scholarly journals Impacts of primary emissions and secondary aerosol formation on air pollution in an urban area of China during the COVID-19 lockdown

2021 ◽  
Vol 150 ◽  
pp. 106426
Author(s):  
Jie Tian ◽  
Qiyuan Wang ◽  
Yong Zhang ◽  
Mengyuan Yan ◽  
Huikun Liu ◽  
...  
Keyword(s):  
Air Pollution ◽  
Urban Area ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Primary Emissions

scholarly journals Influence of fuel ethanol content on primary emissions and secondary aerosol formation potential for a modern flex-fuel gasoline vehicle

2016 ◽  
Author(s):  
Hilkka Timonen ◽  
Panu Karjalainen ◽  
Erkka Saukko ◽  
Sanna Saarikoski ◽  
Päivi Aakko-Saksa ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Organic Compounds ◽  
Fuel Ethanol ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Formation Potential ◽  
Aerosol Mass ◽  
Ethanol Content ◽  
Flex Fuel ◽  
Primary Emissions

Abstract. The effect of fuel ethanol content (10 %, 85 %, 100 %) on primary emissions and on subsequent secondary aerosol formation was investigated for a EURO5 flex-fuel gasoline vehicle. Emissions were characterized during the New European Driving Cycle (NEDC) using a comprehensive setup of high time resolution instruments. Detailed chemical composition of exhaust particulate matter (PM) was studied using a soot particle aerosol mass spectrometer (SP-AMS) and secondary aerosol formation using a potential aerosol mass (PAM) chamber. For the primary gaseous compounds, an increase in total hydrocarbon emissions and a decrease of aromatic BTEX (benzene, toluene, ethylbenzene and xylenes) compounds was observed when the amount of ethanol in fuel increased. In regard to particles, largest primary particulate matter concentrations and potential to form secondary particles were measured for the E10 fuel (10 % ethanol). As the ethanol content of the fuel increased, a significant decrease in average primary particulate matter concentrations over the NEDC cycle was found, PM emissions being 0.45, 0.25 and 0.15 mg m−3 for E10, E85 and E100, respectively. Similarly, a clear decrease in secondary aerosol formation potential was observed with larger contribution of ethanol in fuel. Secondary to primary PM ratios were 13.4, and 1.5 for E10 and E85, respectively. For E100 a slight decrease in PM mass was observed after the PAM chamber, indicating that the PM produced by secondary aerosol formation was less than the PM lost via e.g. wall losses or degradation of POA in the chamber. For all fuel blends, the formed secondary aerosol consisted mostly of organic compounds. For E10 the contribution of organic compounds containing oxygen increased from 35 %, measured for primary organics, to 62 % after the PAM chamber. For E85 the contribution of organic compounds containing oxygen increased from 42 % (primary) to 57 % (after the PAM chamber), whereas for E100 the amount of oxidized organics remained the same (approximately 62 %) with the PAM chamber when compared to the primary emissions.

Impact of harbour emissions on ambient PM10 and PM2.5 in Barcelona (Spain): Evidences of secondary aerosol formation within the urban area

2016 ◽  
Vol 571 ◽  
pp. 237-250 ◽  
Author(s):  
Noemí Pérez ◽  
Jorge Pey ◽  
Cristina Reche ◽  
Joaquim Cortés ◽  
Andrés Alastuey ◽  
...  
Keyword(s):  
Urban Area ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Pm10 And Pm2.5

scholarly journals Dramatic changes in Harbin aerosol during 2018–2020: the roles of open burning policy and secondary aerosol formation

2021 ◽  
Author(s):  
Yuan Cheng ◽  
Qin-qin Yu ◽  
Jiu-meng Liu ◽  
Xu-bing Cao ◽  
Ying-jie Zhong ◽  
...  
Keyword(s):  
Air Pollution ◽  
Biomass Burning ◽  
Northeast China ◽  
Cold Climate ◽  
Quality Data ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Open Burning ◽  
Measurement Period ◽  
Related Increase

Abstract. Despite the growing interest in understanding haze formation in Chinese megacities, air pollution has been largely overlooked for the Harbin-Changchun (HC) metropolitan area located in the severe cold climate region in Northeast China. In this study, we unfolded significant variations of fine particulate matter (PM2.5) in HC’s central city (Harbin) during two sequential heating seasons of 2018–2019 and 2019–2020, and explored major drivers for the observed variations. The two campaigns showed comparable organic carbon (OC) levels but quite different OC sources. The biomass burning (BB) to OC contribution decreased substantially for 2019–2020, which was attributed primarily to the transition of local policies on agricultural fires, i.e., from the “legitimate burning” policy released in 2018 to the “strict prohibition” policy in 2019. Meanwhile, the contribution of secondary OC (OCsec) increased significantly, associated with the much more frequent occurrences of high relative humidity (RH) conditions during the 2019–2020 measurement period. Similar to OCsec, the major secondary inorganic ions, i.e., sulfate, nitrate and ammonium (SNA), also exhibited RH-dependent increases. Given the considerable aerosol water contents predicted for the high-RH conditions, heterogeneous reactions were likely at play in secondary aerosol formation even in the frigid atmosphere in Harbin (e.g., with daily average temperatures down to below −20 °C). In brief, compared to 2018–2019, the 2019–2020 measurement period was characterized by a policy-driven decrease of biomass burning OC, a RH-related increase of OCsec and a RH-related increase of SNA, with the former two factors generally offsetting each other. In addition, we found that open burning activities were actually not eliminated by the “strict prohibition” policy released in 2019, based on a synthesis of air quality data and fire count results. Although not evident throughout the 2019–2020 measurement period, agricultural fires broke out within a short period before crop planting in spring of 2020, and resulted in off-the-chart air pollution for Harbin, with 1- and 24-hour PM2.5 concentrations peaking at ~2350 and 900 μg/m3, respectively. This study indicates that sustainable use of crop residues remains a difficult challenge for the massive agricultural sector in Northeast China.

scholarly journals Dramatic changes in Harbin aerosol during 2018–2020: the roles of open burning policy and secondary aerosol formation

2021 ◽  
Vol 21 (19) ◽  
pp. 15199-15211
Author(s):  
Yuan Cheng ◽  
Qin-qin Yu ◽  
Jiu-meng Liu ◽  
Xu-bing Cao ◽  
Ying-jie Zhong ◽  
...  
Keyword(s):  
Air Pollution ◽  
Biomass Burning ◽  
Northeast China ◽  
Cold Climate ◽  
Quality Data ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Open Burning ◽  
Measurement Period ◽  
Related Increase

Abstract. Despite the growing interest in understanding haze formation in Chinese megacities, air pollution has been largely overlooked for the Harbin–Changchun (HC) metropolitan area, located in the severe cold climate region in northeast China. In this study, we unfolded significant variations of fine particulate matter (PM2.5) in HC's central city (Harbin) during two sequential heating seasons of 2018–2019 and 2019–2020, and we explored major drivers for the observed variations. The two campaigns showed comparable organic carbon (OC) levels but quite different OC sources. The biomass burning (BB) to OC contribution decreased substantially for 2019–2020, which was attributed primarily to the transition of local policies on agricultural fires, i.e., from the “legitimate burning” policy released in 2018 to the “strict prohibition” policy in 2019. Meanwhile, the contribution of secondary OC (OCsec) increased significantly, associated with the much more frequent occurrences of high relative humidity (RH) conditions during the 2019–2020 measurement period. Similar to OCsec, the major secondary inorganic ions, i.e., sulfate, nitrate and ammonium (SNA), also exhibited RH-dependent increases. Given the considerable aerosol water contents predicted for the high-RH conditions, heterogeneous reactions were likely at play in secondary aerosol formation even in the frigid atmosphere in Harbin (e.g., with daily average temperatures down to below −20 ∘C). In brief, compared to 2018–2019, the 2019–2020 measurement period was characterized by a policy-driven decrease of biomass burning OC, a RH-related increase of OCsec and a RH-related increase of SNA, with the first two factors generally offsetting each other. In addition, we found that open burning activities were actually not eliminated by the strict prohibition policy released in 2019, based on a synthesis of air quality data and fire count results. Although not occurring during the 2019–2020 measurement period, agricultural fires broke out within a short period before crop planting in spring of 2020, and this resulted in off-the-charts air pollution for Harbin, with 1 h and 24 h PM2.5 concentrations peaking at ∼ 2350 and 900 µg/m3, respectively. This study indicates that sustainable use of crop residues remains a difficult challenge for the massive agricultural sector in northeast China.

scholarly journals Influence of fuel ethanol content on primary emissions and secondary aerosol formation potential for a modern flex-fuel gasoline vehicle

2017 ◽  
Vol 17 (8) ◽  
pp. 5311-5329 ◽  
Author(s):  
Hilkka Timonen ◽  
Panu Karjalainen ◽  
Erkka Saukko ◽  
Sanna Saarikoski ◽  
Päivi Aakko-Saksa ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Organic Compounds ◽  
Fuel Ethanol ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Formation Potential ◽  
Aerosol Mass ◽  
Ethanol Content ◽  
Flex Fuel ◽  
Primary Emissions

Abstract. The effect of fuel ethanol content (10, 85 and 100 %) on primary emissions and on subsequent secondary aerosol formation was investigated for a Euro 5 flex-fuel gasoline vehicle. Emissions were characterized during a New European Driving Cycle (NEDC) using a comprehensive set-up of high time-resolution instruments. A detailed chemical composition of the exhaust particulate matter (PM) was studied using a soot particle aerosol mass spectrometer (SP-AMS), and secondary aerosol formation was studied using a potential aerosol mass (PAM) chamber. For the primary gaseous compounds, an increase in total hydrocarbon emissions and a decrease in aromatic BTEX (benzene, toluene, ethylbenzene and xylenes) compounds was observed when the amount of ethanol in the fuel increased. In regard to particles, the largest primary particulate matter concentrations and potential for secondary particle formation was measured for the E10 fuel (10 % ethanol). As the ethanol content of the fuel increased, a significant decrease in the average primary particulate matter concentrations over the NEDC was found. The PM emissions were 0.45, 0.25 and 0.15 mg m−3 for E10, E85 and E100, respectively. Similarly, a clear decrease in secondary aerosol formation potential was observed with a larger contribution of ethanol in the fuel. The secondary-to-primary PM ratios were 13.4 and 1.5 for E10 and E85, respectively. For E100, a slight decrease in PM mass was observed after the PAM chamber, indicating that the PM produced by secondary aerosol formation was less than the PM lost through wall losses or the degradation of the primary organic aerosol (POA) in the chamber. For all fuel blends, the formed secondary aerosol consisted mostly of organic compounds. For E10, the contribution of organic compounds containing oxygen increased from 35 %, measured for primary organics, to 62 % after the PAM chamber. For E85, the contribution of organic compounds containing oxygen increased from 42 % (primary) to 57 % (after the PAM chamber), whereas for E100 the amount of oxidized organics remained the same (approximately 62 %) with the PAM chamber when compared to the primary emissions.

scholarly journals Development of the city-scale chemistry transport model CityChem-EPISODE and its application to the city of Hamburg

2018 ◽  
Author(s):  
Matthias Karl
Keyword(s):  
Air Quality ◽  
Urban Area ◽  
Transport Model ◽  
Dispersion Model ◽  
Temporal Correlation ◽  
Urban Atmosphere ◽  
Aerosol Formation ◽  
Urban Background ◽  
New Model ◽  
The City

Abstract. This paper describes the City-scale Chemistry (CityChem) extension of the urban dispersion model EPISODE with the aim to enable chemistry/transport simulations of multiple reactive pollutants on urban scales. The new model is called CityChem-EPISODE. The primary focus is on the simulation of urban ozone concentrations. Ozone is produced in photochemical reaction cycles involving nitrogen oxides (NOx) and volatile organic compounds (VOC) emitted by various anthropogenic activities in the urban area. The performance of the new model was evaluated with a series of synthetic tests and with a first application to the air quality situation in the city of Hamburg, Germany. The model performs fairly well for ozone in terms of temporal correlation and bias at the air quality monitoring stations in Hamburg. In summer afternoons, when photochemical activity is highest, modelled median ozone at an inner-city urban background station was about 30 % lower than the observed median ozone. Inaccuracy of the computed photolysis frequency of nitrogen dioxide (NO2) is the most probable explanation for this. CityChem-EPISODE reproduces the spatial variation of annual mean NO2 concentrations between urban background, traffic and industrial stations. However, the temporal correlation between modelled and observed hourly NO2 concentrations is weak for some of the stations. For daily mean PM10, the performance of CityChem-EPISODE is moderate due to low temporal correlation. The low correlation is linked to uncertainties in the seasonal cycle of the anthropogenic particulate matter (PM) emissions within the urban area. Missing emissions from domestic heating might be an explanation for the too low modelled PM10 in winter months. Four areas of need for improvement have been identified: (1) dry and wet deposition fluxes; (2) treatment of photochemistry in the urban atmosphere; (3) formation of secondary inorganic aerosol (SIA); and (4) formation of biogenic and anthropogenic secondary organic aerosol (SOA). The inclusion of secondary aerosol formation will allow for a better sectorial attribution of observed PM levels. Envisaged applications of the CityChem-EPISODE model are urban air quality studies, environmental impact assessment, sensitivity analysis of sector-specific emission and the assessment of local and regional emission abatement policy options.

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