夏季西北冰洋表层淡水分布的总碱度示踪研究

利用中国第三次北极科学考察在西北冰洋所进行的海水总碱度的测量，通过海水、海冰融化水以及河源淡水三个端元总碱度特征的显著差异计算西北冰洋夏季表层海水中淡水所占的比例。研究表明，西北冰洋海冰融化水所占比例最大区域在加拿大海盆区75°N附近，这是冰缘带位置，往北向高纬度的冰密集中逐渐增加。而河源淡水的组份则与北冰洋的环流密切相关，并且在西北冰洋水体中逐渐累积。

SUMMERTIME FRESH WATER FRACTIONS IN THE SURFACE WATER OF THE WESTERN ARCTIC OCEAN EVALUATED FROM TOTAL ALKALINITY

As a quasi-conservative tracer,total alkalinity(TA) can be used to tracethe relative fractions of fresh water and sea water.In this study,based on TA and related data collected during the Third Chinese Arctic Research Expedition(July—September 2008,CHINARE-2008) and the Fourth Chinese Arctic Research Expedition(July—September 2010,CHINARE-2010),fractions of sea ice meltwater,river runoff and sea water in the surface water of the western Arctic Ocean were determined from salinity and TA relationships.During both surveys,the largest fraction of sea ice meltwater was found around 75°N in the Canada Basin,located at the ice edge.Generally,the fraction of river runoff is less than sea ice meltwater.The river runoff,composed mainly of Yukon River water carried by Bering inflow water and Mackenzie River water,was influenced by currents,and there were two areas where its fraction peaked.Our results showed that the dilution effect of fresh water carried by Bering inflow water during CHINARE-2008 might have been stronger than during CHINARE-2010.The area of the peak sea ice meltwater fraction identified during CHINARE-2010 differed from CHINARE-2008,corresponding to different sea ice conditions.