河流输送硅通量降低的机制及生态效应

Mechanism and ecological effect of river-transported silicon flux reduction

从筑坝成库、硅藻吸收和固定、渔业发展、水体富营养化、水文结构变化几方面对河流输送硅通量降低的影响机制进行了归纳分析，综述了河流输送硅通量降低对河流、河口和近海产生的生态效应。研究表明，河流输送硅通量降低对硅的地球化学循环平衡产生了巨大影响，并造成了一系列的生态变迁。其中，硅藻是河流输送硅通量降低的主要因素，大量繁殖的硅藻将水库水体溶解性硅（DSi）吸收后转化成自身的生物硅（BSi），死亡后沉积到水库底部贮存起来，导致下游河流和海洋缺乏DSi，从而产生对人类具有重大影响的生态效应。

The mechanisms of river-transported silicon flux reduction are analyzed from several aspects including damming, diatom absorption and fixation, fishery, water eutrophication and hydrological changes; besides, the ecological effect of river-transported silicon flux reduction on river, estuary and inshore is evaluated. The results indicate that river-transported silicon flux reduction greatly impacts the geochemical cycle of silicon, resulting in an ecological imbalance. Diatom is a major factor responsible for the river-transported silicon flux reduction. The dissolved silicon in the water body of reservoir is taken up and utilized by diatom. Ultimately the silicon sedimentates and stores in the bottom of reservoir after the death of diatom, which leads to a lack of dissolved silicon in downstream river and ocean, and this brings about serious ecological effect on human beings.