Abstract
ABSTRACT In west Greenland, an approximate chronosequence of landscape evolution and weathering exists between the coast, which has been ice free for long periods, and more recently deglaciated areas along the present day ice margin. Traditional geochemical and isotopic analyses (δ18O, δ2H, 3H, δ34S/δ18O (SO4), and 87Sr/86Sr) along with novel isotopic tools, such as δ37Cl and δ81Br, were used to provide new insights into lake geochemical processes along a transect of lakes from the coast to the ice margin in the Kangerlussuaq region. Evaporation was found to be a key process impacting lake chemistry and isotopic signatures in the ice marginal area, with decreasing importance toward the coast. Evaporative processes were apparent in the δ37Cl and δ81Br isotopic signatures of lake-water chemistry. Consistent with previous work elsewhere (e.g., Blum and Erel, 1995) on increased biotite weathering in glaciated environments, 87Sr/86Sr isotopic ratios were found to be more radiogenic (>0.73) in lakes found in more recently glaciated terrain. Sulfide oxidation was the main source of sulfur (as sulfate) in lakes in the ice marginal area, while the influence of marine aerosols and bacterial sulfate reduction increased further away from the ice sheet around the fjord Kangerlussuaq. Groundwater discharge significant enough to impact lake chemistry was not observed in any of the lakes studied, suggesting that little groundwater–surface water interaction occurs in the study area or that recharge conditions are present in the majority of the lakes studied.
Highlights
The geochemical composition of lake water reflects catchment geology, regional climate, vegetation, and soil development and, importantly, varies on a range of spatial and temporal scales (Kling et al 2000)
Lake samples were taken for the Greenland Analogue Project (GAP; see Claesson Liljedahl et al 2016; Harper et al 2016) in the area from the head of the fjord Kangerlussuaq (Søndre Strømfjord) and extending to the ice sheet (Figure 1)
Lake L20 had an electrical conductivity of 354 μS/cm when sampled in early June 2008, and 1,750 μS/cm when sampled in early September 2010
Summary
The geochemical composition of lake water reflects catchment geology, regional climate, vegetation, and soil development and, importantly, varies on a range of spatial and temporal scales (Kling et al 2000). At lower latitudes landscape perspectives of lake biogeochemistry have tended to focus on nutrients, in part because of catchment cultural disturbance (Kendall 1998; Wagner et al 2011), and DOC, because of the dominance of lakes in boreal landscapes and the key role terrestrially derived dissolved organic carbon (DOC) plays in aquatic ecosystem functioning (Jansson et al 2007). In many of these studies, the use of multiple isotopic tracers has proven invaluable in understanding landscape evolution, in terms of chemical interactions.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
