Seasonal Variation of the Atmospheric Bacterial Community in the Greenlandic High Arctic Is Influenced by Weather Events and Local and Distant Sources

Abstract

The Arctic is a hot spot for climate change with potentially large consequences on a global scale. Aerosols, including bioaerosols, are important players in regulating the heat balance through direct interaction with sunlight and indirectly, through inducing cloud formation. Airborne bacteria are the major bioaerosols with some species producing the most potent ice nucleating compounds known, which are implicated in the formation of ice in clouds. Little is known about the numbers and dynamics of airborne bacteria in the Arctic and even less about their seasonal variability. We collected aerosol samples and wet deposition samples in spring 2015 and summer 2016, at the Villum Research Station in Northeast Greenland. We used amplicon sequencing and qPCR targeting the 16S rRNA genes to assess the quantities and composition of the DNA and cDNA-level bacterial community. We found a clear seasonal variation in the atmospheric bacterial community, which is likely due to variable sources and meteorology. In early spring, the atmospheric bacterial community was dominated by taxa originating from temperate and Subarctic regions and arriving at the sampling site through long-range transport. We observed an efficient washout of the aerosolized bacterial cells during a snowstorm, which was followed by very low concentrations of bacteria in the atmosphere during the consecutive 4 weeks. We suggest that this is because in late spring, the long-range transport ceased, and the local sources which comprised only of ice and snow surfaces were weak resulting in low bacterial concentrations. This was supported by observed changes in the chemical composition of aerosols. In summer, the air bacterial community was confined to local sources such as soil, plant material and melting sea-ice. Aerosolized and deposited Cyanobacteria in spring had a high activity potential, implying their activity in the atmosphere or in surface snow. Overall, we show how the composition of bacterial aerosols in the high Arctic varies on a seasonal scale, identify their potential sources, demonstrate how their community sizes varies in time, investigate their diversity and determine their activity potential during and post Arctic haze.

Regionally sourced bioaerosols drive high-temperature ice nucleating particles in the Arctic

“…Primary biological aerosol particles (PBAP) such as bacteria, spores, pollen, plant debris, or viruses 17 are emitted from vegetation and biological activity on snow and barren land alongside co-emission with sea spray and dust 18 , 19 . PBAP are poorly understood, given the challenges in sampling and quantifying their presence, emissions and sources 20 , especially in the Arctic, where observations are scarce and concentrations are deemed low 21 , 22 . PBAP found in the Arctic can be of both marine (e.g., sea spray and sea ice) and terrestrial origin (e.g., soil and tundra vegetation), locally sourced or transported to the Arctic from lower latitudes 21 .…”

“…Previous studies have reported the presence of PBAP in the Arctic 19 , 21 , 23 – 26 , together with qualitative assessments of their taxonomy 22 , 26 . However, these studies were limited in quantifying PBAP sources due to the limitation with the filter sampling methods used 20 .…”

Changes of In Situ Prokaryotic and Eukaryotic Communities in the Upper Sanya River to the Sea over a Nine-Hour Period

“…Not only that, changes in hydrological conditions, such as soil and runoff inputs [ 29 ], tropical storms, and atmospheric deposition [ 30 ], will also have an impact. Moreover, microbial communities in extreme and simple ecological environments are more susceptible to impacts, and these effects exhibit a clear seasonality [ 31 ].…”

Selection processes of Arctic seasonal glacier snowpack bacterial communities

“…Snow is an effective scavenger of atmospheric particles, including microorganisms. While previous research has suggested that snow might be used to investigate microbial communities in the atmosphere [ 29 ], their respective community structure and diversity are different [ 30 ]. Selective processes occur as snow falls in the atmosphere [ 17 , 23 ].…”

“…This may be the case for the examples used to test the method such as for microbiomes of tropical trees and the human gut [ 44 ]. The advantage of the seasonal snowpack ecosystem is that freshly fallen snow is the main seeding source, because it consists of both microorganisms in clouds (where snowflakes form) and those scavenged from the underlying air during snowfall [ 30 ]. The surface upon which the seasonal snow develops might also constitute a seeding source, in seasonal snow found on glaciers; this would either be ice or previously fallen snow or firn (aged snow older than a year).…”