Study On The Migration And Transformation Of Pollutants In Urban Landscape Water

Urban landscape water generally refers to the transformation of natural rivers and lakes in cities into artificial lakes for sightseeing,which is of great significance to the leisure life and ecological improvement of urban environment.The water in the natural river has strong fluidity and good self-purification ability,After the transformation,the landscape water body has large coverage area,small water flow rate,long water displacement cycle and poor self-purification ability,In addition,the point source discharge within the water body,the water quality discharge standards of domestic,industrial waste water and urban sewage reclaimed water are all lower than those of the landscape water body,which easily leads to the increase of pollutants in the landscape water body and the eutrophication of water body,thus affecting the urban ecological construction.This study took Taohua lake as an example to investigate and analyze the water ecological status and water quality change of Taohua lake.By adopting water quality simulation method,the hydrodynamic and water quality model was established to study the hydrodynamic and water quality change process in the lake,so as to provide reference for improving the water quality of landscape water.The main research contents include:The water environment quality of Taohua lake was investigated.There were sewage discharge points in Taohua lake,among which the pollutant concentration of the third sewage treatment plant was relatively high,and the nitrogen emission concentration was the highest.The total nitrogen concentration at the sewage outlet was as high as 11.36,14.2 mg/1.In 2017,Taohua lake water quality was monitored for one year to analyze the changes of various water quality indicators(cod,dissolved oxygen,ammonia nitrogen,total phosphorus and total nitrogen),It was found that these water quality indexes had significant and seasonal changes in one year.By grey correlation analysis method to evaluate the peach blossom pool water quality,1-December the correlations in 0.722 to 0.81 respectively,the peach blossom pool is obtained the overall water quality level between IV and V class water conclusion.The hydrodynamic characteristics of Taohua lake water area under different runoff into the lake and within one year were analyzed.The results showed that:The flow direction is from south to north,and there is circulation generated around the island and at the curved boundary.The overall flow velocity is small,and the flow velocity of the left and right lakes is smaller than that of the middle river,and the flow velocity of the right lake is greater than that of the left lake.The water flow velocity range in Taohua lake is between Om/s and 0.56 m/s,where the maximum flow velocity is 0.56 m/s under the inflow runoff in P=20%years of high water,and the area larger than 0.07 m/s increases with the increase of the inflow runoff.The flow velocity of multiple locations in the lake is in the range suitable for the growth of algae.If no precautions are taken,the algae in the lake may reproduce too fast and lead to the imbalance of the ecosystem.The water quality model verified by the model was used to simulate the pollutant concentration field in Taohua lake,and the runoff into the lake,the impact of point source pollution on the concentration field and the concentration distribution within the year were studied.Affected by point source pollution,the concentration field of Taohua lake water area has an obvious concentration gradient.The pollutant concentration of the left lake and Chan river is lower than that of the right lake.The concentration of ammonia nitrogen in Taohua lake is above 2.0 mg/1,and its water quality has exceeded the five water quality standards.The whole lake is mainly polluted by total nitrogen and ammonia nitrogen.With the increase of runoff into the lake,the water flow rate increases,and the transport capacity of pollutants also improves,especially at the sewage discharge outlet of the third sewage treatment plant.The attenuation trend of pollutants is from the source term to the lake and the downstream.The area near the point source is affected by the point source emissions,and the concentration of various pollutants fluctuates up and down.The concentration value in the lake on the left is slightly lower than that of the whole lake and shows certain regularity.The third sewage treatment plant's point source discharge has a great influence on the water quality of right lake.