This summer we travelled to Greenland to finish the first phase of the MARCH4G project. We returned to Upernavik in NW Greenland to visit sites we couldn’t last year due to foggy weather, and visited more glacial termini in the Kangerlussuaq, Nuuk, and Narsarsuaq areas in the southwest and far south.
We used sampling procedures developed and tested in 2021, with some important improvements. We did quick surveys of methane concentrations in the meltwater by de-gassing of dissolved methane into in a „shake-bottle“, and when methane supersaturated water was detected, we repeated the de-gassing step with larger volumes and a pure nitrogen atmosphere. This was certainly more time- and resource consuming but it provided us with larger amounts of clean gas samples necessary for advanced analyses (stable and radioisotopes).
Moreover, our collaboration with the MetICE project allowed us to use some cheap methane sensors developed by Christian Juncher Jørgensen and his team. Data from these sensors will hopefully give us additional information on methane concentration fluctuations over time from several important sites.
We all appreciate that the season is over with no major problems (as in, everyone made it back) and with a set of samples which will take some time to analyse but hopefully help us write a new chapter in the book of Greenland ice sheet carbon cycling under climate heating.