OXYGEN-ISOTOPE STUDIES FROM ICELAND TO AN EAST GREENLAND FJORD - BEHAVIOR OF GLACIAL MELTWATER PLUME

A detailed study of the oxygen isotope composition (delta(18)O) was ca rried out along a transect between Iceland and East Greenland, which i ncludes the West Iceland Shelf, Denmark Strait, the Kangerdlugssuaq Tr ough on the East Greenland Shelf and the Kangerdlugssuaq Fjord, Vertic al profiles of the oxygen isotope composition in a fjord with tidewate r glaciers were studied for the first time. In this study, three disti nct water masses are identified from oxygen isotope measurements: (1) North Atlantic Water of delta(18)O approximate to 0 parts per thousand occupies the Icelandic Shelf, Denmark Strait subsurface, and deep wat ers of the Kangerdlugssuaq Trough and Fjord; (2) the East Greenland Cu rrent of delta(18)O approximate to -2 parts per thousand occupies surf ace water at the western Denmark Strait and the Kangerdlugssuaq Trough ; (3) glacial meltwater (delta(18)O ranges from -30 to -20 parts per t housand in source) flows at the surface of the Kangerdlugssuaq Fjord. Surface delta(18)O data distinctively identify the East Greenland Fron t between North Atlantic Water and the East Greenland Current in Denma rk Strait. Vertical profiles of delta(18)O show the steady increase fr om surface to deep water at the stations west of the front with well m ixed water at stations east of the front. We did not find any subsurfa ce glacial meltwater intrusion in Kangerdlugssuaq fjord, unlike the re ported 'cold tongue' in Antarctic fjords, Instead Arctic Intermediate Water (winter cooled North Atlantic Water) penetrates to the head of t he fjord and fills the bottom part of the fjord. A linear relationship between salinity and delta(18)O shows that there was no significant c ontribution from the sea ice meltwater in this study site. The dominan t source of freshwater in the Kangerdlugssuaq Fjord is glacial meltwat er. A simple model using delta(18)O was developed to illustrate glacia l meltwater dynamics in the fjord, and to estimate the length of the g lacial meltwater plume. Model results agree well with the data within the fjord and near the fjord mouth and a plume length is estimated to be 250 km from the glacial face. However, a diversion of the model fro m the data is observed at about 70 km away from the mouth of the fjord because of the influence by the East Greenland Current and the Coriol is effect.