Investigation into cryoconite holes at a cold based glacier, Wright Lower Glacier, Wright Valley, Antarctica

Investigation into cryoconite hole chemistry, surface area cover and construction was investigated as part of wider project looking at the seasonal melt regime of the Wright Lower Glacier. Chemistry: Water samples were collected from cryoconite hole water at 10 location on the surface of the glacier. Samples were collected with a syringe after drilling a hole in the ice lid and samples were filtered for solute, organic carbon and isotope analysis. Additional ice samples were collected to compare characteristics of the cryoconite hole ice with the surrounding ice. Other features recorded at each site include hole dimensions and maps of the cryoconite holes in the immediate vicinity of the flag (ablation stake markers). In order to better characterise the contribution of melt from different ice types, conductivity and dissolved oxygen measurements were made in 20 cryoconite holes.This involved using a multiparameter probe to measure levels in cryoconite hole water and similarly from melted ice lids. The dimensions of the holes were also measured to attempt to characterise the depth and dispersal of the cryoconite hole layer on the surface of the glacier. Area cover: In order to gain an idea of the change of cryoconite hole coverage on the glacier surface over the season, a cryoconite hole survey was completed. A 10m by 10m square was set up of which 5m by 10m was on the flat surface above a north facing cliff and the other half was at the base of the cliff. The hole diameter in two directions was recorded and re-measured approximately every 10 days. In addition, the refrozen surface below the north facing cliff was measured to ascertain whether the pooling effect of the cliff melt had any bearing on the cryoconite hole population. Construction: Three types of cryoconite holes were constructed by a) using a very light covering of sediment, b) filling in sediment in a circle to a thickness of approx 2mm and c) filling in a circle approx 5mm thick, near the edge of a North facing cliff to examine cryoconite hole construction.