三峡水库干流氮和磷含量的季节变化

三峡水库成库后对6个水平断面、4个垂直断面采样分析,对水体水质参数、不同化学形态N以及不同物理形态P的水平分布和垂直分布进行了研究。研究结果表明,成库后TP、NH3-N、NO2--N、NO3--N、IN含量范围分别在0.06～0.34、0.01～0.72、0.002～0.100、0.76～2.09、0.855～2.52 mg/L。TP分布为丰水期>平水期>枯水期,受悬浮物沉降的影响,TP在水库区域含量低于上游区。枯水期、平水期水体中TP以可溶解态为主,丰水期以颗粒态为主。NO2--N、NO3--N、IN含量均为平水期>枯水期>丰水期。水体中IN以NO3--N为主,占IN70%～90%。NO2--N比例最低,占IN3.5%以下。表明水体虽受成库影响流速减缓,但水体依然有较强的自净能力。垂直分布上,TP、IN在3个层次变化不显著,未出现分层现象。各采样站点TP、NO3--N、IN通量和流量有显著相关。

Seasonal Variation of Nitrogen and Phosphorus in Three-Gorge Reservoir

Through sampling and analysis of 6 horizontal stations and 4 vertical stations in Three Gorges area, the spatial variation of water quality parameter, diverse forms nitrogen and phosphorus were revealed in Feb., May and Aug., 2004. Concentration of TP,NH₃-N,NO₂^--N, NO₃^--N,IN ranged from 0.06-0.34 mg/L,0.01-0.72 mg/L,0.002-0.100 mg/L,0.76-2.09 mg/L,0.855-2.52 mg/L,respectively. TP value of reservoir area is normal beyond upstream. Due to particulate deposition, concentration of TP in flood season is higher than normal and dry season. The main form of phosphorus is dissolved phosphorus in normal and dry season. Particle phosphorus is main forms of phosphorus in flood season. Pollution of nitrogen is serious in Three-gorge reservoir. Concentration of NO₂^--N,NO₃^--N, IN is higher in normal season than dry and flood season. NO₃^--N is the main forms of IN and the rate of NO₃^--N in IN ranged from 79%-90%. The rate of NO₂^--N in IN was the most lowest and ranged below 3.5%. Through water flow slower than before, the ability of water self-purification was still strong. On vertical direction, variation of N and P were not notable and it was not layered. There was significant correlation between TP,NO₃^--N,IN load and water discharge.