Restoration and Purification of Submerged Macrophytes in Eutrophic Gehu Lake during Winter and Spring

From the late autumn to the early winter,submerged macrophytes were introduced to the enclosures in Eutrophic Gehu.Five macrophytes community,Potamageton crispus-Elodea nuttallii community,Potamageton crispus community and Elodea nuttallii community were constructed respectively.The restoration and purification of submerged macrophytes of four communities were investigated.The results show Potamageton crispus-Elodea nuttallii community not only remains effective on removal of the concentration of water nutrition in winter and spring,but also reduces bad affection caused by the death of vallisneria spirals(five macrophytes community).During winter and spring,comparing with open lake,the removal rate of TN,TP,NH3-N and Chl.a in Potamageton crispus-Elodea nuttallii community is 62.9%,31.5%,53.9% and 46.1% averagely,and the rate of CODMn is 9.7% only.Comparing with two kinds of monotypic macrophytes community,the removal effect of Elodea nuttallii on TN is better than Potamageton crispus,while the removal effect of Potamageton crispus on TP is better on the contrary.