Figure 1.

Sampling sites and camp location on the south-western Greenland ice sheet (A), with insert showing the relative position of the sampling region within Greenland. Transect 1 (sites S1a, S2 and S3) was performed on the 27th July 2016 (DOY = 209) and transect 2 (sites S1b, S2, S3) on the 5th August 2016 (DOY = 218). Images show the supraglacial surface environment of sites S1a (B), S2 (C) and S3 (D) during transect 1, illustrating the conspicuous increase in surface impurities apparent across transects toward the ice sheet margin. Ancylonema nordenskiöldii (E) and Mesotaenium berggrenii (F) were shown by this study to dominate surface ice across transects (scale bars = 10 μm in both cases).