The body of the Bellingshausen Ice Dome as a biogeochemical space

Abstract

The investigation of glacial sediments has not received a lot of attention, but the processes in place on the surface of glaciers are quite interesting and multidirectional. In this article, we focused on glacial sediments material sampled from the surface of the Bellingshausen Ice Dome (King George Island, South Shetland Islands, Antarctica). These sediments have different genesis: material from cryoconite holes, denuded layers of volcanic ash, flushed ash and soils and soil-like bodies formed in the glacial zone. Chemical analysis of the samples showed that the bulk composition of sediments is as follows: SiO₂ > Fe₂O₃ > Al₂O₃ > SO₃ > CaO > MgO > Na₂O > TiO₂ > K₂O > P₂O₅ > MnO (with SiO₂ content 50–55%, Fe₂O₃ – 17–23%, Al₂O₃ – 6–12%). The loss on ignition was maximum (10–11%) for samples taken at the top of the dome. Calculation of geochemical indexes showed that the mineral part of the samples is a product of erosion and sedimentation processes and is less chemically weathered in the lower part of the ice dome. The weathering type is fersiallitic. The maximum content of organogenic compounds (Total organic carbon – up to 5%, ammonium nitrogen – up to 116 mg/kg and mobile potassium – up to 373 mg/kg) also recorded at the top of the glacial dome; this may be associated with microbiological activity in cryoconite holes and the penetration of organic material from bird fauna. The low content of organogenic compounds on the slopes is caused by the processes of their washout with melt water. The content of trace metals Zn, Ni, and Pb found at higher elevations and distribution of Cu and Cd have more a local character associated with tourism activities and anthropogenic influence from year-round scientific stations. Thus, a number of multidirectional processes take place in the glacial sediments on the Bellingshausen Ice Dome, these are not simple denuded layers of ancient volcanic ash. The glacier cover can be considered as a “living” biogeochemical shell, accumulating products of microbiological and anthropogenic activity, products of erosion and sedimentation and organic matter of ornithogenic origin.