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You searched for subject:(particle hygroscopic growth). Showing records 1 – 2 of 2 total matches.

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Queensland University of Technology

1. Modini, Robin Lewis. Investigation of the effect of organics on the water uptake of marine aerosols.

Degree: 2010, Queensland University of Technology

Water uptake refers to the ability of atmospheric particles to take up water vapour from the surrounding atmosphere. This is an important property that affects particle size and phase and therefore influences many characteristics of aerosols relevant to air quality and climate. However, the water uptake properties of many important atmospheric aerosol systems, including those related to the oceans, are still not fully understood. Therefore, the primary aim of this PhD research program was to investigate the water uptake properties of marine aerosols. In particular, the effect of organics on marine aerosol water uptake was investigated. Field campaigns were conducted at remote coastal sites on the east coast of Australia (Agnes Water; March-April 2007) and west coast of Ireland (Mace Head; June 2007), and laboratory measurements were performed on bubble-generated sea spray aerosols. A combined Volatility-Hygroscopicity-Tandem Differential Mobility Analyser (VH-TDMA) was employed in all experiments. This system probes the changes in the hygroscopic properties of nanoparticles as volatile organic components are progressively evaporated. It also allows particle composition to be inferred from combined volatility-hygroscopicity measurements. Frequent new particle formation and growth events were observed during the Agnes Water campaign. The VH-TDMA was used to investigate freshly nucleated particles (17-22.5 nm) and it was found that the condensation of sulphate and/or organic vapours was responsible for driving particle growth during the events. Aitken mode particles (~40 nm) were also measured with the VH-TDMA. In 3 out of 18 VH-TDMA scans evaporation of a volatile, organic component caused a very large increase in hygroscopicity that could only be explained by an increase in the absolute water uptake of the particle residuals, and not merely an increase in their relative hygroscopicity. This indicated the presence of organic components that were suppressing the hygroscopic growth of mixed particles on the timescale of humidification in the VH-TDMA (6.5 secs). It was suggested that the suppression of water uptake was caused by either a reduced rate of hygroscopic growth due to the presence of organic films, or organic-inorganic interactions in solution droplets that had a negative effect on hygroscopicity. Mixed organic-inorganic particles were rarely observed by the VH-TDMA during the summer campaign conducted at Mace Head. The majority of particles below 100 nm in clean, marine air appeared to be sulphates neutralised to varying degrees by ammonia. On one unique day, 26 June 2007, particularly large concentrations of sulphate aerosol were observed and identified as volcanic emissions from Iceland. The degree of neutralisation of the sulphate aerosol by ammonia was calculated by the VH-TDMA and found to compare well with the same quantity measured by an aerosol mass spectrometer. This was an important verification of the VH-TMDA‘s ability to identify ammoniated sulphate aerosols based on the simultaneous measurement of…

Subjects/Keywords: marine aerosols, water uptake, hygroscopic growth, VH-TDMA, atmospheric aerosols, organic aerosols, sea spray aerosols, sulphate aerosols, atmospheric new particle formation, nucleation events, nucleation mode, Aitken mode, accumulation mode; aerosol composition, volatility, HTDMA, deliquescence, water uptake suppression, organic films, bubble chamber

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Modini, R. L. (2010). Investigation of the effect of organics on the water uptake of marine aerosols. (Thesis). Queensland University of Technology. Retrieved from https://eprints.qut.edu.au/46884/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Modini, Robin Lewis. “Investigation of the effect of organics on the water uptake of marine aerosols.” 2010. Thesis, Queensland University of Technology. Accessed July 09, 2020. https://eprints.qut.edu.au/46884/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Modini, Robin Lewis. “Investigation of the effect of organics on the water uptake of marine aerosols.” 2010. Web. 09 Jul 2020.

Vancouver:

Modini RL. Investigation of the effect of organics on the water uptake of marine aerosols. [Internet] [Thesis]. Queensland University of Technology; 2010. [cited 2020 Jul 09]. Available from: https://eprints.qut.edu.au/46884/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Modini RL. Investigation of the effect of organics on the water uptake of marine aerosols. [Thesis]. Queensland University of Technology; 2010. Available from: https://eprints.qut.edu.au/46884/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Queensland University of Technology

2. Johnson, Graham Richard. The Formation and Growth of Marine Aerosols and the Development of New Techniques for their In-situ Analysis.

Degree: 2005, Queensland University of Technology

Marine aerosols have attracted increasing attention over the past 15 years because of their potential significance for global climate modelling. The size distribution of these aerosols extends from super-micrometer sea salt mode particles down through 150 nm accumulation mode particles, 40 nm Aitken mode particles and nucleation mode particles which extend from 25 nm right down to clusters of a few molecules. The process by which the submicrometer modes form and grow and their composition have remained topics of debate throughout this time in large part because of the difficulties associated with determining their composition and relating it to proposed models of the formation process. The work compared the modality of marine aerosol influencing the South-east-Queensland region with that of other environmental aerosols in the region. The aerosol was found to be consistent with marine aerosols observed elsewhere with concentrations below 1000 cm-3 and frequently exhibiting the distinct bimodal structure associated with cloud processing, consisting of an Aitken mode at approximately 40 nm, an accumulation mode in the range 100-200 nm and a coarse mode attributed to sea salt between 600 and 1200 nm. This work included the development of two new techniques for aerosol research. The first technique measures aerosol density using a combination of aerosol size distribution and gravimetric mass concentration measurements. This technique was used to measure the density of a number of submicrometer aerosols including laboratory generated NaCl aerosol and ambient aerosol. The densities for the laboratory generated aerosols were found to be similar to those for the bulk materials used to produce them. The technique, extended to super-micrometer particle size range may find application in ambient aerosol research where it could be used to discriminate between periods when the aerosol is dominated by NaCl and periods when the density is more representative of crustal material or sulfates. The technique may also prove useful in laboratory or industrial settings for investigating particle density or in case where the composition is known, morphology and porosity. The second technique developed, integrates the existing physicochemical techniques of volatilisation and hygroscopic growth analysis to investigate particle composition in terms of both the volatilisation temperatures of the chemical constituents and their contribution to particle hygroscopic behaviour. The resulting volatilisation and humidification tandem differential mobility analyser or VH-TDMA, has proven to be a valuable research tool which is being used in ongoing research. Findings of investigations relating the composition of the submicrometer marine aerosol modes to candidate models for their formation are presented. Sea salt was not found in the numerically dominant particle type in coastal nucleation mode or marine Aitken and accumulation modes examined on the Southeast…

Subjects/Keywords: Aerosol size distribution; modality; environmental aerosols; marine aerosols; aerosol density; ambient aerosol; VH-TDMA; particle hygroscopic growth; volatility; iodine oxides; non sea salt sulfate; sea salt aerosols; coastal aerosol; marine biota; algae; photolysis; photochemical; thermal decomposition; volatilisation and humidification tandem differential mobility analyser; ultra fine particles.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Johnson, G. R. (2005). The Formation and Growth of Marine Aerosols and the Development of New Techniques for their In-situ Analysis. (Thesis). Queensland University of Technology. Retrieved from https://eprints.qut.edu.au/16117/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Johnson, Graham Richard. “The Formation and Growth of Marine Aerosols and the Development of New Techniques for their In-situ Analysis.” 2005. Thesis, Queensland University of Technology. Accessed July 09, 2020. https://eprints.qut.edu.au/16117/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Johnson, Graham Richard. “The Formation and Growth of Marine Aerosols and the Development of New Techniques for their In-situ Analysis.” 2005. Web. 09 Jul 2020.

Vancouver:

Johnson GR. The Formation and Growth of Marine Aerosols and the Development of New Techniques for their In-situ Analysis. [Internet] [Thesis]. Queensland University of Technology; 2005. [cited 2020 Jul 09]. Available from: https://eprints.qut.edu.au/16117/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Johnson GR. The Formation and Growth of Marine Aerosols and the Development of New Techniques for their In-situ Analysis. [Thesis]. Queensland University of Technology; 2005. Available from: https://eprints.qut.edu.au/16117/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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