scholarly journals Vertical distribution of particle-phase dicarboxylic acids, oxoacids and α-dicarbonyls in the urban boundary layer based on the 325-meter tower in Beijing

2020 ◽  
Author(s):  
Wanyu Zhao ◽  
Hong Ren ◽  
Kimitaka Kawamura ◽  
Huiyun Du ◽  
Xueshun Chen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Oxalic Acid ◽  
Vertical Distribution ◽  
Organic Acids ◽  
Anthropogenic Activities ◽  
Ground Surface ◽  
Dicarboxylic Acids ◽  
Ground Level ◽  
Water Soluble ◽  
Motor Vehicles

Abstract. Vertical distribution of dicarboxylic acids, oxoacids, α-dicarbonyls, and other organic tracer compounds in fine aerosols (PM2.5) was investigated from the ground surface (8 m) to 260 m at a 325-meter meteorological tower in Beijing in the summer of 2015. Results showed that the concentrations of oxalic acid (C2), the predominant diacid, were more abundant at 120 m (210 ± 154 ng m−3) and 260 m (220 ± 140 ng m−3) than those at the ground level (160 ± 90 ng m−3). Concentrations of phthalic acid (Ph) decreased with the increase of heights, demonstrating that the vehicular exhausts at the ground surface was the main contributor. Positive correlations were noteworthy for C2/total diacids with mass ratios of C2 to main oxoacids (Pyr, ωC2) and α-dicarbonyls (Gly, MeGly) in polluted days (0.42 ≤ r2 ≤ 0.65), especially at the ground level. In clean days, the ratios of carbon content in oxalic acid to water soluble organic carbon (C2-C/WSOC) showed larger values at 120 m and 260 m than those at the ground surface. However, in polluted days, the C2-C/WSOC ratio mainly reached its maximum at the ground level. These phenomena may indicate the enhanced contribution of aqueous-phase oxidation to oxalic acid in polluted days. Combined with the influence of wind field, total diacids, oxoacids and α-dicarbonyls decreased by 22 %–58 % under the control on anthropogenic activities during the 2015 Victory Parade period. Furthermore, the PMF results showed that the secondary formation routes (secondary sulfate formation and secondary nitrate formation) were the dominant contributors (37–44 %) to organic acids, followed by biomass burning (25–30 %) and motor vehicles (18–24 %). In this study, the organic acids at the ground level were largely associated with local traffic emissions, while the long-range atmospheric transport followed by photochemical aging contributed more to diacids and related compounds in the boundary layer over Beijing than the ground surface.

scholarly journals Vertical distribution of particle-phase dicarboxylic acids, oxoacids and <i>α</i>-dicarbonyls in the urban boundary layer based on the 325 m tower in Beijing

2020 ◽  
Vol 20 (17) ◽  
pp. 10331-10350
Author(s):  
Wanyu Zhao ◽  
Hong Ren ◽  
Kimitaka Kawamura ◽  
Huiyun Du ◽  
Xueshun Chen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Oxalic Acid ◽  
Organic Acids ◽  
Anthropogenic Activities ◽  
Ground Surface ◽  
Dicarboxylic Acids ◽  
Ground Level ◽  
Urban Boundary Layer ◽  
Water Soluble ◽  
Motor Vehicles

Abstract. Vertical distributions of dicarboxylic acids, oxoacids, α-dicarbonyls and other organic tracer compounds in fine aerosols (PM2.5) were investigated at three heights (8, 120 and 260 m) based on a 325 m meteorological tower in urban Beijing in the summer of 2015. Results showed that the concentrations of oxalic acid (C2), the predominant diacid, were more abundant at 120 m (210±154 ng m−3) and 260 m (220±140 ng m−3) than those at the ground surface (160±90 ng m−3). Concentrations of phthalic acid (Ph) decreased with the increase in height, indicating that local vehicular exhausts were the main contributor. Positive correlations were noteworthy for C2 ∕ total diacids with mass ratios of C2 to main oxoacids (Pyr and ωC2) and α-dicarbonyls (Gly and MeGly) in polluted days (0.42≤r2≤0.65), especially at the ground level. In clean days, the ratios of carbon content in oxalic acid to water-soluble organic carbon (C2−C ∕ WSOC) showed larger values at 120 and 260 m than those at the ground surface. However, in polluted days, the C2−C ∕ WSOC ratio mainly reached its maximum at ground level. These phenomena may indicate the enhanced contribution of aqueous-phase oxidation to oxalic acid in polluted days. Combined with the influence of wind field, total diacids, oxoacids and α-dicarbonyls decreased by 22 %–58 % under the control on anthropogenic activities during the 2015 Victory Parade period. Furthermore, the positive matrix factorisation (PMF) results showed that the secondary formation routes (secondary sulfate formation and secondary nitrate formation) were the dominant contributors (37 %–44 %) to organic acids, followed by biomass burning (25 %–30 %) and motor vehicles (18 %–24 %). In this study, the organic acids at ground level were largely associated with local traffic emissions, while the long-range atmospheric transport followed by photochemical ageing contributed more to diacids and related compounds in the urban boundary layer than the ground surface in Beijing.

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 High resolution vertical distribution and sources of HONO and NO<sub>2</sub> in the nocturnal boundary layer in urban Beijing, China

2019 ◽  
Author(s):  
Fanhao Meng ◽  
Min Qin ◽  
Ke Tang ◽  
Jun Duan ◽  
Wu Fang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Resolution ◽  
Vertical Distribution ◽  
Heterogeneous Reaction ◽  
Ground Surface ◽  
Ground Level ◽  
Urban Atmosphere ◽  
Surface Measurement ◽  
Enhanced Absorption ◽  
Haze Episode

Abstract. The production of HONO on aerosol surfaces and ground surfaces in urban atmosphere is of interests. However, ground surface measurement commonly in our society is not able to distinguish these two parts. Here, for the first time, we reported high-resolution vertical profile measurements of HONO and NO2 in urban Beijing at night using an incoherent broadband cavity enhanced absorption spectrometer (IBBCEAS) amounted on a movable container which attached to a meteorological tower of 325 m high. The mixing ratios of HONO during one haze episode (E1), the clean episode (C2) and another haze episode (E3) were 4.26 ± 2.08, 0.83 ± 0.65, and 3.54 ± 0.91 ppb, respectively. High-resolution vertical profiles revealed that the vertical distribution of HONO is consistent with stratification and layering in the nocturnal urban atmosphere below 250 m. Direct emissions from combustion processes contributed 51.1 % to ambient HONO concentration at night. The HONO production from the heterogeneous conversion of NO2 on the aerosol surfaces cannot explain HONO vertical measurements at night, indicating that the heterogeneous reaction of NO2 on ground surfaces dominated the nocturnal HONO production. The nocturnal HONO in the boundary layer is primarily derived from the heterogeneous conversion of NO2 at ground level and direct emissions; it is then transported throughout the column by vertical convection. ϕNO2 → HONO, the HONO yield from deposited NO2, is used to evaluate HONO production from the heterogeneous conversion of NO2 at night. The derived ϕNO2 → HONO values on 9 (C2), 10 (C2) and 11 December (E3) were 0.10, 0.08, and 0.09, respectively, indicating a significant production of HONO from heterogeneous reaction of NO2 at ground level. The similar ϕNO2 → HONO values measured during clean and haze episodes suggest that the heterogeneous conversion potential of NO2 at ground level is consistent at night. Furthermore, the dry deposition loss of HONO to the ground surface and vertical mixing effects associated with convection reached a near steady state at midnight on 11–12 December, indicating that significant quantities of HONO are deposited to the ground surface at night, and the ground surface is the source and sink of HONO at night.

scholarly journals Characterization of Aerosol Composition, Aerosol Acidity and Organic Acid Partitioning at an Agriculture-Intensive Rural Southeastern U.S. Site

2018 ◽  
Author(s):  
Theodora Nah ◽  
Hongyu Guo ◽  
Amy P. Sullivan ◽  
Yunle Chen ◽  
David J. Tanner ◽  
...  
Keyword(s):  
Oxalic Acid ◽  
Organic Acids ◽  
Organic Acid ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Molar Concentration ◽  
Particle Phase ◽  
Aerosol Composition ◽  
Phase Water ◽  
Acetic Acids

Abstract. The implementation of stringent emission regulations has resulted in the decline of anthropogenic pollutants including sulfur dioxide (SO2), nitrogen oxides (NOx) and carbon monoxide (CO). In contrast, ammonia (NH3) emissions are largely unregulated, with emissions projected to increase in the future. We present real-time aerosol and gas measurements from a field study conducted in an agricultural-intensive region in the southeastern U.S. during the fall of 2016 to investigate how NH3 affects particle acidity and SOA formation via the gas-particle partitioning of semi-volatile organic acids. Particle water and pH were determined using the ISORROPIA-II thermodynamic model and validated by comparing predicted inorganic HNO3-NO3− and NH3-NH4+ gas-particle partitioning ratios with measured values. Our results showed that despite the high NH3 concentrations (study average 8.1 ± 5.2 ppb), PM1 were highly acidic with pH values ranging from 0.9 to 3.8, and a study-averaged pH of 2.2 ± 0.6. PM1 pH varied by approximately 1.4 units diurnally. Formic and acetic acids were the most abundant gas-phase organic acids, and oxalate was the most abundant particle-phase water-soluble organic acid anion. Measured particle-phase water-soluble organic acids were on average 6 % of the total non-refractory PM1 organic aerosol mass. The measured molar fraction of oxalic acid in the particle phase (i.e., particle-phase oxalic acid molar concentration divided by the total oxalic acid molar concentration) ranged between 47 and 90 % for PM1 pH 1.2 to 3.4. The measured oxalic acid gas-particle partitioning ratios were in good agreement with their corresponding thermodynamic predictions, calculated based on oxalic acid’s physicochemical properties, ambient temperature, particle water and pH. In contrast, gas-particle partitioning of formic and acetic acids were not well predicted for reasons currently unknown. For this study, higher NH3 concentrations relative to what has been measured in the region in previous studies had minor effects on PM1 organic acids and their influence on the overall organic aerosol and PM1 mass concentrations.

scholarly journals Aircraft observations of water-soluble dicarboxylic acids in the aerosols over China

2016 ◽  
Author(s):  
Yan-Lin Zhang ◽  
Kimitaka Kawamura ◽  
Ping Qing Fu ◽  
Suresh K. R. Boreddy ◽  
Tomomi Watanabe ◽  
...  
Keyword(s):  
Oxalic Acid ◽  
Organic Compounds ◽  
Aqueous Phase ◽  
Dicarboxylic Acids ◽  
Liquid Water Content ◽  
Water Soluble ◽  
Aircraft Observations ◽  
Volatile Organic ◽  
Intercontinental Transport ◽  
Surface Measurements

Abstract. Vertical profiles of low molecular weight dicarboxylic acids, related organic compounds and SOA tracer compounds in particle phase have not yet been simultaneously explored in East Asia, although there is growing evidence that aqueous phase oxidation of volatile organic compounds may be responsible for the elevated organic aerosols (OA) in the free troposphere. Here, we found consistently good correlation of oxalic acid, the most abundant organics globally, with its precursors as well as biogenic-derived secondary OA (SOA) compounds in Chinese tropospheric aerosols by aircraft measurements. Anthropogenically derived dicarboxylic acids (i.e., C5 and C6 diacids) at high altitudes were 4–20 times higher than those from surface measurements and even occasionally dominant over oxalic acid at altitude higher than 2 km, which is in contrast to the predominance of oxalic acid previously reported globally including the tropospheric and surface aerosols. This indicates an enhancement of tropospheric SOA formation from anthropogenic precursors. Furthermore, oxalic acid-tosulfate ratio maximized at altitude of ~2 km, explaining aqueous-phase SOA production that was supported by good correlations with predicted liquid water content, organic carbon and biogenic SOA tracers. These results demonstrate that elevated oxalic acid and related SOA compounds from both the anthropogenic and biogenic sources may substantially contribute to tropospheric OA burden over polluted regions of China, implying aerosol-associated climate effects and intercontinental transport.

scholarly journals Distributions of low molecular weight dicarboxylic acids, ketoacids and α-dicarbonyls in the marine aerosols collected over the Arctic Ocean during late summer

2012 ◽  
Vol 9 (11) ◽  
pp. 4725-4737 ◽  
Author(s):  
K. Kawamura ◽  
K. Ono ◽  
E. Tachibana ◽  
B. Charriére ◽  
R. Sempéré
Keyword(s):  
Oxalic Acid ◽  
Arctic Ocean ◽  
Late Summer ◽  
Dicarboxylic Acids ◽  
Water Soluble ◽  
The Arctic ◽  
Marine Atmosphere ◽  
Marine Aerosols ◽  
Δ13c Values ◽  
The Arctic Ocean

Abstract. Oxalic and other small dicarboxylic acids have been reported as important water-soluble organic constituents of atmospheric aerosols from different environments. Their molecular distributions are generally characterized by the predominance of oxalic acid (C2) followed by malonic (C3) and/or succinic (C4) acids. In this study, we collected marine aerosols from the Arctic Ocean during late summer in 2009 when sea ice was retreating. The marine aerosols were analyzed for the molecular distributions of dicarboxylic acids as well as ketocarboxylic acids and α-dicarbonyls to better understand the source of water-soluble organics and their photochemical processes in the high Arctic marine atmosphere. We found that diacids are more abundant than ketoacids and α-dicarbonyls, but their concentrations are generally low (< 30 ng m−3), except for one sample (up to 70 ng m−3) that was collected near the mouth of Mackenzie River during clear sky condition. Although the molecular compositions of diacids are in general characterized by the predominance of oxalic acid, a depletion of C2 was found in two samples in which C4 became the most abundant. Similar depletion of oxalic acid has previously been reported in the Arctic aerosols collected at Alert after polar sunrise and in the summer aerosols from the coast of Antarctica. Because the marine aerosols that showed a depletion of C2 were collected under the overcast and/or foggy conditions, we suggest that a photochemical decomposition of oxalic acid may have occurred in aqueous phase of aerosols over the Arctic Ocean via the photo dissociation of oxalate-Fe (III) complex. We also determined stable carbon isotopic compositions (δ13C) of bulk aerosol carbon and individual diacids. The δ13C of bulk aerosols showed −26.5‰ (range: −29.7 to −24.7‰, suggesting that marine aerosol carbon is derived from both terrestrial and marine organic materials. In contrast, oxalic acid showed much larger δ13C values (average: −20.9‰, range: −24.7‰ to −17.0‰) than those of bulk aerosol carbon. Interestingly, δ13C values of oxalic acid were higher than C3 (av. −26.6‰) and C4 (−25.8‰) diacids, suggesting that oxalic acid is enriched with 13C due to its photochemical processing (aging) in the marine atmosphere.

scholarly journals Functional Analysis of Organic Acids on Different Oilseed Rape Species in Phytoremediation of Cadmium Pollution

Plants ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 884
Author(s):  
Shi Li ◽  
Sixiu Le ◽  
Xin Wang ◽  
Jiuyuan Bai ◽  
Rui Wang ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Oxalic Acid ◽  
Organic Acids ◽  
Brassica Juncea ◽  
Oilseed Rape ◽  
Contaminated Soil ◽  
Brassica Campestris ◽  
Anthropogenic Activities ◽  
Mature Stage ◽  
Antioxidant Enzyme Activities

Cadmium (Cd) pollution in soil is becoming increasingly serious due to anthropogenic activities, which not only poses a threat to the ecological environment, but also causes serious damage to human health via the biological chain. Consequently, special concerns should be paid to develop and combine multiple remediation strategies. In this study, different subspecies of oilseed rape, Brassica campestris, Brassica napus and Brassica juncea were applied, combined with three organic acids, acetic acid, oxalic acid and citric acid, in a simulated Cd-contaminated soil. Various physiological and biochemical indexes were monitored in both plant seedling, growth period and mature stage. The results showed that organic acids significantly promoted the growth of Brassica campestris and Brassica juncea under Cd stress. The photosynthesis and antioxidant enzyme activities in Brassica campestris and Brassica juncea were induced at seedling stage, while that in Brassica napus were suppressed and disturbed. The enrichment of Cd in oilseed rape was also obviously increased. Brassica juncea contained relatively high resistance and Cd content in plant but little Cd in seed. Among the three acids, oxalic acids exhibited the most efficient promoting effect on the accumulation of Cd by oilseed rape. Here, a comprehensive study on the combined effects of oilseed rape and organic acids on Cd contaminated soil showed that Brassica juncea and oxalic acid possessed the best effect on phytoremediation of Cd contaminated soil. Our study provides an optimal way of co-utilizing oilseed rape and organic acid in phytoremediation of Cd contaminated soil.

scholarly journals Current challenges in modelling far-range air pollution induced by the 2014–2015 Bárðarbunga fissure eruption (Iceland)

2016 ◽  
Vol 16 (17) ◽  
pp. 10831-10845 ◽  
Author(s):  
Marie Boichu ◽  
Isabelle Chiapello ◽  
Colette Brogniez ◽  
Jean-Christophe Péré ◽  
Francois Thieuleux ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Vertical Distribution ◽  
Planetary Boundary Layer ◽  
Large Scale ◽  
Temporal Dynamics ◽  
Ground Level ◽  
Optical Absorption Spectroscopy ◽  
Sulfate Aerosols ◽  
Volcanic Cloud

Abstract. The 2014–2015 Holuhraun lava-flood eruption of Bárðarbunga volcano (Iceland) emitted prodigious amounts of sulfur dioxide into the atmosphere. This eruption caused a large-scale episode of air pollution throughout Western Europe in September 2014, the first event of this magnitude recorded in the modern era. We gathered chemistry-transport simulations and a wealth of complementary observations from satellite sensors (OMI, IASI), ground-based remote sensing (lidar, sunphotometry, differential optical absorption spectroscopy) and ground-level air quality monitoring networks to characterize both the spatial-temporal distributions of volcanic SO2 and sulfate aerosols as well as the dynamics of the planetary boundary layer. Time variations of dynamical and microphysical properties of sulfate aerosols in the aged low-tropospheric volcanic cloud, including loading, vertical distribution, size distribution and single scattering albedo, are provided. Retrospective chemistry-transport simulations at low horizontal resolution (25 km  ×  25 km) capture the correct temporal dynamics of this far-range air pollution event but fail to reproduce the correct magnitude of SO2 concentration at ground-level. Simulations at higher spatial resolution, relying on two nested domains with finest resolution of 7.3 km  ×  7.3 km, improve substantially the far-range vertical distribution of the volcanic cloud and subsequently the description of ground-level SO2 concentrations. However, remaining discrepancies between model and observations are shown to result from an inaccurate representation of the planetary boundary layer (PBL) dynamics. Comparison with lidar observations points out a systematic under-estimation of the PBL height by the model, whichever the PBL parameterization scheme. Such a shortcoming impedes the capture of the overlying Bárðarbunga cloud into the PBL at the right time and in sufficient quantities. This study therefore demonstrates the key role played by the PBL dynamics in accurately modelling large-scale volcanogenic air pollution.

scholarly journals How well do tall-tower measurements characterize the CO<sub>2</sub> mole fraction distribution in the planetary boundary layer?

2015 ◽  
Vol 8 (4) ◽  
pp. 1657-1671 ◽  
Author(s):  
L. Haszpra ◽  
Z. Barcza ◽  
T. Haszpra ◽  
Zs. Pátkai ◽  
K. J. Davis
Keyword(s):  
Boundary Layer ◽  
Vertical Distribution ◽  
Planetary Boundary Layer ◽  
Mole Fraction ◽  
Lower Troposphere ◽  
Co2 Flux ◽  
Ground Level ◽  
Rural Site ◽  
Mole Fraction Profile ◽  
Tall Tower

Abstract. Planetary boundary layer (PBL) CO2 mole fraction data are needed by transport models and carbon budget models as both input and reference for validation. The height of in situ CO2 mole fraction measurements is usually different from that of the model levels where the data are needed; data from short towers, in particular, are difficult to utilize in atmospheric models that do not simulate the surface layer well. Tall-tower CO2 mole fraction measurements observed at heights ranging from 10 to 115 m above ground level at a rural site in Hungary and regular airborne vertical mole fraction profile measurements (136 vertical profiles) above the tower allowed us to estimate how well a tower of a given height could estimate the CO2 mole fraction above the tower in the PBL. The statistical evaluation of the height-dependent bias between the real PBL CO2 mole fraction profile (measured by the aircraft) and the measurement at a given elevation above the ground was performed separately for the summer and winter half years to take into account the different dynamics of the lower troposphere and the different surface CO2 flux in the different seasons. The paper presents (1) how accurately the vertical distribution of CO2 in the PBL can be estimated from the measurements on the top of a tower of height H; (2) how tall of a tower would be needed for the satisfaction of different requirements on the accuracy of the estimation of the CO2 vertical distribution; (3) how accurate of a CO2 vertical distribution estimation can be expected from the existing towers; and (4) how much improvement can be achieved in the accuracy of the estimation of CO2 vertical distribution by applying the virtual tall-tower concept.

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