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

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.

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

10.5194/acp-2020-726 ◽

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.

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

10.5194/acp-2017-554 ◽

2017 ◽

Cited By ~ 2

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.

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Supplementary material to "Characteristics, primary sources and secondary formation of water soluble organic aerosols in downtown Beijing"

10.5194/acp-2020-726-supplement ◽

2020 ◽

Author(s):

Qing Yu ◽

Jing Chen ◽

Weihua Qin ◽

Siming Cheng ◽

Yuepeng Zhang ◽

...

Keyword(s):

Organic Aerosols ◽

Water Soluble ◽

Primary Sources ◽

Secondary Formation ◽

Supplementary Material

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Large contribution of fossil-fuel derived secondary organic carbon to water-soluble organic aerosols in winter haze of China

10.5194/acp-2017-1130 ◽

2017 ◽

Author(s):

Yan-Lin Zhang ◽

Imad El-Haddad ◽

Ru-Jin Huang ◽

Kin-Fai Ho ◽

Jun-Ji Cao ◽

...

Keyword(s):

Organic Carbon ◽

Source Apportionment ◽

Atmospheric Chemistry ◽

Coal Combustion ◽

Large Fraction ◽

Organic Aerosols ◽

Water Soluble ◽

Primary Sources ◽

Large Contribution ◽

Secondary Organic Carbon

Abstract. Water-soluble organic carbon (WSOC) is a large fraction of organic aerosols (OA) globally and has significant impacts on climate and human health. The sources of WSOC remain very uncertain in polluted regions. Here we present a quantitative source apportionment of WSOC isolated from aerosols in China using radiocarbon (14C) and offline high-resolution time-of-flight aerosol mass spectrometer measurements. Fossil emissions on average accounted for 32–47 % of WSOC. Secondary organic carbon (SOC) dominated both the non-fossil and fossil derived WSOC, highlighting the importance of secondary formation to WSOC in severe winter haze episodes. Contributions from fossil emissions to SOC were 61 ± 4 % and 50 ± 9 % in Shanghai and Beijing, respectively, significantly larger than those in Guangzhou (36 ± 9 %) and Xi'an (26 ± 9 %). The most important primary sources were biomass burning emissions, contributing 17–26 % of WSOC. The remaining primary sources such as coal combustion, cooking and traffic were generally very small but not negligible contributors, as coal combustion contribution could exceed 10 %. Taken together with earlier 14C source apportionment studies in urban, rural, semi-urban, and background regions in Asia, Europe and USA, we demonstrated a dominant contribution of non-fossil emissions (i.e., 75 ± 11 %) to WSOC aerosols in the North Hemisphere; however, the fossil fraction is substantially larger in aerosols from East Asia and the East Asian pollution outflow especially during winter due to increasing coal combustion. Inclusion of our findings can improve a modelling of effects of WSOC aerosols on climate, atmospheric chemistry and public health.

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Secondary formation of water-soluble organic acids andα-dicarbonyls and their contributions to total carbon and water-soluble organic carbon: Photochemical aging of organic aerosols in the Arctic spring

Journal of Geophysical Research Atmospheres ◽

10.1029/2010jd014299 ◽

2010 ◽

Vol 115 (D21) ◽

Cited By ~ 86

Author(s):

Kimitaka Kawamura ◽

Hideki Kasukabe ◽

Leonard A. Barrie

Keyword(s):

Organic Carbon ◽

Organic Acids ◽

Organic Aerosols ◽

Water Soluble ◽

Total Carbon ◽

The Arctic ◽

Secondary Formation ◽

Water Soluble Organic Carbon ◽

Soluble Organic Carbon ◽

Photochemical Aging

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Large contribution of fossil fuel derived secondary organic carbon to water soluble organic aerosols in winter haze in China

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-4005-2018 ◽

2018 ◽

Vol 18 (6) ◽

pp. 4005-4017 ◽

Cited By ~ 14

Author(s):

Yan-Lin Zhang ◽

Imad El-Haddad ◽

Ru-Jin Huang ◽

Kin-Fai Ho ◽

Jun-Ji Cao ◽

...

Keyword(s):

Organic Carbon ◽

Source Apportionment ◽

Atmospheric Chemistry ◽

Coal Combustion ◽

Large Fraction ◽

Organic Aerosols ◽

Water Soluble ◽

Primary Sources ◽

Large Contribution ◽

Secondary Organic Carbon

Abstract. Water-soluble organic carbon (WSOC) is a large fraction of organic aerosols (OA) globally and has significant impacts on climate and human health. The sources of WSOC remain very uncertain in polluted regions. Here we present a quantitative source apportionment of WSOC, isolated from aerosols in China using radiocarbon (14C) and offline high-resolution time-of-flight aerosol mass spectrometer measurements. Fossil emissions on average accounted for 32–47 % of WSOC. Secondary organic carbon (SOC) dominated both the non-fossil and fossil derived WSOC, highlighting the importance of secondary formation to WSOC in severe winter haze episodes. Contributions from fossil emissions to SOC were 61 ± 4 and 50 ± 9 % in Shanghai and Beijing, respectively, significantly larger than those in Guangzhou (36 ± 9 %) and Xi'an (26 ± 9 %). The most important primary sources were biomass burning emissions, contributing 17–26 % of WSOC. The remaining primary sources such as coal combustion, cooking and traffic were generally very small but not negligible contributors, as coal combustion contribution could exceed 10 %. Taken together with earlier 14C source apportionment studies in urban, rural, semi-urban and background regions in Asia, Europe and the USA, we demonstrated a dominant contribution of non-fossil emissions (i.e., 75 ± 11 %) to WSOC aerosols in the Northern Hemisphere; however, the fossil fraction is substantially larger in aerosols from East Asia and the eastern Asian pollution outflow, especially during winter, due to increasing coal combustion. Inclusion of our findings can improve a modelling of effects of WSOC aerosols on climate, atmospheric chemistry and public health.

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A non-toxic, reversibly released imaging probe for oral cancer that is derived from natural compounds

Scientific Reports ◽

10.1038/s41598-021-93408-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Magda Ghanim ◽

Nicola Relitti ◽

Gavin McManus ◽

Stefania Butini ◽

Andrea Cappelli ◽

...

Keyword(s):

Oral Cancer ◽

Cancer Progression ◽

Intraoperative Imaging ◽

Critical Role ◽

Water Soluble ◽

Stem Cell Marker ◽

Squamous Cells ◽

Tissue Identification ◽

Tumorigenic Potential ◽

The Impact

AbstractCD44 is emerging as an important receptor biomarker for various cancers. Amongst these is oral cancer, where surgical resection remains an essential mode of treatment. Unfortunately, surgery is frequently associated with permanent disfigurement, malnutrition, and functional comorbidities due to the difficultly of tumour removal. Optical imaging agents that can guide tumour tissue identification represent an attractive approach to minimising the impact of surgery. Here, we report the synthesis of a water-soluble fluorescent probe, namely HA-FA-HEG-OE (compound 1), that comprises components originating from natural sources: oleic acid, ferulic acid and hyaluronic acid. Compound 1 was found to be non-toxic, displayed aggregation induced emission and accumulated intracellularly in vesicles in SCC-9 oral squamous cells. The uptake of 1 was fully reversible over time. Internalization of compound 1 occurs through receptor mediated endocytosis; uniquely mediated through the CD44 receptor. Uptake is related to tumorigenic potential, with non-tumorigenic, dysplastic DOK cells and poorly tumorigenic MCF-7 cells showing only low intracellular levels and highlighting the critical role of endocytosis in cancer progression and metastasis. Together, the recognised importance of CD44 as a cancer stem cell marker in oral cancer, and the reversible, non-toxic nature of 1, makes it a promising agent for real time intraoperative imaging.

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Contrasting signatures of the sources and types of aerosols in the western and eastern Himalayas: Radiative implications

10.5194/egusphere-egu21-5916 ◽

2021 ◽

Author(s):

Arun Bs ◽

Mukunda Gogoi ◽

Prashant Hegde ◽

Suresh Babu

Keyword(s):

Mineral Dust ◽

Water Soluble ◽

The Other ◽

Anthropogenic Source ◽

Chemical Compositions ◽

Eastern Himalayas ◽

Chemical Aging ◽

Other Hand ◽

Secondary Formation ◽

The Impact

The rapid changes in the pattern of atmospheric warming over the Himalayas, along with severe degradation of Himalayan glaciers in recent years suggest the inevitability of accurate source characterization and quantification of the impact of aerosols on the Himalayan atmosphere and snow. In this regard, extensive study of the chemical compositions of aerosols at two distinct regions, Himansh (32.4&#7484;N, 77.6&#7484;E, ~ 4080 m a.s.l) and Lachung (27.4&#7484;N, 88.4&#7484;E, ~ 2700 m a.s.l), elucidates distinct signatures of the sources and types of aerosols prevailing over the western and eastern parts of Himalayas. The mass-mixing ratios of water-soluble (Na+, NH4+, K+, Ca2+, Mg2+, Cl-, SO42-, NO3-, MSA-, C2O42-), carbonaceous (EC, OC, WSOC) and selected elemental (Al, Fe, Cu, Cr, Ti) species depicted significant abundance of mineral dust aerosols (~ 67%), along with a significant contribution of carbonaceous aerosols (~ 9%) during summer to autumn (August-October) over the western Himalayan site. On the other hand, the eastern Himalayan site is found to be dominant of OC (~ 53% in winter) followed by SO42- (as high as 37% in spring) and EC (8-12%) during August to February. However, OC/EC and WSOC/OC ratios showed significantly higher values over both the sites (~ 12.5, and 0.56 at Himansh; ~ 5.7 and ~ 0.74 at Lachung) indicating the secondary formation of organic aerosols via chemical aging over both the sites. The enrichment factors estimated from the concentrations of trace elements over the western Himalayan site revealed the influence of anthropogenic source contribution from the regional hot-spots of Indo-Gangetic Plains, in addition to that of west Asia and the Middle East countries. On the other hand, the source apportionment of aerosols (based on positive matrix factorization - PMF model) over the eastern Himalayas demonstrated the biomass-burning aerosols (25.94%), secondary formation of aerosols via chemical aging (15.94%), vehicular and industrial emissions (20.54%), primary emission sources associated with mineral dust sources (22.28%) and aged secondary aerosols (15.31%) as the major sources of aerosols. Due to abundant anthropogenic source impacts at the eastern Himalayan site, the atmospheric forcing is most elevated in winter (13.4 &#177; 4.4 Wm-2), which is more than two times the average values seen at the western Himalayan region during the study period. The heavily polluted eastern part of the IGP is a potential anthropogenic source region contributing to the aerosol loading at the eastern Himalayas. These observations have far-reaching implications in view of the role of aerosols on regional radiative balance and their impact on snow/glacier coverage.

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