北极沿岸地区水体中氢氧稳定同位素组成及水分转化过程研究

Stable Oxygen and Hydrogen Isotopes in Water and Water Cycle along the Arctic Coast

2010年7月参加第三届北京中学生北极科学考察活动,收集了北极沿岸地区的挪威斯瓦尔巴德群岛(Svalbard)、冰岛、格陵兰沿岸地区的海水、沿岸海水、海冰表面冰样、地表径流等水体样品,对样品进行了氢氧稳定同位素成分测定,分析了北极沿岸地区水体的水循环过程.结果表明,该地区不同水体中的稳定同位素具有不同特征.沿岸海水中δ18 O与δD的变化受到了陆地来水的影响,而且与离海岸远近、取样点是开放海域还是峡谷地带、陆地的大小都有关系;海水、降水(包括径流、冰川冰、海冰上层冰)的δ18 O与δD关系线存在着完全不同的结果,而受陆地补充影响明显的海水中δ18 O与δD关系线介于二者之间.通过稳定同位素方法可以估算出近岸海水中陆地补给与平均海水补给的贡献率,在格陵兰峡谷深处的海水中有约1/3来自于冰川融水,而约2/3来源于平均海洋水.

Aimed at understanding the water cycle process in the Arctic coast, ocean water, coast sea water, surface snow on sea ice and land surface water were sampled in Svalbard Islands, Iceland, Greenland during the expedition, July-August, 2010. These samples were analyzed in laboratory for oxygen and hydrogen isotopes. It is revealed that there is huge differentia of stable isotope component in various water samples. Through the analysis of δ^18O and 3D in these water samples, it is found that the coast sea water are apparently affected by terrestrial water, and the stable isotopes in water are also related to the distance to the land and the size of the land, whether in the open sea or in the fjord. It is also found that in ocean water the relation between of δ^18 O and 3D is different from that in fresh water （including land surface runoff, glacier ice and upper sea ice）. The mixed water of terrestrial water and ocean water collected in the fjord of Greenland has a relation between δ^18 O and 3D falling in between the ocean water and fresh water. The isotope method is found can be used to evaluate the contribution ratio of glacier melting water to the total in the Greenland coast. The results shows that about 1/3 of fjord sea water comes from glacier melting water, and the others comes from the open ocean, with the contribution of open sea water increasing with the distance from the coast.