• Arctic;
  • carbon monoxide;
  • dissolved organic carbon;
  • gas exchange;
  • ice algae;
  • sea ice

[1] We monitored the spatiotemporal progression of dissolved organic carbon (DOC) and carbon monoxide (CO), along with general meteorological, hydrographic, and biological variables, in first-year sea ice in the western Canadian Arctic between mid-March and early July 2008. DOC and CO concentrations fluctuated irregularly in surface ice, but followed the concentration of ice algae in bottom ice, i.e., low at the start of ice algal accumulation, highly enriched during the peak-bloom and early post-bloom, and depleted again during sea ice melt. Vertical profiles of DOC and CO typically decreased downward in early spring and were variable in the melting season. In the presence of high bottom ice algal biomass in mid-spring, DOC and CO exhibited high concentrations in the bottom (DOC: 563 ± 434 μmol L−1; CO: 82.9 ± 84 nmol L−1) relative to the surface (DOC: 56 ± 26 μmol L−1; CO: 16.8 ± 7 nmol L−1). Landfast ice contained higher levels of DOC and CO than drifting ice. Cruise-mean DOC and CO inventories in sea ice were 87 ± 51 mmol m−2 and 13.9 ± 10 μmol m−2, respectively. Net productions of DOC and CO linked to the ice algal bloom were assessed to be 75 mmol m−2 and 13.2 μmol m−2. Sea ice in the study area was estimated to contribute 7.4 × 107 moles of CO a−1 to the atmosphere. This study suggests that sea ice plays important roles in the cycling of organic carbon and trace gases.