[Effects of rehabilitation of submerged macrophytes on nutrient level of a eutrophic lake].

The effects of rehabilitation of submerged aquatic vegetation on nutrient level of eutrophic waters were investigated by using large-scale enclosure system installed in a hyper-eutrophicated lake, Lake Donghu of Wuhan. The concentrations of total nitrogen (TN) and total phosphorus (TP) of the enclosures with artificially recovered submerged macrophytes were significantly lower than those of the macrophyte-free control enclosure and the lake water, and the TP of macrophyte enclosure was found to be around 0.1 mg.L-1 and relatively stable. The concentration of ammonia and nitrite of the macrophyte enclosures were lower than those of the control and the lake water. However, the nitrate concentrations did not differ among the various water bodies. It was demonstrated that re-establishment of submerged macrophytes could efficiently reduce the nutrient level and thus control the overgrowth of the undesirable algae and improve water quality in the eutrophic lakes.