United Kingdom: projects/activities

Based upon research previously undertaken at Sheffield University, nutrients released from High Arctic glaciers during the summer ablation season are shown to rarely be in balance with bulk inputs deposited on the glacier surface as winter accumulation. Nutrient budgets suggest glaciers to release an excess of nitrate relative to annual bulk deposition, whilst up to 40% of the Ammonium deposited on the glacier surface appears to be sequestered from the inorganic budget (Hodson., in prep). Contrary to popular understanding, such an imbalance would suggest glaciers to be agents of nutrient storage, release and utilisation. In conjunction with a range of recent research (Sharp et.al, 1999., Skidmore et.al, 2000) this may potentially demonstrate high Arctic glaciers to be dynamic biological systems supporting a plethora of microbial life, rather than biologically inert cryospheric entities as so widely perceived in much of the research literature. Ammonium and Nitrate are nutrients of key importance not only to the maintenance of microbial life in such hostile environments, but also to the primary productivity of ice-marginal freshwater and marine ecosystems. However, as yet, their dynamics have proved difficult to explain. Field research undertaken during summer 2002 used natural isotopes to fingerprint sources and sinks of nutrients within the glacial system, thereby enabling a better understanding of biogeochemical cycling within the glacial environment. Whilst analysis of isotopic samples from this field season is still ongoing, new areas of research have been highlighted. The significance of organic nutrients in biogeochemical cycling has largely been regarded as insignificant, especially with regard to glacier geochemistry (reference). However, large fluxes of organic carbon have been observed emanating from the subglacial drainage of glacier Midre-Lovenbreen (Wynn, unpublished Data) and Dissolved Organic Nitrogen (DON) is now known to represent upto 40-50% of annual nitrogen inputs in glacier snowpacks (Hodson, in prep). Furthermore, bacteria, cysts and algae present within small supraglacial melt pools known as ‘cryoconite holes’, hold the potential to utilise inorganic nutrients and retain them in the organic phase. Consequently, omitting the role of organic nutrients from glacial biogeochemical studies allows only a limited understanding of the chemical and biological interactions occurring within Arctic glaciers. A field study addressing the significance of dissolved organic nutrients within glacial systems is to be undertaken during summer 2003. A new method is currently being investigated which will allow the concentration and subsequent isotopic analysis of dissolved organic nutrients retained on ion exchange resins. Use of environmental isotopes in conjunction with major ion chemistry will help determine the provenance, fate and bioavailability of organic nutrients within the glacial system. Lysimeters inserted into the snowpack will enable the release of organic nutrients into the glacier to be continuously monitored, allowing subsequent changes in meltwater isotopic signatures to be studied relative to this. Particular emphasis shall be given to Nutrient cycling within cryoconite holes and fluxes of organic matter emanating from the subglacial drainage as these represent two possible sites of organic/inorganic interaction. Fieldwork is to be undertaken on Midre-Lovenbreen, Svalbard, a polythermal glacier well known and studied by the author. Initial sample processing shall be accomplished in the laboratory facilities provided in Ny-Alesund, whilst subsequent isotopic analysis is to be undertaken at the British Geological Survey in Nottingham.

This project will construct detailed phosphorus budgets for polar catchments occupied by glaciers and freshwater systems undergoing rapid response to climate warming. These are Midre Lovenbreen, Svalbard; Jebsen Creek, Signy Island (maritime Antarctic) and Storglaciaren, northern Sweden. The relationship between meltwater production, pathway and phosphorus liberation from glacial sediments will be examined closely. Emphasis will be given to phosphorus sorption dynamics in turbid glacial streams and their receiving waters (fjords and lakes).

To determine where different types of impurities (primarily specific inorganic chemical species and microbes) are located on a microspopic scale within the ice and what controls their distribution.