Revista Chilena de Historia Natural 85 (4): 393-407, 2012
SPECIAL FEATURE
Observations of cryoconite hole system processes on an Antarctic glacier
Cryoconite holes are water-filled depressions that form on glacier surfaces when uneven
distributions of sediment cause differential melting to occur. Cryoconite holes are important features of cold glacier systems, as they
enhance meltwater generation, enable the development of complex drainage networks and facilitate the growth of microbial
communities on the glacier surface. This paper describes the development of a cryoconite hole hydrological network on an Antarctic
glacier, and explores the implications for nutrient storage and delivery within the glacier system. Field measurements included
measuring the internal dimensions and repeat mapping of cryoconite holes across the glacier surface, and laboratory analysis included
cation and anion analysis on clean ice and cryoconite hole samples. Results showed the distribution of cryoconite holes was
determined by surface topography and local ablation rates. Planar surfaces are characterised by the highest density of cryoconite
holes. Cryoconite holes are rare within supraglacial channels and surfaces with high ablation rates. The negative correlation between
cryoconite hole density and ablation rate means that the glacier surface need to be relatively stable in order for the cryoconite hole to
develop and persist. Furthermore, cryoconite holes are likely to contribute up to 1/3 of the meltwater generated on planar surfaces,
however not all of this water is stored in the holes. Water may be drained via channels, cracks and intergranular drainage, however the
relative importance of each is not yet known. As cryconite holes are relatively nutrient rich compared with clean glacier ice, the nature
of connections between cryoconite holes are important for determining nutrient delivery both across the glacier, and to the proglacial
region.
Key words:
biogeochemistry,
drainage system, glacier hydrology, meltwater, solute.
