富营养化水体中藻类生长限制因素的确定及其应用

DETERMINATION OF ALGAL GROWTH LIMITING FACTORS IN CHAOHU LAKE AND ITS APPLICATION

在富营养化的巢湖,围隔实验结果表明磷和其它营养元素不是水体藻类的生长限制因素。藻类生长的正磷酸盐阈值浓度为0.019mg/l。它低于巢湖的实际浓度。湖水的矿物性浊度很高,净生产力在一米水深以下呈现负值。数据表明光强在大多数时间是藻类生长的限制因素,在巢湖治理过程中,需大幅降低流域内的磷负荷,使湖水平均溶解态总磷浓度从目前的0.049mg/l降至0.019mg/l以下,因此巢湖的治理和恢复是一个缓慢的过程。

Enclosure experiments were carried out to investigate factors limiting algal growth in Chaohu Lake, China, where Microcystis was the dominant algal species. Phosphorus and other nutrient elements were not the limiting factors in this lake. The threshold of soluble reactive phosphorus concentration for algal development was determined as 0.019mg/l, which was lower than the actual concentration in the lake. The lake water contained a large quantity of suspended mineral particles and had high turbidity. The net primary productivity was negative at levels deeper than 1.0m. Evidences indicated that for most of the time it was light which limited algal growth during the algal development seasons. It is proposed that a large-scale reduction in the phosphorus load would be required to reduce the dissolved phosphorus from 0.049mg/l the present level to less than 0.019mg/Lin the lake restoration managemant, which will be a long-term process.