白令海北部表层沉积物中的生源组分分布特征及其古海洋学意义

DISTRIBUTION PATTERN OF BIOGENIC COMPONENTS IN SURFACE SEDIMENTS OF THE NORTHERN BERING SEA AND THEIR PALEOCEANOGRAPHIC IMPLICATIONS

对中国首次和第3次北极科学考察在白令海北部所采取的29个表层沉积物中的TOC、生源Opal和Ca-CO3含量等进行了研究,结果发现,TOC的高值出现在外陆架至中陆架区,其次为海盆区,白令海峡至内陆架最低;Opal的高值出现在海盆至陆坡边缘区,其次为外陆架至中陆架,白令海峡至内陆架最低;CaCO3的高值出现在内陆架至中陆架区,外陆架至海盆最低。外陆架至中陆架区高的TOC和Opal与该区现代上层水体中较高的叶绿素浓度和营养盐含量有关,反映了上层水体季节性的浮游植物勃发和高的初级生产力。内陆架至中陆架区域相对高的CaCO3可能与浮游植物颗石藻Emiliania huxleyi长期持续的勃发有关,而外陆架至海盆低的CaCO3可能与CaCO3溶解作用相关。外陆架和中陆架高的TOC和Opal可能来源于浮游生物的勃发和有机碳的输入。它们的Corg/N值介于6～9之间,说明其有机质主要来源于海洋自生的沉积,有机碳的输入可能受生物泵的控制。TOC和Opal的相关性分析显示了较高的相关系数(0.71),反映有机碳与硅藻关系密切,硅藻等浮游植物的初级生产力可能控制着生物泵对碳的吸收和释放。

Biogenic components in total 29 surface sediments,which were taken from the northern Bering Sea during the First and Third Chinese National Arctic Expedition cruises,are analyzed for probing into the relationship between surface primary productivity,chlorophyll and nutrient conditions in this area.The results show that the highest TOC percentages appear on the outer-middle shelf,with the higher in the basin,and the lowest in the area from the inner shelf to the Bering Strait;the highest biogenic opal percentages appear in the basin and slope,with the higher on the outer-middle shelf,and the lowest in the area from the inner shelf to the Bering Strait.On the contrary,the highest CaCO3 percentages are found on the inner-middle shelf,and the lowest on the outer shelf and slope and in the basin.High TOC and opal percentages on the outer-middle shelf are related to high chlorophyll and nutrient levels in the upper water column,suggesting that this area has the seasonal phytoplankton bloom and high primary productivity.Relative high CaCO3 on the outer-middle shelf are associated with the long-term bloom of phytoplankton coccolithophore Emiliania huxleyi,and low CaCO3 in the area from the outer shelf to the basin are linked with calcium carbonate dissolution.Phytoplankton bloom and organic carbon input are responsible for increasing organic carbon and opal percentages on the outer to middle shelf.Corg/N ratio in surface sediments ranges dominantly in 6~9,implying that the organic carbon is originated mainly from marine source and controlled by biological pump process.High correlative coefficient（0.71） between organic carbon and biogenic opal shows a closer relationship between organic carbon and diatom.Primary productivity of diatom and other phytoplankton can control the absorption and release of carbon by the biological pump.