INVESTIGATION ON THE BIOLOGICAL AND CHEMICAL MARKERS OF THE ACIDIFICATION OF LAND WATERS

该项目的目的是找出某些化学和生物指标，这些指标代表了受酸化严重影响的水生系统的环境状况。特别关注沉积物中的有机分子，因为它们可能被用于微生物群落的分子化石，预计这些分子化石对水质的改善具有明显的敏感性。对日本被称为“无机酸湖”(pH=3-5)的湖泊的部分湖相沉积物中残留的脂分子和硅藻进行了调查。它们要么受到酸性温泉溶解火山气体的影响，要么受到地下水渗入火成岩中含有的硫化物矿物的影响。一些湖泊在最近经历了明显的水质变化，原因是人为或自然事件，如开挖水道将酸性河水引入湖中，或附近发生地震。本项目购买的LON色谱仪用于描述流域和湖泊的水质。用气相色谱和气相色谱-质谱仪分析表明，在许多湖泊沉积物中发现了长链支链碳氢化合物、醇和脂肪酸的特殊性质，被鉴定为正构异构体。根据历史事件，这些有机分子与某些硅藻树枝之间的巧合或缺失以及类似的垂直变化表明，它们可能是湖泊酸化的生物地球化学指标，尽管它们的来源生物仍有待解开。

The purpose of this project was to find out certain chemical and biological indicators such that represent environmental conditions of the aquatic systems significantly affected by acidification. Particular attention was paid on organic molecules in sediments, since they might be used for molecular fossils of the microbial community which are expected to be distinctly sensitive against improverishment of the water quality. Lipid molecules and diatom frustules remaining in some lacustrine sediments were surveyed for lakes known as "inorganically acidic lakes"(pH=3-5) in Japan. They are under the influence either of acid hot springs dissolving volcanic gasses or ground waters percolating sulfide minerals contained in the igneous rocks. Some lakes have experienced conspicuous alterations of the water quality in the near-past, due to artificial or natural events such as an excavation of the waterway introducing an acidic river water to the lake or an earthquake occurred in the near-by site. lon chromatograph analyzer purchased in this project was used for description of the water quality in the watersheds and the lakes. Analyzes by use of gas chromatograph and gas chromatograph-mass spectrometry demonstrated in many lake sediments an occurrence of the peculiar nature of long-chain branched hydrocarbons, alcohols and fatty acids identified as anteiso structural isomers. Coincidental occurrences or absence and similar vertical variations between these organic molecules and certain kinds of diatom frustules in accordance with the historical events, suggested that they can be promising biogeochemical indicators of the lake acidification, although their source organisms remain to be unraveled.