Quantitative Study On Pollutant Reduction By Ecological Measures In Coastal Structure

The traditional coastal structure serves a function of resisting storms,damp and waves,but its construction destroys the surrounding natural environment,making it difficult for nearby aquatic organisms and attached organisms to survive.Benthic plankton in the sea area plays a role in degrading and absorbing pollutants.Therefore,the traditional coastal structure also has a certain negative influence on water purification.The ecological coastal structure takes into account the requirements of aquatic organisms on the habitat environment,and takes ecological measures on the basis of ensuring the function of traditional coastal structure,so as to provide a better living environment for organisms and realize a virtuous cycle of mutual promotion in water purification and biological survival.Ecological coastal structure has been widely used abroad,but the construction research in China started late and is still in the exploratory stage.There are few quantitative studies on its ecological environment improvement effect in China.The ecological measures to reduce pollutants in the coastal structure are divided into four categories: terrestrial vegetation in the ecological slope protection area of the supratidal zone,salt marsh vegetation in the salt marsh wetland area of the intertidal zone,algae or seaweed in the subtidal zone,attachment and benthos in the intertidal zone.Taking Liaoning Liuhe estuary ecological project as an example,the terrestrial vegetation in the ecological slope protection area of the supratidal zone and the salt marsh vegetation in the salt marsh wetland area are taken as the main research objects based on the structure and function of the ecological coastal zone.The main pollutant reduction mechanisms include denitrification of microorganisms in salt marsh wetland area,absorption and utilization of vegetation,absorption and utilization of vegetation in supratidal ecological slope protection,interception of solid suspended solids,net flow,infiltration,mineralization,etc.According to the above pollutant reduction mechanism,some coastal reaches of Liaodong Bay are simulated to quantify the reduction effect of ecological measures on pollutants.By integrating and abstracting the ecological measures in the study area,and by means of on-site measurement,experimental acquisition,online acquisition,approximate processing,etc.,the data of hydrology,topography,soil,land use,climate and other aspects in the study area are obtained and established into a database,and a large-scale model of the ecological slope protection area in the supratidal zone and the salt marsh wetland area in the intertidal zone in Ann AGNPS is established.According to the seasonal characteristics,two types of high According to the wetland conditions in different ranges of low water level,the quantitative results of nitrogen and phosphorus reduction by the mechanisms of plant absorption,wetland denitrification,slope protection and interception in the study area are obtained,and compared with the experimental data and previous literature data,the results are in good agreement.The hydrodynamic module of Mike21 coupled with Ecolab water quality module is used as a supplementary model to take into account the hydrodynamic force and periodic tidal level changes.The pollutant reduction mechanisms included in the calculation include vegetation absorption and utilization,microbial denitrification in wetlands,simulated pollutant transport and diffusion,and compared with the part in which the reduction mechanism coincides with the results of the Ann AGNPS Model with the same time history.The error of the two models is small,and the results are reliable.Based on the above model,combined with the actual situation of the project,the actual characteristics of the project are abstracted into ecological characteristic parameters,and the variables of temperature,denitrification reaction rate,vegetation absorption efficiency and rainfall are controlled respectively.Multiple working conditions are established and compared with the actual working conditions,and the response effects of each pollutant reduction on the above ecological measure characteristic parameters are obtained.This simulation provides a method for quantitatively evaluating the environmental benefits of the sea.The research results can be extended to scientifically and quantitatively evaluate the role of ecological coastal structure and attached vegetation in water quality improvement,as well as assist in the formulation of relevant domestic standards and provide a certain basis for the planning,construction and ecological function of ecological engineerings in coastal areas.