| Wupai reservoir in wusheng County is located in the middle reaches of changtansi River and Wushui village of Feilong town.It was started in December1956 and completed in December 1976.It is a medium-sized reservoir mainly for flood control and irrigation,with comprehensive utilization of power generation and aquaculture.The water surface area is more than 4000 mu,the rainwater collection area is 316.22km2,the total storage capacity is 52.15 million m3,and the effective storage capacity is 31.15 million m3.There used to be clear water and beautiful fish,fat birds.However,in the past 20 years,with the acceleration of economic growth and urbanization in the basin,the rapid development of industry,planting industry,aquaculture and service industry in the basin,and the improper development and utilization of water resources and tourism resources,the coexistence of point source pollution and non-point source pollution,the superposition of domestic pollution and production pollution,the interweaving of water pollution and ecological degradation,and the serious threat to the ecological environment.In this paper,by collecting the historical monitoring data of the main road of the five drainage reservoir and the monitoring data of the site distribution,the water environment quality of the five drainage reservoir is investigated and analyzed,the main problems of the pollution of the five drainage reservoir are found out,the main pollution factors and the key treatment objects are identified,and on this basis,the targeted treatment measures are put forward.The main research results are as follows:1.From June 2017 to November 2018,the concentrations of COD,HSA index,ammonia nitrogen,TP,TN and other monitoring indicators in the core of the fifth drainage reservoir,the monitoring section in front of the dam,the water body of the main road exceeded the standard in several months,The over standard rate of TP and TN is 100%.The monitoring indexes of wupai reservoir are evaluated by using single factor index evaluation and environmental index evaluation,It is concluded that in November 2018,the ammonia nitrogen of wupai reservoir reached the class III water quality standard of surface water;the permanganate index and cod were class IV water quality standards;the TN and TP content exceeded the class V water quality standard,which was class V,and the overall water quality evaluation of wupai reservoir was class V water quality standard.In November 2018,TN pollution index was 3.10;TP pollution index was 7.8;NH3-N pollution sub index was 0.76;permanganate pollution sub index was 1.06;COD pollution sub index was 1.15;wupai reservoir environmental pollution comprehensive index Qi was 13.87.The main pollution factors of wupai reservoir are n and P,and the water body is in medium eutrophication state.To achieve the class III water quality management goal,wupai reservoir mainly controls the total amount of N and P in storage.2.Among the nutrients in the sediment of the fifth drainage reservoir,91%of the alkali hydrolyzed nitrogen,92% of the available phosphorus,84% of the available nitrogen,67% of the total phosphorus and 67% of the organic matter are all at a high level or above.By comparing the contents of the total phosphorus and the available phosphorus in the sediment with the contents of Fe,Mn and Al in the sediment Through correlation analysis,it is found that TP is positively correlated with Fe,Mn and Al,especially TP is significantly correlated with Mn,so it is concluded that Fe,Mn,Al and other elements in sediment have certain control effect on phosphorus.3.The self-made phosphorus locking agent with the proportion of iron salt and aluminum salt was used in the simulation experiment of sediment pollution prevention and control in five drainage reservoirs to explore the effect of different doses of phosphorus locking agent on sediment pollution prevention and control.The experimental results show that:(1)When 100 g phosphorus locking agent is added to the experimental water body,the phosphorus locking agent can completely cover the sediment to form a covering layer.The covering layer will hinder the gas from entering and leaving the water body,the contact between microorganisms and organic matters,and affect the relevant reactions in the water body,so that the monitoring indexes such as do,COD,ammonia nitrogen,and high ferocity index in the water body reach the lowest point and tend to the stable value in a longer time than without the addition of the phosphorus locking agent The longer the experimental group was,the more phosphorus locking agent was added,the thicker the covering layer was,and the longer the time was needed;(2)In the water body without phosphorus locking agent,phosphorus in the sediment will be released to the water body continuously under anaerobic condition until it reaches the maximum value,and then it tends to be stable without any change,In the whole process,the phosphorus content released from the sediment to the water body was in the range of 0.83-0.97mg/l,while in the water body,the phosphorus content of the five experimental groups added phosphorus locking agents was always below 0.05mg/l,without any increase,and the change trend of phosphorus content in the five experimental groups was basically the same.According to the limit value of class III water quality standard in environmental quality standard for surface water(GB 3838-2002),five groups of experiments were carried out by adding phosphorus locking agent.The TP content in the water body was less than or equal to 0.05mg/l,which reached the class III water quality standard and the water quality standard of wupai reservoir.So it shows that 100 g of phosphorus locking agent can completely cover the sediment,and the release of phosphorus in the sediment can be effectively controlled,And when the phosphorus locking agent can completely cover the sediment,increasing the amount of phosphorus locking agent will only change the thickness of the covering layer,but will not affect the phosphorus release in the sediment.In the specific gymnastics,the optimal dosage of phosphorus locking agent in the experimental water is 100 g / barrel,which is equivalent to 1.43 kg phosphorus locking agent / m2 water surface in practical application,which can better control the release of phosphorus in the sediment.The results of this study provide a new and effective way to control the release of phosphorus from sediment,and have a certain practical significance for water pollution control. |
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