三峡水库主要入库河流磷营养盐特征及其来源分析

以2004～2005年的三峡水库3条主要入库河流(长江、嘉陵江、乌江)中的水文、水质的调查参数为依据,研究了三峡水库入库河流中主要的水文变化特征、磷营养盐的季节性分布规律、形态组成及富营养化状态.结果表明,3条入库河流的流量、悬浮物呈现明显的季节性变化,丰水期的悬浮物含量明显高于枯水期.3条入库河流总磷的平均值在0.12～0.29 mg/L之间,均远远高于20世纪70年代的总磷含量,长江朱沱断面水体的磷含量高于嘉陵江北碚断面和乌江武隆断面的磷含量.总磷含量(TP)中以总颗粒态磷酸盐(TPP)为主,平均占75%以上;3个监测断面中流量、悬浮物与TP、TPP均呈显著正相关性,TPP和TP也呈显著正相关性.结果表明泥沙将颗粒态磷带入河流是主要的磷污染源,总磷的污染受面源污染影响较大.氮和磷都不是三峡水库入库河流中浮游植物的限制因子,3条入库河流中的N/P值较高(＞30),表明磷有可能被优先消耗到低值.

Analysis of Phosphorus Distribution Characters and Their Sources of the Major Input Rivers of Three Gorges Reservoir

The seasonal characters of the water flux and suspended substance, phosphorus in the water of input rivers of Three Gorges Reservoir (TGR) were discussed, and the their distributions among three major input rivers (Changjiang river, Jialingjiang river and Wujiang river) were studied, according to the survey conducted from Jan. 2004 to Dec. 2005. The results indicate that those parameters' seasonal changes are obvious. The flux and suspended substance in abundant water period are more higher than them in low water period, which displays suspended substance origins from bedload and that the water and soil severely lose in drainage areas of three input rivers. In the three monitor sections of input rivers of TGR, the average contents per year of total phosphorus are about 0.12-0.29 mg/L, which exceeds the 1970s level of the three input rivers. Most of total phosphate is total solid phosphate (TPP) exceeding 75% of them. TP and TPP have both distinct positive correlation with the flux and suspended substance in water of input rivers of TGR, and TPP and TP have also the same correlation, which means that phosphate pollution in the input rivers of TGR comes from bedload. The nonpoint source pollution has had far-reaching influence upon phosphate pollution. Nitrogen and phosphate are not the major limiting factor of the nutritious salts in the input rivers of TGR. The rate of between nitrogen and phosphate (N/P) is in higher level (above 30), that is phosphate first will reach lower level and maybe become the limiting factor of the nutritious salts in the input rivers of TGR.