Terrestrial Origin for Abundant Riverine Nanoscale Ice-Nucleating Particles

Knackstedt, Kathryn A.; Moffett, Bruce F.; Hartmann, S.; Wex, Heike; Hill, Thomas C. J.; Glasgo, Liz D; Reitz, Laura A.; Augustin-Bauditz, Stefanie; Beall, Benjamin F. N.; Bullerjahn, George S.; Fröhlich-Nowoisky, Janine; Grawe, Sarah; Lubitz, Jasmin; Stratmann, Frank; McKay, R. Michael L.

doi:10.1021/acs.est.8b03881

Cited by 31 publications

(29 citation statements)

References 77 publications

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“…The steep curve of the FF curves exhibited by the samples suggest that the nature of ice nucleating material or active site is relatively homogeneous. These freezing temperatures are consistent with recently identified river nanoscale INPs (Knackstedt et al, 2018;Moffett et al, 2018). The FFs were then normalized by the organic carbon concentration in the solution measured by a TOC analyser to yield nm values as a function of temperature (Fig.…”

Section: Photochemistry Affects the Ice Nucleating Ability Of Domsupporting

confidence: 79%

Photomineralization mechanism changes the ability of dissolved organic matter to activate cloud droplets and to nucleate ice crystals

Borduas-Dedekind¹,

Ossola²,

David³

et al. 2019

Preprint

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Abstract. An organic aerosol particle has a lifetime of approximately one week in the atmosphere during which it will be exposed to sunlight. Yet, the effect of photochemistry on the propensity of organic matter to participate in the initial cloud-forming steps is difficult to predict. In this study, we quantify on a molecular scale the effect of photochemical exposure of naturally occurring dissolved organic matter (DOM) and of a fulvic acid standard on its ability to form mixed-phase clouds, by acting as cloud condensation nuclei (CCN) and by acting as ice nucleating particles (INPs). We find that photochemical processing, equivalent to 4.6 days in the atmosphere, of DOM increases its ability to form cloud droplets by up to a factor of 2.5 but decreases its ability to form ice crystals at a loss rate of &#8722;0.04&#176;CT50 h&#8722;1 of sunlight at ground level. In other words, the ice nucleation activity of photooxidized DOM can require up to 4 degrees colder temperatures for 50&#8201;% of the droplets to activate as ice crystals under immersion freezing conditions. This temperature change could impact the ratio of ice to water droplets within a mixed phase cloud by delaying the onset of glaciation and by increasing the supercooled liquid fraction of the cloud, thereby modifying the radiative properties and the lifetime of the cloud. Concurrently, a photomineralization mechanism was quantified by monitoring the loss of organic carbon and the simultaneous production of organic acids, such as formic, acetic, oxalic and pyruvic acids, CO and CO2. This mechanism explains and predicts the observed increase in CCN and decrease in INP efficiencies. Indeed, we show that photochemical processing can be a dominant atmospheric aging process, impacting CCN and INP efficiencies and concentrations. Photomineralization can thus alter the aerosol-cloud radiative effects of organic matter by modifying the supercooled liquid water-to-ice crystal ratio in mixed-phase clouds with implications for cloud lifetime, precipitation patterns and the hydrological cycle.

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Section: Photochemistry Affects the Ice Nucleating Ability Of Domsupporting

confidence: 79%

Photomineralization mechanism changes the ability of dissolved organic matter to activate cloud droplets and to nucleate ice crystals

Borduas-Dedekind¹,

Ossola²,

David³

et al. 2019

Preprint

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“…First, the ice nucleating entities in these microlayer studies were active at small unit sizes, between 20 and 200 nm. Additionally, fatty acids would not be expected to be destroyed by thermal treatments to 100 C. Heat lability was a specic feature of the microlayer ice nucleation entities reported by Wilson et al 4 and Irish et al 5 Heat lability and small INP sizes also characterize the majority of ice nucleating entities found in river waters, 18,19 which are thought to be of cell-free, fungal origin (i.e., macromolecules, such as proteins 18 ). The possibility of fatty acid contributions to INP emissions from river regions has not been noted or yet explored.…”

Section: Introductionmentioning

confidence: 93%

Ice nucleation by particles containing long-chain fatty acids of relevance to freezing by sea spray aerosols

DeMott

Mason

McCluskey

et al. 2018

Environ. Sci.: Processes Impacts

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Heterogeneous ice nucleation in the atmosphere regulates cloud properties, such as phase (ice versus liquid) and lifetime. Aerosol particles of marine origin are relevant ice nucleating particle sources when marine aerosol layers are lifted over mountainous terrain and in higher latitude ocean boundary layers, distant from terrestrial aerosol sources. Among many particle compositions associated with ice nucleation by sea spray aerosols are highly saturated fatty acids. Previous studies have not demonstrated their ability to freeze dilute water droplets. This study investigates ice nucleation by monolayers at the surface of supercooled droplets and as crystalline particles at temperatures exceeding the threshold for homogeneous freezing. Resultsshow the poor efficiency of long chain fatty acid (C16, C18) monolayers in templating freezing of pure water droplets and seawater subphase to temperatures of at least À30 C, consistent with theory. This contrasts with freezing of fatty alcohols (C22 used here) at nearly 20 C warmer. Evaporation of mL-sized droplets to promote structural compression of a C19 acid monolayer did not favor warmer ice formation of drops.Heterogeneous ice nucleation occurred for nL-sized droplets condensed on 5 to 100 mm crystalline particles of fatty acid (C12 to C20) at a range of temperatures below À28 C. These experiments suggest that fatty acids nucleate ice at warmer than À36 C only when the crystalline phase is present. Rough estimates of ice active site densities are consistent with those of marine aerosols, but require knowledge of the proportion of surface area comprised of fatty acids for application. Environmental signicanceIce phase transitions in clouds over or near oceans may be triggered primarily by aerosol particles from oceanic emissions. While the specic particles or phases triggering ice formation remain poorly understood, their low efficiencies for freezing water can lead to deep cloud supercooling. Following the nding of long chain fatty acids as major components of some marine ice nucleating particles, this study explores their ice nucleation efficiencies and mechanisms. Fatty acids induced freezing when micron-sized solid particles were exposed to pure water at temperatures below À28 C, varying non-monotonically by chain length. Freezing most likely occurred via particle surface defects rather than as monolayers. Studies to quantify the fatty acid size distribution in sea spray aerosols are needed to develop parameterizations from such work.

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“…Efficient INPs may also originate from extracts of plant-based material, including proteinaceous material and polysaccharides (Augustin et al, 2013;Dreischmeier et al, 2017;Koop and Zobrist, 2009;Pummer et al, 2012Pummer et al, , 2015Wilson et al, 2015). In addition, organic matter may also act as INPs in the immersion freezing mode (Borduas-Dedekind et al, 2019;Hill et al, 2016;Hiranuma et al, 2015;Irish et al, 2019;Knackstedt et al, 2018;Knopf et al, 2018;Wilson et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Spatial and temporal variability in the ice-nucleating ability of alpine snowmelt and extension to frozen cloud fraction

2020

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Abstract. Ice-nucleating particles (INPs) produce ice from supercooled water droplets through heterogeneous freezing in the atmosphere. INPs have often been collected at the Jungfraujoch research station (at 3500 m a.s.l.) in central Switzerland; yet spatially diverse data on INP occurrence in the Swiss Alps are scarce and remain uncharacterized. We address this scarcity through our Swiss alpine snow sample study which took place during the winter of 2018. We collected a total of 88 fallen snow samples across the Alps at 17 different locations and investigated the impact of altitude, terrain, time since last snowfall and depth upon freezing temperatures. The INP concentrations were measured using the home-built DRoplet Ice Nuclei Counter Zurich (DRINCZ) and were then compared to spatial, temporal and physicochemical parameters. Boxplots of the freezing temperatures showed large variability in INP occurrence, even for samples collected 10 m apart on a plain and 1 m apart in depth. Furthermore, undiluted samples had cumulative INP concentrations ranging between 1 and 200 INP mL−1 of snowmelt over a temperature range of −5 to −19 ∘C. From this field-collected dataset, we parameterized the cumulative INP concentrations per cubic meter of air as a function of temperature with the following equation cair*(T)=e-0.7T-7.05, comparing well with previously reported precipitation data presented in Petters and Wright (2015). When assuming (1) a snow precipitation origin of the INPs, (2) a cloud water content of 0.4 g m−3 and (3) a critical INP concentration for glaciation of 10 m−3, the majority of the snow precipitated from clouds with glaciation temperatures between −5 and −20 ∘C. Based on the observed variability in INP concentrations, we conclude that studies conducted at the high-altitude research station Jungfraujoch are representative for INP measurements in the Swiss Alps. Furthermore, the INP concentration estimates in precipitation allow us to extrapolate the concentrations to a frozen cloud fraction. Indeed, this approach for estimating the liquid water-to-ice ratio in mixed-phase clouds compares well with aircraft measurements, ground-based lidar and satellite retrievals of frozen cloud fractions. In all, the generated parameterization for INP concentrations in snowmelt could help estimate cloud glaciation temperatures.

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Terrestrial Origin for Abundant Riverine Nanoscale Ice-Nucleating Particles

Cited by 31 publications

References 77 publications

Photomineralization mechanism changes the ability of dissolved organic matter to activate cloud droplets and to nucleate ice crystals

Photomineralization mechanism changes the ability of dissolved organic matter to activate cloud droplets and to nucleate ice crystals

Ice nucleation by particles containing long-chain fatty acids of relevance to freezing by sea spray aerosols

Spatial and temporal variability in the ice-nucleating ability of alpine snowmelt and extension to frozen cloud fraction

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