Abstract:
In order to investigate the characteristics of nitrogen and phosphorus pollution in the west bank of the Wangyu River and its impact on the water quality of the Taihu Lake, the concentrations of nitrogen and phosphorus in various forms were measured at four representative tributaries in the west bank of the Wangyu River in November of 2017, and March and June of 2018. The form composition, seasonal and spatial distribution of nitrogen and phosphorus and their influence on the quality of water diversion were studied. The results are as follows:(1)The average concentrations of TN in Bodugang, Xutangqiaohe, Gushiqiaohe and Zhangtanghe were 4.93, 5.20, 2.27, 3.78 mg·L
-1, respectively, and the average TP concentrations were 0.18, 0.23, 0.16, 0.15 mg·L
-1, respectively; NO
3--N and PO
43--P were the main forms of nitrogen and phosphorus, respectively. (2)The average concentration of TN in Bodugang, Xutangqiaohe and Gushiqiaohe in summer were the highest, which were as 1.24, 1.44 and 2.01 times as that of the lowest season, respectively; Along the inflow direction to Wangyu River, the concentration of nitrogen and phosphorus in the four tributaries had a downward trend. However, the water quality of the river entry section of the tributaries does not meet the water quality target (Class Ⅲ) of the regional water function zoning. (3)91.3% of the water sections in the study area were at the moderate eutrophication level and 56.5% of the water sections were in phosphorus-limited state. (4)EC, COD
Mn and Chl-a were the main factors affecting the distribution of nitrogen and phosphorus forms. The influx of nutrients in the study area has a great impact on the water quality of the Wangyu River, especially phosphorus pollution. It is necessary to strengthen the reduction of dissolved phosphorus concentration in water bodies. Nitrogen pollution is the most serious in summer which is the diversion period of the Wangyu River. It is necessary to strengthen the pollution control of the tributaries entering the river to ensure the water quality during water diversion.