DISSOLVED ORGANIC-MATTER IN ARCTIC MULTIYEAR SEA-ICE DURING WINTER - MAJOR COMPONENTS AND RELATIONSHIP TO ICE CHARACTERISTICS

Ice cores were collected between 10.03.93 and 15.03.93 along a 200 m p rofile on a large ice flee in Fram Strait. The ice was typical of Arct ic multi-year ice, having a mean thickness along the profile of 2.56 /- 0.53 m. It consisted mostly of columnar ice (83%) grown through con gelation of seawater at the ice bottom, and the salinity profiles were characterized by a linear increase from 0 psu at the top to values ra nging between 3 and 5 psu at depth. Distributions of dissolved organic carbon (DOC) and nitrogen (DON) and major nutrients were compared wit h ice texture, salinity and chlorophyll a. DOC, DON, dissolved inorgan ic nitrogen (DIN), NH4+ and NO2- were present in concentrations in exc ess of that predicted by dilution curves derived from Arctic surface w ater values. Only NO3- was depleted, although not exhausted. High DOC and DON values in conjunction with high NH+4 levels indicated that a s ignificant proportion of the dissolved organic matter (DOM) was a resu lt of decomposition/grazing of ice algae and/or detritus. The combinat ion of high NH4+ and NO2- points to regeneration of nitrogen compounds . There was no significant correlation between DOC and Chl a in contra st to DON, which had a positively significant correlation with both sa linity and Chl a, and the distribution of DOM in the cores might best be described as a combination of both physical and biological processe s. There was no correlation between DOC and DON suggesting an uncoupli ng of DOC and DON dynamics in multi year ice.