Assessment Of Surface Water Total Nitrogen On Typical Ecosystem Of Chinese Ecosystem Research Network(CERN) And Sources Analysis

With the accelerated process of industrialization and urbanization, the nitrogen concentration is becoming higher and higher. It has two serious influences on environment, on the one hand, it resulted in water eutrophication and destroy the ecological balance which is a serious ecological crisis. On the other hand, the migrate and accumulation of excess nitrogen to the groundwater have an adverse impact on the safety of drinking water.This paper mainly evaluate the total nitrogen concentration of typical terrestrial ecosystems surface water using the long term well network monitoring data from2004～2010of the Chinese Ecosystem Research Network (CERN). The monitoring data come from33typical terrestrial ecosystems including fourteen agricultural ecosystems, five oasis ecosystems, nine forest ecosystems, two grass ecosystems, one urban ecosystems and two lake ecosystems. The paper mainly discussed the regional difference and assessed eutrophication degree of surface water by comparison the differences of surface water total nitrogen among different ecosystems.It provide scientific basis to predict the seasonal variation trend of surface water total nitrogen in typical terrestrial ecosystems and improve the protection of regional water environment. The results are as followes:The surface water total nitrogen concentration in typical terrestrial ecosystems ranged from0.01～84.78mg·L-1. The average total nitrogen concentration trend of still surface water in CERN was that oasis (7.35±1.8mg·L-1)> agriculture (4.41±0.16mg·L-1)>grass (3.82±0.59mg·L-1)> forest(1.63±0.29mg·L-1) and oasis (7.15±1.81mg·L-1)> urban (5.94±0.29)> agriculture (4.38±0.54mg·L-1)>grass (3.73±0.54mg·L-1)> forest (1.72±0.54mg·L-1) of fluent surface water. The average surface water total nitrogen concentration of agricultural, oasis, urban, grass ecosystems exceeded the class V guideline of the Chinese National Quality Standards for Surface Waters except the forest ecosystem which only exceeded the class III standards.There was serious total nitrogen pollution in agricultural and oasis ecosystem. The surface water total nitrogen concentration exceeded the class V guideline of the Chinese National Quality Standards for Surface Waters with the exceeding rates ranged from90-100%,however, the exceeding rates of the class V guideline and III guideline was low in Shenyang.The spatial variation of surface water total nitrogen in forest ecosystem was that southern> northern> southwestern. There was significant regional differences among the forest ecosystems and this was mainly attributed to the regional backgrounds, elevation, human activities and atmospheric nitrogen deposition.The monitoring data of Taihu lake and Donghu Lake showed that there was obvious seasonal variation of total nitrogen in lake ecosystem. The total nitrogen concentration was higher from March to May and lower from July to September in Taihu lake ecosystem.