Abstract
The past hydrological study about water pollution had been focused on the detection of pollution source and/or the estimation of the pollution level. However, much more detail information about the foodweb structures and the matter flows are required to restore the polluted sites appropriately. Stable isotope analysis seems to be most useful for the monitoring of eutrophication and foodweb structures. Nitrogen isotope ratios of nitrate, plant and primary consumers increased in the aquatic systems with large anthropogenic impacts. This was due to the input of anthropogenic nitrogen with high nitrogen isotope ratios and/or the enhanced denitrification and ammonia volatilization. Stable isotope analysis that could be applicable from foodweb structures to nutrient cycling should become one of the most important research tools that can integrate the hydrology and ecology.
