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Biological Particles Including Bacteria as Ice Nucleators

March 19th, 2008 by inansel · No Comments

In the article “Ubiquity of Biological Ice Nucleators in Snowfall” Christner et al., it is made clear how important biological particles are as ice nucleators and how many of these particles are bacteria. One thing that I found interesting is how high of a temperature bacteria can act as an ice nucleator, -2C. It is known that aerosols in the atmosphere act as catalysts for ice nucleation, but what Christner found was that 69 to 100% of these ice nucleators are biological. Since the atmospheric ice nuclei concentrations at temperatures above -10C are so small 19 samples of fresh snowfall were taken from multiple places in both the high and mid latitudes. These samples were then analyzed by a heat treatment, which inactivated the biological ice nucleators, and then these could be seperated from ice nucleators of mineral origin. This showed that out of all the ice nucleators, the biological ones represented the majority if not all of the nucleators. This was then further broken down to find the bacterial nucleators by adding lysozyme to the sample to disrupt the cell wall and reduce ice-nucleation activity in bacteria. The experiment found 0 to 85% of the ice nuecleators were susceptible to lysozyme and thus bacteria, but do to incomplete hydrolysis or resistance to lysozyme this could be underestimating the bacteria concentration. The one amazing finding to me was that biological ice nucleators were found in Antarctica albeit at the lowest concentration of the 19 samples, but it shows these particles had to have traveled long distances and stayed active as an ice nucleator. Christer believes this research can be used for further discovery of the connections between the biosphere and climate, and also aid in improving climate forecast models.

Tags: MTR3440 · Uncategorized

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