Simulations of Artic Ice Algal Biogeochemistry Reveal Source of Atmospheric Sulfur
Marine biogeochemistry influences high-latitude climate through fluxes of greenhouse gases and aerosol precursors, and it is now becoming clear that such processes extend from open waters well into the sea-ice pack. DOE-funded investigators have constructed the first simulations of sea ice sources for dimethyl sulfide (DMS), the primary natural carrier of sulfur atoms from the ocean to the atmosphere. The sulfur is oxidized to form sulfate, which reduces incoming solar radiation. Complete nutrient cycling and ecodynamics were introduced into the Los Alamos sea ice model (CICE), a component of the Community Earth System Model, with interactive silicon, nitrogen, and sulfur processing attached. Under brine stress, the model ice algal metabolism produced sufficient organosulfur to support high concentrations of DMS in leads and marginal waters. Dissolved distributions along the migrating pack edge were compared with available measurements for the trace gas, which proved to be rare. Significant sulfur fluxes to the atmosphere are attributable to sea ice biology in peripheral seas such as the Okhotsk or Bering and also throughout the Canadian Archipelago. Emissions follow the seasonally retreating ice margin. However, the observational database is so sparse that alternate scenarios could not be excluded. A renewal of measurement activity was recommended to remedy this situation. Upcoming Arctic sea ice changes are likely to significantly impact high-latitude aerosols through sulfur channels represented in the model.
Elliott, S., C. Deal, G. Humphries, E. Hunke, N. Jeffery, M. Jin, M. Levasseur, and J. Stefels. 2012. “Pan-Arctic Simulation of Coupled Nutrient-Sulfur Cycling Due to Sea Ice Biology: Preliminary Results,” Journal of Geophysical Research Biogeosciences 117, G01016, DOI: 10.1029/2011JG001649.