Abstract:

In order to investigate spatial distribution characteristics of nitrogen and phosphorus in upstream rivers in Lake Taihu Basin beside the northwest part of the lake,water qualities of 39 rivers were monitored in the water systems of WujinZhihu Port,Taoge,River Danbianmeng (Danjinlicao,Biandan and Mengjin) and Yilihe in August of 2010.Our study showed that the average concentrations of TN in the four water systems were 388 mg/L,283 mg/L,291 mg/L and 193 mg/L respectively.The proportions of DTN in TN were 9180%,7843%,7001% and 8444% respectively,so that DTN was the major nitrogen pollution components in the water systems.The proportions of NO-3N in DTN were 6747%,5275%,7748% and 4281% respectively,and the proportions of NH+4N in DTN were 1633%,3316%,1127% and 4351% respectively.The average concentrations of TP were 059 mg/L,030 mg/L,026 mg/L and 015 mg/L respectively,and the proportions of DTP in TP were 6213%,4019%,4673% and 3197% respectively.The proportions of PO3-4P in DTP were 2073%,5461%,4327% and 7772% respectively.The N and P pollution in the water system of WujinZhihu Harbor is the most serious in the four water systems.The dominant pollution factor that influences the water quality of upstream rivers in Lake Taihu Basin beside the northwest part of the lake was nitrogen,in which dissolved DTN was the major component. Since the northwest part of the lake is a disastrous area with heavy cyanobacterial bloom,large amount of DTN input to this part will be a potential risk for the ecosystem in the lake