scholarly journals Flight-based chemical characterization of biomass burning aerosols within two prescribed burn smoke plumes

2011 ◽  
Vol 11 (24) ◽  
pp. 12549-12565 ◽  
Author(s):  
K. A. Pratt ◽  
S. M. Murphy ◽  
R. Subramanian ◽  
P. J. DeMott ◽  
G. L. Kok ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Radiative Forcing ◽  
Cloud Condensation Nuclei ◽  
Chemical Characterization ◽  
Potassium Sulfate ◽  
Prescribed Burn ◽  
Smoke Plumes ◽  
Mass Fractions

Abstract. Biomass burning represents a major global source of aerosols impacting direct radiative forcing and cloud properties. Thus, the goal of a number of current studies involves developing a better understanding of how the chemical composition and mixing state of biomass burning aerosols evolve during atmospheric aging processes. During the Ice in Clouds Experiment-Layer Clouds (ICE-L) in the fall of 2007, smoke plumes from two small Wyoming Bureau of Land Management prescribed burns were measured by on-line aerosol instrumentation aboard a C-130 aircraft, providing a detailed chemical characterization of the particles. After ~2–4 min of aging, submicron smoke particles, produced primarily from sagebrush combustion, consisted predominantly of organics by mass, but were comprised primarily of internal mixtures of organic carbon, elemental carbon, potassium chloride, and potassium sulfate. Significantly, the fresh biomass burning particles contained minor mass fractions of nitrate and sulfate, suggesting that hygroscopic material is incorporated very near or at the point of emission. The mass fractions of ammonium, sulfate, and nitrate increased with aging up to ~81–88 min and resulted in acidic particles. Decreasing black carbon mass concentrations occurred due to dilution of the plume. Increases in the fraction of oxygenated organic carbon and the presence of dicarboxylic acids, in particular, were observed with aging. Cloud condensation nuclei measurements suggested all particles >100 nm were active at 0.5% water supersaturation in the smoke plumes, confirming the relatively high hygroscopicity of the freshly emitted particles. For immersion/condensation freezing, ice nuclei measurements at −32 °C suggested activation of ~0.03–0.07% of the particles with diameters greater than 500 nm.

scholarly journals Flight-based chemical characterization of biomass burning aerosols within two prescribed burn smoke plumes

2011 ◽  
Vol 11 (6) ◽  
pp. 17507-17550 ◽  
Author(s):  
K. A. Pratt ◽  
S. M. Murphy ◽  
R. Subramanian ◽  
P. J. DeMott ◽  
G. L. Kok ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Radiative Forcing ◽  
Cloud Condensation Nuclei ◽  
Chemical Characterization ◽  
Potassium Sulfate ◽  
Prescribed Burn ◽  
Smoke Plumes ◽  
Mass Fractions

Abstract. Biomass burning represents a major global source of aerosols impacting direct radiative forcing and cloud properties. Thus, the goal of a number of current studies involves developing a better understanding of how the chemical composition and mixing state of biomass burning aerosols evolve during atmospheric aging processes. During the Ice in Cloud Experiment – Layer Clouds (ICE-L) in fall of 2007, smoke plumes from two small Wyoming Bureau of Land Management prescribed burns were measured by on-line aerosol instrumentation aboard a C-130 aircraft, providing a detailed chemical characterization of the particles. After ~2–4 min of aging, submicron smoke particles, produced primarily from sagebrush combustion, consisted predominantly of organics by mass, but were comprised primarily of internal mixtures of organic carbon, elemental carbon, potassium chloride, and potassium sulfate. Significantly, 100 % of the fresh biomass burning particles contained minor mass fractions of nitrate and sulfate, suggesting that hygroscopic material is incorporated very near or at the point of emission. The mass fractions of ammonium, sulfate, and nitrate increased with aging up to ~81–88 min and resulted in acidic particles, with both nitric acid and sulfuric acid present. Decreasing black carbon mass concentrations occurred due to dilution of the plume. Increases in the fraction of oxygenated organic carbon and the presence of dicarboxylic acids, in particular, were observed with aging. Cloud condensation nuclei measurements suggested all particles >100 nm were active at 0.5 % water supersaturation in the smoke plumes, confirming the relatively high hygroscopicity of the freshly emitted particles. For immersion/condensation freezing, ice nuclei measurements at −32 °C suggested activation of ~0.03–0.07 % of the particles with diameters greater than 500 nm.

scholarly journals Real time chemical characterization of local and regional nitrate aerosols

2009 ◽  
Vol 9 (11) ◽  
pp. 3709-3720 ◽  
Author(s):  
M. Dall'Osto ◽  
R. M. Harrison ◽  
H. Coe ◽  
P. I. Williams ◽  
J. D. Allan
Keyword(s):  
Organic Carbon ◽  
Mass Spectrometer ◽  
Western Europe ◽  
Time Of Flight ◽  
Chemical Characterization ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Neural Network Algorithm ◽  
Pm2.5 And Pm10

Abstract. Nitrate aerosols make a very major contribution to PM2.5 and PM10 in western Europe, but their sources and pathways have not been fully elucidated. An Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) and a Compact Time of Flight Aerosol Mass Spectrometer (C-ToF-AMS) were deployed in an urban background location in London, UK, collecting data as part of the REPARTEE-I experiment. During REPARTEE-I, daily PM10 concentrations ranged up to 43.6 μg m−3, with hourly nitrate concentrations (measured by AMS) of up to 5.3 μg m−3. The application of the ART-2a neural network algorithm to the ATOFMS data characterised the nitrate particles as occurring in two distinct clusters (i.e. particle types). The first (33.6% of particles by number) appeared to be locally produced in urban locations during nighttime, whilst the second (22.8% of particles by number) was regionally transported from continental Europe. Nitrate in locally produced aerosol was present mainly in particles smaller than 300 nm, whilst the regional nitrate presented a coarser mode, peaking at 600 nm. In both aerosol types, nitrate was found to be internally mixed with sulphate, ammonium, elemental and organic carbon. Nitrate in regional aerosol appeared to be more volatile than that locally formed. During daytime, a core of the regionally transported nitrate aerosol particle type composed of organic carbon and sulphate was detected.

scholarly journals Comprehensive airborne characterization of aerosol from a major bovine source

2008 ◽  
Vol 8 (3) ◽  
pp. 10415-10479 ◽  
Author(s):  
A. Sorooshian ◽  
S. M. Murphy ◽  
S. Hersey ◽  
H. Gates ◽  
L. T. Padro ◽  
...  
Keyword(s):  
Size Distribution ◽  
Water Uptake ◽  
Cloud Condensation Nuclei ◽  
Droplet Growth ◽  
Hygroscopic Growth ◽  
Organic Mass ◽  
Mixing State ◽  
Mass Spectral ◽  
Mass Fractions

Abstract. We report an extensive airborne characterization of aerosol downwind of a massive bovine source in the San Joaquin Valley (California) on two flights during July 2007. The Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter probed chemical composition, particle size distribution, mixing state, sub- and supersaturated water uptake behavior, light scattering properties, and the interrelationship between these parameters and meteorology. Total PM1.0 levels and concentrations of organics, nitrate, and ammonium were enhanced in the plume from the source as compared to the background aerosol. Organics dominated the plume aerosol mass (~56–64%), followed either by sulfate or nitrate, and then ammonium. Particulate amines were detected in the plume aerosol by a particle-into-liquid sampler (PILS) and via mass spectral markers in the Aerodyne cToF-AMS. Amines were found to be a significant atmospheric base even in the presence of ammonia; particulate amine concentrations are estimated as at least 14–23% of that of ammonium in the plume. Enhanced sub- and supersaturated water uptake and reduced refractive indices were coincident with lower organic mass fractions, higher nitrate mass fractions, and the detection of amines. Kinetic limitations due to hydrophobic organic material are shown to have likely suppressed droplet growth. After removing effects associated with size distribution and mixing state, the normalized activated fraction of cloud condensation nuclei (CCN) increased as a function of the subsaturated hygroscopic growth factor, with the highest activated fractions being consistent with relatively lower organic mass fractions and higher nitrate mass fractions. Subsaturated hygroscopic growth factors for the organic fraction of the aerosol are estimated based on employing the Zdanovskii-Stokes Robinson (ZSR) mixing rule. Representative values for a parameterization treating particle water uptake in both the sub- and supersaturated regimes are reported for incorporation into atmospheric models.

scholarly journals Measurement report: PM<sub>2.5</sub>-bound nitrated aromatic compounds in Xi'an, Northwest China – seasonal variations and contributions to optical properties of brown carbon

2021 ◽  
Vol 21 (5) ◽  
pp. 3685-3697
Author(s):  
Wei Yuan ◽  
Ru-Jin Huang ◽  
Lu Yang ◽  
Ting Wang ◽  
Jing Duan ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Seasonal Variations ◽  
Light Absorption ◽  
Aromatic Compounds ◽  
Radiative Forcing ◽  
Northwest China ◽  
Individual Species ◽  
Brown Carbon ◽  
Mass Fractions ◽  
Different Seasons

Abstract. Nitrated aromatic compounds (NACs) are a group of key chromophores for brown carbon (light-absorbing organic carbon, i.e., BrC) aerosol, which affects radiative forcing. The chemical composition and sources of NACs and their contributions to BrC absorption, however, are still not well understood. In this study, PM2.5-bound NACs in Xi'an, Northwest China, were investigated for 112 daily PM2.5 filter samples from 2015 to 2016. Both the total concentrations and contributions from individual species of NACs show distinct seasonal variations. The seasonally averaged concentrations of NACs are 2.1 (spring), 1.1 (summer), 12.9 (fall), and 56 ng m−3 (winter). Thereinto, 4-nitrophenol is the major NAC component in spring (58 %). The concentrations of 5-nitrosalicylic acid and 4-nitrophenol dominate in summer (70 %), and the concentrations of 4-nitrocatechol and 4-nitrophenol dominate in fall (58 %) and winter (55 %). The NAC species show different seasonal patterns in concentrations, indicating differences in emissions and formation pathways. Source apportionment results using positive matrix factorization (PMF) further show large seasonal differences in the sources of NACs. Specifically, in summer, NACs were highly influenced by secondary formation and vehicle emissions (∼ 80 %), while in winter, biomass burning and coal combustion contributed the most (∼ 75 %). Furthermore, the light absorption contributions of NACs to BrC are wavelength-dependent and vary greatly by season, with maximum contributions at ∼ 330 nm in winter and fall and ∼ 320 nm in summer and spring. The differences in the contribution to light absorption are associated with the higher mass fractions of 4-nitrocatechol (λmax⁡= 345 nm) and 4-nitrophenol (λmax⁡= 310 nm) in fall and winter, 4-nitrophenol in spring, and 5-nitrosalicylic acid (λmax⁡= 315 nm) and 4-nitrophenol in summer. The mean contributions of NACs to BrC light absorption at a wavelength of 365 nm in different seasons are 0.14 % (spring), 0.09 % (summer), 0.36 % (fall), and 0.91 % (winter), which are about 6–9 times higher than their mass fractional contributions of carbon in total organic carbon. Our results indicate that the composition and sources of NACs have profound impacts on the BrC light absorption.

scholarly journals In Situ Chemical Characterization of Aged Biomass-Burning Aerosols Impacting Cold Wave Clouds

2010 ◽  
Vol 67 (8) ◽  
pp. 2451-2468 ◽  
Author(s):  
Kerri A. Pratt ◽  
Andrew J. Heymsfield ◽  
Cynthia H. Twohy ◽  
Shane M. Murphy ◽  
Paul J. DeMott ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Biomass Burning ◽  
Single Particle ◽  
Cloud Condensation Nuclei ◽  
Chemical Characterization ◽  
Cloud Droplet ◽  
Cloud Microphysics ◽  
Particle Mass ◽  
Cold Wave ◽  
Biomass Burning Particles

Abstract During the Ice in Clouds Experiment–Layer Clouds (ICE-L), aged biomass-burning particles were identified within two orographic wave cloud regions over Wyoming using single-particle mass spectrometry and electron microscopy. Using a suite of instrumentation, particle chemistry was characterized in tandem with cloud microphysics. The aged biomass-burning particles comprised ∼30%–40% by number of the 0.1–1.0-μm clear-air particles and were composed of potassium, organic carbon, elemental carbon, and sulfate. Aerosol mass spectrometry measurements suggested these cloud-processed particles were predominantly sulfate by mass. The first cloud region sampled was characterized by primarily homogeneously nucleated ice particles formed at temperatures near −40°C. The second cloud period was characterized by high cloud droplet concentrations (∼150–300 cm−3) and lower heterogeneously nucleated ice concentrations (7–18 L−1) at cloud temperatures of −24° to −25°C. As expected for the observed particle chemistry and dynamics of the observed wave clouds, few significant differences were observed between the clear-air particles and cloud residues. However, suggestive of a possible heterogeneous nucleation mechanism within the first cloud region, ice residues showed enrichments in the number fractions of soot and mass fractions of black carbon, measured by a single-particle mass spectrometer and a single-particle soot photometer, respectively. In addition, enrichment of biomass-burning particles internally mixed with oxalic acid in both the homogeneously nucleated ice and cloud droplets compared to clear air suggests either preferential activation as cloud condensation nuclei or aqueous phase cloud processing.

Chemical Characterization of Water-Soluble Organic Aerosols at Jeju Island Collected During ACE-Asia

2004 ◽  
Vol 1 (1) ◽  
pp. 13 ◽  
Author(s):  
Hong Yang ◽  
Jinhui Xu ◽  
Wai-Shing Wu ◽  
Chun Hong Wan ◽  
Jian Zhen Yu
Keyword(s):  
Organic Carbon ◽  
South Korea ◽  
Chemical Characterization ◽  
Water Soluble ◽  
Asia Pacific ◽  
Carbon Mass ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon ◽  
Aerosol Characterization

Environmental Context. Atmospheric aerosols — particles suspended in the atmosphere — are responsible for many phenomena, including formation of cloud condensation nuclei and degradation of regional visibility. Water-soluble organic carbon (WSOC) components make up a significant fraction of the aerosols' carbon mass, and have consequently received increasing attention from researchers. The chemical composition of the WSOC fraction, and thus their sources and effects, are not well known. This study focusses on WSOC from samples collected in South Korea as part of ACE-Asia (Asia-Pacific Regional Aerosol Characterization Experiment), a large international collaboration including Asia, the USA, Europe and Australia. Abstract.During the Asia-Pacific Regional Aerosol Characterization Experiment (ACE-Asia) intensive field campaign, aerosol samples of less than 2.5 μm diameter were collected at Jeju Island, South Korea, for chemical characterization of the water-soluble organic carbon (WSOC) fraction. The WSOC fraction had an average mass concentration of roughly half of that of sulfate and accounted for about two-thirds of the organic carbon mass. Thirty individual water-soluble organic compounds, belonging to the classes of mono- and di-carboxylic acids, aliphatic amines, and amino acids, were identified, accounting for 14% of the WSOC on a carbon basis. Oxalic acid was the most abundant single component. An additional 3% of the WSOC was estimated to be monomeric carbohydrates. Thermal analysis of the aerosol’s water extracts indicated that a significant fraction (~50%) of WSOC was thermally recalcitrant, possibly consisting of polymeric materials.

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