CRYOCONITES
Posted on Wednesday 22 August 2012
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These dark formations are found around both the North and South poles and in glaciers. The name comes from the Latin: 'cryo' means 'ice' and 'conite' means dust. Arctic explorer Nils A. E. Nordenskiöld discovered and named them during his visit to the Greenland ice sheet in 1870.
Cryoconites begin as airborne sediment carried to the ice by wind. This sediment is composed of mineral dust that comes from deserts, volcanic eruptions,and soot. The soot comes from man made and natural fires, diesel engines, and coal-fired power plants. Cryoconite has less than 5 percent soot, but this gives it its dark colour. This dark sediment falls on to the ice with the snowfall, and the darkness of the sediment decreases the albedo (reflectivity) of the ice. This increases the absorption of the heat of the Sun and increases the melting of the ice.
As the dark matter sinks into the ice, more ice is melted on the way down, creating a hole. The holes ca
n vary in width and depth and have been known to be as long as 5 metres. Microorganisms can fall into these holes in the summer months, developing a small living community. An ice lid forms in winter, which encloses the organisms witha small amount of water. When summer returns the lid melts and the colony continues to grow, year upon year. If cryoconites are common in glacial regions then they could be changing the nutrient balance in the area, as there would be more carbon,nitrogen etc than thought.
When the glacier in which the cryoconites have formed begins to melt, the cryoconites melt away and disappear. The microbial communities that existed within them however are released in this melt and act as a 'seed population' and colonise the soil that has just been deglaciated.
The photo shows cryoconites on Midre Lovebreen , near Ny-Ã…lesund, on the island ofSvalbard. The largest cryoconite 'hole' is ~ 4 cm india meter and they are all ~ 20 cm deep.
When the glacier in which the cryoconites have formed begins to melt, the cryoconites melt away and disappear. The microbial communities that existed within them however are released in this melt and act as a 'seed population' and colonise the soil that has just been deglaciated.
The photo shows cryoconites on Midre Lovebreen , near Ny-Ã…lesund, on the island ofSvalbard. The largest cryoconite 'hole' is ~ 4 cm india meter and they are all ~ 20 cm deep.
