Abstract
Abstract. We studied the ice nucleation properties of 12 different species of fungal spores chosen from three classes: Agaricomycetes, Ustilaginomycetes, and Eurotiomycetes. Agaricomycetes include many types of mushroom species and are widely distributed over the globe. Ustilaginomycetes are agricultural pathogens and have caused widespread damage to crops. Eurotiomycetes are found on all types of decaying material and include important human allergens. We focused on these classes because they are thought to be abundant in the atmosphere and because there is very little information on the ice nucleation ability of these classes of spores in the literature. All of the fungal spores investigated contained some fraction of spores that serve as ice nuclei at temperatures warmer than homogeneous freezing. The cumulative number of ice nuclei per spore was 0.001 at temperatures between −19 °C and −29 °C, 0.01 between −25.5 °C and −31 °C, and 0.1 between −26 °C and −31.5 °C. On average, the order of ice nucleating ability for these spores is Ustilaginomycetes > Agaricomycetes ≃ Eurotiomycetes. The freezing data also suggests that, at temperatures ranging from −20 °C to −25 °C, all of the fungal spores studied here are less efficient ice nuclei compared to Asian mineral dust on a per surface area basis. We used our new freezing results together with data in the literature to compare the freezing temperatures of spores from the phyla Basidiomycota and Ascomycota, which together make up 98% of known fungal species found on Earth. The data show that within both phyla (Ascomycota and Basidiomycota), there is a wide range of freezing properties, and also that the variation within a phylum is greater than the variation between the average freezing properties of the phyla. Using a global chemistry–climate transport model, we investigated whether ice nucleation on the studied spores, followed by precipitation, can influence the transport and global distributions of these spores in the atmosphere. Simulations suggest that inclusion of ice nucleation scavenging of these fungal spores in mixed-phase clouds can decrease the annual mean concentrations of fungal spores in near-surface air over the oceans and polar regions, and decrease annual mean concentrations in the upper troposphere.
Highlights
Fungal spores, which are the reproductive structures in the lifecycle of fungi, are abundant in the atmosphere (Després et al, 2012; Madelin, 1994; Bauer et al, 2008)
All of the fungal spores investigated contained some fraction of spores that serve as ice nuclei at temperatures warmer than homogeneous freezing
The freezing data suggests that, at temperatures ranging from −20 ◦C to −25 ◦C, all of the fungal spores studied here are less efficient ice nuclei compared to Asian mineral dust on a per surface area basis
Summary
Fungal spores, which are the reproductive structures in the lifecycle of fungi, are abundant in the atmosphere (Després et al, 2012; Madelin, 1994; Bauer et al, 2008). Average fungal spore concentrations of 1 to 10 L−1 have been reported in the continental boundary layer (Elbert et al, 2007), and peak concentrations of 20 to 35 L−1 have been observed. Haga et al.: Ice nucleation and its effect on atmospheric transport of fungal spores previously (Oliveira et al, 2005; Ho et al, 2005; Goncalves et al, 2010; Quintero et al, 2010; Khattab and Levetin, 2008; Nayar and Jothish, 2013). These spores can be transported large distances and transported to high altitudes in the troposphere (Hirst et al, 1967; Gregory, 1978; Bowers et al, 2009; Amato et al, 2007; Ebner et al, 1989; Fulton, 1966; Kelly and Pady, 1953; Pady and Kelly, 1953; Pady and Kapica, 1955; Proctor and Parker, 1938), and even into the stratosphere (Smith et al, 2010; Imshenetsky et al, 1978; Griffin, 2004)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
