperature favored the sulfur oxidation rate in the condensation mode (0.43–0.65 μm) and reduced the nitrogen oxidation rate in the droplet mode (0.65–2.1 μm). The NO 3 − /SO 4 2 − mass ratio in PM 2.1 (73% of the samples) exceeded 1.0, suggesting that vehicle exhaust currently makes a greater contribution to aerosol pollution than stationary sources in Beijing.
