The relevance of nanoscale biological fragments for ice nucleation in clouds

O’Sullivan, Daniel; Murray, Benjamin J.; Ross, James F.; Whale, Thomas F.; Price, H. C.; Atkinson, James; Umo, Nsikanabasi Silas; Webb, Michael E.

doi:10.1038/srep08082

Cited by 213 publications

(293 citation statements)

References 47 publications

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“…In this figure the blanks refer to the freezing properties of the sample after 0.02 µm filtration. The blanks may still contain some INPs since some particles < 0.02 µm in diameter can act as INPs (Dreischmeier et al, 2017;O'Sullivan et al, 2015). The freezing properties of the blanks (after correction for freezing point depression by the salts) are similar to or lower than the freezing properties of ultrapure water, which are also shown in Fig.…”

Section: Inps In the Microlayer And Bulk Seawatermentioning

confidence: 56%

“…Between 15 to 20 droplets of the sample, with volumes of 0.6 µL each, were deposited onto a hydrophobic glass slide (HR3-215; Hampton Research, Aliso Viejo, CA, USA) using a pipette. The slides were put into an airtight cell (Parsons et al, 2004) attached to a cold stage and analysed by the DFT as detailed in Wheeler et al (2015). The droplets were cooled at a constant rate of 5 • C min −1 from 0 to −35 • C. Each experiment was repeated three times using three different slides.…”

Section: Ice-nucleation Properties Of the Samples 221 Droplet Freezmentioning

confidence: 99%

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Ice-nucleating particles in Canadian Arctic sea-surface microlayer and bulk seawater

et al. 2017

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Abstract. The sea-surface microlayer and bulk seawater can contain ice-nucleating particles (INPs) and these INPs can be emitted into the atmosphere. Our current understanding of the properties, concentrations, and spatial and temporal distributions of INPs in the microlayer and bulk seawater is limited. In this study we investigate the concentrations and properties of INPs in microlayer and bulk seawater samples collected in the Canadian Arctic during the summer of 2014. INPs were ubiquitous in the microlayer and bulk seawater with freezing temperatures in the immersion mode as high as −14 • C. A strong negative correlation (R = −0.7, p = 0.02) was observed between salinity and freezing temperatures (after correction for freezing depression by the salts). One possible explanation is that INPs were associated with melting sea ice. Heat and filtration treatments of the samples show that the INPs were likely heat-labile biological materials with sizes between 0.02 and 0.2 µm in diameter, consistent with previous measurements off the coast of North America and near Greenland in the Arctic. The concentrations of INPs in the microlayer and bulk seawater were consistent with previous measurements at several other locations off the coast of North America. However, our average microlayer concentration was lower than previous observations made near Greenland in the Arctic. This difference could not be explained by chlorophyll a concentrations derived from satellite measurements. In addition, previous studies found significant INP enrichment in the microlayer, relative to bulk seawater, which we did not observe in this study. While further studies are needed to understand these differences, we confirm that there is a source of INP in the microlayer and bulk seawater in the Canadian Arctic that may be important for atmospheric INP concentrations.

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Section: Inps In the Microlayer And Bulk Seawatermentioning

confidence: 56%

Section: Ice-nucleation Properties Of the Samples 221 Droplet Freezmentioning

confidence: 99%

Ice-nucleating particles in Canadian Arctic sea-surface microlayer and bulk seawater

et al. 2017

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“…For example, the IN activity of K-feldspar (Atkinson et al, 2013) may be altered by a change in composition of surface ions (Zolles et al, 2015). However, the lack of any effect upon heating samples to 60 • C suggests this was not the case (see also O'Sullivan et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…Mortierella alpina is a saprobe utilizing decaying organic matter (Wagner et al, 2013), and due to its ability to solubilize phosphorus also develops a mutualistic association with another fungal genus that forms mycorrhizal symbioses with sagebrush (Wicklow-Howard, 1994;Zhang et al, 2011). All 39 isolates tested by initiated freezing at −5 to −6 • C. They also typically released 10 8 to 10 9 small (< 10 nm) INPs per gram fresh weight of mycelium that nucleated between −5 and −8 • C (see O'Sullivan et al, 2015). For the three most common clades, which occurred in agricultural and lodgepole pine forest soils, digestion of isolates with papain lowered the INP concentration by ≈ 3-4 orders of magnitude , suggesting the INP was a protein.…”

Section: In Fungimentioning

confidence: 99%

Sources of organic ice nucleating particles in soils

et al. 2016

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Abstract. Soil organic matter (SOM) may be a significant source of atmospheric ice nucleating particles (INPs), especially of those active > −15 • C. However, due to both a lack of investigations and the complexity of the SOM itself, the identities of these INPs remain unknown. To more comprehensively characterize organic INPs we tested locally representative soils in Wyoming and Colorado for total organic By contrast, lysozyme, which digests bacterial cell walls, only reduced INPs active at ≥ −7.5 or ≥ −6 • C, depending on the soil. The known IN bacteria were not detected in any soil, using PCR for the ina gene that codes for the active protein. We directly isolated and photographed two INPs from soil, using repeated cycles of freeze testing and subdivision of droplets of dilute soil suspensions; they were complex and apparently organic entities. Ice nucleation activity was not affected by digestion of Proteinase K-susceptible proteins or the removal of entities composed of fulvic and humic acids, sterols, or aliphatic alcohol monolayers. Organic INPs active colder than −10 to −12 • C were resistant to all investigations other than heat, oxidation with H 2 O 2 , and, for some, digestion with papain. They may originate from decomposing plant material, microbial biomass, and/or the humin component of the SOM. In the case of the latter then they are most likely to be a carbohydrate. Reflecting the diversity of the SOM itself, soil INPs have a range of sources which occur with differing relative abundances.

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“…Additionally, no correlation was found between freezing temperature and bacterial cell counts in the Arctic microlayer (Extended data Figure 4), which suggests that whole bacterial cells were not responsible for the observed ice nucleation. Given that terrestrial biological systems such as pollens 23,24 and fungi 25,26 have been found to produce nanoscale or 'macromolecular' INPs unconnected with whole cells, we considered the possibility that marine INPs are associated with exudates from phytoplankton or other marine microorganisms. This hypothesis is not only supported by the filtration tests, but by a tentative correlation between the North Pacific microlayer sample ice activation onsets with both the dissolved organic carbon concentration (DOC, >0.2 µm) and polysaccharide-rich transparent exopolymer particles (TEP) which are associated with phytoplankton exudates (Extended data Figure 5).…”

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confidence: 99%

A marine biogenic source of atmospheric ice-nucleating particles

Wilson

Ladino

Alpert

et al. 2015

Nature

522

644

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The amount of ice present in clouds can affect cloud lifetime, precipitation and radiative properties 1,2 . The formation of ice in clouds is facilitated by the presence of airborne ice nucleating particles 1,2 . Sea spray is one of the major global sources of atmospheric particles, but it is unclear to what extent these particles are capable of nucleating ice 3-11 . Sea spray aerosol contains large amounts of organic material that is ejected into the atmosphere during bubble bursting at the organically enriched sea-air interface or sea surface microlayer [12][13][14][15][16][17][18][19] . Here we show that organic material in the sea surface microlayer nucleates ice under conditions relevant for mixed-phase cloud and high-altitude ice cloud formation. The ice nucleating material is likely biogenic and less than ~0.2 μm in size. We find that exudates separated from cells of the marine diatom T. Pseudonana nucleate ice and propose that organic material associated with phytoplankton cell exudates is a likely candidate for the observed ice nucleating ability of the microlayer samples. Global model simulations of marine organic aerosol in combination with our measurements suggest that marine organic material may be an important source of ice nucleating particles in remote marine environments such as the Southern Ocean, North Pacific and North Atlantic.Atmospheric ice nucleating particles (INPs) allow ice to nucleate heterogeneously at higher temperatures or lower relative humidity than is typical for homogeneous ice nucleation. Heterogeneous ice nucleation proceeds via different pathways depending on temperature and humidity. In low altitude mixed-phase clouds, INPs are commonly immersed in supercooled liquid droplets and freezing can occur on them at temperatures between -36 and 0°C 2 . At higher altitudes and lower temperatures (<-36°C) where cirrus clouds form, nucleation occurs below water saturation, proceeding by homogeneous, deposition or immersion-in-solution nucleation 1 . Understanding the sources of atmospheric INPs is important because they affect cloud lifetime, cloud albedo and precipitation 1,2 . Recent modelling work has shown that the ocean is potentially an important source of biogenic atmospheric INPs particularly in remote, high latitude regions 9,10 . However, it has never been directly shown that there is a source of atmospheric INPs associated with organic material found in marine waters or sea-spray aerosol.Organic material makes up a substantial fraction of sub-micron sea-spray aerosol and it is estimated that 10±5 Tg yr -1 of primary organic sub-micron aerosol is emitted from marine sources globally 12 . Rising bubbles scavenge surface active organic material from the water column at their interfaces and this process facilitates the formation of the organic enriched sea-air interface known as the sea surface microlayer (SML). This organic material is ejected into the atmosphere during bubble bursting resulting in sea spray aerosol containing similar organic material to that of the microlaye...

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The relevance of nanoscale biological fragments for ice nucleation in clouds

Cited by 213 publications

References 47 publications

Ice-nucleating particles in Canadian Arctic sea-surface microlayer and bulk seawater

Ice-nucleating particles in Canadian Arctic sea-surface microlayer and bulk seawater

Sources of organic ice nucleating particles in soils

A marine biogenic source of atmospheric ice-nucleating particles

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