Analysis Of Ecosystem Environmental Characteristics And Health Assessment In Liaohe Reserve

Liaohe River Reserve,based on the protection of the natural ecosystem functions of the Liaohe River Mainstream and the environmental protection of the Liaohe River,integrating ecological protection,water conservation,biodiversity maintenance,water purification,flood prevention and other ecological functions,is the one that ensures water ecological security,resource development,and sustainable use.The research on the health of river reserve is one of the important issues related to the orderly,healthy and sustainable development of human society.Based on the concept of river system and theory of river health research,the relevant researches of ecosystem health of river reserve were carried out in this paper.The main work and achievements of this paper are as follows:The water and sediment samples were collected from 44 sites of the Liaohe River Mainstream.The pH,conductivity,dissolved oxygen,chemical oxygen demand,biochemical oxygen demand,total nitrogen,total phosphorus and volatile phenol in the water and ammonia-nitrogen,heavy metals,PAHs,OCPs,and OPs in the sediments are tested.Data analysis suggests that in the Liaohe River Mainstream water,COD and BODs rise from the normal flow period to the high flow period and decline from the high flow period to the drought period;The content of total nitrogen shows a upward trend in turn in the normal flow period,high flow period and drought period;In different monitoring sections,the average contents of sediments are apparently higher than the soil background value in Liaoning and the surface soil value of the Liaohe River Basin.Use the geo-accumulation index method to conduct the analysis for the heavy metal pollution;Use Hakanson's potential ecological risk index(RI)to evaluate the ecological hazard of heavy metal element in the sediment.The results show that most heavy metal pollution belongs to no pollution and light pollution;the most sections of Liaohe River Mainstream suffer from moderate ecological hazards and minor ecological hazards.The soil monitoring sites of 17 riparian habitats and 30 riparian zone were arranged along the riparian zone of the Liaohe River Mainstream.The soil organic matter,total nitrogen,available nitrogen,total phosphorus,and available phosphorus,hexachlorocyclohexane(HCH)and dichlorodiphenyltrichloroethane(DDT)in the riparian habitat as well as polycyclic aromatic hydrocarbons(PAHs),organochlorine pesticides(OCPs),organophosphorus pesticides(OPs)and heavy metals Cr,Ni,Cu,Zn,As,Cd,Pb were tested.In general,the above ions in the riparian soil of the Liaohe River Mainstream show higher levels in the upper reaches than in the lower reaches,and the high flow period is higher than that in the drought period and the normal flow period.3-and 4-rings and 4-and 5-rings are the principal thing in the PAHs composition of the riparian soil of middle and lower reaches.In the riparian soil,the content of DDTs pesticides is slightly higher than that in HCHs,and the DDTs content shows a downward trend from the upper reaches to the lower reaches;In the reserve,the richness of microbial diversity in the riparian soil in the lower reaches is similar to that of in the upper and middle reaches,and that of in the middle and lower reaches is the lowest.There is a similar uniformity coefficient of the distribution of microbial communities in the reserve.Compared with HCHs,DDTs had a significant effect on microbial community diversity and richness index.The samples of macrozoobenthos and fishes were analized which were collected in the 21 monitoring sites in the tributary and mainstream of Liaohe.The composition,density and diversity of washing farmland of the four different sedimentary River farmland,Tieling and Panjin were analyzed.The results showed that:In Liaohe River Reserve,48 species of macrobenthos were found,belonging to 4 classes,7 orders and 20 families.Limnodrilus udekemianus and Limnodrilus claparedeianus are the main dominant species.The species number of benthic animals is higher in the Tieling area and lower in the washed farmland of the Tieling River at the Fudedian.The distribution characteristics of the biodiversity index are basically the same as the number of species,and the distribution characteristics are relatively low in Panjin Area and the sedimentary river field from Liuhe Section to Panshanzha Section.The dominant species of water systems in the basin are also different.The sedimentary river field from Liuhe Section to Panshanzha Section has lower distribution characteristics.According to the characteristics of multi-objective and multi-factor of river health evaluation,a comprehensive evaluation index system of river health in Liaohe Reserve is constructed,which is hierarchical,classified,contains qualitative and quantitative indicators.Assessment indicator system is divided into three levels:the first-level indicator is the River Health Index(RHI),which is used to reflect the overall characteristics of the river health status;the second-level indicators include river hydrological indicators,river morphology indicators,water physicochemical indicators,and river biological indicators,riparian indicators,riparian soil physicochemical indicators and river social function indicators;The third-level indicator is the river hydrological indicator,selecting 4 indicators:flow velocity,water volume,water conservancy project interference and water temperature;River morphology indicators select 5 indicators:the degree of river bending,river bank stability,vertical connectivity,horizontal connectivity,and river bank shoal,deep pool and side shoal index.The physicochemical indicator selects 6 indicators:total phosphorus(TP),total nitrogen(TN),dissolved oxygen(DO),BOD,COD,and volatile phenol;The river biological indicators select 4 indicators:fish richness index,macrobenthic diversity index,damage degree of invasive alien species,and aquatic habitat disturbance index;The indicators of the riparian zone include the shoal,deep pool and side shoal index,riparian buffer rate,and wetland retention rate.The riparian soil physicochemical indicators take the content of soil organic matter,total phosphorus,and available phosphorus into account.Riparian soil indicators mainly involve in the HCHs,DDT and PHAs in the soil.The riparian biological indicators consider the soil indicator species retention rate,rare species rate,habitat complexity,plaque fragmentation index and plant diversity index.The social function indicators mainly cover the flood safety index and water landscape comfort.Traditional river ecological health assessment methods shall give corresponding weights to assessment indicators,and there is some subjectivity.In order to evaluate river ecological health more objectively and reasonably,the mutation theory is combined with the comprehensive assessment method,and the normalization formula is adopted to quantify the.importance of each objective in the assessment indicator system in this paper,which reduces the subjectivity of the comprehensive assessment and makes the analysis,decision and assessment more correct and reasonable.The fuzzy clustering method is used to classify different sections(outfalls),and classified repair model is put forward.