Absorption properties of marine-derived material in Arctic sea ice

The distribution and concentration of particulate and dissolved material were determined for first year and multiyear sea ice collected from the fast ice off Barrow, Alaska. The particles were identified as intact algal cells, bacteria, organic aggregates colonized by bacteria and detrital particles. The largest concentrations of particles occurred in the zones of fine grain or in zones of concentrated brine drainage features. The absorption efficiencies of these particles in combination with measured particle concentrations were shown to provide a reasonable estimate of the bulk particulate spectral absorption coefficients in the case of a first year ice sample. The sum of the absorption coefficients of the particulate and dissolved fractions were up to an order of magnitude greater than the absorption coefficients of pure ice. The enhanced absorption of visible radiation by the entrapped material was estimated to cause increases in sea ice temperature of up to 3 degree(s)C per day in the absence of snow cover. The marine- derived particulate and dissolved materials are not negligible contributors to the optical and thermal characteristics of sea ice.