Meltwater chemistry and solute export from a Greenland Ice Sheet catchment, Watson River, West Greenland

Solute export from the Greenland Ice Sheet (GrIS) to coastal regions around Greenland is likely to increase in the future as a consequence of increasing icemelt production. Here, we present hydrochemical characteristics, solute and major ion exports and chemical denudation rates for 2007-2010 for the Watson River sector of the GrIS that drains into the fjord Kangerlussuaq. The hydrochemistry is dominated by Ca2+ and HCO3- with a relatively high molar K+/Na+ ratio of 0.6 +/- 0.1, typical for meltwaters draining a gneissic lithology. Low molar Ca2+/Na+ and Mg2+/Na+ ratios indicate that weathering of disseminated carbonates contributes less than silicate weathering to the chemical composition. The solute export varied between 33 x 10(3) (2009) and 61 x 10(3) tons (2010), showing that increasing discharge leads to increasing solute export at the catchment scale. Deviations between ion yield estimates derived from use of discharge-weighted and mean daily concentrations methods were generally less than 5%, indicating that the choice of method is of less importance. The chemical denudation rates ranged between 36 and 56 Sigma* meq(+) m(-2) per year, which are lower than previous records from glacierized catchments. However, when normalized by discharge the denudation rates are comparable to other Arctic sites. When extrapolating the results from the Watson River catchment to the entire Greenland for 2007-2010, the solute export from Greenland meltwater varied between 7.1 x 10(6) and 7.8 x 10(6) tons, whilst the major ion export was between 6.4 x 10(6) and 7.3 x 10(6) tons. Dissolved Fe, a potential biolimiting nutrient for primary productivity in the North Atlantic, had annual export rates from Greenland between 15 x 10(3) and 52 x 10(3) tons. (C) 2014 Elsevier B.V. All rights reserved.