How Dissolved Organic Matter Composition Responds to Changes in Sea Ice Cover in the western Arctic Ocean.

The Arctic Ocean is undeniably changing, with significant losses in sea ice cover causing an increase in the amount of light penetrating into the ocean. In this paper, we aim to assess the influence of sea ice concentration on the quality and quantity of dissolved organic matter (DOM) in the polar mixed layer waters of the central Canada Basin over an 11-year period (2007-2017). The low sea ice years were characterized by lower humic material intensity and abundances relative to high ice years, likely the result of preferential photo degradation of aromatic material when sea ice concentration is reduced. The proteinaceous character of DOM was also enhanced when sea ice was low. This could be attributed to enhanced primary production associated with greater light penetration and/or the release of protein-like material when humic DOM is photo degraded. Together these results showed that the change in sea ice concentration observed between 2007 and 2017 has already influenced the quantity and quality FDOM in central Canada Basin surface and deeper waters.