Belzile, C. Département d'océanographie, Université du Québec à Rimouski, claudebelzile@hotmail.com
Johannessen, S. Department of Oceanography, Dalhousie University, schjohan@is2.dal.ca
Gosselin, M. Département d'océanographie, Université du Québec à Rimouski, michel_gosselin@uqar.uquebec.ca
Demers, S. Institut National de la Recherche Scientifique - Océanologie, serge_demers@uqar.uquebec.ca
Miller, W. Department of Oceanography, Dalhousie University, millerwl@is.dal.ca

 
TRANSMISSION OF ULTRAVIOLET IRRADIANCE THROUGH FIRST-YEAR SEA ICE IN THE NORTH WATER POLYNYA (76-79 deg. N) IN LATE SPRING.
 
Vertical profiles of ultraviolet irradiance (UV) and photosynthetically available radiation (PAR) were measured under five large ice floes located in the North Water Polynya, northern Baffin Bay, in June 1998. We also measured both the total and the vertical distribution of absorption by chromophoric dissolved organic matter (CDOM) and particulate organic matter (POM) in three melted ice cores. The ice thickness and snow depth varied from 0.6 to 1.3 m and from 1 to 9 cm, respectively. The ice-snow interface was infiltrated by sea water. About 2-13% of incident UV-B irradiance was transmitted; transmission increased to 5-19% for UV-A, and to 6-13% for PAR. CDOM and POM contributed significantly to the attenuation of irradiance within the ice. The implications for the bottom-ice algal community will be discussed in the context of ozone depletion.
 
Day: Tuesday, Feb. 2
Time: Poster
Location: Sweeney Center
 
Code: SS27TU0524H