bioRxiv2018
Snowfall is a global phenomenon highly integrated with hydrology and ecology. Forays into studying bioaerosols and their dependence on aeolian movement are largely constrained to either precipitation-independent analyses or in-silico models. Though snowpack and glacial microbiological studies have been conducted, little is known about the biological component of meteoric snow. Through culture-independent phylogenetic and geochemical analyses, we show that the geographical location at which snow precipitates determines snowfalls geochemical and microbiological composition. Storm-tracking, furthermore, can be used as a valuable environmental indicator to trace down what factors are influencing bioaerosols. We estimate annual deposits of up to ~10 kg of bacterial / archaeal biomass per hectare along our study area of the eastern Front Range in Colorado. The dominant kinds of microbiota captured in an analysis of seven snow events at two different locations, one urban, one rural, across the winter of 2016/2017 included phyla Proteobacteria, Bacteroidetes, Firmicutes and Acidobacteria, though a multitude of different kinds of organisms were found in both. Taxonomically, Bacteroidetes were more abundant in Golden (urban plain) snow while Proteobacteria were more common in Sunshine (rural mountain) samples. Chemically, Golden snowfall was positively correlated with some metals and anions. The work also hints at better informing the everything is everywhere hypotheses of the microbial world and that atmospheric transport of microbiota is not only common, but is capable of disseminating vast amounts of microbiota of different physiologies and genetics that then affect ecosystems globally. Snowfall, we conclude, is a significant repository of microbiological material with strong implications for both ecosystem genetic flux and general bio-aerosol theory.\n\nImportanceSnowfall is commonplace to the temperate and polar regions of the world. As an interface between the atmosphere, hydrosphere and earth, snow is responsible for high annual deposits of moisture globally, and, can serve as a water bank in the form of both permanent snow fields and glaciers. Essential to general ecosystem function, snow can also be considered a transporter of aerosolized material. Given the magnitude of microbiota deposited by snowfall, which we report, it is likely that biological material within snowfall, with its geochemical underpinning-- and the associated genetic banks--have significant downstream ecological effects.\n\nUnderstanding what is contained in snowfall becomes especially urgent in a warming climate where high-impact meteorological and ecological changes are imminent and likely. With climate-induced changes to snowfall patterns, surface ecosystems are likely to be impacted by ensuing changes in microbiota deposition. Thus, the ecosystem function of soils, rock and surface waters are also likely to be impacted; these changes, in turn, greatly influence agriculture, weathering and infrastructure.