scholarly journals Characteristics, primary sources and secondary formation of water soluble organic aerosols in downtown Beijing

2020 ◽  
Author(s):  
Qing Yu ◽  
Jing Chen ◽  
Weihua Qin ◽  
Siming Cheng ◽  
Yuepeng Zhang ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Dominant Role ◽  
Critical Role ◽  
Correlation Coefficients ◽  
Water Soluble ◽  
Primary Sources ◽  
Formation Mechanisms ◽  
Secondary Sources ◽  
Pmf Model ◽  
Secondary Formation

Abstract. Water soluble organic compounds (WSOC) account for a large proportion of aerosols and play a critical role in various atmospheric chemical processes. In order to investigate the primary sources and secondary production of WSOC in downtown Beijing, the day and night PM2.5 samples in January (winter), April (spring), July (summer) and October (autumn) of 2017 were collected and analyzed for WSOC and organic tracers in this study. WSOC showed the highest concentration in winter and comparable levels in the other seasons, and dominated by its hydrophobic fraction (HULIS-C). Some typical organic tracers were chosen to evaluate the emission strength and secondary formation for the major sources of WSOC. According to the diurnal patterns and correlation coefficients with the key influencing factors, most SOA tracers were closely related to gaseous photooxidation in summer, but mainly generated via aqueous-phase processing in other seasons. These organic tracers were applied into the positive matrix factorization (PMF) model to calculate the source contributions of WSOC as well as its hydrophobic and hydrophilic portions. The secondary sources contributed over 50 % to WSOC, with higher contributions in summer (75.7 %) and winter (67.7 %), and the largest contributor was aromatic SOC. Besides, the source apportionment results under different pollution levels suggested that controlling biomass burning and the aromatic precursors would be effective to reduce WSOC during the haze episodes in cold seasons. The possible formation mechanisms of the total secondary organic carbon (SOC) as well as hydrophobic and hydrophilic SOC were also explored in this study. The aqueous-phase process appeared to dominate in the SOC formation in winter and spring, while gas-phase photooxidation played a dominant role in summer. Besides, the gaseous photooxidation played a major role in the generation of hydrophobic SOC, whereas aqueous-phase reactions posed vital effects on the formation of hydrophilic SOC.

scholarly journals Characteristics, primary sources and secondary formation of water-soluble organic aerosols in downtown Beijing

2021 ◽  
Vol 21 (3) ◽  
pp. 1775-1796
Author(s):  
Qing Yu ◽  
Jing Chen ◽  
Weihua Qin ◽  
Siming Cheng ◽  
Yuepeng Zhang ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Aqueous Phase ◽  
Critical Role ◽  
Organic Aerosols ◽  
Sampling Period ◽  
Water Soluble ◽  
Photochemical Oxidation ◽  
Primary Sources ◽  
Secondary Formation ◽  
The Impact

Abstract. Water-soluble organic carbon (WSOC) accounts for a large proportion of aerosols and plays a critical role in various atmospheric chemical processes. In order to investigate the primary sources and secondary production of WSOC in downtown Beijing, day and night fine particulate matter (PM2.5) samples in January (winter), April (spring), July (summer) and October (autumn) 2017 were collected and analyzed for WSOC and organic tracers in this study. WSOC was dominated by its moderately hydrophilic fraction and showed the highest concentration in January and comparable levels in April, July and October 2017. Some typical organic tracers were chosen to evaluate the emission strength and secondary formation of WSOC. Seasonal variation of the organic tracers suggested significantly enhanced formation of anthropogenic secondary organic aerosols (SOAs) during the sampling period in winter and obviously elevated biogenic SOA formation during the sampling period in summer. These organic tracers were applied into a positive matrix factorization (PMF) model to calculate the source contributions of WSOC as well as its moderately and strongly hydrophilic portions. The secondary sources contributed more than 50 % to WSOC, with higher contributions during the sampling periods in summer (75.1 %) and winter (67.4 %), and the largest contributor was aromatic SOC. In addition, source apportionment results under different pollution levels suggested that controlling biomass burning and aromatic precursors would be effective to reduce WSOC during the haze episodes in cold seasons. The impact factors for the formation of different SOA tracers and total secondary organic carbon (SOC) as well as moderately and strongly hydrophilic SOC were also investigated. The acid-catalyzed heterogeneous or aqueous-phase oxidation appeared to dominate in the SOC formation during the sampling period in winter, while the photochemical oxidation played a more critical role during the sampling period in summer. Moreover, photooxidation played a more critical role in the formation of moderately hydrophilic SOC, while the heterogeneous or aqueous-phase reactions had more vital effects on the formation of strongly hydrophilic SOC.

scholarly journals Primary and secondary aerosols in Beijing in winter: sources, variations and processes

2016 ◽  
Vol 16 (13) ◽  
pp. 8309-8329 ◽  
Author(s):  
Yele Sun ◽  
Wei Du ◽  
Pingqing Fu ◽  
Qingqing Wang ◽  
Jie Li ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Biomass Burning ◽  
Coal Combustion ◽  
Dominant Role ◽  
Liquid Water Content ◽  
Oxidation States ◽  
Gas Chromatography Mass Spectrometry ◽  
Formation Mechanisms ◽  
Aerosol Composition ◽  
Secondary Aerosols

Abstract. Winter has the worst air pollution of the year in the megacity of Beijing. Despite extensive winter studies in recent years, our knowledge of the sources, formation mechanisms and evolution of aerosol particles is not complete. Here we have a comprehensive characterization of the sources, variations and processes of submicron aerosols that were measured by an Aerodyne high-resolution aerosol mass spectrometer from 17 December 2013 to 17 January 2014 along with offline filter analysis by gas chromatography/mass spectrometry. Our results suggest that submicron aerosols composition was generally similar across the winter of different years and was mainly composed of organics (60 %), sulfate (15 %) and nitrate (11 %). Positive matrix factorization of high- and unit-mass resolution spectra identified four primary organic aerosol (POA) factors from traffic, cooking, biomass burning (BBOA) and coal combustion (CCOA) emissions as well as two secondary OA (SOA) factors. POA dominated OA, on average accounting for 56 %, with CCOA being the largest contributor (20 %). Both CCOA and BBOA showed distinct polycyclic aromatic hydrocarbons (PAHs) spectral signatures, indicating that PAHs in winter were mainly from coal combustion (66 %) and biomass burning emissions (18 %). BBOA was highly correlated with levoglucosan, a tracer compound for biomass burning (r2 = 0.93), and made a considerable contribution to OA in winter (9 %). An aqueous-phase-processed SOA (aq-OOA) that was strongly correlated with particle liquid water content, sulfate and S-containing ions (e.g. CH2SO2+) was identified. On average aq-OOA contributed 12 % to the total OA and played a dominant role in increasing oxidation degrees of OA at high RH levels (> 50 %). Our results illustrate that aqueous-phase processing can enhance SOA production and oxidation states of OA as well in winter. Further episode analyses highlighted the significant impacts of meteorological parameters on aerosol composition, size distributions, oxidation states of OA and evolutionary processes of secondary aerosols.

scholarly journals Size-resolved aerosol water-soluble ionic compositions in the summer of Beijing: implication of regional secondary formation

2009 ◽  
Vol 9 (6) ◽  
pp. 23955-23986 ◽  
Author(s):  
S. Guo ◽  
M. Hu ◽  
Z. B. Wang ◽  
J. Slanina ◽  
Y. L. Zhao
Keyword(s):  
Fine Particles ◽  
Secondary Compounds ◽  
Water Soluble ◽  
Rural Site ◽  
Urban Site ◽  
Condensation Process ◽  
Pmf Model ◽  
Secondary Formation ◽  
Aerosol Pollution ◽  
Peking University

Abstract. To characterize aerosol pollution in Beijing, size-resolved aerosols were collected by MOUDIs during CAREBEIJING-2006 field campaign at Peking University (urban site) and Yufa (upwind rural site). Fine particle concentrations (PM1.8 by MOUDI) were 99.8±77.4 μg/m3 and 78.2±58.4 μg/m3, with PM1.8/PM10 ratios of 0.64±0.08 and 0.76±0.08 at PKU and Yufa, respectively, and secondary compounds accounted for more than 50% in fine particles. PMF model was used to resolve the particle modes. Three modes were resolved at Yufa, representing condensation, droplet and coarse mode. However, one more droplet mode with bigger size was resolved, which was considered probably from regional transport. Condensation mode accounted for 10%–60% of the total mass at both sites, indicating it must be taken into account in summer. The formation of sulfate was mainly attributed to in-cloud or aerosol droplet process (PKU 80%, Yufa 70%) and gas condensation process (PKU 14%, Yufa 22%). According to the thermodynamic instability of NH4NO3, size distributions of nitrate were classified as three categories by RH. The existence of Ca(NO3)2 in droplet mode indicated the reaction of HNO3 with crustal particles was also important in fine particles. Linear regression gave a rough estimation that 69% of the PM10 and 87% of the PM1.8 at PKU were regional contributions. Sulfate, ammonium and oxalate were formed regionally, with the regional contributions of 90%, 87% and 95% to PM1.8. Nitrate formation was local dominant. In summary regional secondary formation led to aerosol pollution in the summer of Beijing.

scholarly journals Understanding primary and secondary sources of ambient carbonyl compounds in Beijing using the PMF model

2013 ◽  
Vol 13 (6) ◽  
pp. 15749-15781
Author(s):  
W. T. Chen ◽  
M. Shao ◽  
S. H. Lu ◽  
M. Wang ◽  
L. M. Zeng
Keyword(s):  
Source Apportionment ◽  
Carbonyl Compounds ◽  
Anthropogenic Sources ◽  
Positive Matrix ◽  
Secondary Sources ◽  
Pmf Model ◽  
Five Factors ◽  
Secondary Formation ◽  
Volatile Organic ◽  
Peking University

Abstract. Carbonyls are important intermediates in atmospheric photochemistry. To determine the relative contributions of primary and secondary carbonyl sources in Beijing, carbonyls and other trace gases were measured at Peking University in winter and summer. The Positive Matrix Factorization (PMF) model was used for source apportionment. As volatile organic compounds (VOCs) will undergo photochemical processes in the atmosphere, and such processes may interfere with factors identification, the relationships between the contributions of the resolved PMF factors to each non-methane hydrocarbon (NMHC) species and its kOH value were used to distinguish between photochemically aged factors and fresh factors. As the result of PMF, five factors were resolved in winter, and two of them were identified as sources of photochemically aged emissions. In summer, four factors were resolved, including an aged factor. Carbonyls in the aged factors were simulated by NMHCs consumption and the corresponding carbonyl production yields, and the simulated abundances agreed well with the results obtained by PMF. The source apportionment results indicated that secondary formation was the major source of carbonyls in both seasons, with the contribution of 51.2% and 46.0%. For the three major carbonyl species, primary anthropogenic sources contributed 28.9% and 32.3% to ambient formaldehyde, 53.7% and 41.6% to acetaldehyde, 68.1% and 56.2% to acetone in winter and summer, respectively.

scholarly journals Significant Seasonal Change in Optical Properties by atmospheric humic-like substances (HULIS) in Water-Soluble Organic Carbon Aerosols

2017 ◽  
Author(s):  
Heejun Han ◽  
Guebuem Kim
Keyword(s):  
Optical Properties ◽  
Organic Carbon ◽  
Uv Radiation ◽  
Dominant Role ◽  
Critical Role ◽  
Organic Aerosols ◽  
Water Soluble ◽  
Photochemical Degradation ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon

Abstract. Atmospheric humic-like substance (HULIS) is an important fraction of water-soluble organic carbon (WSOC) accounting for the light-absorbing properties of organic aerosols. HULIS is responsible for light-absorbing properties of organic aerosols in the atmosphere. Although various sources of HULIS have been studied extensively, its sinks are poorly constrained. In this study, we found seasonal changes in the optical and chemical characteristics of HULIS and WSOC, which are decreased by approximately 80 % and 30 %, respectively, from the cold season (Oct–Jan) to the warm season (Jun–Sep) due to enhanced solar ultraviolet (UV) radiation. The dominant role of photochemical degradation on light-absorbing organic aerosols, as a sink of HULIS, was further confirmed based on a laboratory experiment by evaluating impact of UV radiation on the optical properties of HULIS and WSOC contents. Our results suggest that seasonal variation of HULIS in WSOC is resulted mainly by photo-induced degradation in the atmosphere. Thus, photochemical degradation of HULIS seems to play a critical role on seasonal variations in the light-absorbing properties of organic aerosols as well as the biogeochemical impact of WSOC on Earth’s surface.

scholarly journals Measurement report: Vertical distribution of atmospheric particulate matter within the urban boundary layer in southern China – size-segregated chemical composition and secondary formation through cloud processing and heterogeneous reactions

2020 ◽  
Vol 20 (11) ◽  
pp. 6435-6453 ◽  
Author(s):  
Shengzhen Zhou ◽  
Luolin Wu ◽  
Junchen Guo ◽  
Weihua Chen ◽  
Xuemei Wang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Particulate Matter ◽  
Vertical Distribution ◽  
Aqueous Phase ◽  
Ground Level ◽  
Urban Boundary Layer ◽  
Water Soluble ◽  
Heterogeneous Reactions ◽  
Formation Mechanisms ◽  
Autumn And Winter

Abstract. Many studies have recently been done on understanding the sources and formation mechanisms of atmospheric aerosols at ground level. However, vertical profiles and sources of size-resolved particulate matter within the urban boundary layer are still lacking. In this study, vertical distribution characteristics of size-segregated particles were investigated at three observation platforms (ground level, 118 m, and 488 m) on the 610 m high Canton Tower in Guangzhou, China. Size-segregated aerosol samples were simultaneously collected at the three levels in autumn and winter. Major aerosol components, including water-soluble ions, organic carbon, and elemental carbon, were measured. The results showed that daily average fine-particle concentrations generally decreased with height. Concentrations of sulfate and ammonium in fine particles displayed shallow vertical gradients, and nitrate concentrations increased with height in autumn, while the chemical components showed greater variations in winter than in autumn. The size distributions of sulfate and ammonium in both seasons were characterized by a dominant unimodal mode with peaks in the size range of 0.44–1.0 µm. In autumn, the nitrate size distribution was bimodal, peaking at 0.44–1.0 and 2.5–10 µm, while in winter it was unimodal, implying that the formation mechanisms for nitrate particles were different in the two seasons. Our results suggest that the majority of the sulfate and nitrate is formed from aqueous-phase reactions, and we attribute coarse-mode nitrate formation at the measurement site to the heterogeneous reactions of gaseous nitric acid on existing sea-derived coarse particles in autumn. Case studies further showed that atmospheric aqueous-phase and heterogeneous reactions could be important mechanisms for sulfate and nitrate formation, which, in combination with adverse weather conditions such as temperature inversion and calm wind, led to haze formation during autumn and winter in the Pearl River Delta (PRD) region.

scholarly journals Size-resolved aerosol water-soluble ionic compositions in the summer of Beijing: implication of regional secondary formation

2010 ◽  
Vol 10 (3) ◽  
pp. 947-959 ◽  
Author(s):  
S. Guo ◽  
M. Hu ◽  
Z. B. Wang ◽  
J. Slanina ◽  
Y. L. Zhao
Keyword(s):  
Fine Particles ◽  
Secondary Compounds ◽  
Water Soluble ◽  
Rural Site ◽  
Urban Site ◽  
Condensation Process ◽  
Pmf Model ◽  
Secondary Formation ◽  
Aerosol Pollution ◽  
Peking University

Abstract. To characterize aerosol pollution in Beijing, size-resolved aerosols were collected by MOUDIs during CAREBEIJING-2006 field campaign at Peking University (urban site) and Yufa (upwind rural site). Fine particle concentrations (PM1.8 by MOUDI) were 99.8±77.4 μg/m3 and 78.2±58.4 μg/m3, with PM1.8/PM10 ratios of 0.64±0.08 and 0.76±0.08 at PKU and Yufa, respectively, and secondary compounds accounted for more than 50% in fine particles. PMF model analysis was used to resolve the particle modes. Three modes were resolved at Yufa, representing condensation, droplet and coarse mode. However, one more droplet mode with bigger size was resolved, which was considered probably from regional transport. Condensation mode accounted for 10%–60% of the total mass at both sites, indicating that the gas-to-particle condensation process was important in summer. The formation of sulfate was mainly attributed to in-cloud or aerosol droplet process (PKU 80%, Yufa 70%) and gas condensation process (PKU 14%, Yufa 22%). According to the thermodynamic instability of NH4NO3, size distributions of nitrate were classified as three categories by RH. The existence of Ca(NO3)2 in droplet mode indicated the reaction of HNO3 with crustal particles was also important in fine particles. A rough estimation was given that 69% of the PM10 and 87% of the PM1.8 in Beijing urban were regional contributions. Sulfate, ammonium and oxalate were formed regionally, with the regional contributions of 90%, 87% and 95% to PM1.8. Nitrate formation was local dominant. In summary regional secondary formation led to aerosol pollution in the summer of Beijing.

scholarly journals Relasi Kuasa Ulama Sufi dan Negara dalam Kultur-Budaya Politik Indonesia

2021 ◽  
pp. 70
Author(s):  
Rubaidi Rubaidi
Keyword(s):  
Critical Role ◽  
Primary Source ◽  
The State ◽  
Primary Sources ◽  
Secondary Sources ◽  
Problematic Relationship ◽  
The People ◽  
Election Process ◽  
Religion And State ◽  
The Public Sphere

This article examines the critical role of the dimensions of Sufism represented by Sufi ulama in the public sphere (political power) state, either directly or indirectly. In Indonesian historicity, the relationship between Sufi ulama and the state has lasted centuries, even to the modern era. In political theory, there is a "descending of power" and an "ascending of power". Descending power is identical to religiopolitical power, namely power based on religion by placing Sufi scholars as representatives of the people and above the king's power. Power is interpreted as a political system that separates religion and state. This problematic relationship places Sufi ulama in a transcendent way to become part of the state both directly and remotely. Examples of ascending of power are shown clearly through the figures of Habib Lutfi bin Yahya and KH. Maimun Zubair (Mbah Maimun) is in the midst of a potential nation clash during the 2019 presidential election process. This study is based on secondary sources in related references and primary sources. The primary source is based on the thoughts of a Sufi teacher and the murshid of Majelis Shalawat Kubro, Shalawat Muhammad, and Shalawat Adlimiyah in East Java.

scholarly journals Understanding primary and secondary sources of ambient carbonyl compounds in Beijing using the PMF model

2014 ◽  
Vol 14 (6) ◽  
pp. 3047-3062 ◽  
Author(s):  
W. T. Chen ◽  
M. Shao ◽  
S. H. Lu ◽  
M. Wang ◽  
L. M. Zeng ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Carbonyl Compounds ◽  
Anthropogenic Sources ◽  
Urban Site ◽  
Positive Matrix ◽  
Secondary Sources ◽  
Pmf Model ◽  
Five Factors ◽  
Secondary Formation ◽  
Volatile Organic

Abstract. Carbonyl compounds are important intermediates in atmospheric photochemistry. To explore the relative contributions of primary and secondary carbonyl sources, carbonyls and other volatile organic compounds (VOCs) were measured at an urban site in both winter and summer in Beijing. The positive matrix factorization (PMF) model was used for source apportionment of VOCs. As VOCs undergo photochemical processes in the atmosphere, and such processes may interfere with factor identification, the relationships between the contributions of the resolved PMF factors to each non-methane hydrocarbon (NMHC) species and its kOH value were used to distinguish fresh factors and photochemically aged factors. As the result of PMF, five factors were resolved in winter, and two of them were identified as photochemically aged emissions. In summer, four factors were resolved, including one aged factor. Carbonyls abundances from aged factors were simulated by VOCs consumption and the corresponding carbonyl production yields, and the simulated abundances agreed well with the results obtained by the PMF model. The source apportionment results indicated that secondary formation was the major source of carbonyls in both winter and summer, with the respective contributions of 51.2% and 46.0%. For the three major carbonyl species, primary anthropogenic sources contributed 28.9% and 32.3% to ambient formaldehyde, 53.7% and 41.6% to acetaldehyde, 68.1% and 56.2% to acetone in winter and summer, respectively.

scholarly journals Importance of Ammonia Gas-Particle Conversion Ratio in Haze Formation in the Rural Agricultural Environment

2020 ◽  
Author(s):  
Jian Xu ◽  
Jia Chen ◽  
Na Zhao ◽  
Guochen Wang ◽  
Guangyuan Yu ◽  
...  
Keyword(s):  
Fine Particles ◽  
Critical Role ◽  
Conversion Ratio ◽  
Water Soluble ◽  
Formation Mechanisms ◽  
Ammonia Gas ◽  
Haze Pollution ◽  
Inorganic Species ◽  
High Ammonia ◽  
Haze Formation

Abstract. Ammonia in the atmosphere is essential for the formation of fine particles that impact air quality and climate. Despite extensive prior research to disentangle the relationship between ammonia and haze pollution, the role of ammonia in haze formation in the high ammonia emitted regions is still not well understood. Aiming to better understand secondary inorganic aerosol (SNA) formation mechanisms under high ammonia conditions, one-year hourly measurement of water-soluble inorganic species (gas and particle) was conducted in a rural supersite in Shanghai. Exceedingly high levels of agricultural ammonia, constantly around 30 μg m−3, were observed. We find that ammonia gas-particle conversion ratio (ACR), as opposed to ammonia concentrations, plays a critical role in SNA formation during the haze period. By assessing the effects of various parameters, including temperature (T), aerosol water content (AWC), aerosol pH, and activity coefficient, it seems that AWC plays predominant regulating roles for ACR. We propose a self-amplifying feedback mechanism associated with ACR for the formation of SNA, which is consistent with diurnal variations of ACR, AWC, and SNA. Our results imply that reduction of ammonia emissions alone may not reduce SNA effectively at least in rural agricultural sites in China.

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