基金项目: | Acknowledgments This research was supported by the National Natural Science Foundation of China (Grant nos. 40930848, 50921001 and 51079021) and Norwegian research project AMORA, supported mainly by the Research Council of Norway (Grant no. 193592/S30), and the Chinese Arctic and Antarctic Administration, SOA. The authors also thank the staff assisting us during the ice camp in the 4th CHINARE-Arctic in 2010. |