Research On After-dredging Ecological Restoration Technology And Assessment On Effect For The Water Environment Of Baiyangdian Lake

Substrate dredging,as a major engineering measure for allochthonous management of endogenous pollution in lakes,can effectively reduce endogenous pollution load,improve water quality,and improve the water ecological environment.However,after substrate dredging,the water environment ecosystem primarily faces problems such as nutrient release,toxic substance resuspension,and destruction of benthic habitats.However,because of the differences in water bodies,the effects of each restoration technology are frequently inconsistent,and there are few studies related to the restoration of the Baiyangdian water ecosystem.In this paper,we conducted research and effect evaluation on the restoration technology of Baiyangdian water ecosystem after dredging based on the general contracting project of Baiyangdian endogenous pollution control pilot project.The research region was subjected to a substratum survey,sediment survey,water quality assessment,and aquatic flora and fauna survey.The major source of endogenous pollution was discovered to be the substrate,which was usually weakly alkaline,and the heavy metal concentration,total phosphorus content,and total nitrogen content were primarily concentrated in the substrate pollution layer and reduced with increasing depth.The water’s COD and ammonia nitrogen concentrations are lower than the specification’s standard limit for Class Ⅳ water.However,the total nitrogen and total phosphorus concentrations in the water body exceed the Class Ⅳ standard limit,and the species and density of organisms in the water environment,such as sludge and eutrophic environments,are high,while the biodiversity index is low,implying that ecological restoration measures are required to effectively reduce the endogenous pollution load.Baiyangdian’s pilot area for ecological restoration technology measures comprises water aeration,aquatic plant restoration,aquatic animal restoration,and substrate improvement after substrate dredging.The examination of pharmaceutical screening test results demonstrated that the use of porous bio-polymer and microbial composition TH-IV for substrate improvement had significant advantages.Dwarf and giant bittercress were identified as the dominant submerged plant populations in the aquatic plant community,and fragrant cattail and reed were identified as water-holding plants.A combination of fish(snakehead fish,Mandarin fish),benthic animals(green shrimp,snails),and zooplankton(Daphnia magna)was chosen to strengthen Baiyangdian’s biological chain.The solution layer solar aerator is used to raise the dissolved oxygen level of the bottom water,prevent anaerobic organism activity,eliminate the black odor of the water body,and inhibit cyanobacteria development.Water quality,bottom sediment,phytoplankton,and benthic animals in the pilot area of Baiyangdian were monitored and analyzed after the implementation of ecological restoration technology measures.It was discovered that the diversity index of aquatic organisms in the post-construction stabilization period increased compared to that before construction,indicating that the aquatic community became more complex after the ecological restoration technology measures were implemented.While total nitrogen and ammonia nitrogen levels in the aquatic environment did not change much,dissolved oxygen,chemical oxygen demand,and total phosphorus levels all progressively improved.Based on the fuzzy hierarchical analysis,an evaluation system was established to evaluate the ecological restoration effect of Baiyangdian after dredging,and the four criteria of water quality and substrate,zooplankton,phytoplankton,and benthic fauna were all excellent through the second level fuzzy evaluation,and the overall evaluation of the ecological restoration effect of Baiyangdian after dredging was excellent.