Microorganisms Associated With Dust on Alpine Snow

Zoe R. Courville,Lauren B. Farnsworth,Stacey J. Doherty,John M. Fegyveresi,Alison K. Thurston,Robyn A. Barbato,Shelby A. Rosten,R. M. Jones,Jeff Derry,Ross M. Lieblappen

doi:10.3389/feart.2020.00122

Abstract

We investigated snow microstructure and microbial composition from snow samples collected from western Colorado, a region that experiences frequent dust deposition events. We developed a methodology to quantify the amount, size and location of dust particles within the snow matrix through analysis of X-ray micro-computed tomography data. Concurrently, we determined the microbial composition in sampled dust layers through DNA sequencing. We found that dust particles were generally embedded in the snow grains, with a small fraction of the dust particles’ surface area exposed to air. Microbial community composition varied more by alpine site rather than residence time of the dust within the snowpack, with the recently deposited dust layer harboring both the highest diversity and highest concentration of dust particles. The presence of microbiota in the dust-impacted snowpack has important implications for snowpack stability, melting and biogeochemistry.

Highlights

Dust deposition on a snow surface accelerates snow melt primarily by causing the snow surface to become darker and secondarily through dry and wet snow metamorphic processes and snow grain growth that occur before the onset of melt (Conway et al, 1996; Skiles et al, 2018)
We examined three separate sub-samples for the individual dust event layer sample
The merged layer from Swamp Angel had the highest number of dust particles contained within the scanned sample, while merged layer from Berthoud Pass had the lowest number of dust particles

Summary

Introduction

Dust deposition on a snow surface accelerates snow melt primarily by causing the snow surface to become darker and secondarily through dry and wet snow metamorphic processes and snow grain growth that occur before the onset of melt (Conway et al, 1996; Skiles et al, 2018). The focus of our study was to investigate dust-associated microbial deposition on snowpack and structure and to examine aerosolized microbial communities through dust transport, including dust provenance within a larger project examining the ultimate contribution of dust deposition, and microbial component, to the timing and onset of melt within our study area. Our hypothesis driving this focused area of the larger work is that microbiota present on dust particles deposited on the snow could be linked to source regions. Aerosolized dust particulates have been accepted as a major

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Conclusion