Patterns and Changes in Dissolved Organic Carbon (DOC) across Lakes in Southwestern Greenland

Abstract:

Rapid warming of the Arctic over the last few decades has led to changes in biogeochemical cycling of both aquatic and terrestrial ecosystems in the region. Decreases in permafrost and changes in hydrological connectivity have changed the movement of ions and nutrients across the landscape. The combined effects of increased temperature and altered terrestrial inputs can lead to changes in lake productivity as well. Although all of the Arctic is warming, Greenland has demonstrated the greatest average rate of temperature increase over the past few decades relative to other areas. Therefore, we assessed dissolved organic carbon (DOC) within 26 lakes in southwestern Greenland from the ice sheet towards the coast during the summers of 2013 and 2014. In these lakes, DOC concentrations ranged from 4-40 ppm and were fairly consistent across the Arctic growing season. However, these results indicate widespread changes in DOC over the last decade, ranging from no change to a 60% reduction of in-lake concentrations. We hypothesize that rapid climate change in the region has led to these changes in carbon availability and processing across the landscape and within lake basins. While the exact mechanisms are still being explored, such changes within a short time scale can have implications for carbon cycling in the Arctic and globally in the near future.