| Abstract:The restoration of degraded wetlands is a hot issue internationally at present, and improvement effects evaluation of degraded wetlands restoration is an important part of wetland restoration research and is of great significance in modern wetland ecological restoration and wetland management. In this paper, we extensively studied related literature, and then selected the theories of restoration of degraded wetlands and practices related to evaluation of wetland restoration. Connotation and functions of wetlands has been identified, and concept of wetland degradation and recovery, measures and principles of wetland restoration were addressed. We also summarized the research progress of wetland restoration at home and abroad, and, summed up the practices of wetland restoration evaluation, in order to further explore the evaluation of wetlands restoration in Taihu Lake Basin to provide a theoretical basis and reference methods.In this paper, we determined and selected assessment parameters, date collection methods, appropriate methods of assessment and evaluation standards, which focused on improvement effects of ecological restoration project on water environment in Taihu Lake Basin, with consideration of domestic and international wetland restoration assessment practices. Ecological restoration projects’ turning fishpond to lake’ in Shanghai Dalian Lakeside area and Suzhou Youhu gulf were selected as case study to investigate water quality assessment and analysis. Dalian Lake, which located in water resources area in Qingpu District, suffered serious aquiculture pollution. The monitoring results before restoration projects showed that the water quality was ranged worse than Class V. Youhu gulf, as a fish farming area of high density, suffered serious agricultural production and rural life non-point source pollution. The water quality was ranged Class IV before restoration projects. In order to improve the water quality, relevant departments launched ecological restoration in the two areas including fish ponds transformation, water system reconstruction, sediment ecological dredging and macrophyte restoration. The objective of this article was to track and analysis seasonal changes of water quality using physiochemical and biological indexes throughout the period of the ecological restoration project, to assess effects of ecological restoration project on water environment through analyzing differences between water parameters before and after the project, as well as that inside and outside the project area. And to put forward the sensitive testing parameters focused on ecological restoration of different wetlands through the correlation analysis of biological parameters and the physicochemical indexs in the engineering area.The research results indicated that water quality of Dalian Lake has been improved after restoration. Concentration of the dissolved oxygen and transparency increased with seasons, while concentration of TN, CODMn, phytoplankton biomass and chlorophyll a declined. And concentration of TP, NH4+-N and NO3-N fluctuated without uniform trend. Compared with the prior restored, DO, TP, TN, CODMn, chlorophyll a and phytoplankton abundance has greatly improved. Average concentrations of TP, TN, NO3--N, NH4+-N and COD in ecological restoration area were0.12mg·L-1,0.42mg-L"1,0.06mg-L"1,4.90mg·L-1and0.11mg·L-1, decreased by62.50%,72.19%,92.86%,8.92%and63.33%, respectively, while average concentration of DO was8-11mg·L-1, increased by11.10%compared to the unprotected area. The integrated water quality identification index was3.412, the basic stability of the surface water Class III standard; phytoplankton abundance and biomass was well controlled, phytoplankton flora improved. The outlet water quality is significantly better than the inlet water quality. Water environment of Youhu gulf wetland also has been significantly improved. Concentrations of the dissolved oxygen in summer and autumn were both lower than that in spring, and concentration of transparency of the water fluctuates between69-82cm, without significant difference between seasons. Water TOC, TN, NO3-N declined with the seasons, while CODMn did not decline significantly. Concentrations of TP and NH4+-N changed in seasonal fluctuations without uniform trend. Compared with the water situation before restoration, CODMn, TP and the dissolved oxygen were improved. Average concentrations of the dissolved oxygen and transparency have been increased compared to the unprotected area, while CODMn significantly reduced and total organic carbon did not decline significantly. Average concentrations of TP and TN in unprotected area was significantly exceeded at0.24mg·L-1and1.63mg·L-1, while which dropped to0.13mg·L-1and0.56mg·L-1respectively after the restoration, and concentrations of ammonia nitrogen, nitrate nitrogen also decreased significantly. WQI value of unprotected water was of4.512, ranged class IV, which indicated the water is in serious polluted state; the WQI value of restored water was of3.401, ranged class III, which shows the water is in good state.The correlation analysis between the physiochemical indexs and biological indexs in project area shows that assessment of different (size, human disturbance) wetland ecological restoration on water environmental may focus on different monitoring parameters, and, taking more than two reference systems can improve the effectiveness and credibility of wetland restoration assessment. |
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