A possible role of ground-based microorganisms on cloud formation in the atmosphere

Ekström, Sanna; Nozière, Barbara; Hultberg, Malin; Alsberg, Tomas; Magnér, Jörgen; Nilsson, E. Douglas; Artaxo, Paulo

doi:10.5194/bg-7-387-2010

Cited by 69 publications

(75 citation statements)

References 45 publications

(44 reference statements)

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“…Finally, these discrepancies in aerosol water uptake below and above water saturation have been observed in marine atmospheres Ovadnevaite et al, 2011). It has been hypothesized that the presence of biopolymers and biosurfactants in aerosol derived from sea-spray in biologically active waters contributes to this phenomena (O'Dowd et al, 2004;Ekström et al, 2010;Ovadnevaite et al, 2011).…”

Section: Atmospheric Implicationsmentioning

confidence: 99%

Discontinuities in hygroscopic growth below and above water saturation for laboratory surrogates of oligomers in organic atmospheric aerosols

et al. 2016

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Abstract. Discontinuities in apparent hygroscopicity below and above water saturation have been observed for organic and mixed organic-inorganic aerosol particles in both laboratory studies and in the ambient atmosphere. However, uncertainty remains regarding the factors that contribute to observations of low hygroscopic growth below water saturation but enhanced cloud condensation nuclei (CCN) activity for a given aerosol population. Utilizing laboratory surrogates for oligomers in atmospheric aerosols, we explore the extent to which such discontinuities are influenced by organic component molecular mass and viscosity, non-ideal thermodynamic interactions between aerosol components, and the combination of these factors. Measurements of hygroscopic growth under subsaturated conditions and the CCN activity of aerosols comprised of polyethylene glycol (PEG) with average molecular masses ranging from 200 to 10 000 g mol −1 and mixtures of PEG with ammonium sulfate (AS) were conducted. Experimental results are compared to calculations of hygroscopic growth at thermodynamic equilibrium conducted with the Aerosol Inorganic Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model, and the potential influence of kinetic limitations on observed water uptake was further explored through estimations of water diffusivity in the PEG oligomers. Particle-phase behavior, including the prevalence of liquid-liquid phase separation (LLPS), was also modeled with AIOMFAC. Under subsaturated relative humidity (RH) conditions, we observed little variability in hygroscopic growth across PEG systems with different molecular masses; however, an increase in CCN activity with increasing PEG molecular mass was observed. This effect is most pronounced for PEG-AS mixtures, and, in fact, an enhancement in CCN activity was observed for the PEG10000-AS mixture as compared to pure AS, as evidenced by a 15 % reduction in critical activation diameter at a supersaturation of 0.8 %. We also observed a marked increase in apparent hygroscopicity for mixtures of higher molecular mass PEG and AS under supersaturated conditions as compared to subsaturated hygroscopic growth. AIOMFAC-based predictions and estimations of water diffusivity in PEG suggest that such discontinuities in apparent hygroscopicity above and below water saturation can be attributed, at least in part, to differences in the sensitivity of water uptake behavior to surface tension effects. There is no evidence that kinetic limitations to water uptake due to the presence of viscous aerosol components influenced hygroscopic growth. For the systems that display an enhancement in apparent hygroscopicity above water saturation, LLPS is predicted to persist to high RH. This indicates a miscibilityPublished by Copernicus Publications on behalf of the European Geosciences Union. 12768 N. Hodas et al.: Discontinuities in the hygroscopicity of oligomers gap and is likely to influence bulk-to-surface partitioning of PEG at high RH, impacting droplet surface tension and CCN activity....

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Section: Atmospheric Implicationsmentioning

confidence: 99%

Discontinuities in hygroscopic growth below and above water saturation for laboratory surrogates of oligomers in organic atmospheric aerosols

et al. 2016

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“…Selective enrichment of specific surfactant materials -in the sea-surface microlayer and in atmospheric aerosolshas been well described (Barger and Garret, 1970;Mukerjee and Handa, 1981;Blanchard, 1990;Tseng et al, 1992;Oppo et al, 1999;Ekström et al, 2010). This enrichment of surfactants is even more increased at the sea surface during rough sea conditions, when wave breaking action causes air bubbles to be trapped beneath the water surface (O'Dowd and de Leeuw, 2007).…”

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confidence: 99%

Dissolved organic matter in sea spray: a transfer study from marine surface water to aerosols

et al. 2012

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Abstract. Atmospheric aerosols impose direct and indirect effects on the climate system, for example, by absorption of radiation in relation to cloud droplets size, on chemical and organic composition and cloud dynamics. The first step in the formation of Organic primary aerosols, i.e. the transfer of dissolved organic matter from the marine surface into the atmosphere, was studied. We present a molecular level description of this phenomenon using the high resolution analytical tools of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and nuclear magnetic resonance spectroscopy (NMR). Our experiments confirm the chemoselective transfer of natural organic molecules, especially of aliphatic compounds from the surface water into the atmosphere via bubble bursting processes. Transfer from marine surface water to the atmosphere involves a chemical gradient governed by the physicochemical properties of the involved molecules when comparing elemental compositions and differentiating CHO, CHNO, CHOS and CHNOS bearing compounds. Typical chemical fingerprints of compounds enriched in the aerosol phase were CHO and CHOS molecular series, smaller molecules of higher aliphaticity and lower oxygen content, and typical surfactants. A nontargeted metabolomics analysis demonstrated that many of these molecules corresponded to homologous series of oxo-, hydroxy-, methoxy-, branched fatty acids and mono-, diand tricarboxylic acids as well as monoterpenes and sugars. These surface active biomolecules were preferentially transferred from surface water into the atmosphere via bubble bursting processes to form a significant fraction of primary organic aerosols. This way of sea spray production leaves a selective biological signature of the surface water in the corresponding aerosol that may be transported into higher altitudes up to the lower atmosphere, thus contributing to the formation of secondary organic aerosol on a global scale or transported laterally with possible deposition in the context of global biogeocycling.

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“…E. coli and P. aeruginosa have been used as model microorganisms in studies dealing with primary biological aerosol particles (4). These bioaerosol particles have been proposed to act as cloud condensation nuclei (CCN) (6,15), suggesting a possible transfer of these opportunistic pathogens into rainwater through cloud droplets. Turkum et al (2008) suggested that most of the species found in rainwater were derived from aerosol and gasphase components (47).…”

Section: Resultsmentioning

confidence: 99%

Influence of Air Quality on the Composition of Microbial Pathogens in Fresh Rainwater

Kaushik

Balasubramanian

Cruz

2012

Appl Environ Microbiol

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In this study, the microbiological quality of fresh rainwater was assessed from 50 rain events under tropical weather conditions for a year. The levels of four major opportunistic waterborne pathogens, namely, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Aeromonas hydrophila, in rainwater samples were quantified by using a robust and sensitive quantitative PCR (qPCR) method. Of the 50 rainwater samples, 25 were found to be positive for at least one pathogen: 21 for E. coli, 16 for P. aeruginosa, 6 for K. pneumoniae, and 1 for A. hydrophila. In addition to the microbiological assessment of rainwater samples, we also studied the influence of prevailing air quality on the microbial quality of rainwater over the sampling period. A significant change in the diversity and relative abundance of the basic microbial indicator organisms in rainwater was observed during a major regional air pollution episode in Southeast Asia due to biomass-burning emissions. Water shortage is becoming a major problem worldwide due to the increased demands of growing population and urbanization (29,38). In an effort to ensure a sustainable future, a global search for alternative sources of water is ongoing, and rainwater harvesting has received considerable attention (1,13,23,44,45). However, the use of rainwater for drinking purposes is impeded by issues of water quality in terms of chemical and microbiological contamination and its potential health risks (1). While numerous studies on the chemical contamination of rainwater have been conducted (5,11,27,30,43), its microbial quality remains relatively unknown due to the analytical challenge involved in the detection of a range of contaminants, particularly pathogens.Some previous studies have reported that roof-harvested rainwater is generally acceptable for drinking and household purposes (12,13,16,26), while more-recent studies have revealed the presence of waterborne pathogens in rainwater samples (1,3,11,22,34,35,43). Differences in the characteristics of the catchment area, the type of water tanks, their cleanliness, and other factors, such as roof material, the intensity of human activities in the catchment area (urban or rural), and the presence of insects and birds on the rooftop, could be responsible for the contradictory results in the literature on the microbial quality of rainwater (10,17,18,34,39,46). Numerous studies conducted on the chemical composition of rainwater and roof runoff have demonstrated links between chemical contaminants and weather patterns, and between atmospheric transport and deposition (9,19,24,48). However, little is known about such links with respect to microbial composition. In order to identify sources of microorganisms in roof-harvested rainwater, it is desirable to study the microbial flora of fresh rainwater prior to its collection and storage, with no contamination from external sources.Microbial water quality monitoring is generally directed toward indicator microorganisms such as coliforms, Escherichia coli, and Klebsiel...

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A possible role of ground-based microorganisms on cloud formation in the atmosphere

Cited by 69 publications

References 45 publications

Discontinuities in hygroscopic growth below and above water saturation for laboratory surrogates of oligomers in organic atmospheric aerosols

Discontinuities in hygroscopic growth below and above water saturation for laboratory surrogates of oligomers in organic atmospheric aerosols

Dissolved organic matter in sea spray: a transfer study from marine surface water to aerosols

Influence of Air Quality on the Composition of Microbial Pathogens in Fresh Rainwater

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