Origins of Carbon Isotope Signals in Tropical and Polar Oceans: 0-25,000 Years B.P.

南大洋极锋附近表层水的碳同位素信号在增量C-13中的丰度为1.0/mil。然而，极锋地区浮游有孔洞的下部显示出较大的C-13变化，这是由于极锋随时间的迁移，与南极中间水(AAIW)碳同位素组成的变化有关。在热带地区，德尔塔C-13信号很小，其起源还存在争议。这项拟议研究的目的是隔离热带和极地地表水同位素记录中的全球、瞬变、热力学和“红场”变化。为过去250公里范围内从局部水域到极地水域岩心的两年稳定同位素研究提供了资金。来破译碳同位素信号的来源。这项研究将有助于解决极锋位置和强度的变化。有孔虫Cd/Ca比值的分析与碳同位素分析一起，可能有助于确定这两个系统的脱钩是否可以用来识别AAIW的存在。

The carbon-isotopic signal of the Southern Ocean surface waters near the polar front is enriched in delta C-13 by 1.0 per mil. However, downcore the planktonic forams in the polar front region show a greater variation in C-13 because of the migrations of the front through time, linked to changes in carbon-isotopic composition of the Antarctic Intermediate Water (AAIW). In the tropics the delta C-13 signal is small and its origin is debated. The objective of the proposed research is to isolate global, transient, thermodynamic, and "Redfield" changes in the tropical and polar surface water isotopic records. Funds are provided for a two years' stable-isotopic study of cores from the topical to polar waters spanning the past 250 k.yrs. to decipher the origin of the carbon-isotopic signal. The study will help resolve the changes in the position and intensity of the polar front. The analyses of Cd/Ca ratios of forams Cibicides sp. along with their carbon-isotopic analyses may help determine if the decoupling of the two systems can be used to identify the presence of AAIW.