scholarly journals Enhancement of secondary aerosol formation by reduced anthropogenic emissions during Spring Festival 2019 and enlightenment for regional PM<sub>2.5</sub> control in Beijing

2020 ◽  
Author(s):  
Yuying Wang ◽  
Zhanqing Li ◽  
Qiuyan Wang ◽  
Xiaoai Jin ◽  
Peng Yan ◽  
...  
Keyword(s):  
Particle Number ◽  
Surface Ozone ◽  
Sulfur Oxidation ◽  
Anthropogenic Emissions ◽  
Aerosol Formation ◽  
Spring Festival ◽  
Sulfate Formation ◽  
Oxidation Ratio ◽  
The Impact ◽  
Mass Concentrations

Abstract. A comprehensive field experiment measuring aerosol chemical and physical properties at a suburban site in Beijing around the 2019 Spring Festival was carried out to investigate the impact of reduced anthropogenic emissions on aerosol formation. Sharply reduced sulfur dioxide (SO2) and nitrogen dioxide (NO2) concentrations during the festival holiday resulted in an unexpected increase in the surface ozone (O3) concentration, leading to enhancement of the atmospheric oxidation capacity. Simultaneously, the reduced anthropogenic emissions resulted in massive decreases in particle number concentration at all sizes and the mass concentrations of organics and black carbon. However, the mass concentrations of inorganics (especially sulfate) decreased weakly. Detailed analyses of the sulfur oxidation ratio and the nitrogen oxidation ratio suggest that sulfate formation during the holiday could be promoted by enhanced nocturnal aqueous-phase chemical reactions between SO2 and O3 under moderate relative humidity (RH) conditions (40 % 

scholarly journals Enhancement of secondary aerosol formation by reduced anthropogenic emissions during Spring Festival 2019 and enlightenment for regional PM<sub>2.5</sub> control in Beijing

2021 ◽  
Vol 21 (2) ◽  
pp. 915-926
Author(s):  
Yuying Wang ◽  
Zhanqing Li ◽  
Qiuyan Wang ◽  
Xiaoai Jin ◽  
Peng Yan ◽  
...  
Keyword(s):  
Surface Ozone ◽  
Regional Analysis ◽  
Sulfur Oxidation ◽  
Photochemical Reactions ◽  
Anthropogenic Emissions ◽  
Aerosol Formation ◽  
Spring Festival ◽  
Oxidation Ratio ◽  
The Impact ◽  
Mass Concentrations

Abstract. A comprehensive field experiment measuring aerosol chemical and physical properties at a suburban site in Beijing around the 2019 Spring Festival was carried out to investigate the impact of reduced anthropogenic emissions on aerosol formation. Sharply reduced sulfur dioxide (SO2) and nitrogen dioxide (NO2) concentrations during the festival holiday resulted in an unexpected increase in the surface ozone (O3) concentration caused by the strong O3-titration phenomenon. Simultaneously, the reduced anthropogenic emissions resulted in massive decreases in particle number concentration at all sizes and the mass concentrations of organics and black carbon. However, the mass concentrations of inorganics (especially sulfate) decreased weakly. Detailed analyses of the sulfur oxidation ratio and the nitrogen oxidation ratio suggest that sulfate formation during the holiday could be promoted by enhanced nocturnal aqueous-phase chemical reactions between SO2 and O3 under moderate relative humidity (RH) conditions (40 % < RH < 80 %). Daytime photochemical reactions in winter in Beijing mainly controlled nitrate formation, which was enhanced a little during the holiday. A regional analysis of air pollution patterns shows that the enhanced formation of secondary aerosols occurred throughout the entire Beijing–Tianjin–Hebei (BTH) region during the holiday, partly offsetting the decrease in particle matter with an aerodynamic diameter less than 2.5 µm. Our results highlight the necessary control of O3 formation to reduce secondary pollution in winter under current emission conditions.

scholarly journals Ammonium nitrate promotes sulfate formation through uptake kinetic regime

2021 ◽  
Vol 21 (17) ◽  
pp. 13269-13286
Author(s):  
Yongchun Liu ◽  
Zemin Feng ◽  
Feixue Zheng ◽  
Xiaolei Bao ◽  
Pengfei Liu ◽  
...  
Keyword(s):  
Formation Rate ◽  
Sulfur Oxidation ◽  
Ambient Air ◽  
Particle State ◽  
Kinetic Regime ◽  
Uptake Kinetic ◽  
Rate Determining Step ◽  
Sulfate Formation ◽  
Oxidation Ratio

Abstract. Although the anthropogenic emissions of SO2 have decreased significantly in China, the decrease in SO42- in PM2.5 is much smaller than that of SO2. This implies an enhanced formation rate of SO42- in the ambient air, and the mechanism is still under debate. This work investigated the formation mechanism of particulate sulfate based on statistical analysis of long-term observations in Shijiazhuang and Beijing supported with flow tube experiments. Our main finding was that the sulfur oxidation ratio (SOR) was exponentially correlated with ambient RH in Shijiazhuang (SOR = 0.15+0.0032×exp⁡(RH/16.2)) and Beijing (SOR = -0.045+0.12×exp⁡(RH/37.8)). In Shijiazhuang, the SOR is linearly correlated with the ratio of aerosol water content (AWC) in PM2.5 (SOR = 0.15+0.40×AWC/PM2.5). Our results suggest that uptake of SO2 instead of oxidation of S(IV) in the particle phase is the rate-determining step for sulfate formation. NH4NO3 plays an important role in the AWC and the change of particle state, which is a crucial factor determining the uptake kinetics of SO2 and the enhanced SOR during haze days. Our results show that NH3 significantly promoted the uptake of SO2 and subsequently the SOR, while NO2 had little influence on SO2 uptake and SOR in the presence of NH3.

Results on an Inter-model Comparison on Secondary Aerosol Formation

2021 ◽  
Author(s):  
Jiani Tan ◽  
Joshua Fu ◽  
Gregory Carmichael ◽  
Hang Su ◽  
Yafang Cheng
Keyword(s):  
Model Comparison ◽  
Model Performance ◽  
Sulfur Oxidation ◽  
Pollution Indices ◽  
Aerosol Formation ◽  
Transport Models ◽  
Secondary Aerosol ◽  
Third Phase ◽  
Chemical Transport Models ◽  
Oxidation Ratio

&lt;p&gt;This study aims at comparing the gas-to-particle conversion mechanisms adopted by regional chemical transport models (CTMs). We use the results from twelve regional CTMs from the third phase of the Model Inter-Comparison Study for Asia (MICS-Asia III). The simulations are conducted over East Asia for the whole year of 2010. The models used are WRF-CMAQ (version 4.7.1 and v5.0.2), WRF-Chem (v3.6.1 and v3.7.1), GEOS-Chem, NHM-Chem, NAQPMS and NU-WRF. Measurements from 54 EANET sites, 86 sites of the Air Pollution Indices (API) and 35 local sites, remote sensing products from AERONET and satellite data from MODIS are used to evaluate model performance on PM&lt;sub&gt;10&lt;/sub&gt;, PM&lt;sub&gt;2.5&lt;/sub&gt; and its components and aerosol optical depth (AOD). To investigate the inter-model differences in secondary aerosol formation, we compare the Sulfur Oxidation Ratio (SOR) and Nitrogen Oxidation Ratio (NOR) values by different models with observations at the EANET sites. The preliminary results show that the inter-model differences in the oxidation ratio (50%) are almost of the same magnitude as those in simulating the concentrations of particles. The results suggest large uncertainties in the gas-particle conversion process in modelling secondary aerosol formation.&lt;/p&gt;

Studies of urban aerosol particle number and mass concentrations with a mobile platform: The roles of COVID-19, traffic, and meteorology

2021 ◽  
Author(s):  
Otto Klemm ◽  
David F. Berger ◽  
Bettina Breuer ◽  
Sophia Buchholz ◽  
Laura Ehrnsperger ◽  
...  
Keyword(s):  
Central Europe ◽  
Aerosol Particle ◽  
Particle Number ◽  
Meteorological Conditions ◽  
Urban Aerosol ◽  
Strong Impact ◽  
Traffic Intensity ◽  
Day Of The Week ◽  
The Impact ◽  
Mass Concentrations

&lt;p&gt;Although urban air pollution is on the decline in central Europe, it still causes several hundreds of thousands of premature deaths per year. The EU standards of atmospheric aerosol particle mass concentrations PM10 and PM2.5 (&amp;#181;g m&lt;sup&gt;-3&lt;/sup&gt;) have not been exceeded anymore in Germany in 2020, yet there is a rather large uncertainty about the toxicity of particle number concentrations PN (cm&lt;sup&gt;-3&lt;/sup&gt;), for which no legal limits are established. High PN concentrations are typically caused by the exhaust of motorized road vehicles. From 2019 through 2021, national lockdowns in response to the COVID-19 pandemic resulted in reduced human activity. The traffic intensity was heavily reduced, which should have led to an equally strong reaction of the urban aerosol particle concentrations, specifically the PN concentrations. For NO&lt;sub&gt;x&lt;/sub&gt; and PM10, it has been shown for sections of central Europe that the decrease of urban concentrations was not as intense as expected by traffic reduction, because lockdowns coincided with periods of low wind speeds and poor atmospheric exchange conditions. We performed meteorological and air chemistry measurements with an instrumented cargo bicycle before, during, and after the COVID-19 lockdown periods in M&amp;#252;nster, Germany. During each ride, two circular routes around the city center were realized, a high-traffic route and a low-traffic route. A complex picture emerged with varying impact of the day of the week, selection of route, meteorological conditions, and traffic intensity driving the PN and PM concentrations. Single-ride high-resolution analysis showed convincingly that the multitude of exhaust plumes from motorized vehicles exerted a strong impact on the PN concentrations. A relative importance analysis was performed on the entire dataset. According to the statistical analysis, PM10 responded most to the day of the week. Although the traffic intensity was also low on weekends, the impact of traffic on PM10 was rather low. Presumably, PM10 responded either to a specific traffic component such as commercial, low-duty vehicles, or to other business with weakly cycles such as construction activity. The meteorological conditions exert impact mostly through the relative humidity, which affects particle growth and reduction of the PN concentration. The role of the lockdowns was quite little overall. For future research, a more complete coverage of the seasons of the year is recommended as well as the inclusion of NO&lt;sub&gt;x&lt;/sub&gt; measurements on board of the cargo bicycle.&amp;#160;&lt;/p&gt;

scholarly journals Decreasing Trends of Particle Number and Black Carbon Mass Concentrations at 16 Observational Sites in Germany from 2009 to 2018

2019 ◽  
Author(s):  
Jia Sun ◽  
Wolfram Birmili ◽  
Markus Hermann ◽  
Thomas Tuch ◽  
Kay Weinhold ◽  
...  
Keyword(s):  
Time Series ◽  
Black Carbon ◽  
Urban Areas ◽  
Mass Concentration ◽  
Particle Number ◽  
Regional Scale ◽  
Particle Diameter ◽  
Anthropogenic Emissions ◽  
Mitigation Policies ◽  
Mass Concentrations

Abstract. Anthropogenic emissions are a dominant contributor to air pollution. Consequently, mitigation policies have attempted to reduce anthropogenic pollution emissions in Europe since the 1990s. To evaluate the effectiveness of these mitigation policies, the German Ultrafine Aerosol Network (GUAN) was established in 2008, focusing on black carbon and sub-micrometer aerosol particles, especially ultrafine particles. In this investigation, trends of the size-resolved particle number concentrations (PNC) and the equivalent black carbon (eBC) mass concentration over a 10-year period (2009–2018) were evaluated for 16 observational sites for different environments among GUAN. The trend analysis was done for both, the full-length time series and on subsets of the time series in order to test the reliability of the results. The results show generally decreasing trends of both, the PNCs for all size ranges as well as eBC mass concentrations in all environments, except PNC in 10–30 nm at regional background and mountain sites. The annual slope of the eBC mass concentration varies between −7.7 % and −1.8 % per year. The slopes of the PNCs varies from −6.3 % to 2.7 %, −7.0 % to −2.0 %, and −9.5 % to −1.5 % per year (only significant trends) for 10–30 nm, 30–200 nm, and 200–800 nm particle diameter, respectively. The regional Mann-Kendall test yielded regional-scale trends of eBC mass concentration, N[30–200] and N[200–800] of −3.8 %, −2.0 % and −2.4 %, respectively, indicating an overall decreasing trend for eBC mass concentration and sub-micrometer PNC (except N[10–30]) all over Germany. The most significant decrease was observed on working days and during daytime in urban areas, which implies a strong evidence of reduced anthropogenic emissions. For the seasonal trends, stronger reductions were observed in winter. Possible reasons for this reduction can be the increased average ambient temperatures and wind speed in winter, which resulted in less domestic heating and stronger dilution. In addition, decreased precipitation in summer also diminishes the decrease of the PNCs and eBC mass concentration. For the period of interest, there were no significant changes in long-range transport patterns. The most likely factors for the observed decreasing trends are declining anthropogenic emissions due to emission mitigation policies of the European Union.

scholarly journals Characterizing the impact of urban emissions on regional aerosol particles: airborne measurements during the MEGAPOLI experiment

2014 ◽  
Vol 14 (3) ◽  
pp. 1397-1412 ◽  
Author(s):  
E. J. Freney ◽  
K. Sellegri ◽  
F. Canonaco ◽  
A. Colomb ◽  
A. Borbon ◽  
...  
Keyword(s):  
Gas Phase ◽  
Organic Aerosol ◽  
Aerosol Formation ◽  
Air Mass ◽  
Airborne Measurements ◽  
Aerosol Mass ◽  
Urban Emissions ◽  
The Impact ◽  
The City ◽  
Mass Concentrations

Abstract. The MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation) experiment took place in July 2009. The aim of this campaign was to study the aging and reactions of aerosol and gas-phase emissions in the city of Paris. Three ground-based measurement sites and several mobile platforms including instrument equipped vehicles and the ATR-42 aircraft were involved. We present here the variations in particle- and gas-phase species over the city of Paris, using a combination of high-time resolution measurements aboard the ATR-42 aircraft. Particle chemical composition was measured using a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS), giving detailed information on the non-refractory submicron aerosol species. The mass concentration of black carbon (BC), measured by a particle absorption soot photometer (PSAP), was used as a marker to identify the urban pollution plume boundaries. Aerosol mass concentrations and composition were affected by air-mass history, with air masses that spent longest time over land having highest fractions of organic aerosol and higher total mass concentrations. The Paris plume is mainly composed of organic aerosol (OA), BC, and nitrate aerosol, as well as high concentrations of anthropogenic gas-phase species such as toluene, benzene, and NOx. Using BC and CO as tracers for air-mass dilution, we observe the ratio of ΔOA / ΔBC and ΔOA / ΔCO increase with increasing photochemical age (−log(NOx / NOy)). Plotting the equivalent ratios of different organic aerosol species (LV-OOA, SV-OOA, and HOA) illustrate that the increase in OA is a result of secondary organic aerosol (SOA) formation. Within Paris the changes in the ΔOA / ΔCO are similar to those observed during other studies in London, Mexico City, and in New England, USA. Using the measured SOA volatile organic compounds (VOCs) species together with organic aerosol formation yields, we were able to predict ~50% of the measured organics. These airborne measurements during the MEGAPOLI experiment show that urban emissions contribute to the formation of OA and have an impact on aerosol composition on a regional scale.

scholarly journals Reanalysis of and attribution to near-surface ozone concentrations in Sweden during 1990–2013

2017 ◽  
Vol 17 (22) ◽  
pp. 13869-13890 ◽  
Author(s):  
Camilla Andersson ◽  
Heléne Alpfjord ◽  
Lennart Robertson ◽  
Per Erik Karlsson ◽  
Magnuz Engardt
Keyword(s):  
Transport Model ◽  
Linear Trend ◽  
Surface Ozone ◽  
Vegetation Indices ◽  
High Sensitivity ◽  
Anthropogenic Emissions ◽  
Data Sets ◽  
Near Surface ◽  
The Impact ◽  
Surface O3

Abstract. We have constructed two data sets of hourly resolution reanalyzed near-surface ozone (O3) concentrations for the period 1990–2013 for Sweden. Long-term simulations from a chemistry-transport model (CTM) covering Europe were combined with hourly ozone concentration observations at Swedish and Norwegian background measurement sites using retrospective variational data analysis. The reanalysis data sets show improved performance over the original CTM when compared to independent observations. In one of the reanalyses, we included all available hourly near-surface O3 observations, whilst in the other we carefully selected time-consistent observations. Based on the second reanalysis we investigated statistical aspects of the distribution of the near-surface O3 concentrations, focusing on the linear trend over the 24-year period. We show that high near-surface O3 concentrations are decreasing and low O3 concentrations are increasing, which is reflected in observed improvement of many health and vegetation indices (apart from those with a low threshold). Using the CTM we also conducted sensitivity simulations to quantify the causes of the observed change, focusing on three factors: change in hemispheric background concentrations, meteorology and anthropogenic emissions. The rising low concentrations of near-surface O3 in Sweden are caused by a combination of all three factors, whilst the decrease in the highest O3 concentrations is caused by European O3 precursor emissions reductions. While studying the impact of anthropogenic emissions changes, we identified systematic differences in the modeled trend compared to observations that must be caused by incorrect trends in the utilized emissions inventory or by too high sensitivity of our model to emissions changes.

scholarly journals Environmentally dependent dust chemistry of a super Asian dust storm in March 2010: observation and simulation

2017 ◽  
Author(s):  
Qiongzhen Wang ◽  
Xinyi Dong ◽  
Joshua S. Fu ◽  
Jian Xu ◽  
Congrui Deng ◽  
...  
Keyword(s):  
Air Quality ◽  
Dust Storm ◽  
Model Simulation ◽  
Eastern China ◽  
Heterogeneous Reactions ◽  
Anthropogenic Emissions ◽  
Aerosol Formation ◽  
Air Quality Model ◽  
Near Surface ◽  
The Impact

Abstract. Near surface and vertical in situ measurements of atmospheric aerosols were conducted in Shanghai during March 19–27, 2010 to explore the transport and chemical evolution of dust aerosols in a super dust storm. An air quality model with optimized physical dust emission scheme and newly implemented dust chemistry was utilized to study the impact of dust chemistry on regional air quality. Two discontinuous dust periods were observed with one travelling over Northern China (DS1) and the other passing over the coastal regions of Eastern China (DS2). Stronger mixing extents between dust and anthropogenic emissions were found in DS2, reflecting by the higher SO2/PM10 and NO2/PM10 ratios as well as typical pollution elemental species such as As, Cd, Pb, and Zn. As a result, the concentrations of SO42− and NO3− and the ratio of Ca2+/Ca were more elevated in DS2 than in DS1 but opposite for the [NH4+]/[SO42−+NO3−] ratio, suggesting the heterogeneous reactions between calcites and acid gases were significantly promoted in DS2 due to the higher level of relative humidity and gaseous pollution precursors. Lidar observation showed a columnar effect on the vertical structure of aerosol optical properties in DS1 that dust dominantly accounted for ~80–90 % of the total aerosol extinction from near the ground to ~700 m. In contrast, the dust plumes in DS2 were refrained within lower altitudes while the extinction from spheric particles exhibited maximum at a high altitude of ~800 m. The model simulation reproduced relatively consistent results with observations that strong impacts of dust heterogeneous reactions on secondary aerosol formation occurred in areas where the anthropogenic emissions were intensive. Compared to the sulfate simulation, the nitrate formation on dust is suggested to be improved in the future modeling efforts.

Climate/chemistry feedbacks and biogenic emissions

2007 ◽  
Vol 365 (1856) ◽  
pp. 1727-1740 ◽  
Author(s):  
John A Pyle ◽  
Nicola Warwick ◽  
Xin Yang ◽  
Paul J Young ◽  
Guang Zeng
Keyword(s):  
Surface Ozone ◽  
Future Climate ◽  
Tropospheric Chemistry ◽  
Biogenic Emissions ◽  
Anthropogenic Emissions ◽  
Model Calculations ◽  
The Future ◽  
The Tropics ◽  
The Impact

The oxidizing capacity of the atmosphere is affected by anthropogenic emissions and is projected to change in the future. Model calculations indicate that the change in surface ozone at some locations could be large and have significant implications for human health. The calculations depend on the precise scenarios used for the anthropogenic emissions and on the details of the feedback processes included in the model. One important factor is how natural biogenic emissions will change in the future. We carry out a sensitivity calculation to address the possible increase in isoprene emissions consequent on increased surface temperature in a future climate. The changes in ozone are significant but depend crucially on the background chemical regime. In these calculations, we find that increased isoprene will increase ozone in the Northern Hemisphere but decrease ozone in the tropics. We also consider the role of bromine compounds in tropospheric chemistry and consider cases where, in a future climate, the impact of bromine could change.

Sign in / Sign up

Export Citation Format

Share Document