Determination of Concentration and Fluxes of Total Nitrogen in River Entries of Danjiangkou Reservoir

With respect of high content of total nitrogen (TN) in Dangjiangkou Reservoir,TN concentrations were determined over a whole year as well as water quality and quality on river entries to Hanjiang Reservoir. Results showed that TN amount from rivers flowing into Hanjiang Reservoir was 24,503t/a,and its distribution from river entries in Hubei and Shaanxi Province were comparable with proportion of incoming water quantity of each province. TN from incoming water of Shaanxi Province accounted for 68.2% of total amount of TN,while the contributing of rivers entries in Hubei to TN were as Du River 18%,Shending River 7%,Si River 4%,Guanshan River 0.9%,Lang River 0.7%,Jian River 0.5% and Tian River 0.5%. Monthly changes of TN concentrations were consistent with the incoming water quantity. TN amount in reservoir was mainly concentrated between May and September,which accounted for 77% of the whole year. According to environmental capacity and pollutant carrying characteristics,rivers flowing into the reservoir can be divided to four types including capacity pollution,point source pollution,agricultural non -point source pollution and combined pollution. Therefore,different measures such as both point and non-point should be taken into account in different rivers to control the pollution.