A short article I wrote for the EGU blog about biological darkening of ice and snow was posted last month. The article was built around an aerial view of our 2016 field camp on the Greenland Ice Sheet, where large areas of dark ice are clearly visible.
The dark colour is due to a collection of dusts, soot and algal cells, with the algal cells doing the bulk of the darkening. A second figure in the article shows the algal cells under the microscope along with the spectra of reflected light from the algal ice surfaces. This was one of several EGU blog posts about icy biology, including this one and this one!