The spatial and temporal dynamics of colored dissolved organic matter (CDOM) were examined during the North Water polynya study from April to July 1998. Few data have been collected pertaining to the dynamics of CDOM in Arctic marine ecosystems and none during the progression of an Arctic polynya. Unlike in other marine ecosystems, ultraviolet absorption by CDOM was highest near the surface of the water column and increased in concert with the development of the polynya. Analysis of ice core samples revealed that sea-ice may be a significant source of CDOM and indicated that Arctic marine ecosystems have different controls of CDOM production and loss than do low latitude, open ocean systems. We hypothesize that the frequent surface CDOM maxima in Arctic ecosystems is the result of sea-ice providing a substrate for enhanced autochthonous formation of CDOM. ¿ 2000 American Geophysical Union