Use of Sedimentary Nitrogen and Carbon Isotopic Composition for Reconstruction of the Past History of the Equatorial Pacific Upwelling Region

利用沉积氮和碳同位素组成重建赤道太平洋上升流区的过去历史

• 批准号: 9115641
• 负责人: Mark Altabet
• 金额: $ 27.05万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-11-01 至 1994-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9115641&HistoricalAwards=false
• 关键词: Use; Sedimentary; Nitrogen; Carbon; Isotopic

Preliminary results obtained from a north-south transect in the equatorial Pacific suggest that the &15N in the surficial sediments of this region is strongly affected by the nitrate concentration in the overlying euphotic zone. Similarly, carbon isotopic composition of phytoplankton reflects ambient ıCO2(aq)! and evidence exists that &13C in sedimentary organic matter is a measure for this parameter in the equatorial Pacific. This raises the possibility that &15N and &13C of sedimentary organic matter might respectively record past nitrate and ıCO2(aq)! distributions in surface waters. There is evidence for glacial to interglacial changes in both the magnitude and latitudinal distribution of production in the equatorial Pacific that might have influenced the global carbon cycle. Sedimentary isotopic composition (&15N and &13C - both bulk and fractions thereof) will be used for the reconstruction of past changes in the distribution of nitrate and CO2(aq) in equatorial Pacific surface waters over the last 160 kyrs, as a means both to confirm and to delineate the mechanisms for these past changes in productivity. Studies will be made of water column and early diagenetic processes which control the isotopic composition of buried organic matter. Also sediment analyses will be used to reconstruct paleoceanographic nutrient and CO2(aq) distributions in surface waters.

从北-南样带获得的初步结果 赤道太平洋的15 N表明， 该地区的沉积物受硝酸盐的强烈影响， 浓度在上覆透光层。 同样，碳 浮游植物的同位素组成反映了环境中的<$CO2（aq）！ 有证据表明，沉积有机质中的13 C是一种 在赤道太平洋测量该参数。 这 提出了沉积有机质的15 N和13 C可能 物质可能分别记录过去的硝酸盐和<$CO2（aq）！ 分布于沃茨水域。 有证据表明， 与间冰期的大小和纬度变化有关 赤道太平洋的生产分布， 影响了全球碳循环。 沉积同位素 组成（15 N和13 C-其本体和部分） 将用于重建过去的变化， 赤道太平洋NO_3 ~-和CO_2（aq）的分布 在过去的160 kyrs的表面沃茨，作为一种手段，既确认 并描述这些过去变化的机制， 生产力 对水柱和早期成岩作用进行了研究 控制地下岩石同位素组成的过程 有机物 此外，沉积物分析将用于 重建古海洋营养盐和CO2（aq）分布 在表面沃茨。