Sea ice supports highly dynamic, and at times highly productive assemblages of auto- and heterotrophic organisms. Central to the biogeochemical cycling of carbon and nitrogen within sea ice is the production and lability of dissolved organic matter (DOM). DOM is produced through excretion, mortality, cell lysis, and amplified by inefficient feeding by grazers. It has been hypothesised that there are significant DOM pools in sea ice systems, although measurements of DOM in sea ice have only rarely been made. The significance of DOM for ice based productivity and carbon turnover therefore remains highly speculative. The dissolved organic carbon and nitrogen (DOC, DON) of sea ice from the Amundsen, Bellingshausen and Weddell Seas were investigated in 1992, 1994 and 1997. Measurements were made on melted sea ice sections in 1994 and 1997 and in sea ice brines in 1992. These studies confirm that DOC and DON can reach up to 30 and 8 times higher concentrations compared to those in surface waters, respectively. This DOM tends to be carbon enriched with a mean DOC:DON ratio of 14. Measurements made on a limited data set showed that carbohydrates constitute on average 35% of the DOC pool with highly variable contributions.
AWI Organizations > Biosciences > Ecological Chemistry