川原大池の淡水化と柱状堆積物中の脂質成分

概要

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Lipids from sediment cores of Lake Kawahara Oike which changed from brackish to fresh water between 1962 and 1979 were examined. The sediments of core A were black mud in the top 12 cm and grey mud from 12 to 35cm. The grey mud contained higher values of hop-22(29)-ene, farnesol, phytol and 4-methylsterols. The abundance of these compounds was certainly caused by the biological production in the brackish water lake during the time of deposition of the grey mud. The black mud in the top 12cm contained n-alkanes, n-aldehydes, alkane-2-ones and n-alcohols with a high L/H and a low CPI. A high L/H and low CPI are attributed to autochthonous inputs of planktonic debris in the fresh water lake. The grey mud in the 12-35cm range contained the same compounds as the black mud, but with a low L/H and a high CPI which are indicative of higher plant origins. The grey mudsamples also have large amounts of β-sitosterol and stigmasterol which are markers for terrigenous higher plants. The characterization of these compounds in the grey mud indicate transport of higher plant debris by the river to Lake Kawahara Oikeduring the time the lake was brackish. Oil pollution induced petroleum hydrocarbons were not detected in the core samples because of the absence of an unresolved complex mixture (hump).
1993-05-31