Snow covers about 35% of the Earth's surface during the year and represents one of the most important climatic and ecological systems. It is a physically, chemically, and biologically dynamic system. Mercury (Hg) can be emitted both by anthropogenic processes and from land surfaces through natural processes. Once released, due to its long atmospheric residence time, Hg can undergo long-range transport and arrive in remote regions such as the Arctic, where it is subsequently deposited. Atmospheric Hg is principally deposited onto the cryosphere and finally comes to hydrological systems. The abundance of microorganisms on the snow varies significantly, ranging from 102 cells to 102-105 per milliliter of melted snow on the South Pole or in high mountain and Arctic snow, respectively. Microorganisms in the snow in polar regions are also analyzed for their metabolic activity and for the production of molecules of interest. This research aimed at surveying in the snow Hg pollution level, assessing bacterial community activity, and isolating biotechnologically-promising bacterial strains in terms of their bioremediation potentialities. Our preliminary results underline that the snow is an interesting and unique ecosystem, especially in terms of bacterial composition and activities. Very relevant results are found in intermediate snow deposition layers, where the concentrations of chlorophyll-a and enzymatic activities are the highest. The microbial activities detected in the snow are comparable to (and in some cases higher than) those retrieved in previous studies. An increase in Hg concentration is observed in the snow along the depth of snow accumulation, probably due to the increase in snow density. Finally, Hg-tolerant bacterial strains have been isolated. Further analyses are currently in progress, especially for the evaluation and quantification of the presence of mer genes, nevertheless new insights on snow-associated microbial communities are reported.
Mercury concentration and microbial communities in Arctic snow, a unique ecological niche
Papale M;Rappazzo AC;Caruso G;Azzaro F;Decembrini F;Maimone G;Azzaro M;Lo Giudice A
2023
Abstract
Snow covers about 35% of the Earth's surface during the year and represents one of the most important climatic and ecological systems. It is a physically, chemically, and biologically dynamic system. Mercury (Hg) can be emitted both by anthropogenic processes and from land surfaces through natural processes. Once released, due to its long atmospheric residence time, Hg can undergo long-range transport and arrive in remote regions such as the Arctic, where it is subsequently deposited. Atmospheric Hg is principally deposited onto the cryosphere and finally comes to hydrological systems. The abundance of microorganisms on the snow varies significantly, ranging from 102 cells to 102-105 per milliliter of melted snow on the South Pole or in high mountain and Arctic snow, respectively. Microorganisms in the snow in polar regions are also analyzed for their metabolic activity and for the production of molecules of interest. This research aimed at surveying in the snow Hg pollution level, assessing bacterial community activity, and isolating biotechnologically-promising bacterial strains in terms of their bioremediation potentialities. Our preliminary results underline that the snow is an interesting and unique ecosystem, especially in terms of bacterial composition and activities. Very relevant results are found in intermediate snow deposition layers, where the concentrations of chlorophyll-a and enzymatic activities are the highest. The microbial activities detected in the snow are comparable to (and in some cases higher than) those retrieved in previous studies. An increase in Hg concentration is observed in the snow along the depth of snow accumulation, probably due to the increase in snow density. Finally, Hg-tolerant bacterial strains have been isolated. Further analyses are currently in progress, especially for the evaluation and quantification of the presence of mer genes, nevertheless new insights on snow-associated microbial communities are reported.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
