| With the rapid social and economic development, water eutrophication has become a serious environmental problem facing humanity.Using aquatic plant,especially submerged plants for ecological restoration is the important means of handling contaminated water. the deterioration of The water quality and the degree of eutrophication is increasing in Gehu Lake day by day . it seriously restricted the economic development of Changzhou. Then Taihu lake lost natural barrier of the water quality protection . Reconstruct different forms of submerged macrophytes in the enclosures to study on the purification of various pollutants from eutrophicated Gehu Lake. The results show that:Introduced Potamogeton crispus turions 10 and Elodea nuttallii plants 4kg in the late fall to construct the P. crispus-E. nuttallii community in the the biomass of 525g/m2. During winter and spring,comparing with open lake,TN,TP,NH3-N,Chl.a concentration decreased by in P. crispus-E. nuttallii community is 50.6%,24.0%,52.6%,28.7% averagely,CODMn concentration decreased is 6.5% only;During summer and autumn,construct the C.demersum-E. nuttallii community,the Biomass stabilized at about 500g/m2, had no significant effect on CODMn and TN concentration,but the average removal performance of TP,NH3-N,Chl.a were satisfified in this planted enclosure were compared to the lake open area,respectively .Introduced P. crispus turions 10/m2 and E. nuttallii plants 200g/m2 In the late fall,and Introduced Ceratophyllum demersum 250g/m2 In the early summer. Reconstruct the P. crispus-E. nuttallii community during the winter and spring in the succession for the C. demersum-E. nuttallii community during the summer and autumn through enclosure experiment. Results showed that the average removal ratios of TN,NH3-N,TP,Chl.a in this planted enclosure were 27.1%,50.6%,36.2%,25.1% compared to the lake open area,respectively. Gehu lake water quality Satisfied national surface water standardⅤcompared to the inferiorⅤof the original state(Exceptly the concentration of TN is slightly higher),the average of TLI(∑)in the whole of year reduced to 66.155 from 69.372.the removal effect of C. demersum-P. crispus-M. spicatum cover for TN,TP,NH3-N,Chl.a,CODMn is more remarkable than C.demersum-P.crispus cover in the remaining submerged macrophytes area from Dahong Port of Gehu Lake, and surpass the P. crispus-E. nuttallii-C. demersum community in the enclosure. Combine each community can prove that:P. crispus,E. nuttallii,C.demersum,M. spicatum can be used in the reconstruction of submerged macrophytes community in Gehu Lake. Furthermore P. crispus and E. nuttallii can be used as pioneer species species during winter and spring,C.demersum and M. spicatum can be used as pioneer species during summer and autumn.Bmac and SD/ZM,TP and Chl.a exist significant linear relationship during the course of constructing submerged community. It will be more conducive to the growth of submerged macrophytes by improving external light intensity. It will control effectively algae growth by removing TP of the lake through submerged macrophytes. Comparing with the contrast space,the average elimination speed rate of NH3-N,TP,Chl.a declined in negative exponent form with the time continuing basically by reconstructing submerged macrophytes community. the removal capacity of various pollutants is more stable and better by constructing C. demersum-E. nuttallii community . |
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