The Arctic region, with magnificent ice cover on the surface of the Arctic Ocean and adjacent seas, is not only extremely sensitive to but also has strong amplification effects on climate change. Observations during the past decades have documented substantial retreat and thinning of the Arctic sea-ice cover, a process that is accelerating. Its feedback and impact on the global climate has become an important subject of current climate change research. Calcite tests of planktonic foraminifers are major constituents in pelagic sediments, and they provide valuable materials for the reconstruction of past oceanographic conditions. However, research is still sparse in the Arctic sea area because of limited availability of the materials for investigation. Here, we present a study of modern foraminifers from the plankton tow samples taken in the Makarov Basin of the Arctic Ocean during the fourth Arctic expedition of China. We have analyzed ecological information stored in the modern planktonic foraminifers and in their stable isotope signals, and established a relationship between the distribution of the main taxa and the environment. Our main observations are as follows:(1) in the Makarov Basin, the polar species Neogloboquadrina pachyderma(sinistral coiling) dominates the [150 lm planktonic foraminiferal assemblages.(2) The planktonic foraminifers live mainly in the upper halocline at a water depth of 50–100 m and less in the depth interval of 100–200 m.(3) Temperature change in the halocline can affect the absolute abundance of planktonic foraminifers and their distribution in the water column. The warmer halocline is more favorable to the development of planktonic foraminifers.(4) A lighter d18O value(2.11 %) of N. pachyderma(sin.) is recorded in the depth interval of 100–200 m, which is likely related to the isotopically light brines separated out during sea ice freezing. The relatively heavy d18O value(1.68 %–2.68 %, average 2.27 %) in the depth interval of 50–100 m may be influenced by the low salinit
通过白令海北部陆坡区B2-9站位沉积物柱样高分辨率的生物标志物(菜子甾醇、甲藻甾醇、长链烯酮、n-C30-diol)提取和分析,获得了近1万年来浮游植物群落和初级生产力、高碳烷烃输入与陆源植被变化等相关记录,研究结果显示,全新世以来表层浮游植物和初级生产力都经历了"高-低-高"的变化过程,并具有明显的阶段性,可能受控于陆架坡折处海冰的分布、上层海洋营养盐供应和全新世气候与环境的变迁;浮游植物群落结构较为稳定,硅藻是初级生产力的主要贡献者,甲藻次之,颗石藻和黄绿藻比前两者低了1个数量级,硅藻与甲藻之间具有明显的竞争关系,前者明显占据优势,是白令海有机碳汇的主要贡献者;正构烷烃总量分别在7.8 ka BP,6.7 ka BP和5.4 ka BP,经历了3次阶梯状的下降过程,并呈现出4个相对稳定的阶段,其主要受控于早全新世海平面上升以及周边陆地植被源区的气候与环境变化;正构烷烃分子组合特征显示其来自陆地高等植物、且陆源植被结构较为稳定,木本植物占据优势;单体碳同位素研究表明正构烷烃的主碳峰为n-C27,对烷烃总量的贡献最大,可能与当时陆源繁盛的木本植物及输入有关,含量较高的n-C23则可能主要来源于北半球沿海广泛分布的一类沉水植物。
