海洋堆積物の窒素同位体比に関する研究 : 窒素同位体比による海洋表層環境の復元 (1997年度日本海洋学会岡田賞受賞記念講演)

概要

論文の詳細を見る
The nitrogen isotopic ratio (δ^<15>N) of sedimentary organic matter is a newly developed chemical tracer which can be used to reconstruct paleo-biogeochemical condition of ocean surface water. Firstly in this article, factors controlling the δ^<15>N values of sinking particles are discussed on the basis of spatio-temporal variations of sinking particle δ^<15>N in the western Pacific Ocean. And it is concluded that nitrate mass balance between surface and sub-surface water layers determines the δ^<15>N of sinking particles through large isotope fractionation process during uptake of nitrate by phytoplankton, although some constant alteration processes during sinking and sedimenting of particles must also affect the absolute values of δ^<15>N in sediment cores. Secondly in order to demonstrate the potentials of δ^<15>N in paleoceanography, glacial/interglacial changes in the water current and upwelling system in the western equatorial Pacific Ocean are reconstructed using sedimentary δ^<15>N values, and the changes of intensity and location of upwelling system are clearly illustrated.
1997-12-05