Trace elements in benthic foraminifera of sediment core V30-49

Eastern tropical Atlantic benthic foraminiferal Ba/Ca and Cd/Ca data from core V30-949 (3093 m) reveal large inferred changes in nutrient concentrations of deep Atlantic waters during the last 250 kyr. Relative changes in North Atlantic Deep Water contribution to this site are estimated by scaling the V30-49 Cd/Ca record to values of modern end-member water masses; these estimates agree well with the relative structure and timing of circulation changes in the eastern tropical Atlantic reconstructed from a d13C record-based mixing model (Raymo et al., 1997, doi:10.1029/97PA01019). Temporal differences between V30-49 Cd/Ca and Ba/Ca records suggest that the Ba/Ca record reflects changes in circulation with an additional increase in the Ba composition of deep Atlantic water masses during glacial episodes, possibly resulting from increased productivity. Similarity between the d13C and Ba/Ca records suggests that carbon isotopes in the deep glacial Atlantic also reflect productivity increases.来自岩芯V30-949（水深3093米）的东热带大西洋底栖有孔虫钡钙比（Ba/Ca）与镉钙比（Cd/Ca）数据，揭示了过去25万年间大西洋深层水营养盐浓度的显著推断变化。北大西洋深层水（North Atlantic Deep Water）对该站位贡献的相对变化，可通过将V30-49的Cd/Ca记录标准化至现代端元水团（end-member water masses）的数值进行估算；该估算结果与基于d13C记录的混合模型重建的东热带大西洋环流变化的相对结构与时间特征高度吻合（Raymo等，1997，doi:10.1029/97PA01019）。V30-49的Cd/Ca与Ba/Ca记录之间的时间差异表明，Ba/Ca记录不仅反映了环流变化，还体现了冰期事件中大西洋深层水团钡元素组成的额外升高，这一现象可能源于海洋生产力的提升。d13C与Ba/Ca记录之间的相似性表明，冰期大西洋深层水体的碳同位素信号同样反映了海洋生产力的提升。