13 October 2010A team of researchers from Bristol Glaciology Centre spent this summer monitoring runoff from the Greenland Ice Sheet at Leverett Glacier in south west Greenland. The team, headed by Jemma Wadham, were interested in how meltwater flows at the bed of the ice sheet, and how this may be linked to changing dynamics of outlet glaciers. Changes in runoff biogeochemistry can be used to infer changes in drainage system structure and hence how meltwater transits through the subglacial drainage system. The outlet was monitored for 3 months by water quality sensors and through manual and automatic sampling. The outlet monitoring was complemented by dye and gas tracing studies, and by other research teams studying the microbiology of the ice sheet, led by Alex Anesio; the interactions between runoff and ice sheet motion, headed by Pete Nienow at the University of Edinburgh; and large scale ice motion studies by Alun Hubbard’s team from the University of Aberystwyth and the University of Swansea.
As an integral part of the runoff monitoring, PhD students Catie Butler and Emily Lawson and researcher Liz Bagshaw were testing new samplers made available by RS Hydro. Automatic samples were collected every 2 hours by the ISCO Avalanche Portable Refrigerated Sampler which were then filtered by Catie and returned to Bristol for analysis. The high frequency sampling of the autosampler allowed identification of short-lived hydrological changes, such as the rapid drainage of large lakes on the ice sheet surface, which would have been poorly resolved by the more traditional twice-daily manual sampling. The sampler was sited next to the turbid meltwater stream and samples were pumped up by a long hose. The sampler and built-in refrigerator were powered by a solar panel.
A continuous sensor array was also deployed in the proglacial river to monitor changes in geochemical properties of the glacial runoff. The Manta 2 Multi Parameter Water Quality Sonde was used to monitor pH, water temperature, electrical conductivity, and relative turbidity and water depth, in addition to Campbell Scientific and PreSens sensors. The robust sonde coped well with the very turbid meltwater flow, so data were sampled and recorded every 15 minutes and then downloaded daily using a small laptop.
PhD Student Catie Butler uses the Avalanche Autosampler at the Leverett Glacier, south west Greenland (Photo credit: Greg Lis)
Liz Bagshaw dons her wellies to use the Manta water quality sonde to monitor changes in runoff biogeochemistry
Image by Dr Jemma Wadham