Author(s): Jian Jiao; Pengfei Du
Linked Author(s):
Keywords: Nutrients; Influencing factors; Statistical relation; Control treatment; Miyun Reservoir
Abstract: Miyun reservoir has become the most important source of drinking water for Beijing. In the past 30 years, with the economic growth and increase of population, the nutrient load of Miyun reservoir increased gradually, which increased the risk for the bloom of harmful algae. This study collected water samples from the river basins at different scales to analyzed the concentration of total nitrogen (TN), nitrate (NO3 --N), ammonium (NH4 +-N), total phosphorus (TP) and index of potassium permanganate (CODMn) in the water body. And the characteristics of spatial distribution of nutrients were analyzed. Based on establishing the statistical relationship with concentration of nutrients in the water body and the influencing factors, the empirical statistical models were established to adequately address the management for nutrient load reduction in the upper-river basin of the Miyun reservoir. The results were as follows. The annual mean concentration of TN, NO3 --N, NH4 +-N, TP and CODMn of the rivers in the upper -river basin were 3. 86, 2. 59, 0. 110, 0. 027 and 2. 03 mg/L. The concentration of TN and NO3 --N in the Chao River were higher than others. The concentrations of CODMn in the rivers of the surrounding area of Miyun Reservoir were higher than others. The annual mean concentration of TP (CTP (a) ) had a good linear function with annual concentration of suspended solids (CS (a) ): CTP (a) = 0. 025CS (a) + 0. 024, for suspended solids are carriers for the transportation of phosphorous. Because of the sands from the croplands, the annual mean concentration of TP also had a good linear function with the ratio of cropland area to the total basin area (RC): CTP (a) = 0. 002RC + 0. 017. The annual mean concentration of CODMn (CCOD (a) ) had a good power function with the drainage area (S): CCOD (a) = 4. 677S-0. 098, for organic compound and reducing substances in the water body were liable to be deposited or evaporated when being transported. Because of more influence of human activities, the annual mean concentration of TN (CTN (a) ) had a good linear function with the density of people (D) of the basins: CTN (a) = 0. 051D +1. 339, and the annual concentration of NO3 --N also had a good linear function with the density of people of the basins. The differences of the annual mean concentration of NH4 +-N were not obvious between basins, +-N were lost when being transported in the land surface runoff. For sediment and much of the NH4 particles were carriers for phosphorus transported in rivers, soil conservation may play an important role for phosphorus load reduction. For nitrogen were liable to be transported in water body without carriers, comprehensive control treatment that consist of nutrient, tillage, irrigation, drainage and manure management practices are necessary for reducing nitrogen load. The knowledge gained from this study may provide important suggestion for the ecological plan of the upper-river basin of Miyun reservoir.
Year: 2013