三峡水库藻类“水华”预测

根据三峡库区江段16条一级支流以及重庆市35座大中型〖JP2〗水库的调查资料，分析天然河流与水库两种不同水流条件下，水体叶绿素a浓度与总磷和透明度的关系。结果发现,在水库环境中，水体叶绿素a的浓度与总磷以及与透明度都具有较好的相关性，但在河流条件下则没有明显的关系。由于三峡库区江段大多数支流的营养水平已达到富营养化状况，当三峡水库建成、水流条件发生变化后，在支流河口等水域存在爆发“水华”的风险。为此，我们根据1998年枯水期，在三峡库区长江江段流域面积大于100 km2的40条支流河口实测的总磷浓度，利用所建立的水库环境中总磷与叶绿素a 浓度的关系，对三峡成库后在局部水域爆发“水华”的可能性和程度进行了分析，并提出了相应的对策。

RISK FORECAST OF ALGAL BLOOM IN THE THREE GORGES RESERVOIR

The relationship between total phosphorus(TP),water clarity(SD,called Secchi disk depth) and chlorophyll-a in the Three Gorges Reservoir Area-including 16 tributaries and 35 big or middle reservoirs in Chongqing City-was studied.The chlorophyll-a concentration in the Three Gorges Reservoir Area after impoundment was predicted by using the TP and Chlorophyll-a relationship based on the present TP concentrations in 40 branch stream estuaries at dry seasons in 1998.The trend of eutrophication in the Three Gorges Reservoir was analyzed by the predicted chlorophyll-a concentration.It is shown that the reservoirs at tributary rivers,most of which were in a high trophic status,exhibited a good relationship between chlorophyll-a concentration and TP concentration and water clarity.In some natural branches such as Wujiang river,the concentration of TP and chlorophyll-a showed no obvious relationship even in algal bloom condition.It is shown that the current status is the key reason for water eutrophication in the Three Gorges Reservoir Area.It is predicted that algal bloom may occur in some water areas in the reservoir after the completion of Three Gorges Project.