The Cloud Condensation Nuclei (CCN) properties of 2-methyltetrols and C3-C6 polyols from osmolality and surface tension measurements

Ekström, Sanna; Nozière, Barbara; Hansson, Hans‐Christen

doi:10.5194/acp-9-973-2009

Cited by 39 publications

(25 citation statements)

References 33 publications

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“…Therefore, it is reasonable that soil‐derived glucose was found abundantly in coarse particles larger than 3.0 μ m, being in contrast to levoglucosan (Figure 6c), whose origin is associated with biomass burning. Recently, CCN efficiencies of saccharides have been reported to be lower than those of organic acids owing to their absence of dissociation in water, and their contributions to cloud formation are less than those of diacids [ Ekstrom et al , 2009; Rosenorn et al , 2006; Varga et al , 2007]. Thus, less abundance of levoglucosan on coarse mode (Figure 6c) may mean that cloud/fog formation over the mountaintop does not significantly affect its size distribution.…”

Section: Resultsmentioning

confidence: 99%

Water‐soluble organic compounds in PM_2.5 and size‐segregated aerosols over Mount Tai in North China Plain

et al. 2009

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[1] Daytime and nighttime PM 2.5 samples were collected at the summit of Mount Tai (1534 m) located in North China Plain during a week in 2006 summer. Size-segregated aerosol particles were also collected using an eight-stage impactor during the same period. Samples were analyzed for various water-soluble organic compounds using GC/FID and GC/MS techniques. Among the species identified in PM 2.5 samples, dicarboxylic acids (C 2 -C 11 ) were found as the most abundant compound class, followed by ketocarboxylic acids, saccharides, polyols and polyacids, and dicarbonyls. Daytime concentrations of most compounds were found to be 2-3 times higher than in nighttime. Such a diurnal variation was first interpreted by the depressed transport of pollutants in nighttime from the lowlands to the mountaintop owing to the decreased heights of planetary boundary layer, and second by the photochemical production in daytime. The diurnal variation trends of secondary organic aerosols (SOA) such as diacids at the mountain site are the same as those on lowlands, but the diurnal patterns of primary organic aerosols (POA) on the mountaintop are in contrast to those on lowlands, where POA such as saccharides and polyols are usually higher in nighttime owing to the accumulation within inversion layer developed. The eight-stage impactor samples showed bimodal distributions of diacids and related compounds peaking at size ranges of 0.70-1.1 mm and 5.8-9.0 mm. In the present study, water-soluble organics in the fine mode are largely originated from biomass burning and/or photooxidation of gaseous precursors and the subsequent adsorption on the preexisting particles, whereas those in the coarse mode are mainly derived from suspended soil particles and pollens and in part via the hygroscopic growth of fine particles and formation of cloud/fog droplets.

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Section: Resultsmentioning

confidence: 99%

Water‐soluble organic compounds in PM_2.5 and size‐segregated aerosols over Mount Tai in North China Plain

et al. 2009

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“…For this, time-dependent Köhler curves were calculated for a representative sample (04 June 2009) and taking into account the time variations of σ . These curves were calculated point by point using the same approach as shown in the study by Ekström et al 1535. and from the Köhler equation:1…”

Section: Discussionmentioning

confidence: 99%

“…σ was replaced in equation (5) by the time-dependent expression (equation (1)) obtained by fitting the experimental curve for the sample of 04 June 2009. The Raoult’s term, a w , was obtained from osmometric measurements153536. As such measurements could not be made with the samples studied in this work, those made previously with rhamnolipid15, which had the most similar properties, were used:…”

Section: Discussionmentioning

confidence: 99%

The dynamic surface tension of atmospheric aerosol surfactants reveals new aspects of cloud activation

2014

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The activation of aerosol particles into cloud droplets in the Earth’s atmosphere is both a key process for the climate budget and a main source of uncertainty. Its investigation is facing major experimental challenges, as no technique can measure the main driving parameters, the Raoult’s term and surface tension, σ, for sub-micron atmospheric particles. In addition, the surfactant fraction of atmospheric aerosols could not be isolated until recently. Here we present the first dynamic investigation of the total surfactant fraction of atmospheric aerosols, evidencing adsorption barriers that limit their gradient (partitioning) in particles and should enhance their cloud-forming efficiency compared with current models. The results also show that the equilibration time of surfactants in sub-micron atmospheric particles should be beyond the detection of most on-line instruments. Such instrumental and theoretical shortcomings would be consistent with atmospheric and laboratory observations and could have limited the understanding of cloud activation until now.

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“…Ekström et al [, ] suggest based on surface tension measurements and model calculations that biosurfactants lead to exceptional cloud nucleating efficiency. However, the authors did not directly measure CCN activity to confirm this hypothesis.…”

Section: Introductionmentioning

confidence: 99%

Surfactant effect on cloud condensation nuclei for two‐component internally mixed aerosols

2016

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This work presents experimental data on the cloud condensation nuclei (CCN) activity of two‐component mixtures containing surfactants. Nine binary systems were tested combining strong ionic (sodium dodecyl sulfate) and nonionic surfactants (Zonyl FS‐300 and Triton X‐100) with nonsurfactant compounds (glucose, ammonium sulfate, or sodium chloride). Control tests were performed for systems combining organic (glucose) and inorganic compounds (ammonium sulfate or sodium chloride). Results show that CCN activity deviates strongly relative to predictions made from measurements of bulk surface tension. Köhler theory accounting for surface tension reduction and surface partitioning underpredicts the CCN activity of particles containing Zonyl FS‐300 and Triton X‐100. Partitioning theory better describes data for Zonyl FS‐300 and Triton X‐100 when limiting surface adsorption to 1.5 monolayers of the growing drop. Deviations from predictions were observed. Likely explanations include solute‐solute interactions and nonspherical particle shape. The findings presented here examine in detail the perturbation of CCN activity by surfactants and may offer insight into both the success and limitations of physical models describing CCN activity of surface active molecules.

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The Cloud Condensation Nuclei (CCN) properties of 2-methyltetrols and C3-C6 polyols from osmolality and surface tension measurements

Cited by 39 publications

References 33 publications

Water‐soluble organic compounds in PM_2.5 and size‐segregated aerosols over Mount Tai in North China Plain

Water‐soluble organic compounds in PM_2.5 and size‐segregated aerosols over Mount Tai in North China Plain

The dynamic surface tension of atmospheric aerosol surfactants reveals new aspects of cloud activation

Surfactant effect on cloud condensation nuclei for two‐component internally mixed aerosols

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The Cloud Condensation Nuclei (CCN) properties of 2-methyltetrols and C3-C6 polyols from osmolality and surface tension measurements

Cited by 39 publications

References 33 publications

Water‐soluble organic compounds in PM2.5 and size‐segregated aerosols over Mount Tai in North China Plain

Water‐soluble organic compounds in PM2.5 and size‐segregated aerosols over Mount Tai in North China Plain

The dynamic surface tension of atmospheric aerosol surfactants reveals new aspects of cloud activation

Surfactant effect on cloud condensation nuclei for two‐component internally mixed aerosols

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Product

Resources

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Water‐soluble organic compounds in PM_2.5 and size‐segregated aerosols over Mount Tai in North China Plain

Water‐soluble organic compounds in PM_2.5 and size‐segregated aerosols over Mount Tai in North China Plain