三峡水库蓄水前后长江干流主要污染物浓度变化趋势分析研究

利用三峡库区长江干流1998年-2010年水质监测数据,以1998年-2003年代表蓄水前,2004年-2010年代表蓄水后,对比分析蓄水前后主要污染物浓度变化情况,用Spearman秩相关系数法判断其变化趋势的显著性。分析可知,蓄水后氨氮、化学需氧量、总磷指标的平均浓度要低于蓄水前,氨氮、化学需氧量浓度变化幅度大于蓄水前,总磷浓度变化幅度小于蓄水前;Spearman秩相关系数计算结果表明,三峡水库常年回水区内的断面,污染物浓度多数呈下降趋势,但只有晒网坝和培石断面的氨氮指标浓度下降趋势具有显著意义。

Variation Tendencies of Major Pollutants Concentration in Mainstream of Changjiang River Before And After in Three Gorges Dam

The 1998-2010 water quality monitoring data in mainstream of Changjiang River in Three Gorges Dam watershed were separated into a pre-storage period （1998-2003） and a post-storage period（2004-2010）. The concentration changes of major pollutants before and after storage were analyzed.The significance of changing trends was tested by Spearman rank correla-tion coefficient.The results show that compared with the pre-storage period, the average concentrations of ammonia nitrogen （NH3 -N）, chemical oxygen demand（COD）, and total phosphorus（TP） were all lower after storage.The changing amplitudes of NH3 -N and COD were larger and the changing amplitude of TP was smaller compared with the pre -storage period.Spearman rank correlation analysis shows that in the sections in perennial backwater zone, concentrations of most pollutants decreased, but not significantly except NH3 -N in Shaiwang Dam and Peishi sections.