Natural radioactive isotopes in glacier meltwater studies

Abstract

Glaciers are decaying due to global warming. Svalbard is a very sensitive area within the European High Arctic and studies on glacier changes and evolutions are representative for the Arctic. The present work aims glaciers at Spitsbergen; we investigated meltwater supplied by glacierized basins in introducing radioactive isotope measurements in combination with classical parameters. Among the natural radioactive elements, the most promising is the noble gas radon, more precisely the isotope 222 Rn, with a short half life of 3.8 days and the possibility of automated continuous measurements. Measurements of radon in glacier meltwater showed surprisingly high concentrations thus enabling investigations with radon as valuable tracer. Only meltwater in contact with rock or sediments has the possibility to be charged with radon. Varying radon concentrations can be linked to changes in mixing meltwater from different origins, roughly the surface of glaciers (supraglacial), within (englacial) and under ice (subglacial). We are able to collect information on the glacier drainage system and its evolution over time and thus contribute to the study of glacier dynamics.Results from three sampling periods on Werenskioldbreen glacier, covering different glaciological seasons, are presented and discussed in this study. The potential results of further continuous measurements will give supplementary information on drainage footpaths and the style and system of the draining of glaciers. Our study intends also a better understanding of the response of glaciers to environmental parameters and, on a longer term, to make a contribution to climate change studies.

Utility of 222Rn as a passive tracer of subglacial distributed system drainage

“…Hence, by its nature, distributed system meltwater should acquire significantly higher 222 Rn activities than meltwater that flows through open channels. Discrete 222 Rn measurements in small glacial watersheds have been used to infer the transition from distributed to channelized drainage (Kies et al, 2011;Bhatia et al, 2011;Kies et al, 2015). This paper expands upon these earlier studies by examining the utility of long term continuous 222 Rn measurements in the proglacial river of a large GrIS outlet glacier during the spring and summer of 2011 and 2012.…”

“…Radon-222 has been used as a tracer of sediment pore watersurface water exchange processes in a diverse range of environmental systems including rivers (McCallum et al, 2012), the coastal ocean (Burnett and Dulaiova, 2003;Dulaiova et al, 2008), and in small glacier catchments (Kies et al, 2011;Bhatia et al, 2011;Kies et al, 2015). In the following discussion, we explore the utility of 222 Rn in tracing and quantifying meltwater fluxes from the subglacial distributed system at a large Greenland outlet glacier, Leverett Glacier.…”

Groundwater Discharge in the Arctic: A Review of Studies and Implications for Biogeochemistry

“…Discrete samples of electrical conductivity and radon were measured in water at the outflow at various times and compared. The results of this study showed that water at the discharge site was high in radon, and its electrical conductivity was indicative of water in close interaction with the subglacial till, even flowing through the till as distributed system flow (groundwater) [44]. Conversely, water low in radon and electrical conductivity at the discharge sites was more representative of water that transited through the subglacial environment in channels [44].…”

“…The results of this study showed that water at the discharge site was high in radon, and its electrical conductivity was indicative of water in close interaction with the subglacial till, even flowing through the till as distributed system flow (groundwater) [44]. Conversely, water low in radon and electrical conductivity at the discharge sites was more representative of water that transited through the subglacial environment in channels [44]. Water with intermediate levels of these parameters, or a mix of high and low, was indicative of a mix of the distributed system and channelized flow or other processes [44].…”

“…An early study of Werenskiold Glacier (4 on Figure 2) by Kies et al [44] explored the applicability of pairing measurements of radon with electrical conductivity to describe the pathways of subglacial meltwater at discharge sites at the glacier's terminus [44]. Discrete samples of electrical conductivity and radon were measured in water at the outflow at various times and compared.…”