三峡水库二期蓄水后次级河流回水河段富营养化调查

在三峡水库二期蓄水后,135 m水位线下的支流尽管多数仍保持狭长的河流态势,但回水段的流速明显降低,成为名副其实的人工湖泊,适合藻类生长。库区支流的总磷、总氮浓度普遍偏高,能为藻类生长提供充足的营养盐,2005年4月的监测资料表明TP平均浓度为0.148 mg/L,TN为1.90 mg/L,远远高于湖库水体出现富营养化的TP和TN临界浓度0.020、.2 mg/L。如果气候条件合适,支流回水河段就具备了发生富营养化所需的流速、营养盐、水温等基本条件,有可能出现“水华”现象。调查结果表明,在2005年4月,库区13条支流有5条的回水河段水体营养程度达到富营养,应该引起足够重视。

Research on Eutrophication in the Backwater Reach of Tributaries of the Three Gorges Reservoir after Second Water Storage

Though the tributaries under 135 m lever maintained slim flow pattern after second water storage in the Three Gorges Reservoir,the speed in the backwater reach reduced obviously,so it became the lake which was suitable for growth of algae.The total phosphorus(TP) and nitrate(TN) were high in general,which provided ample nutrition.The monitor data of April in 2005 indicated the concentration of TP and TN were 0.148 and 1.90 mg/L respectively,which were higher than critical concentrations of eutrophication(0.02 and 0.2 mg/L respectively).If the climate conditions were appropriate,the backwater reach of tributaries possessed the basic conditions of eutrophication that included flow,nutritional salt and water temperature,and would occur "water bloom".The monitor results suggested that among the 13 pieces of river in the Three Gorges Reservoir,there were 5 pieces of river whose backwater reach got to eutrophication,so they should arouse more recognitions.