三峡水库支流回水区富营养化时空分布特征

为了解三峡水库175m水位蓄水后库区支流回水区富营养化现状,探索支流回水区富营养化时空变化规律,在三峡库区支流回水区开展了富营养化普查和监测。结果表明,库区支流总磷浓度为0.035~0.65 mg/L,平均浓度为0.157 mg/L,总氮浓度为0.681~5.690 mg/L,平均浓度为2.037mg/L,远远高于湖库水体出现富营养化的总磷和总氮临界浓度0.02、0.2 m g/L,库区支流营养盐条件适宜藻类生长。在每年4~9月的春季、盛夏和夏秋之交的非暴雨时段,当气温和光照适宜,支流回水核心区富营养化现象明显,出现藻类"疯长"的水华现象,但受气温变化影响明显,库区的富营养化现象仍是间歇的,局部的。

Space-Time Distribution of Eutrophication in Backwater Zones of Branch Rivers in the Three Gorges Reservoir

In order to master the status of eutrophication and the space-time distribution,investigation and monitoring is carried out in backwater zones of branch rivers in the Three Gorges Reservoir.The investigation results show that,in the branch rivers,total phosphorus （TP） is 0.035～0.65 （mean 0.157） mg/L and total nitrogen （TN） is 0.681～5.690 （mean 2.037） mg/L,which are far higher than the critical concentrations of 0.02 mg/L and 0.2 mg/L,respectively.The nutritive salt conditions in the watershed are favorable for algal growth.During the non-rainstorm periods in spring,summer and the summer-fall transition from April to September,when temperature and daylight are suitable,severe eutrophication occurs in the backwater zones of branch rivers,accompanied by algal bloom when algae ＂crazy＂ grow.However,the eutrophication can be affected by temperature changes,so eutrophication in the watershed is intermittent and locally distributed.