三峡水库蓄水后氮、磷营养盐的特征分析

根据2004年4月调查结果,对三峡库区二期蓄水后的氮、磷营养盐浓度及分布进行研究。结果表明,二期蓄水后水体总磷、总氮的质量浓度平均为0.083 mg/L、1.56 mg/L,其中总溶解性磷比例介于32%~82%,总溶解性氮为72%~95%。总磷浓度受蓄水的影响较大,坝前区总磷浓度在蓄水后显著降低,ρ(N)/ρ(P)值提高。由于氮、磷营养盐浓度偏高,库区水体在二期蓄水后呈现富营养化趋势。营养盐浓度对不同类型水体富营养化的影响程度存在差异,蓄水后长江干流为贫营养和中营养状态,而部分支流回水段已达到了富营养化程度,存在潜在的水华爆发现象。

Characters of nitrogen and phosphorus of the Three Gorges Reservoir after impounding

Based on the results investigated in April 2004,the concentration and distribution of N and P in the Three Gorges Reservoir were analyzed.The results show that the contents of total phosphorus and total nitrogen are about 0.083?mg/L and 1.56?mg/L respectively in the Three Gorges Reservoir.Total dissolved phosphorus is about 32%～82% of total phosphorus,while total dissolved nitrogen is about 72%～95% of total nitrogen.Impounding has great impacts on the concentration of total phosphorus.The TP content decreases remarkably after impounding,and ρ(N)/ρ(P) rate increases accordingly.High nutritious salt concentration results in eutrophication of waters in the reservoir after the second stage of impounding.However,impact of nutritious matters on the eutrophication of different water bodies is different.The mainstream of the Yangtze River is oligotrophic and mesotrophic,while backwaters of some tributaries is eutrophic and algal bloom exists potentially.