Abstract:This study was conducted to analyze the variation characteristics of carbon and nitrogen contents in water during the growing season inan alpine grassland watershed in the Tibetan Plateau. The results show that the dissolved carbon (DOC), dissolved organic nitrogen （DON）,ammonium nitrogen （NH4+-N）and nitrate nitrogen （NO3--N）concentration in water of the alpine grassland watershed are respectively2.95 -6.96mg.L -1, 0.45 -1.15mg.L -1, 0.02 -0.88mg.L -1 and 0.16 -0.36mg.L -1. DOC, DON and NO3--N increased to a peak in the middle ofSeptember and then decreased, however, NH4+-N had no significant seasonal variation characteristics. The dissolved nitrogen concentration isDON>NO3--N>NH4+-N. Precipitation, soil temperature at 20, 40, 60, 90, 120cm depth, and soil moisture at 10, 20, 40, 60cm depth havesignificant positive correlation (P<0.001) with DOC and DON contents in the water. There is a significant positive correlation (P<0.05) betweenNH4+-N and precipitation, air and water temperature. The NO3--N has a significant positive correlation with precipitation.
