Assessment Of Benthic Ecological Health In Baiyangdian Lake

The health of the ecological environment of Baiyangdian plays an important role in maintaining the ecological balance of the Beijing-Tianjin-Hebei region,but the long-term discharge of domestic and industrial sewage from the upstream rivers has led to serious eutrophication,low biodiversity,and accumulation of pollutants in the sediments.Therefore,it is very necessary to carry out ecological management of Baiyangdian Lake.Benthic ecological health evaluation provides support for lake management.Based on the results of field sampling and survey in Baiyangdian,this paper establishes a benthic ecological health evaluation index system suitable for Baiyangdian,determines the corresponding weight calculation method and index scoring standards;compares the integrity of different benthic organisms in different seasons(spring,summer,and autumn).The evaluation results of the index are compared with the water quality evaluation results based on the TOPSIS model;the benthic index of biological integrity,submerged plant index of biological integrity,dissolved oxygen and comprehensive nutritional status index are used as the index system,and the results of the whole year benthic ecological health assessment were investigated by the average health score of three seasons,discusses the influence of the microbial index of biological integrity and the geological accumulation index on the evaluation results,and explores the benthic ecological health evaluation index system applicable to Baiyangdian,and on this basis,conducts the governance of the pilot area Evaluation,and put forward ecological protection countermeasures and suggestions.The main findings are as follows:(1)The results of benthic ecological health assessment using a single species biological integrity index are biased.The benthic index of biological integrity,submerged plant index of biological integrity and microbial index of biological integrity were calculated in different seasons.As a whole,the integrity index of benthic and submerged plants in summer is better than that in spring and autumn.Comparing the evaluation results of different indicator species,it is found that the percentage of sampling sites with submerged plant index of biological integrity at the“best” level is 76.47%,which is greater than the benthic index of biological integrity(58.83%)and greater than the microbial index of biological integrity(56%),which indicates if only one biological integrity index is used to evaluate benthic ecological health,there may be deviations,so it is a better choice to combine different biological integrity indexes as a biological indicator for benthic ecological health evaluation.(2)The evaluation level of the biological integrity index of most sampling sites is higher than the water quality evaluation level.Comparing the evaluation levels of biological integrity indexes of different species with the water quality evaluation levels based on the TOPSIS model,it is found that the water quality evaluation levels of some sampling sites are higher than the evaluation levels of benthic integrity in spring and summer,except for the reduction of domestic sewage discharge in autumn.The evaluation grade of biological integrity index in spring,summer and autumn was higher than that of water quality.Water quality assessment and biological integrity assessment have their respective focuses,and biological integrity assessment and water quality assessment should be considered comprehensively when conducting lake management.(3)The annual evaluation results of the ecological health of the Baiyangdian in the three seasons of spring,summer and autumn are averaged.Using benthic index of biological integrity,submerged plant index of biological integrity,dissolved oxygen and comprehensive nutritional status index as the indicator system,the annual health assessment result is: 23.08% of the sampling sites(Quantou,Caiputai and Houtang)at the “good” level,76.92% of the sampling sites(Nanliuzhuang,Yuanyangdao,Zhainan,Wangjiazhai,Yangzhuangzi,Zaolinzhuang,Jinlongdian,Duancun,Shaochedian,and Guangdianzhangzhuang)were at the “middle” level.(4)The addition of one of the microbial index of biological integrity and the geoaccumulation index to the index system will affect the evaluation level of some sampling sites.When the two indexes are added at the same time,the health level of all sampling sites does not change but the health scores change.Specifically: After adding the microbial index of biological integrity to the index system,the health level of Nanliuzhuang increased from “poor” to “middle”;after adding the geoaccumulation index,the health level of Duancun decreased from “good” to“middle”;adding two indicators at the same time there is no change in the health level,indicating that the two indicators have little effect on the evaluation of the benthic ecological health of Baiyangdian.(5)There is a trend of recovery in the pilot area of endogenous pollution control.Using benthic index of biological integrity,submerged plant index of biological integrity,dissolved oxygen and comprehensive nutrient status index as the index system,conduct benthic ecological health evaluation on the pilot area of the governance,and compare it with the same season before the governance.The health level of the region is lowered by one level,and the governance will have a certain degree of impact on the benthic ecology.At the same time,the benthic ecological health level of the ecological dredging area and the in-situ remediation area is the same as that of the untreated control area,but the health score of the remediation area is slightly higher than that of the control area,indicating that the benthic ecology of the remediation area has a tendency to recover.