溪洛渡水电工程拦沙对三峡水库富营养化潜在影响的初步研究

从泥沙吸附的角度，探讨金沙江溪洛渡水电站拦沙对三峡水库溶解性磷负荷的影响。2006年11月在金沙江、长江干流和支流岷江、沱江采集了淤积泥沙和水样，测定了泥沙的全磷、有效磷和磷固定量及水的溶解性磷等指标。岷江和沱江泥沙的有效磷含量远高于金沙江和长江干流，反映了四川盆地支流的磷污染较干流严重；干流泥沙的有效磷含量向下游呈增加和磷固定量向下游呈减少的趋势，反映了干流泥沙沿途不断吸附四川盆地支流汇入干流中的溶解性磷，磷固定能力有所降低。根据金沙江宜宾与长江朱沱泥沙的有效磷含量和磷固定量，金沙江来沙年吸附溶解性磷分别为382和6 885 t，分别相当于朱沱站的26%和468％。溪洛渡水库拦蓄泥沙，金沙江来沙吸附长江干流溶解性磷的量将有所减少。水库投入运行后的前50年，以有效磷含量计，金沙江来沙的磷吸附量占朱沱年溶解性磷总量的比例从26%降至10%；以磷固定量计，从468％降至174%。长江干流进入三峡水库的年溶解性磷总量有可能增加16%～294%。金沙江来沙降低三峡入库磷负荷的实际功能，可能介于有效磷含量和磷固定量的计算值之间，具体值还需开展进一步的试验研究。

POTENTIAL IMPACT OF SEDIMENT RETAINING BY XILUODU HYDROPOWER PROJECT TO THE EUTROPHICATION OF THREE GORGES RESERVOIR

In November，2006，sediment and water samples in Jinsha River，the Yangtze River mainstream，Ming River and Tuo River were collected respectively.And then a series of indices of phosphorus of the sediment samples were tested，including total phosphorus，available phosphorus，fixed phosphorus and dissolved phosphorus.The results showed that the available phosphorus in Ming River sediment samples and Tuo River sediment samples were significantly higher than those in Jinsha River and the Yangtze River mainstream，which reflected the phosphorus pollution of the Yangtze River branch in Sichuan Basin was severer than that in the mainstream.The available phosphorus in mainstream samples increases from upstream to downstream，while the fixed phosphorus decreases.It reflects that the sediment in mainstream has absorbed the dissolved phosphorus from the branches in Sichuan Basin，so the fixation capacity of sediment in mainstream was reducing.According to the difference values of available phosphorus in sediment samples from Jinsha River (Yibing Station) and the Yangtze River (Zhutuo Station)，calculated value of dissolved phosphorus absorbed by sediment in Jinsha River was 382 t/a and the capacity of dissolved phosphorus absorbed by sediment in Jinsha River was 6 885 t/a，which account for 26% and 468% of the annual dissolved phosphorus of the Zhutuo Station，respectively.It is likely that the real value of dissolved phosphorus absorbed by sediment in Jinsha River lies between 382~6 885 t/a，which reduced the load of phosphorus entering the Three Gorges Reservoir，although the real value needs further researching.When the Xiluodu Hydropower Project were built up，assuming that the sediment outflow from the reservoir is a fixed value in the 50 years，the value of dissolved phosphorus entering the Three Gorges Reservoir would increase 16%～294%.