後期第四紀における基礎生産力の推定法

概要

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It has been suggested that the observed late Quaternay fluctuation in atmospheric CO_2 concentrations is a function of temporal changes in global ocean circulation and the level of primary productivity in the ocean. Therefore the estimation of palaeo-productivity offers clues to understand the large fluctuation of atmospheric CO_2 in association with the climatic change and to predict future changes in the greenhouse effects which result from the contribution of anthropogenic CO_2 to natural carbon cycle in the earth surface. In this paper, the various reconstruction methods for the estimation of palaeo-productivity are reviewed. Quantitatively estimation has been proposed, using equations based upon organic carbon accumulation rates and assemblages of foraminifers and diatoms. On the other hand, qualitative estimates have been made, using accumulation rates of biogenic opal, inorganic elements and biogenic fossils. Although various reconstruction methods provide a relatively good signal of productivity changes, the further studies on degradation of sinking particles within the water column and on the ealy diagenesis in the surface sediments are required in order to produce productivity estimates with more precise productivity oscillations and a more absolute productivity level.
日本海洋学会の論文
1997-04-05