Tracing sources of freshwater contributions to first-year sea ice in Svalbard fjords

Abstract

Salinity, δ18O, and total alkalinity were determined from sea ice cores collected from various fjords (Billefjorden, Tempelfjorden, Raudfjorden, Rijpfjorden, and Palanderbukta) around Spitsbergen and Nordaustlandet, Svalbard between February and April 2013. The data were used to determine whether ice cores could be used to quantitatively evaluate contributions of meteoric water (glacial meltwater, river runoff, and precipitation) to the fjords instead of traditional methods that rely on data collected from the water column where brine introduced during sea ice formation can complicate interpretation. The majority of the cores exhibited only small contributions (≤5%) of meteoric water ice compared to that derived from seawater; however, cores collected close to the front of Tunabreen, a tidewater glacier located at the head of Tempelfjorden, contained a significant contribution (36%) of meteoric water ice. The shape of the vertical δ18O profiles, as well as excess total alkalinities (relative to salinity) from the Tempelfjorden cores suggested that the source of this meteoric water was subglacial meltwater discharged from Tunabreen during fall and/or winter. Although cores were also collected close to the front of Nordenskiöldbreen (a tidewater glacier in Billefjorden), these did not exhibit a large meltwater influence. We speculate that the combination of the 2004 surge and subsequent retreat of Tunabreen, combined with the cyclonic circulation pattern of warm Atlantic waters that intruded into the Isfjorden system in mid-January of 2012 might have played a role in the apparently larger meltwater contribution to Tempelfjorden. Increasing Atlantic water temperatures in the West Spitsbergen Current and larger and/or more frequent intrusion of these waters into Isfjorden reduces winter sea ice growth and can thereby aid in the melt of tidewater glaciers (during summer and winter months). These interactions have important implications on glacier flow and deserve further study.