Study On Water Ecosystem Health Assessment System Construction And Its Application In Northern Shallow Lake

Water ecosystem health assessment is an important technical link in current water environment protection,aiming at grasping the ecological status of watershed.China’s water ecosystem health assessment started relatively late,and there is no systematic assessment process.Based on the current water ecosystem health assessment needs in China,this paper constructed a water ecosystem health assessment system suitable for China’s water environment status on the basis of the existing international water ecological assessment system,and carried out an assessment study on Baiyangdian Basin by means of outdoor collection,indoor identification and laboratory analysis.The feasibility and scientificity of the water ecological health evaluation system constructed in this paper are further verified.The main achievements are as follows:This paper studied the water ecosystem health assessment system in developed countries and regions,summarized the applicable conditions,advantages and disadvantages of each assessment system and its reference significance to China.In the process of constructing water ecological evaluation system in China,the evaluation indexes and evaluation process of biological,habitat and water quality factors in water ecological health evaluation in China were clearly put forward.The pilot study was carried out in Baiyangdian lake,the representative of shallow lakes in northern China.Baiyangdian Basin,the largest lake in Hebei Province,belongs to the Haihe River basin and is known as "Pearl of North China" and "South of the Yangtze River in the North".In this study,water ecological health assessment was constructed for 14 areas of Baiyangdian Basin,including Hudingdian District,Nanliuzhuang District and Caiputai District,which was composed of three factors: biology,habitat and water quality.The aquatic ecosystem health evaluation system constructed in this paper includes seven biological evaluation indexes of zoobenthos,five biological evaluation indexes of fish,10 habitat evaluation indexes and 13 water quality evaluation indexes.The results showed that the overall condition of Daiyangdian was good,and the biological health status of the evaluated sites ranged from normal to sub-healthy.In terms of habitat elements,71%of the sites were slightly disturbed,15% of the sites were slightly disturbed,and 14% of the sites were moderately disturbed or severely disturbed to varying degrees,which should be paid attention to.In terms of water quality factors,the water quality of monitoring points in Baiyangdian is mainly distributed between class III and Class IV,with 64.4% of the points being class IV and 37.7% of the points being class III.The environmental pressure leading to the water quality not reaching the standard is mainly the index of macarate and total nitrogen.In the comprehensive evaluation of the three elements of Baiyangdian Basin,the results of the comprehensive evaluation of the three elements of Laowangdian District,Zaolinzhuang District,Shaochedian District,East Of Quantou District,Guangdianzhangzhuang District,Zaozhadian District,Mapengdian District and Hudingdian District were sub-health.The comprehensive evaluation results of the three elements of Wanloudian District,Caiputai District,Julongdian District,Dujiadian District,Xiaobaiyangdian District and Nanliuzhuang District were average.The results of biological and habitat evaluation in Baiyangdian Basin are generally good,and the environmental pressure mainly comes from water quality.Based on the results of water ecosystem health assessment in Baiyangdian Basin,the feasibility and scientificity of the constructed assessment system were verified.Results for our country to establish the water of the shallow lakes ecosystem health evaluation system to provide support,from the perspective of biological integrity help our quantitative master in water ecosystem health status quo and future trends,comprehensive analysis of environmental pressure source,basin for the state administrative department of environmental protection and environmental pollution normalized control to provide scientific support.