* Green tide: Due to mass increase of floating current in eutrophicated lake or river with slow velocity, the phenomenon of accumulation of the floating current on the water surface causing the color of water to be substantially green. Eutrophication occurs due to accumulation of material which become nutrient for breeding of plankton such as carbon, nitrogen and phosphorus etc. in the water.
* Due to continuation of heat waves, seriously amount of green tides occurred in main rivers of Korea such as Keum River and Youngsan River, raising problems such as causing bad odor and destructing the river ecosystem.
* However, although currents such as green tides raises various problems such as destruction of ecosystem, etc., they can be used as useful resource in the areas of bio fuel production or sewage processing, etc. and application of technology using currents such as green tides, etc. are continuously being used actually.