scholarly journals Suspendable macromolecules are responsible for ice nucleation activity of birch and conifer pollen

2012 ◽  
Vol 12 (5) ◽  
pp. 2541-2550 ◽  
Author(s):  
B. G. Pummer ◽  
H. Bauer ◽  
J. Bernardi ◽  
S. Bleicher ◽  
H. Grothe
Keyword(s):  
Radiative Forcing ◽  
Pollen Grains ◽  
Ice Nucleation ◽  
Cloud Formation ◽  
Distribution Area ◽  
Ice Cloud ◽  
Ice Nuclei ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
The Impact

Abstract. The ice nucleation of bioaerosols (bacteria, pollen, spores, etc.) is a topic of growing interest, since their impact on ice cloud formation and thus on radiative forcing, an important parameter in global climate, is not yet fully understood. Here we show that pollen of different species strongly differ in their ice nucleation behaviour. The average freezing temperatures in laboratory experiments range from 240 to 255 K. As the most efficient nuclei (silver birch, Scots pine and common juniper pollen) have a distribution area up to the Northern timberline, their ice nucleation activity might be a cryoprotective mechanism. Far more intriguingly, it has turned out that water, which has been in contact with pollen and then been separated from the bodies, nucleates as good as the pollen grains themselves. The ice nuclei have to be easily-suspendable macromolecules located on the pollen. Once extracted, they can be distributed further through the atmosphere than the heavy pollen grains and so presumably augment the impact of pollen on ice cloud formation even in the upper troposphere. Our experiments lead to the conclusion that pollen ice nuclei, in contrast to bacterial and fungal ice nucleating proteins, are non-proteinaceous compounds.

scholarly journals Birch and conifer pollen are efficient atmospheric ice nuclei

2011 ◽  
Vol 11 (10) ◽  
pp. 27219-27241 ◽  
Author(s):  
B. G. Pummer ◽  
H. Bauer ◽  
J. Bernardi ◽  
S. Bleicher ◽  
H. Grothe
Keyword(s):  
Radiative Forcing ◽  
Global Climate ◽  
Pollen Grains ◽  
Ice Nucleation ◽  
Cloud Formation ◽  
Distribution Area ◽  
Ice Cloud ◽  
Ice Nuclei ◽  
Ice Nucleation Activity ◽  
The Impact

Abstract. The ice nucleation of bioaerosols (bacteria, pollen, spores, etc.) is a topic of growing interest, since their impact on ice cloud formation and thus on radiative forcing, an important parameter in global climate, is not yet fully understood. Here we show that pollen of different species strongly differ in their ice nucleation behaviour. The average freezing temperatures in laboratory experiments range from 240 K to 255 K. As the most efficient nuclei (silver birch, Scots pine and common juniper pollen) have a distribution area up to the Northern timberline, their ice nucleation activity may be a cryoprotective mechanism. Far more intriguingly, it has turned out that water, which has been in contact with pollen and then been separated from the bodies, nucleates as good as the pollen grains themselves. So the ice nuclei have to be easily-suspendable macromolecules located on the pollen surface. Once extracted, they can be distributed further through the atmosphere than the heavy pollen grains and so augment the impact of pollen on ice cloud formation even in the upper Troposphere. Our experiments lead to the conclusion that pollen ice nuclei, in contrast to bacterial and fungal ice nucleating proteins, are non-proteinaceous compounds.

scholarly journals Subpollen particles (SPP) of birch as carriers of ice nucleating macromolecules

2021 ◽  
Author(s):  
Julia Burkart ◽  
Jürgen Gratzl ◽  
Teresa M. Seifried ◽  
Paul Bieber ◽  
Hinrich Grothe
Keyword(s):  
Protein Concentration ◽  
Birch Pollen ◽  
Pollen Grains ◽  
Ice Nucleation ◽  
Cloud Formation ◽  
Ultrapure Water ◽  
Fluorescence Excitation ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
The Relationship

Abstract. Within the last years pollen grains have gained increasing attention due to their cloud forming potential. Especially the discovery that ice nucleating macromolecules (INM) or subpollen particles (SPP) obtained from pollen grains are able to initiate freezing has stirred up interest in pollen. INM or SPP are much smaller and potentially more numerous than pollen grains and could significantly affect cloud formation in the atmosphere. However, INM and SPP are not clearly distinguished and explanations on how these materials could distribute in the atmosphere are missing. In this study we focus on birch pollen and investigate the relationship between pollen grains, INM and SPP. According to the usage of the term SPP in the medical fields we define SPP as the starch granules contained in pollen grains. We develop an extraction method to generate large quantities of SPP and show that INM are loosley attached to SPP. Further, we find that purified SPP are not ice nucleation active: after several times of washing SPP with ultrapure water the ice nucleation activity completely disappears. To our knowledge this is the first study to investigate the ice nucleation activity of isolated SPP. To study the chemical nature of the INM we use fluorescence spectroscopy. Fluorescence excitation-emission maps indicate a strong signal in the protein range (maximum around λex = 280 nm and λem = 330 nm) that correlates with the ice nucleation activity. In contrast, with purified SPP this signal is lost. We also quantify the protein concentration with the Bradford assay. The protein concentration ranges from 77.4 μg mL−1 (Highly concentrated INM) to below 2.5 μg mL−1 (purified SPP). The results indicate a linkage between ice nucleation activity and protein concentration. Even though purified SPP are not ice nucleation active they could act as carriers of INM and distribute those in the atmosphere.

Subpollen particles (SPP) of birch as carriers of ice nucleating macromolecules

2021 ◽  
Author(s):  
Julia Burkart ◽  
Jürgen Gratzl ◽  
Teresa Seifried ◽  
Paul Bieber ◽  
Hinrich Grothe
Keyword(s):  
Protein Concentration ◽  
Birch Pollen ◽  
Pollen Grains ◽  
Ice Nucleation ◽  
Early Spring ◽  
Cloud Formation ◽  
Starch Granules ◽  
Fluorescence Excitation ◽  
Nucleation Activity ◽  
Ice Nucleation Activity

<p>Wind pollinated trees such as birch trees release large amounts of pollen to the atmosphere during their blooming season in early spring. Due to the large size of pollen (birch pollen diameter: 20-25 µm) and short residence time in the atmosphere, their impact on cloud formation was believed to be negligible. However, in recent years studies have shown that ice nucleating materials, so called ice nucleating macromolecules (INM), much smaller in size can be extracted from pollen. At the same time there is evidence from medical studies that pollen can rupture under conditions of high humidity in the atmosphere and expel cytoplasmic material including starch granules, commonly referred to as subpollen particles (SPP). INM or SPP are much smaller and potentially more numerous than pollen and could significantly affect cloud formation in the atmosphere.</p><p>In this study, we focus on birch pollen and investigate the relationship between pollen grains, INM and SPP. According to the usage of the term SPP in the medical field we define SPP as the starch granules contained in pollen grains. We develop an extraction method to generate large quantities of SPP and investigate their ice nucleation activity. To our knowledge, this is the first study to investigate the ice nucleation activity of isolated SPP. We show that INM are only loosely attached to SPP and that purified SPP are not ice nucleation active: after several times of washing SPP with ultrapure water the ice nucleation activity completely disappears. In addition, we study the chemical nature of the INM with fluorescence spectroscopy and quantify the protein concentration with the Bradford assay. Fluorescence excitation-emission maps indicate a strong signal in the protein range (maximum around λ<sub>ex</sub> = 280 nm and λ<sub>em</sub> = 330 nm) that correlates with the ice nucleation activity. In contrast, with purified SPP this signal is lost. The protein concentration ranges from 77.4 μg mL<sup>-1</sup> for highly concentrated INM to below 2.5 μg mL<sup>-1</sup> for purified SPP. The results thereby indicate a linkage between ice nucleation activity and protein concentration. Purified SPP are not ice nucleation active but could, however, act as carriers of INM and distribute those in the atmosphere.</p>

scholarly journals Macromolecular fungal ice nuclei in <i>Fusarium</i>: effects of physical and chemical processing

2019 ◽  
Vol 16 (23) ◽  
pp. 4647-4659 ◽  
Author(s):  
Anna T. Kunert ◽  
Mira L. Pöhlker ◽  
Kai Tang ◽  
Carola S. Krevert ◽  
Carsten Wieder ◽  
...  
Keyword(s):  
Fusarium Species ◽  
Ice Nucleation ◽  
Cumulative Number ◽  
Genus Fusarium ◽  
Biological Particles ◽  
Ice Nuclei ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
The Impact ◽  
Atmospherically Relevant

Abstract. Some biological particles and macromolecules are particularly efficient ice nuclei (IN), triggering ice formation at temperatures close to 0 ∘C. The impact of biological particles on cloud glaciation and the formation of precipitation is still poorly understood and constitutes a large gap in the scientific understanding of the interactions and coevolution of life and climate. Ice nucleation activity in fungi was first discovered in the cosmopolitan genus Fusarium, which is widespread in soil and plants, has been found in atmospheric aerosol and cloud water samples, and can be regarded as the best studied ice-nucleation-active (IN-active) fungus. The frequency and distribution of ice nucleation activity within Fusarium, however, remains elusive. Here, we tested more than 100 strains from 65 different Fusarium species for ice nucleation activity. In total, ∼11 % of all tested species included IN-active strains, and ∼16 % of all tested strains showed ice nucleation activity above −12 ∘C. Besides Fusarium species with known ice nucleation activity, F. armeniacum, F. begoniae, F. concentricum, and F. langsethiae were newly identified as IN-active. The cumulative number of IN per gram of mycelium for all tested Fusarium species was comparable to other biological IN like Sarocladium implicatum, Mortierella alpina, and Snomax®. Filtration experiments indicate that cell-free ice-nucleating macromolecules (INMs) from Fusarium are smaller than 100 kDa and that molecular aggregates can be formed in solution. Long-term storage and freeze–thaw cycle experiments revealed that the fungal IN in aqueous solution remain active over several months and in the course of repeated freezing and thawing. Exposure to ozone and nitrogen dioxide at atmospherically relevant concentration levels also did not affect the ice nucleation activity. Heat treatments at 40 to 98 ∘C, however, strongly reduced the observed IN concentrations, confirming earlier hypotheses that the INM in Fusarium largely consists of a proteinaceous compound. The frequency and the wide distribution of ice nucleation activity within the genus Fusarium, combined with the stability of the IN under atmospherically relevant conditions, suggest a larger implication of fungal IN on Earth’s water cycle and climate than previously assumed.

scholarly journals Survival and ice nucleation activity ofPseudomonas syringaestrains exposed to simulated high-altitude atmospheric conditions

2018 ◽  
Author(s):  
Gabriel Guarany de Araujo ◽  
Fabio Rodrigues ◽  
Fabio Luiz Teixeira Gonçalves ◽  
Douglas Galante
Keyword(s):  
Pseudomonas Syringae ◽  
Water Samples ◽  
Cloud Water ◽  
Ice Nucleation ◽  
Important Process ◽  
High Altitudes ◽  
Ice Nuclei ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
The Impact

ABSTRACTThe epiphytic bacteriumPseudomonas syringaeproduces the most efficient and well-studied biological ice nuclei (IN) known. Bioaerosols containing these cells have been proposed to influence cloud glaciation, an important process in the initiation of precipitation. The presence of this species has been reported on rain, snow, and cloud water samples, but how these organisms can survive the harsh conditions present on the high atmosphere still remains to be better understood. In this study, the impact caused by this type of environment onP. syringaewas assayed by measuring their viability and IN activity. Two strains, of the pathovarssyringaeandgarcae, were compared toEscherichia coli.While UV-C radiation effectively inactivated these cells, thePseudomonaswere much more tolerant to UV-B. TheP. syringaestrains were also more resistant to “environmental” UV radiation from a solar simulator, composed of UV-A and UV-B. The response of their IN after long exposures to this radiation varied: only one strain suffered a relatively small 10-fold reduction in IN activity at -5 °C. Desiccation at different relative humidity values also affected the IN, but some activity at -5 °C was still maintained for all tests. The pathovargarcaetended to be more resistant to the stress treatments than the pathovarsyringae, particularly to desiccation, though its IN were found to be more sensitive. Compared toE. coli, theP. syringaestrains seemed relatively better adapted to survival under conditions present on the atmosphere at high altitudes.IMPORTANCEThe plant-associated bacteriumPseudomonas syringaeproduces on its outer membrane highly efficient ice nuclei which are able to induce the freezing of supercooled water. This ability has been linked to increased frost damaged on colonized leaves and also to the formation of ice in clouds, an important process leading to precipitation.P. syringaehas been found on rain, snow, and cloud water samples, confirming its presence on the atmosphere. This study aimed to assess the survival of these cells and the maintenance of their ice nucleation activity under stressing conditions present in high altitudes: ultraviolet radiation and desiccation.P. syringaestrains were shown to at least partially tolerate these factors, and their most efficient ice nuclei, while affected, could still be detected after all experiments.

scholarly journals The Impact of (bio-)organic substances on the ice nucleation activity of the K-feldspar microcline in aqueous solutions

2021 ◽  
Author(s):  
Kristian Klumpp ◽  
Claudia Marcolli ◽  
Thomas Peter
Keyword(s):  
Amino Acids ◽  
Citric Acid ◽  
Carboxylic Acids ◽  
Water Activity ◽  
Active Sites ◽  
Ice Nucleation ◽  
Organic Substances ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
The Impact

Abstract. Potassium-feldspars (K-feldspars), such as microcline, are considered key dust minerals inciting ice nucleation in mixed phase clouds. Besides the high ice nucleation activity of microcline, recent studies also revealed a high sensi-tivity of microcline towards interaction with solutes on its surface. Here, we investigate the effect of organic and bio-organic substances on the ice nucleation activity of microcline, with the aim to better understand the underlying sur-face interactions. We performed immersion freezing experiments with microcline in solutions of three carboxylic acids, five amino acids and two polyols to represent these compound classes. By means of a differential scanning calorimeter we investigated the freezing of emulsified droplets of microcline suspended in various solutions. Depend-ing on the type of solute, different effects were observed. In the case of carboxylic acids (acetic, oxalic and citric acid), the measured heterogeneous onset temperatures, Thet, showed no significant deviation from the behavior pre-dicted by the water activity criterion, Thet(aw) = Tmelt(aw+Δaw), which relates Thet with the melting point temperature Tmelt via a constant water activity offset Δaw. While this behavior could be interpreted as a lack of interaction of the solute molecules with the surface, the carboxylic acids caused the fraction of heterogeneously frozen water, Fhet(aw), to decrease by up to 40 % with increasing solute concentrations. In combination, unaltered Thet(aw) and reduced Fhet(aw) suggest that active sites were largely deactivated by the acid molecules, but amongst those remaining active are also the best sites with the highest Thet. A deviation from this behavior is citric acid, which showed not only a de-crease in Fhet, but also a decrease in Thet of up to 4 K for water activities below 0.99, pointing to a depletion of the best active sites by interactions with the citrate ions. When neutralized solutions of the acids were used instead, the de-crease in Fhet became even more pronounced. The slope of Thet(aw) was different for each of the neutralized acid solu-tions. In the case of amino acid solutions, we found a decrease in Thet (up to 10 K), significantly below the Δaw-criterion, as well as a reduction in Fhet (up to 60 %). Finally, in case of the investigated polyols, no significant devia-tion of Thet from the Δaw-criterion was observed, and no significant deviation of Fhet in comparison to a pure water suspension was found. Furthermore, we measured the effects of aging on the ice nucleation activity in experiments with microcline suspended in solutions for up to seven days, and tested the reversibility of the interaction with the solutes after aging for 10 days. For citric acid, an ongoing irreversible degradation of the ice nucleation activity was observed, whereas the amino acids showed completely reversible effects. In summary, our experiments demonstrate a remarkable sensitivity of microcline ice nucleation activity to surface interactions with various solutes, underscoring the importance of the history of such particles from source to frozen cloud droplet in the atmosphere.

scholarly journals Enhanced ice nucleation activity of coal fly ash aerosol particles initiated by ice-filled pores

2019 ◽  
Author(s):  
Nsikanabasi Silas Umo ◽  
Robert Wagner ◽  
Romy Ullrich ◽  
Alexei Kiselev ◽  
Harald Saathoff ◽  
...  
Keyword(s):  
Fly Ash ◽  
Significant Role ◽  
Coal Fly Ash ◽  
Aerosol Particles ◽  
Ice Nucleation ◽  
Temperature Cycling ◽  
Cloud Formation ◽  
Ice Formation ◽  
Nucleation Activity ◽  
Ice Nucleation Activity

Abstract. Ice-nucleating particles (INPs), which are precursors for ice formation in clouds, can alter the microphysical and optical properties of clouds, hence, impacting the cloud lifetimes and hydrological cycles. However, the mechanisms with which these INPs nucleate ice when exposed to different atmospheric conditions are still unclear for some particles. Recently, some INPs with pores or permanent surface defects of regular or irregular geometries have been reported to initiate ice formation at cirrus temperatures via the liquid phase in a two-step process, involving the condensation and freezing of supercooled water inside these pores. This mechanism has therefore been labelled as pore condensation and freezing (PCF). The PCF mechanism allows formation and stabilization of ice germs in the particle without the formation of macroscopic ice. Coal fly ash (CFA) aerosol particles are known to nucleate ice in the immersion freezing mode and may play a significant role in cloud formation. In our current ice nucleation experiments with CFA particles, which we conducted in the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) aerosol and cloud simulation chamber at the Karlsruhe Institute of Technology, Germany, we partly observed a strong increase in the ice-active fraction for experiments performed at temperatures just below the homogeneous freezing of pure water, which could be related to the PCF mechanism. To further investigate the potential of CFA particles undergoing PCF mechanism, we performed a series of temperature-cycling experiments in AIDA. The temperature-cycling experiments involve exposing CFA particles to lower temperatures (down to ~ 228 K), then warming them up to higher temperatures (238 K–273 K) before investigating their ice nucleation properties. For the first time, we report the enhancement of the ice nucleation activity of the CFA particles for temperatures up to 263 K, from which we conclude that it is most likely due to the PCF mechanism. This indicates that ice germs formed in the CFA particles’ pores during cooling remains in the pores during the warming and induces ice crystallization as soon as the pre-activated particles experience ice-supersaturated conditions at warmer temperatures; hence, showing an enhancement in their ice-nucleating ability compared to the scenario where the CFA particles are directly probed at warmer temperatures without temporary cooling. The enhancement in the ice nucleation ability showed a positive correlation with the specific surface area and porosity of the particles. On the one hand, the PCF mechanism could be the prevalent nucleation mode for intrinsic ice formation at cirrus temperatures rather than the previously acclaimed deposition mode. On the other, the PCF mechanism can also play a significant role in mixed-phase cloud formation in a case where the CFA particles are injected from higher altitudes and then transported to lower altitudes after being exposed to lower temperatures.

scholarly journals Deposition and immersion-mode nucleation of ice by three distinct samples of volcanic ash

2015 ◽  
Vol 15 (13) ◽  
pp. 7523-7536 ◽  
Author(s):  
G. P. Schill ◽  
K. Genareau ◽  
M. A. Tolbert
Keyword(s):  
Volcanic Ash ◽  
Mineral Dust ◽  
Global Climate ◽  
Volcanic Eruptions ◽  
Silica Content ◽  
Ice Nucleation ◽  
Ice Nuclei ◽  
Immersion Freezing ◽  
Nucleation Activity ◽  
Ice Nucleation Activity

Abstract. Ice nucleation of volcanic ash controls both ash aggregation and cloud glaciation, which affect atmospheric transport and global climate. Previously, it has been suggested that there is one characteristic ice nucleation efficiency for all volcanic ash, regardless of its composition, when accounting for surface area; however, this claim is derived from data from only two volcanic eruptions. In this work, we have studied the depositional and immersion freezing efficiency of three distinct samples of volcanic ash using Raman microscopy coupled to an environmental cell. Ash from the Fuego (basaltic ash, Guatemala), Soufrière Hills (andesitic ash, Montserrat), and Taupo (Oruanui eruption, rhyolitic ash, New Zealand) volcanoes were chosen to represent different geographical locations and silica content. All ash samples were quantitatively analyzed for both percent crystallinity and mineralogy using X-ray diffraction. In the present study, we find that all three samples of volcanic ash are excellent depositional ice nuclei, nucleating ice from 225 to 235 K at ice saturation ratios of 1.05 ± 0.01, comparable to the mineral dust proxy kaolinite. Since depositional ice nucleation will be more important at colder temperatures, fine volcanic ash may represent a global source of cold-cloud ice nuclei. For immersion freezing relevant to mixed-phase clouds, however, only the Oruanui ash exhibited appreciable heterogeneous ice nucleation activity. Similar to recent studies on mineral dust, we suggest that the mineralogy of volcanic ash may dictate its ice nucleation activity in the immersion mode.

scholarly journals Impact of mineral dust on cloud formation in a Saharan outflow region

2011 ◽  
Vol 11 (12) ◽  
pp. 32363-32390 ◽  
Author(s):  
L. Smoydzin ◽  
A. Teller ◽  
H. Tost ◽  
M. Fnais ◽  
J. Lelieveld
Keyword(s):  
Radiative Forcing ◽  
Mineral Dust ◽  
Eastern Mediterranean ◽  
Cloud Condensation Nuclei ◽  
Coupled Model ◽  
Cloud Formation ◽  
Dust Particles ◽  
Ice Nuclei ◽  
Outflow Region ◽  
The Impact

Abstract. We present a numerical modelling study investigating the impact of mineral dust on cloud formation over the Eastern Mediterranean for two case studies: (i) 25 September 2008 and (ii) 28/29 January 2003. On both days dust plumes crossed the Mediterranean and interacted with clouds forming along frontal systems. For our investigation we used the fully online coupled model WRF-chem. The results show that increased aerosol concentrations due to the presence of mineral dust can enhance the formation of ice crystals. This leads to slight shifts of the spatial and temporal precipitation patterns compared to scenarios where dust was not considered to act as ice nuclei. However, the total amount of precipitation did not change significantly. The only exception occurred when dust entered into an area of orographic ascent, causing glaciation of the clouds, leading to a local enhancement of rainfall. The impact of dust particles acting as giant cloud condensation nuclei on precipitation formation was found to be small. Based on our simulations the contribution of dust to the CCN population is potentially significant only for warm phase clouds. Nevertheless, the dust-induced differences in the microphysical structure of the clouds can contribute to a significant radiative forcing.

scholarly journals Deposition and immersion mode nucleation of ice by three distinct samples of volcanic ash using Raman spectroscopy

2015 ◽  
Vol 15 (2) ◽  
pp. 1385-1420 ◽  
Author(s):  
G. P. Schill ◽  
K. Genareau ◽  
M. A. Tolbert
Keyword(s):  
Volcanic Ash ◽  
Mineral Dust ◽  
Global Climate ◽  
Volcanic Eruptions ◽  
Silica Content ◽  
Ice Nucleation ◽  
Ice Nuclei ◽  
Immersion Freezing ◽  
Nucleation Activity ◽  
Ice Nucleation Activity

Abstract. Ice nucleation on volcanic ash controls both ash aggregation and cloud glaciation, which affect atmospheric transport and global climate. Previously, it has been suggested that there is one characteristic ice nucleation efficiency for all volcanic ash, regardless of its composition, when accounting for surface area; however, this claim is derived from data from only two volcanic eruptions. In this work, we have studied the depositional and immersion freezing efficiency of three distinct samples of volcanic ash using Raman Microscopy coupled to an environmental cell. Ash from the Fuego (basaltic ash, Guatemala), Soufrière Hills (andesitic ash, Montserrat), and Taupo (Oruanui euption, rhyolitic ash, New Zealand) volcanoes were chosen to represent different geographical locations and silica content. All ash samples were quantitatively analyzed for both percent crystallinity and mineralogy using X-ray diffraction. In the present study, we find that all three samples of volcanic ash are excellent depositional ice nuclei, nucleating ice from 225–235 K at ice saturation ratios of 1.05 ± 0.01, comparable to the mineral dust proxy kaolinite. Since depositional ice nucleation will be more important at colder temperatures, fine volcanic ash may represent a global source of cold-cloud ice nuclei. For immersion freezing relevant to mixed-phase clouds, however, only the Oruanui ash exhibited heterogeneous ice nucleation activity. Similar to recent studies on mineral dust, we suggest that the mineralogy of volcanic ash may dictate its ice nucleation activity in the immersion mode.

Sign in / Sign up

Export Citation Format

Share Document