A statistical examination of the chemical differences between interstitial and scavenged aerosol

Noone, Kevin J.; Ogren, J. A.; HALLBERG, ANNELI; Hansson, Hans‐Christen; Wiedensohler, Alfred; SWIETLICKI, ERIK

doi:10.1034/j.1600-0889.1992.t01-1-00011.x

Cited by 11 publications

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“…The hydrophobic nature of EC may strongly suppress the activation of these particles and their incorporation into cloud/fog droplets, diminish precipitation scavenging, and increase its residence time during these events. The results here suggest that aerosol solubility is strongly linked to the aerosol atmospheric lifetime as has been suggested in previous studies showing EC enrichment of the interstitial aerosol found in fog events [ Noone et al , 1992].…”

Section: Resultssupporting

confidence: 81%

Urban aerosol radiative properties: Measurements during the 1999 Atlanta Supersite Experiment

Carrico

Bergin

et al. 2003

J. Geophys. Res.

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[1] As part of the Atlanta Supersite 1999 study, aerosol radiative and related physical and chemical properties are examined on the basis of measurements of PM 2.5 (aerosol particles with aerodynamic diameters, D p , less than 2.5 mm) in urban Atlanta. In addition to potential compliance issues with proposed regulatory standards, PM 2.5 concentrations in Atlanta and the surrounding region are large enough to have an important impact on atmospheric radiative transfer and hence visibility and potentially regional climate. Arithmetic means and standard deviations of the light scattering by PM 2.5 (s sp at 530 nm) and absorption coefficients (s ap at 550 nm) measured at a controlled relative humidity of 49 ± 5% are 121 ± 48 and 16 ± 12 Mm À1 , respectively. Though the mean light extinction coefficient (s ep ) in Atlanta is much larger than background sites, it is comparable to nonurban areas in the interior southeast United States highlighting the contribution of a regional haze here. The single scattering albedo (w o ) in Atlanta is 0.87 ± 0.08 and is $10% lower than reported in nonurban polluted sites, likely a result of the emission of elemental carbon (EC) from mobile sources. A pronounced diel pattern in aerosol properties is observed with clear influences from mobile sources (morning rush hour maxima in concentrations, particularly soot-related indicators) and atmospheric mixing (afternoon minima). A strong linear relationship between s sp and PM 2.5 is observed, and using several techniques, gives a range of mean mass scattering efficiencies (E sp ) from = 3.5 to 4.4 m 2 g À1 . EC and s ap are observed to have a relationship though less strongly correlated than s sp and PM 2.5 . Four methods of determining the mass absorption efficiency of EC give E ap ranging from 5.3 to 18.3 m 2 g À1 . This wide range of values is a result of the variability in aerosol properties, uncertainties in the light absorption method, and in particular, differences in the EC measurement techniques. Best agreement was found using measured EC mass distributions using a multistage impactor in comparison to s ap calculated with a Mie code yielding E ap = 9.5 ± 1.5 m 2 g À1 , while EC mass summed from the impactor stages in comparison to measured s ap gives E ap = 9.3 ± 3.2 m 2 g À1 . Mie light-scattering calculations using inputs of measured mass and EC size distributions give geometric mean light scattering and absorption D p = 0.54 and 0.13 mm, respectively, and show the dominance of the submicrometer diameter particles to light extinction in the urban environment. Based on the measured aerosol optical depth in Atlanta, d a (500 nm) = 0.44 ± 0.22, and other radiative measurements, a best estimate of the average direct aerosol radiative forcing at the top of the atmosphere (a measure of the climate significance) is ÁF = À11 ± 6 W m À2 in Atlanta. This value is an order of magnitude greater than global mean estimates for aerosols underscoring the influence of aerosol particles on radiative transfer in the urban environment.

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Section: Resultssupporting

confidence: 81%

Urban aerosol radiative properties: Measurements during the 1999 Atlanta Supersite Experiment

Carrico

Bergin

et al. 2003

J. Geophys. Res.

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“…Some water-soluble particulate organics such as oxalic acid have wet-scavenging efficiencies comparable to sulfate (). However, clouds and fogs ineffectively scavenge hydrophobic EC in the atmosphere ( − ). A field study in the Po Valley of Italy showed that EC was preferentially enriched in interstitial particles relative to fog droplets and that the fraction of EC scavenged to fog droplets was 6%, considerably lower than 18% of sulfate ( , ).…”

Section: Resultsmentioning

confidence: 99%

“…However, clouds and fogs ineffectively scavenge hydrophobic EC in the atmosphere ( − ). A field study in the Po Valley of Italy showed that EC was preferentially enriched in interstitial particles relative to fog droplets and that the fraction of EC scavenged to fog droplets was 6%, considerably lower than 18% of sulfate ( , ). Chýlek et al () found that over 90% of EC was in interstitial particles in clouds over southern Nova Scotia, Canada.…”

Section: Resultsmentioning

confidence: 99%

Organic and Elemental Carbon Measurements during ACE-Asia Suggest a Longer Atmospheric Lifetime for Elemental Carbon

Lim

Turpin

Russell

et al. 2003

Environ. Sci. Technol.

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During the ACE-Asia intensive field campaign (March 14-April 20, 2001), PM1.0 organic (OC) and elemental carbon (EC) concentrations were measured onboard the NOAA R/V Ronald H. Brown over the Northwest Pacific Ocean using a semi-continuous automated carbon analyzer downstream of a carbon-impregnated filter denuder. This OC and EC measurement achieved a mean time resolution of about 200 min over the Pacific Ocean, substantially lower than that achieved previously (24 h). The semi-continuous measurements, in which the adsorption artifact was substantially reduced using the denuder, showed good agreement with integrated artifact-corrected measurements made without a denuder. Mean particulate OC and EC concentrations were 0.21 and 0.09, 0.70 and 0.29, 1.00 and 0.27, and 2.43 and 0.66 microg of C m(-3) over the background Pacific Ocean, Asian-influenced Pacific Ocean, offshore of Japan, and Sea of Japan, respectively. On April 11, 90-min average OC and EC concentrations peaked at 4.0 and 1.3 microg of C m(-3), respectively, offshore of Korea over the Sea of Japan. The OC/EC ratio of 3.7 over the Sea of Japan and offshore of Japan was substantially higher than that of 2.5 over the Asian-influenced Pacific Ocean, even though backward air mass trajectories put the "Asian-influenced Pacific Ocean" sample downwind. The OC/EC ratio decreased with increasing time since the air mass encountered the source regions of China, Japan, and Korea. This suggests a longer atmospheric residence time for EC than for OC.

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“…The replication technique using collodion film was used to collect individual fog droplets and microparticle-induced X-ray emission were used to obtain their compositions . The counter-flow virtual impactor was used to collect individual cloud droplets on nuclepore filters or copper grids, and their residual particles were analyzed by TEM and SEM. ,, These studies investigated compositions of individual cloud droplets and interstitial aerosol particles in cloud/fog episodes over continental, coastal, and marine areas. The major chemical components of cloud/fog residues were sulfates, nitrates, organics, and element carbon and some metal particles in polluted areas.…”

Section: Introductionmentioning

confidence: 99%

Microscopic Evaluation of Trace Metals in Cloud Droplets in an Acid Precipitation Region

Wang

Collett

et al. 2013

Environ. Sci. Technol.

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Mass concentrations of soluble trace metals and size, number, and mixing properties of nanometal particles in clouds determine their toxicity to ecosystems. Cloud water was found to be acidic, with a pH of 3.52, at Mt. Lu (elevation 1,165 m) in an acid precipitation region in South China. A combination of Inductively Coupled Plasma Mass Spectrometry (ICPMS) and Transmission Electron Microscopy (TEM) for the first time demonstrates that the soluble metal concentrations and solid metal particle number are surprisingly high in acid clouds at Mt. Lu, where daily concentrations of SO2, NO2, and PM10 are 18 μg m(-3), 7 μg m(-3), and 22 μg m(-3). The soluble metals in cloudwater with the highest concentrations were zinc (Zn, 200 μg L(-1)), iron (Fe, 88 μg L(-1)), and lead (Pb, 77 μg L(-1)). TEM reveals that 76% of cloud residues include metal particles that range from 50 nm to 1 μm diameter with a median diameter of 250 nm. Four major metal-associated particle types are Pb-rich (35%), fly ash (27%), Fe-rich (23%), and Zn-rich (15%). Elemental mapping shows that minor soluble metals are distributed within sulfates of cloud residues. Emissions of fine metal particles from large, nonferrous industries and coal-fired power plants with tall stacks were transported upward to this high elevation. Our results suggest that the abundant trace metals in clouds aggravate the impacts of acid clouds or associated precipitation on the ecosystem and human health.

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A statistical examination of the chemical differences between interstitial and scavenged aerosol

Cited by 11 publications

References 0 publications

Urban aerosol radiative properties: Measurements during the 1999 Atlanta Supersite Experiment

Urban aerosol radiative properties: Measurements during the 1999 Atlanta Supersite Experiment

Organic and Elemental Carbon Measurements during ACE-Asia Suggest a Longer Atmospheric Lifetime for Elemental Carbon

Microscopic Evaluation of Trace Metals in Cloud Droplets in an Acid Precipitation Region

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