Studies on natural history of nutrient loading to forested wetland using stable isotope approach

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The monitoring of Water pollution of river system was conducted in Kushiro mire from 1997 to 2003. From the investigation, it was estimated that the geomorphic change in Onnenaigawa River and Hororo river. Value and fluctuation of conductivity of Takkobu river was higher than other rivers. Concentration of phosphate and nitrous acid ammonia were low level in all rivers. There were characteristic of nitric acid in local, no change in seasonal. The high concentration of nitric acid (400-500ppb) was in above site of Horo River (K9) and the site of Onnenai River (K10). Water of K9 and K10 were mixing to lower site of Horo River (K11) that is low concentration of nitric acid. Kushiro mire was a sink of nitric acid. About half nitric acid was disappear from the mire river water.The pH of Lake Ozenuma was neutral from 6.3 to 7.5. On the other hand, the pH of stream water in the mire was acidic about 6 and the stream water of Nushiri area was specially low under 5 pH. Ooe rive which is moderate low pH such as 6.5 was the most large flow. The concentration of nitrate in the Ooe River was relatively high, nitrous acid and phosphate in the river was low level. Acidic stream water was usually low nutrient, mountain stream water was high nutrient revel. The nutrient in out flow such as water of Nushiri River and crib was low nutrient level. The nitrogen of stream water from mountain area to Lake Ozenuma was consumed in the lake. Water temperature of five streams was relatively lower than other stream. I suppose there are the springs of ground water in those streams.