Studies on environmental assessment technique on the estuarine ecosystems using multi-tracer

从1997年至1999年和2005年至2008年，对伊豆-大岛岛、八路友岛和小川群岛的河水和地下水进行了化学分析。小川群岛内陆水域的硝态氮浓度高于夏季。分析结果表明，由于农业用地的利用和人类活动产生的污水，沿海地区地下水的坚果浓度从小川群岛到伊豆群岛是增加的。对海藻氮同位素比值的分析结果表明，八有岛内陆水域的营养物质供应正在减少。这表明了地下水渗漏养分对伊犁群岛海藻植被的重要性。

Chemical analysis of river water and groundwater were carried out for the samples from Izu-Ohshima Island,Hachijyoujima Island and Ogasawara Islands from 1997 to 1999 and from 2005 to 2008. Concentrations of nitrate-N of inland water of Ogasawara Islands werter higher than those in summer. The analytical results show that nutnnt concentrations of the groundwater around the coastal area were increased from Ogasawara Islands to lzu Islands because of land use of agriculture and sewage water from human activity. The analytical results of nitrogen isotope ratio in seaweeds show that the nutrient supply from inland water was decreasing in Hachijyoujima Island. This indicates the importance of nutrient from groundwater seepage for seaweed vegetation in lzu Islands.