サンゴ骨格の炭素同位体比の変動要因に関する研究

概要

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Carbon and oxygen stable isotope ratios of coral skeletons are widely measured and discussed as environmental proxies. Coral skeleton contains less oxygen-18 and carbon-13 compared to the expected values for isotopic equilibrium with ambient seawater. While oxygen isotope ratio is mainly controlled by seawater temperature and salinity, an interpretation of carbon isotope variation is complicated. Carbon isotope ratio is considered to correlate to light intensity through the metabolic reactions of coral-algae symbiotic system. However, a few models for carbon isotope fractionation are proposed. In the process of coral skeletal formation, kinetic isotope effects are also shown to be an important factor, controlling isotopic fractionation. Because kinetic and metabolic isotope effects cause carbon isotopic fractionation in nearly opposite direction, they diminish each other and make interpretation of the isotopic records complicated. The main objective of this study is to review recent studies, which proposed models of stable carbon isotope variations relating to kinetic and metabolic isotope effects of coral skeleton.
日本地球化学会の論文
2006-12-26