The Experts below are selected from a list of 29475 Experts worldwide ranked by ideXlab platform

J Chen - One of the best experts on this subject based on the ideXlab platform.

  • chemical composition and sources of submicron aerosol in a Coastal City of china results from the 2017 brics summit study
    Science of The Total Environment, 2020
    Co-Authors: Yanru Zhang, Youwei Hong, J Chen, Mazhan Zhuang, Guoqing Zhao, Lei Tong, Yuping Chen, Chen Yang, Hang Xiao, Yahui Bian
    Abstract:

    Abstract Chemical compositions of non-refractory submicron aerosol (NR-PM1) were measured via an Aerodyne Aerosol Chemical Speciation Monitor at the Coastal City Xiamen during the 2017 BRICS summit from August 10 to September 10. Mean hourly concentration of NR-PM1 was 13.55 ± 8.83 μg m−3 during the study period, decreasing from 18.83 μg m−3 before-BRICS to 13.02 μg m−3 in BRCIS I and 8.42 μg m−3 in BRICS II. Positive matrix factor analyses resolved four organic aerosols (OA): a hydrocarbon-like OA (HOA, 14.78%), a cooking-related OA (COA, 28.21%), a biomass burning OA (BBOA, 18.00%), and an oxygenated OA (OOA, 39.22%). The contributions of local pollutants like nitrate and HOA reduced, while the proportions of sulfate and OOA increased during the control episodes. The diurnal patterns of NR-PM1 species and OA components in each episode were characterized. The results showed that BC, nitrate, COA, and HOA had peaks in the morning and evening, which became less obvious under the emission control. Moreover, the diurnal variations of all species in Ep 3 with emission control were much flatter due to the effect of transport. Backward trajectories analysis confirmed the long-range transport of air masses from the continent, which resulted in the high proportions of sulfate (43.69%) and OOA (50.28%) in Ep 3. Our study implies the significant effect of emission control on reducing primary pollutants, but the formation of particles during the long-range transport need to be paid more attention when set the air quality control strategies in Coastal cities.

  • exploration of the atmospheric chemistry of nitrous acid in a Coastal City of southeastern china results from measurements across four seasons
    Atmospheric Chemistry and Physics, 2020
    Co-Authors: Jun Duan, Youwei Hong, Yahui Bian, Min Qin, Wu Fang, Pinhua Xie, J Chen
    Abstract:

    Abstract. Because nitrous acid (HONO) photolysis is a key source of hydroxyl (OH) radicals, identifying the atmospheric sources of HONO is essential to enhance the understanding of atmospheric chemistry processes and improve the accuracy of simulation models. We performed seasonal field observations of HONO in a Coastal City of southeastern China, along with measurements of trace gases, aerosol compositions, photolysis rate constants (J), and meteorological parameters. The results showed that the average observed concentration of HONO was 0.54 ± 0.47 ppb. Vehicle exhaust emissions contributed an average of 1.64 % to HONO, higher than the values found in most other studies, suggesting an influence from diesel vehicle emissions. The mean conversion frequency of NO2 to HONO in the nighttime was the highest in summer due to water droplets was evaporated under the condition of high temperatures. Based on a budget analysis, the rate of emission from unknown sources (Runknown) was highest at midday, with values of 14.78 ppb h−1 in summer, 6.49 ppb h−1 in autumn, and 2.18 ppb h−1 in spring. Unknown sources made up the largest proportion of all sources in summer (84.92 %), autumn (80.29 %), and spring (49.98 %), whereas the main source in winter was the homogeneous reaction of NO with OH (56.15 %), due to winter having the highest NO concentration of the four seasons. The value of Runknown had a positive logarithmic relationship with the photolysis of particulate nitrate in spring, summer, and autumn. However, Runknown was limited by particulate acidity under the condition of photolysis of particulate nitrate (J (NO3−_R) × pNO3−) > 1 µg m−3 s−1 in autumn and J(NO3−_R) × pNO3− > 2 µg m−3 s−1 in spring and summer. The variation of HONO at night can be exactly simulated based on the HONO / NOx ratio, while the main sources should be considered for daytime simulations. Compared with O3 photolysis, HONO photolysis has long been an important source of OH, particularly in the morning in spring and winter and around noon in summer and autumn. This study draws a full picture of the sources of HONO across all four seasons and improves the comprehension of HONO chemistry in southeastern Coastal China.

  • characteristics of peroxyacetyl nitrate pan in a Coastal City of southeastern china photochemical mechanism and pollution process
    Science of The Total Environment, 2020
    Co-Authors: Baoye Hu, Youwei Hong, Lingling Xu, Mengren Li, Xin Wu, Hong Wang, J Chen
    Abstract:

    Abstract Peroxyacetyl nitrate (PAN) can effectively indicate photochemical pollution, and also plays a vital role in regional oxidant balance. One-year continuous monitoring of PAN in a Coastal City of southeastern China was investigated. The mean concentration of PAN in winter (0.64 ppb) was close to that in autumn (0.73 ppb), indicating that photochemical pollution was still non-negligible in the cold season. The peak occurrence time between O3 and PAN had a delay of 1–2 h in four seasons, due to the rapid decomposition rate of PAN in midday. Emission sources of the precursors are located to the south of the monitoring site, so high concentrations of PAN and O3 are frequently observed under southerly wind conditions. The air mass with low concentration of PAN (0.22–0.34 ppb) and O3 (18.17–23.67 ppb) originated from the ocean with less anthropogenic air pollutants. Continental air mass with high PAN concentration might be related to the contribution of heterogeneous reactions of PM2.5 to the promotion of PAN formation. In the polluted case, PAN concentration was often higher than 1.0 ppb and reached the peak of 4.2 ppb, suggesting the influence of photochemical reactions and local accumulation. High concentrations of HONO and sufficient ultraviolet radiation might be the main factors for rapid photochemical production of PAN. Besides, the lifetime of PAN in winter under the condition of high PM2.5 concentration (≥35 μg·m−3) was up to 3.246 days. This study provided insights into photochemical mechanism and pollution process in a Coastal City of southeastern China.

  • aerosol light absorption in a Coastal City in southeast china temporal variations and implications for brown carbon
    Journal of Environmental Sciences-china, 2019
    Co-Authors: Yuqing Qiu, Youwei Hong, Xiaoqiu Chen, Yanru Zhang, J Chen, Junjun Deng
    Abstract:

    Abstract Light-absorbing carbonaceous aerosols including black carbon (BC) and brown carbon (BrC) play significant roles in atmospheric radiative properties. One-year measurements of aerosol light absorption at multi-wavelength were continuously conducted in Xiamen, southeast of China in 2014 to determine the light absorption properties including absorption coefficients (σabs) and absorption Angstrom exponent (AAE) in the Coastal City. Light absorptions of BC and BrC with their contributions to total light absorption were further quantified. Mean σabs at 370 nm and 880 nm were 56.6 ± 34.3 and 16.5 ± 11.2 Mm− 1, respectively. σabs presented a double-peaks diurnal pattern with the maximum in the morning and the minimum in the afternoon. σabs was low in warm seasons and high in cold seasons. AAE ranged from 0.26 to 2.58 with the annual mean of 1.46, implying that both fossil fuel combustion and biomass burning influenced aerosol optical properties. σabs of BrC at 370 nm was 24.0 ± 5.7 Mm− 1, contributing 42% to the total absorption. The highest AAE (1.52 ± 0.02) and largest BrC contributions (47% ± 4%) in winter suggested the significant influence of biomass burning on aerosol light absorption. Long-distance air masses passing through North China Plain and the Yangtze River Delta led to high AAE and BrC contributions. High AAE value of 1.46 in July indicated that long-range transport of the air pollutants from intense biomass burning in Southeast Asia would affect aerosol light absorption in Southeast China. The study will improve the understanding of light absorption properties of aerosols and the optical impacts of BrC in China.

  • composition mixing state and size distribution of single submicron particles during pollution episodes in a Coastal City in southeast china
    Environmental Science and Pollution Research, 2019
    Co-Authors: Lingling Xu, Youwei Hong, Xin Wu, Yanru Zhang, Junjun Deng, Zhenyu Hong, J Chen
    Abstract:

    Size-resolved particle composition, size distribution, and mixing state were characterized at the single-particle level during two air pollution episodes during 12–25 January, 2016 in a Coastal City in southeast China. The two pollution episodes occurred under distinct meteorological conditions (i.e., different wind speeds, relative humidity, and backward trajectories); thus, they were assigned to stagnation and transport episodes, respectively. Single-particle data, obtained from single-particle aerosol mass spectrometry (SPAMS), showed that carbonaceous particles were the predominant particles during the whole study period, accounting for more than 60% of the total particles. However, the number fractions of carbonaceous particles and nitrate-containing particles significantly increased in the stagnation episode, while the number fractions of sulfate- and ammonium-containing particles both increased in the transport episode compared to the levels over the whole study period. The potassium-rich (K-rich) particle class was more abundant and more strongly mixed with sulfate in the transport episode, which indicates the impact of biomass burning emissions and the subsequent aging process by acquiring sulfate during transport. The particle classes (e.g., carbonaceous and K-rich classes) had a broader size distribution during the pollution episodes than during the clean episode. The diameters of the size distribution peak for all particle classes (except for dust class) were observed to be larger in the transport episode than in the stagnation episode. This suggests that the particles underwent an extensive aging process through the addition of sulfate and ammonium during transport, leading to the growth of particles.

Youwei Hong - One of the best experts on this subject based on the ideXlab platform.

  • chemical composition and sources of submicron aerosol in a Coastal City of china results from the 2017 brics summit study
    Science of The Total Environment, 2020
    Co-Authors: Yanru Zhang, Youwei Hong, J Chen, Mazhan Zhuang, Guoqing Zhao, Lei Tong, Yuping Chen, Chen Yang, Hang Xiao, Yahui Bian
    Abstract:

    Abstract Chemical compositions of non-refractory submicron aerosol (NR-PM1) were measured via an Aerodyne Aerosol Chemical Speciation Monitor at the Coastal City Xiamen during the 2017 BRICS summit from August 10 to September 10. Mean hourly concentration of NR-PM1 was 13.55 ± 8.83 μg m−3 during the study period, decreasing from 18.83 μg m−3 before-BRICS to 13.02 μg m−3 in BRCIS I and 8.42 μg m−3 in BRICS II. Positive matrix factor analyses resolved four organic aerosols (OA): a hydrocarbon-like OA (HOA, 14.78%), a cooking-related OA (COA, 28.21%), a biomass burning OA (BBOA, 18.00%), and an oxygenated OA (OOA, 39.22%). The contributions of local pollutants like nitrate and HOA reduced, while the proportions of sulfate and OOA increased during the control episodes. The diurnal patterns of NR-PM1 species and OA components in each episode were characterized. The results showed that BC, nitrate, COA, and HOA had peaks in the morning and evening, which became less obvious under the emission control. Moreover, the diurnal variations of all species in Ep 3 with emission control were much flatter due to the effect of transport. Backward trajectories analysis confirmed the long-range transport of air masses from the continent, which resulted in the high proportions of sulfate (43.69%) and OOA (50.28%) in Ep 3. Our study implies the significant effect of emission control on reducing primary pollutants, but the formation of particles during the long-range transport need to be paid more attention when set the air quality control strategies in Coastal cities.

  • exploration of the atmospheric chemistry of nitrous acid in a Coastal City of southeastern china results from measurements across four seasons
    Atmospheric Chemistry and Physics, 2020
    Co-Authors: Jun Duan, Youwei Hong, Yahui Bian, Min Qin, Wu Fang, Pinhua Xie, J Chen
    Abstract:

    Abstract. Because nitrous acid (HONO) photolysis is a key source of hydroxyl (OH) radicals, identifying the atmospheric sources of HONO is essential to enhance the understanding of atmospheric chemistry processes and improve the accuracy of simulation models. We performed seasonal field observations of HONO in a Coastal City of southeastern China, along with measurements of trace gases, aerosol compositions, photolysis rate constants (J), and meteorological parameters. The results showed that the average observed concentration of HONO was 0.54 ± 0.47 ppb. Vehicle exhaust emissions contributed an average of 1.64 % to HONO, higher than the values found in most other studies, suggesting an influence from diesel vehicle emissions. The mean conversion frequency of NO2 to HONO in the nighttime was the highest in summer due to water droplets was evaporated under the condition of high temperatures. Based on a budget analysis, the rate of emission from unknown sources (Runknown) was highest at midday, with values of 14.78 ppb h−1 in summer, 6.49 ppb h−1 in autumn, and 2.18 ppb h−1 in spring. Unknown sources made up the largest proportion of all sources in summer (84.92 %), autumn (80.29 %), and spring (49.98 %), whereas the main source in winter was the homogeneous reaction of NO with OH (56.15 %), due to winter having the highest NO concentration of the four seasons. The value of Runknown had a positive logarithmic relationship with the photolysis of particulate nitrate in spring, summer, and autumn. However, Runknown was limited by particulate acidity under the condition of photolysis of particulate nitrate (J (NO3−_R) × pNO3−) > 1 µg m−3 s−1 in autumn and J(NO3−_R) × pNO3− > 2 µg m−3 s−1 in spring and summer. The variation of HONO at night can be exactly simulated based on the HONO / NOx ratio, while the main sources should be considered for daytime simulations. Compared with O3 photolysis, HONO photolysis has long been an important source of OH, particularly in the morning in spring and winter and around noon in summer and autumn. This study draws a full picture of the sources of HONO across all four seasons and improves the comprehension of HONO chemistry in southeastern Coastal China.

  • characteristics of pm2 5 bound secondary organic aerosol tracers in a Coastal City in southeastern china seasonal patterns and pollution identification
    Atmospheric Environment, 2020
    Co-Authors: Baoye Hu, Xinbei Xu, Youwei Hong, Lingling Xu, Mengren Li, Yanting Chen, Xin Wu, Yanru Zhang, Xiaoqiu Chen
    Abstract:

    Abstract Secondary organic aerosol (SOA) plays an important role in global climate change and air quality, and SOA tracers most directly characterize the sources and formation mechanisms of SOA. Four seasons of observation of SOA tracers was carried out in a Coastal City of southeastern China. Fourteen p.m.2.5-bound SOA tracers, including isoprene (SOAI), α/β-pinene (SOAM), β-caryophyllene (SOAC), and toluene (SOAA), were measured using the GC-MS method. The concentrations of SOA tracers in Fuzhou were 25.9 ± 19.9 ng m−3 (SOAM), 7.45 ± 8.53 ng m−3 (SOAI), 3.15 ± 1.99 ng m−3 (SOAC), and 2.63 ± 1.54 ng m−3 (SOAA). The elevated SOAI concentration in summer was mainly controlled by high biogenic isoprene emission and strong oxidation, and biomass burning contributed strongly to DHOPA (SOAA) in fall. SO42− and H + insitu had an increased impact on later-generation SOAI products and low-NOx SOAM products. Based on the ratio of MGA/MTL and MBTCA/(PA + PNA), atmospheric oxidation capaCity (Ox, =NO2+O3) had a significant impact on the aerosol aging of SOA tracers. The increased proportions of low-NOx SOAI products were 3.23–7.21 times higher than those of high-NOx products from non-haze to haze periods, suggesting the influence of high SO42− concentration and RH on the reaction channel for SOAI formation. The percentages of later-generation SOAM products during RT were 2.46 times higher than those of first-generation products, suggesting the influence of aerosol aging during the regional transport. Both continental Asian outflow and biomass-burning plumes promoted precursor emissions and the formation process of SOA during the haze pollution events. These related findings help to understand the occurrence, sources and formation of SOA in Coastal areas.

  • characteristics of peroxyacetyl nitrate pan in a Coastal City of southeastern china photochemical mechanism and pollution process
    Science of The Total Environment, 2020
    Co-Authors: Baoye Hu, Youwei Hong, Lingling Xu, Mengren Li, Xin Wu, Hong Wang, J Chen
    Abstract:

    Abstract Peroxyacetyl nitrate (PAN) can effectively indicate photochemical pollution, and also plays a vital role in regional oxidant balance. One-year continuous monitoring of PAN in a Coastal City of southeastern China was investigated. The mean concentration of PAN in winter (0.64 ppb) was close to that in autumn (0.73 ppb), indicating that photochemical pollution was still non-negligible in the cold season. The peak occurrence time between O3 and PAN had a delay of 1–2 h in four seasons, due to the rapid decomposition rate of PAN in midday. Emission sources of the precursors are located to the south of the monitoring site, so high concentrations of PAN and O3 are frequently observed under southerly wind conditions. The air mass with low concentration of PAN (0.22–0.34 ppb) and O3 (18.17–23.67 ppb) originated from the ocean with less anthropogenic air pollutants. Continental air mass with high PAN concentration might be related to the contribution of heterogeneous reactions of PM2.5 to the promotion of PAN formation. In the polluted case, PAN concentration was often higher than 1.0 ppb and reached the peak of 4.2 ppb, suggesting the influence of photochemical reactions and local accumulation. High concentrations of HONO and sufficient ultraviolet radiation might be the main factors for rapid photochemical production of PAN. Besides, the lifetime of PAN in winter under the condition of high PM2.5 concentration (≥35 μg·m−3) was up to 3.246 days. This study provided insights into photochemical mechanism and pollution process in a Coastal City of southeastern China.

  • the air pollution governed by subtropical high in a Coastal City in southeast china formation processes and influencing mechanisms
    Science of The Total Environment, 2019
    Co-Authors: Xin Wu, Baoye Hu, Youwei Hong, Lingling Xu, Yanru Zhang, Jinfang Chen, Zhenyu Hong, Yantin Chen, Yahui Bian, Guoqing Zhao
    Abstract:

    Abstract To investigate the impact of the Western Pacific subtropical high (WPSH) on the air pollution episode of Xiamen, a Coastal City in Southeastern China, this study focused on formation processes and influencing mechanisms of an air pollution episode from 17th to 23rd September 2017. The results showed that the WPSH fluctuated in this period and intensified this air pollution with local emissions. The episode was divided into four stages according to WPSH center locations to diagnose the air pollution. Visibility declined below 10 km twice while fine particulate matte (PM2.5) concentration was up to 89.05 μg/m3 during this episode. As a consequence of high temperature (28.33 ± 1.25 °C) resulted from WPSH, atmospheric oxidation at high level (140.81 ± 56.49 μg/m3) was the driving force of secondary aerosols generations. Oxidation determined photo-chemical reactions with the pathways of gas-phase and heterogeneous formation. Sulfate was formed from gas-phase oxidation by SO2 in daytime while heterogeneous reaction occurred at night. Nitrate generation was dominated by not only excess ammonium but also intense oxidation. Reconstruction light extinction results coupling with trajectories revealed that (NH4)2SO4, NH4NO3 and OM were the priority factors to the reduction of atmospheric visibility. These findings provided new insights of air pollution episode diagnosis and indicative function of WPSH impacts on local air quality in Southeast China.

Junjun Deng - One of the best experts on this subject based on the ideXlab platform.

  • aerosol light absorption in a Coastal City in southeast china temporal variations and implications for brown carbon
    Journal of Environmental Sciences-china, 2019
    Co-Authors: Yuqing Qiu, Youwei Hong, Xiaoqiu Chen, Yanru Zhang, J Chen, Junjun Deng
    Abstract:

    Abstract Light-absorbing carbonaceous aerosols including black carbon (BC) and brown carbon (BrC) play significant roles in atmospheric radiative properties. One-year measurements of aerosol light absorption at multi-wavelength were continuously conducted in Xiamen, southeast of China in 2014 to determine the light absorption properties including absorption coefficients (σabs) and absorption Angstrom exponent (AAE) in the Coastal City. Light absorptions of BC and BrC with their contributions to total light absorption were further quantified. Mean σabs at 370 nm and 880 nm were 56.6 ± 34.3 and 16.5 ± 11.2 Mm− 1, respectively. σabs presented a double-peaks diurnal pattern with the maximum in the morning and the minimum in the afternoon. σabs was low in warm seasons and high in cold seasons. AAE ranged from 0.26 to 2.58 with the annual mean of 1.46, implying that both fossil fuel combustion and biomass burning influenced aerosol optical properties. σabs of BrC at 370 nm was 24.0 ± 5.7 Mm− 1, contributing 42% to the total absorption. The highest AAE (1.52 ± 0.02) and largest BrC contributions (47% ± 4%) in winter suggested the significant influence of biomass burning on aerosol light absorption. Long-distance air masses passing through North China Plain and the Yangtze River Delta led to high AAE and BrC contributions. High AAE value of 1.46 in July indicated that long-range transport of the air pollutants from intense biomass burning in Southeast Asia would affect aerosol light absorption in Southeast China. The study will improve the understanding of light absorption properties of aerosols and the optical impacts of BrC in China.

  • composition mixing state and size distribution of single submicron particles during pollution episodes in a Coastal City in southeast china
    Environmental Science and Pollution Research, 2019
    Co-Authors: Lingling Xu, Youwei Hong, Xin Wu, Yanru Zhang, Junjun Deng, Zhenyu Hong, J Chen
    Abstract:

    Size-resolved particle composition, size distribution, and mixing state were characterized at the single-particle level during two air pollution episodes during 12–25 January, 2016 in a Coastal City in southeast China. The two pollution episodes occurred under distinct meteorological conditions (i.e., different wind speeds, relative humidity, and backward trajectories); thus, they were assigned to stagnation and transport episodes, respectively. Single-particle data, obtained from single-particle aerosol mass spectrometry (SPAMS), showed that carbonaceous particles were the predominant particles during the whole study period, accounting for more than 60% of the total particles. However, the number fractions of carbonaceous particles and nitrate-containing particles significantly increased in the stagnation episode, while the number fractions of sulfate- and ammonium-containing particles both increased in the transport episode compared to the levels over the whole study period. The potassium-rich (K-rich) particle class was more abundant and more strongly mixed with sulfate in the transport episode, which indicates the impact of biomass burning emissions and the subsequent aging process by acquiring sulfate during transport. The particle classes (e.g., carbonaceous and K-rich classes) had a broader size distribution during the pollution episodes than during the clean episode. The diameters of the size distribution peak for all particle classes (except for dust class) were observed to be larger in the transport episode than in the stagnation episode. This suggests that the particles underwent an extensive aging process through the addition of sulfate and ammonium during transport, leading to the growth of particles.

  • characteristics and source apportionment of volatile organic compounds for different functional zones in a Coastal City of southeast china
    Aerosol and Air Quality Research, 2018
    Co-Authors: Junjun Deng, J Chen, Xiaoqiu Chen, Zhenyu Hong, Youwei Hong
    Abstract:

    Volatile organic compounds (VOCs) are the key precursors of tropospheric ozone and contributors to the formation of secondary organic aerosols (SOAs). VOCs from six functional zones in a Coastal City in China were collected via SUMMA canister and determined via gas chromatography-mass spectrometry (GC-MS). The average annual concentrations of the total VOCs (TVOCs) were as follows: background site (36.00 µg m–3) < residential site (48.71 µg m–3) < port site (61.09 µg m–3) ≈ development site (62.25 µg m–3) < traffic site (73.82 µg m–3) < industrial site (98.33 µg m–3). The concentrations of TVOCs in spring and summer were higher than in autumn and winter. The ozone formation potentials (OFPs) were calculated, and the results indicated that 1-butene exhibited the highest OFP in the residential zone, while toluene exhibited the highest value in the other functional zones. The ratio of xylene to ethylbenzene was used to analyze the aging of atmospheric VOCs at the background site, which was affected by air pollution transported from urban areas. The sources of VOCs, namely, vehicle exhaust, fuel evaporation, biomass burning, industrial processes, and coal combustion, were identified with the Positive Matrix Factorization (PMF) model. Vehicle exhaust represented the largest source of atmospheric VOCs for every season, ranging 22.41–38.95%; additionally, the percentage of fuel evaporation increased in summer, reaching as high as 25.94%. The contributions of biomass burning were larger in autumn (21.11%) and winter (18.01%) than in spring (11.23%) and summer (16.94%), probably reflecting crop straw burning in the later seasons. Vehicle exhaust was the dominant source of VOCs (30.04–44.39%) in all functional zones, except for the residential site, which received its largest contribution (36.20%) from fuel evaporation.

  • pattern of atmospheric mercury speciation during episodes of elevated pm2 5 levels in a Coastal City in the yangtze river delta china
    Environmental Pollution, 2016
    Co-Authors: Youwei Hong, Yanting Chen, J Chen, Junjun Deng, Zhenchuan Niu, Liqian Yin, Lei Tong, Zhenyu Hong
    Abstract:

    Measurement of atmospheric mercury speciation was conducted in a Coastal City of the Yangtze River Delta, China from July 2013 to January 2014, in conjunction with air pollutants and meteorological parameters. The mean concentrations of gaseous elemental mercury (GEM), particulate bound mercury (HgP) and reactive gaseous mercury (RGM) were 3.26 ± 1.63 ng m−3, 659 ± 931 pg m−3, and 197 ± 246 pg m−3, respectively. High percentages of HgP during haze days were found, due to the increase in direct emissions and gas-particle partitioning of RGM. The average gas-particle partitioning coefficients (Kp) during moderate or severe haze days (PM2.5 > 150 μg m−3) were obviously decreased. GEM and HgP were positively correlated with PM2.5, SO2, NO2 and CO, suggesting a significant contribution of anthropogenic sources. Elevated HgP concentrations in cold seasons and in the morning were observed while RGM exhibited different seasonal and diurnal pattern. The ratio of HgP/SO2 and Pearson correlation analysis suggested that coal combustion was the main cause of increasing atmospheric Hg concentrations. The monitoring site was affected by local, regional and interregional sources. The back trajectory analysis suggested that air mass from northwest China and Huabei Plain contributed to elevated atmospheric Hg in winter and autumn, while southeast China with clean air masses were the major contributor in summer.

  • optical properties of pm2 5 and the impacts of chemical compositions in the Coastal City xiamen in china
    Science of The Total Environment, 2016
    Co-Authors: Junjun Deng, Youwei Hong, Yanting Chen, Yanru Zhang, J Chen
    Abstract:

    Abstract Continuous in situ measurements of optical properties of fine aerosols (PM 2.5 ) were conducted in the urbanized Coastal City Xiamen in Southeast China from November 2013 to January 2014. PM 2.5 samples were also collected and chemical compositions including organic carbon (OC), elemental carbon (EC) and water-soluble inorganic ions were determined to investigate the impacts of chemical compositions on aerosol optical properties. Average values of scattering coefficient (b scat ), absorption coefficient (b abs ), extinction coefficient (b ext ) and single scattering albedo (SSA) were 164.0 Mm − 1 , 22.4 Mm − 1 , 187.0 Mm − 1 and 0.88, respectively. b scat , b abs and b ext showed obvious bi-modal diurnal variations with high values in the morning and at night while low value in the early afternoon, whereas SSA exhibited an opposite diurnal variation. Average b scat and b abs were largest in the wind direction of southwest and were larger with slower wind. b abs was mainly affected by EC, while b scat was affected by ammonium, sulfate, nitrate and OC. The IMPROVE formula was applied to estimate b ext based on the chemical species. Results shows that ammonium sulfate was the largest contributor, accounting for 36.4% of b ext , followed by organic matter (30.6%), ammonium nitrate (20.1%), EC (9.0%) and sea salt (3.9%). The deterioration in visibility was mainly led by increases in secondary aerosols including sulfate and nitrate. Backward trajectories analysis showed that during the sampling period Xiamen was significantly affected by the air masses originating from the Northern and Northeastern areas. Air masses from the Northern associated with relative higher b ext and less relative contribution from ammonium sulfate and more relative contribution from ammonium nitrate, organic matter and sea salt.

Yanting Chen - One of the best experts on this subject based on the ideXlab platform.

  • characteristics of pm2 5 bound secondary organic aerosol tracers in a Coastal City in southeastern china seasonal patterns and pollution identification
    Atmospheric Environment, 2020
    Co-Authors: Baoye Hu, Xinbei Xu, Youwei Hong, Lingling Xu, Mengren Li, Yanting Chen, Xin Wu, Yanru Zhang, Xiaoqiu Chen
    Abstract:

    Abstract Secondary organic aerosol (SOA) plays an important role in global climate change and air quality, and SOA tracers most directly characterize the sources and formation mechanisms of SOA. Four seasons of observation of SOA tracers was carried out in a Coastal City of southeastern China. Fourteen p.m.2.5-bound SOA tracers, including isoprene (SOAI), α/β-pinene (SOAM), β-caryophyllene (SOAC), and toluene (SOAA), were measured using the GC-MS method. The concentrations of SOA tracers in Fuzhou were 25.9 ± 19.9 ng m−3 (SOAM), 7.45 ± 8.53 ng m−3 (SOAI), 3.15 ± 1.99 ng m−3 (SOAC), and 2.63 ± 1.54 ng m−3 (SOAA). The elevated SOAI concentration in summer was mainly controlled by high biogenic isoprene emission and strong oxidation, and biomass burning contributed strongly to DHOPA (SOAA) in fall. SO42− and H + insitu had an increased impact on later-generation SOAI products and low-NOx SOAM products. Based on the ratio of MGA/MTL and MBTCA/(PA + PNA), atmospheric oxidation capaCity (Ox, =NO2+O3) had a significant impact on the aerosol aging of SOA tracers. The increased proportions of low-NOx SOAI products were 3.23–7.21 times higher than those of high-NOx products from non-haze to haze periods, suggesting the influence of high SO42− concentration and RH on the reaction channel for SOAI formation. The percentages of later-generation SOAM products during RT were 2.46 times higher than those of first-generation products, suggesting the influence of aerosol aging during the regional transport. Both continental Asian outflow and biomass-burning plumes promoted precursor emissions and the formation process of SOA during the haze pollution events. These related findings help to understand the occurrence, sources and formation of SOA in Coastal areas.

  • chemical composition structural properties and source apportionment of organic macromolecules in atmospheric pm10 in a Coastal City of southeast china
    Environmental Science and Pollution Research, 2017
    Co-Authors: Yanting Chen, Youwei Hong, J Chen, Jinping Zhao, Hang Xiao
    Abstract:

    Particulate matter (PM10) associated with the fractions of organic macromolecules, including humic acid (HA), kerogen + black carbon (KB), and black carbon (BC), was determined during summer and winter at urban and suburban sites in a Coastal City of southeast China. The organic macromolecules were characterized by elemental analysis (EA), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR), and their sources were identified by using stable carbon/nitrogen isotope (δ13C/δ15N) and the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) Model. The results showed that HA, kerogen (K), and BC accounted for the range of 3.89 to 4.55 % in PM10, while they were the dominant fractions of total organic carbon (TOC), ranging from 64.70 to 84.99 %. SEM analysis indicated that BC particles were porous/nonporous and consisted of spherical and non-spherical (i.e., cylindrical and elongate) structures. The FTIR spectra of HA, KB, and BC exhibited similar functional groups, but the difference of various sites and seasons was observed. HA in PM10 contained a higher fraction of aliphatic structures, such as long-chain fatty and carbohydrates with a carboxylic extremity. The C/N ratio, SEM, and δ13C/δ15N values provided reliable indicators of the sources of HA, K, and BC in PM10. The results suggested that HA and K majorly originated from terrestrial plants, and BC came from the mixture of combustion of terrestrial plants, fossil fuel, and charcoal. The air masses in winter originated from Mongolia (4 %), the northern area of China (48 %), and northern adjacent cities (48 %), suggesting the influence of anthropogenic sources through long-range transport, while the air masses for the summer period came from South China Sea (34 %) and Western Pacific Sea (66 %), representing clean marine air masses with low concentrations of organic macromolecules.

  • pattern of atmospheric mercury speciation during episodes of elevated pm2 5 levels in a Coastal City in the yangtze river delta china
    Environmental Pollution, 2016
    Co-Authors: Youwei Hong, Yanting Chen, J Chen, Junjun Deng, Zhenchuan Niu, Liqian Yin, Lei Tong, Zhenyu Hong
    Abstract:

    Measurement of atmospheric mercury speciation was conducted in a Coastal City of the Yangtze River Delta, China from July 2013 to January 2014, in conjunction with air pollutants and meteorological parameters. The mean concentrations of gaseous elemental mercury (GEM), particulate bound mercury (HgP) and reactive gaseous mercury (RGM) were 3.26 ± 1.63 ng m−3, 659 ± 931 pg m−3, and 197 ± 246 pg m−3, respectively. High percentages of HgP during haze days were found, due to the increase in direct emissions and gas-particle partitioning of RGM. The average gas-particle partitioning coefficients (Kp) during moderate or severe haze days (PM2.5 > 150 μg m−3) were obviously decreased. GEM and HgP were positively correlated with PM2.5, SO2, NO2 and CO, suggesting a significant contribution of anthropogenic sources. Elevated HgP concentrations in cold seasons and in the morning were observed while RGM exhibited different seasonal and diurnal pattern. The ratio of HgP/SO2 and Pearson correlation analysis suggested that coal combustion was the main cause of increasing atmospheric Hg concentrations. The monitoring site was affected by local, regional and interregional sources. The back trajectory analysis suggested that air mass from northwest China and Huabei Plain contributed to elevated atmospheric Hg in winter and autumn, while southeast China with clean air masses were the major contributor in summer.

  • optical properties of pm2 5 and the impacts of chemical compositions in the Coastal City xiamen in china
    Science of The Total Environment, 2016
    Co-Authors: Junjun Deng, Youwei Hong, Yanting Chen, Yanru Zhang, J Chen
    Abstract:

    Abstract Continuous in situ measurements of optical properties of fine aerosols (PM 2.5 ) were conducted in the urbanized Coastal City Xiamen in Southeast China from November 2013 to January 2014. PM 2.5 samples were also collected and chemical compositions including organic carbon (OC), elemental carbon (EC) and water-soluble inorganic ions were determined to investigate the impacts of chemical compositions on aerosol optical properties. Average values of scattering coefficient (b scat ), absorption coefficient (b abs ), extinction coefficient (b ext ) and single scattering albedo (SSA) were 164.0 Mm − 1 , 22.4 Mm − 1 , 187.0 Mm − 1 and 0.88, respectively. b scat , b abs and b ext showed obvious bi-modal diurnal variations with high values in the morning and at night while low value in the early afternoon, whereas SSA exhibited an opposite diurnal variation. Average b scat and b abs were largest in the wind direction of southwest and were larger with slower wind. b abs was mainly affected by EC, while b scat was affected by ammonium, sulfate, nitrate and OC. The IMPROVE formula was applied to estimate b ext based on the chemical species. Results shows that ammonium sulfate was the largest contributor, accounting for 36.4% of b ext , followed by organic matter (30.6%), ammonium nitrate (20.1%), EC (9.0%) and sea salt (3.9%). The deterioration in visibility was mainly led by increases in secondary aerosols including sulfate and nitrate. Backward trajectories analysis showed that during the sampling period Xiamen was significantly affected by the air masses originating from the Northern and Northeastern areas. Air masses from the Northern associated with relative higher b ext and less relative contribution from ammonium sulfate and more relative contribution from ammonium nitrate, organic matter and sea salt.

  • characteristics and sources of atmospheric mercury speciation in a Coastal City xiamen china
    Chemosphere, 2015
    Co-Authors: J Chen, Zhenchuan Niu, Liqian Yin, Lei Tong, Liming Yang, Yanting Chen
    Abstract:

    Abstract Semi-continental monitoring of gaseous elemental mercury (GEM), particulate mercury (Hg p ), and reactive gaseous mercury (RGM) was conducted in the Institute of Urban Environment, CAS in Xiamen, China from March 2012 to February 2013. The average concentrations and relative standard deviations (RSD) were 3.50 (34.6%) ng m −3 , 174.41 (160.9%) pg m −3 , and 61.05 (113.7%) pg m −3 for GEM, Hg p , and RGM, respectively. The higher concentrations of GEM and Hg p were observed in spring and winter months, indicating the combustion source, while RGM showed the different seasonal variation with highest concentration in spring and the minimum value in winter. The concentrations of Hg species were generally elevated in nighttime and low in daytime to reflect the diurnal changes in meteorology, especially the mixing condition of the air masses. The high Hg concentrations were observed in SWW–NW sectors due to calm wind while the low levels in NE–SE due to high speed wind, and the amplitude was much larger for Hg p and RGM. Backward trajectories calculation indicated that summer air masses were much more from ocean with lower Hg while the air masses were mainly from inland area in other seasons. Principal component analysis suggested that combustion and road traffic emissions were the dominant anthropogenic mercury sources for the study area, and the temporal distribution of atmospheric mercury was mainly the result of climatological change.

Yanru Zhang - One of the best experts on this subject based on the ideXlab platform.

  • chemical composition and sources of submicron aerosol in a Coastal City of china results from the 2017 brics summit study
    Science of The Total Environment, 2020
    Co-Authors: Yanru Zhang, Youwei Hong, J Chen, Mazhan Zhuang, Guoqing Zhao, Lei Tong, Yuping Chen, Chen Yang, Hang Xiao, Yahui Bian
    Abstract:

    Abstract Chemical compositions of non-refractory submicron aerosol (NR-PM1) were measured via an Aerodyne Aerosol Chemical Speciation Monitor at the Coastal City Xiamen during the 2017 BRICS summit from August 10 to September 10. Mean hourly concentration of NR-PM1 was 13.55 ± 8.83 μg m−3 during the study period, decreasing from 18.83 μg m−3 before-BRICS to 13.02 μg m−3 in BRCIS I and 8.42 μg m−3 in BRICS II. Positive matrix factor analyses resolved four organic aerosols (OA): a hydrocarbon-like OA (HOA, 14.78%), a cooking-related OA (COA, 28.21%), a biomass burning OA (BBOA, 18.00%), and an oxygenated OA (OOA, 39.22%). The contributions of local pollutants like nitrate and HOA reduced, while the proportions of sulfate and OOA increased during the control episodes. The diurnal patterns of NR-PM1 species and OA components in each episode were characterized. The results showed that BC, nitrate, COA, and HOA had peaks in the morning and evening, which became less obvious under the emission control. Moreover, the diurnal variations of all species in Ep 3 with emission control were much flatter due to the effect of transport. Backward trajectories analysis confirmed the long-range transport of air masses from the continent, which resulted in the high proportions of sulfate (43.69%) and OOA (50.28%) in Ep 3. Our study implies the significant effect of emission control on reducing primary pollutants, but the formation of particles during the long-range transport need to be paid more attention when set the air quality control strategies in Coastal cities.

  • characteristics of pm2 5 bound secondary organic aerosol tracers in a Coastal City in southeastern china seasonal patterns and pollution identification
    Atmospheric Environment, 2020
    Co-Authors: Baoye Hu, Xinbei Xu, Youwei Hong, Lingling Xu, Mengren Li, Yanting Chen, Xin Wu, Yanru Zhang, Xiaoqiu Chen
    Abstract:

    Abstract Secondary organic aerosol (SOA) plays an important role in global climate change and air quality, and SOA tracers most directly characterize the sources and formation mechanisms of SOA. Four seasons of observation of SOA tracers was carried out in a Coastal City of southeastern China. Fourteen p.m.2.5-bound SOA tracers, including isoprene (SOAI), α/β-pinene (SOAM), β-caryophyllene (SOAC), and toluene (SOAA), were measured using the GC-MS method. The concentrations of SOA tracers in Fuzhou were 25.9 ± 19.9 ng m−3 (SOAM), 7.45 ± 8.53 ng m−3 (SOAI), 3.15 ± 1.99 ng m−3 (SOAC), and 2.63 ± 1.54 ng m−3 (SOAA). The elevated SOAI concentration in summer was mainly controlled by high biogenic isoprene emission and strong oxidation, and biomass burning contributed strongly to DHOPA (SOAA) in fall. SO42− and H + insitu had an increased impact on later-generation SOAI products and low-NOx SOAM products. Based on the ratio of MGA/MTL and MBTCA/(PA + PNA), atmospheric oxidation capaCity (Ox, =NO2+O3) had a significant impact on the aerosol aging of SOA tracers. The increased proportions of low-NOx SOAI products were 3.23–7.21 times higher than those of high-NOx products from non-haze to haze periods, suggesting the influence of high SO42− concentration and RH on the reaction channel for SOAI formation. The percentages of later-generation SOAM products during RT were 2.46 times higher than those of first-generation products, suggesting the influence of aerosol aging during the regional transport. Both continental Asian outflow and biomass-burning plumes promoted precursor emissions and the formation process of SOA during the haze pollution events. These related findings help to understand the occurrence, sources and formation of SOA in Coastal areas.

  • the air pollution governed by subtropical high in a Coastal City in southeast china formation processes and influencing mechanisms
    Science of The Total Environment, 2019
    Co-Authors: Xin Wu, Baoye Hu, Youwei Hong, Lingling Xu, Yanru Zhang, Jinfang Chen, Zhenyu Hong, Yantin Chen, Yahui Bian, Guoqing Zhao
    Abstract:

    Abstract To investigate the impact of the Western Pacific subtropical high (WPSH) on the air pollution episode of Xiamen, a Coastal City in Southeastern China, this study focused on formation processes and influencing mechanisms of an air pollution episode from 17th to 23rd September 2017. The results showed that the WPSH fluctuated in this period and intensified this air pollution with local emissions. The episode was divided into four stages according to WPSH center locations to diagnose the air pollution. Visibility declined below 10 km twice while fine particulate matte (PM2.5) concentration was up to 89.05 μg/m3 during this episode. As a consequence of high temperature (28.33 ± 1.25 °C) resulted from WPSH, atmospheric oxidation at high level (140.81 ± 56.49 μg/m3) was the driving force of secondary aerosols generations. Oxidation determined photo-chemical reactions with the pathways of gas-phase and heterogeneous formation. Sulfate was formed from gas-phase oxidation by SO2 in daytime while heterogeneous reaction occurred at night. Nitrate generation was dominated by not only excess ammonium but also intense oxidation. Reconstruction light extinction results coupling with trajectories revealed that (NH4)2SO4, NH4NO3 and OM were the priority factors to the reduction of atmospheric visibility. These findings provided new insights of air pollution episode diagnosis and indicative function of WPSH impacts on local air quality in Southeast China.

  • aerosol light absorption in a Coastal City in southeast china temporal variations and implications for brown carbon
    Journal of Environmental Sciences-china, 2019
    Co-Authors: Yuqing Qiu, Youwei Hong, Xiaoqiu Chen, Yanru Zhang, J Chen, Junjun Deng
    Abstract:

    Abstract Light-absorbing carbonaceous aerosols including black carbon (BC) and brown carbon (BrC) play significant roles in atmospheric radiative properties. One-year measurements of aerosol light absorption at multi-wavelength were continuously conducted in Xiamen, southeast of China in 2014 to determine the light absorption properties including absorption coefficients (σabs) and absorption Angstrom exponent (AAE) in the Coastal City. Light absorptions of BC and BrC with their contributions to total light absorption were further quantified. Mean σabs at 370 nm and 880 nm were 56.6 ± 34.3 and 16.5 ± 11.2 Mm− 1, respectively. σabs presented a double-peaks diurnal pattern with the maximum in the morning and the minimum in the afternoon. σabs was low in warm seasons and high in cold seasons. AAE ranged from 0.26 to 2.58 with the annual mean of 1.46, implying that both fossil fuel combustion and biomass burning influenced aerosol optical properties. σabs of BrC at 370 nm was 24.0 ± 5.7 Mm− 1, contributing 42% to the total absorption. The highest AAE (1.52 ± 0.02) and largest BrC contributions (47% ± 4%) in winter suggested the significant influence of biomass burning on aerosol light absorption. Long-distance air masses passing through North China Plain and the Yangtze River Delta led to high AAE and BrC contributions. High AAE value of 1.46 in July indicated that long-range transport of the air pollutants from intense biomass burning in Southeast Asia would affect aerosol light absorption in Southeast China. The study will improve the understanding of light absorption properties of aerosols and the optical impacts of BrC in China.

  • composition mixing state and size distribution of single submicron particles during pollution episodes in a Coastal City in southeast china
    Environmental Science and Pollution Research, 2019
    Co-Authors: Lingling Xu, Youwei Hong, Xin Wu, Yanru Zhang, Junjun Deng, Zhenyu Hong, J Chen
    Abstract:

    Size-resolved particle composition, size distribution, and mixing state were characterized at the single-particle level during two air pollution episodes during 12–25 January, 2016 in a Coastal City in southeast China. The two pollution episodes occurred under distinct meteorological conditions (i.e., different wind speeds, relative humidity, and backward trajectories); thus, they were assigned to stagnation and transport episodes, respectively. Single-particle data, obtained from single-particle aerosol mass spectrometry (SPAMS), showed that carbonaceous particles were the predominant particles during the whole study period, accounting for more than 60% of the total particles. However, the number fractions of carbonaceous particles and nitrate-containing particles significantly increased in the stagnation episode, while the number fractions of sulfate- and ammonium-containing particles both increased in the transport episode compared to the levels over the whole study period. The potassium-rich (K-rich) particle class was more abundant and more strongly mixed with sulfate in the transport episode, which indicates the impact of biomass burning emissions and the subsequent aging process by acquiring sulfate during transport. The particle classes (e.g., carbonaceous and K-rich classes) had a broader size distribution during the pollution episodes than during the clean episode. The diameters of the size distribution peak for all particle classes (except for dust class) were observed to be larger in the transport episode than in the stagnation episode. This suggests that the particles underwent an extensive aging process through the addition of sulfate and ammonium during transport, leading to the growth of particles.