Cryoconite is a small hole in the surface of the glacier, which serves as a trap for fine sediments composed of small rock particles, soot and bacteria. The dark sediment inside a cryoconite has low albedo – it absorbs solar radiation and promotes ice melting beneath it, forming cylindrical holes. With time, as the layer of sediments becomes thicker, it isolates the underlying ice from heat and a reversed situation occurrs – the ice around cryoconite melts faster, and a cone of ice with a cap of sediments is formed.
Inside cryoconites microecosystems are formed, whose components are:
- terrestrial mineral particles – quartz, feldspar, mica, calcite, clay minerals
- anthropogenic pollutants (soot)
- microbes and organic matter (algae, cyanobacteria, fungi, viruses, humic substances)
The holes can also harbour dormant seeds flown in from far away and invertebrates (like tardigrades).
Cryoconites create a positive feedback mechanism and are a significant contributor to glacial surface melt.