Abstract:

Seawater samples at 9 stations were collected in the Canada Basin during the Second Arctic Scientific Expedition of China (from Jul. to Sep.,2003). The result of chlorofluorocarbons(CFCs)determination showed that the highest concentration of CFC-11 and CCl_4 in the surface water are 6.7 pmol/kg and 9.62 pmol/kg respectively, but they are all undersaturated. The degrees of saturation of CFC-11 in the surface water lies in the range of 70.54% to 84.70% , and that of CCl_4 within 76.54% to 91.53% , probably caused by local ice cover and the invasion of the Pacific water with low CFC concentration. The significant concentration of CFCs at the depth of 2000 m indicated that deep water in the Canada Basin was exchanged and replaced with the open seawater outside. The vertical distributions of CFCs confirmed that the water masses in the Canada Basin were stratified. The method of pCFC-11 and pCCl_4 dating are used to evaluate the apparent ages of water masses.