| Dongying is located in the most downstream part of the Yellow River,and the delta area of the Yellow River’s estuary is dominated by plains.The area mainly takes the reservoir as the drinking water source,the reservoir water mainly refers to the the Yellow River water,while the nitrogen and phosphorus and other nutrients in the water of the Yellow River will gradually enrich after entering the reservoir.Through the investigation and study of Xin’an reservoir,Gu He reservoir,Geng well reservoir and Lijin reservoir in Dongying,it is found that the 4reservoirs have been running in the state of eutrophication for a long time.And water for living and production in this area are derived from these reservoirs.The water quality of the reservoir is directly related to the safety of drinking water.Indoor experiments and outdoor tests were carried out in Xin’an reservoir.The water quality indexes and the control effect of the planktonic algae were mainly studied by aquatic plants,aquatic animals,microbes and their different combinations,so as to provide technical support for controlling eutrophication and controlling algae population in Xin’an Reservoir.The main research contents and experimental results are as follows:(1)4 reservoirs(Xin’an Reservoir,Guhe Reservoir,Gengjing Reservoir,Lijin Reservoir),and some water quality indicators have exceeded the standard to varying degrees.The concentration of total nitrogen(TN)is basically greater than that of 1.0mg/L,and the concentration of total nitrogen(TN)in some reservoirs is even greater than that of 2mg/L in some months.The concentration of total nitrogen can not reach the requirement of class III water;the total number of algae and the rapid growth of chlorophyll a aggravate the eutrophication of the water body.(2)A total of 7 phyla and 36 genera of algae were detected in Xin’an Reservoir.And the eutrophication of Xin’an reservoir was evaluated according to the dominant species evaluation.In the last 5 years,the eutrophication level of the reservoir was basically in the eutrophic level.The nutritional level of the reservoir in the month of 2017 was evaluated by the parameter method.(3)Algae in Xin’an reservoir dominated by cyanobacteria,green algae and diatoms.The change trend of algae was marked by the change of temperature.Since Mar and April,the total number of algae increased significantly,reaching the highest value in the month of 7~9,and the highest value was sometimes more than 100 million/L.(4)The study on the effect of aquatic plants and their different combinations on eutrophication and algae control shows that Canna,water hyacinth and water spinach can all show the ability to reduce the concentration of nutrients in water and control the number of algae.The better removal of total nitrogen and ammonia nitrogen in the water hyacinth,reached 67.02%and 21.75%respectively;better removal of total phosphorus and permanganate index of Canna,reached 47.01%and 25.45%respectively;water spinach better effect on removing a total algae and chlorophyll,respectively 36.58%and 38.58%.(5)The study on the effects of aquatic animals and their different combinations on eutrophication and algae control showed that the drop of 80g/m3 on the concentration of algae and nutrients by silver carp and Bighead in the proportion of 3:1 had a good removal effect.The total algae total decreased from 75.235 million/L to 21.370 million/L,total nitrogen reduced from 1.82mg/L to 0.46mg/L,total phosphorus reduced from 0.059 mg/L to 0.018 mg/L;permanganate index 4.73 mg/L decreased to 2.09 mg/L.(6)The study on eutrophication and algae control effect of different biological chain combinations shows that the more complete the biological chain combination,the better the control effect on nutrient concentration and algae quantity in water body.The comprehensive application of zoobenthos and biological fillers has realized the comprehensive treatment of water body by animals,plants and microbes.(7)The outdoor study on the effect of silver carp and Bighead on eutrophication and algae control showed that the release of different density of fish seedlings could reduce and control the number of algae,and to some extent reduce the physical and chemical indexes of water bodies.The effect of 60g/m~3 and 80g/m~3 is better.The test results show that the eutrophication and algae pollution in the Dongying plain reservoir in the lower reaches of the Yellow River are more common,so it is very important to take a reasonable method and method for effective control of the reservoir.Floating bed plants have significant effects on removing nutrients and nutrients in water,and also have a certain effect on limiting algae multiplication.When the density of silver carp and Bighead is 80g/m3,it shows a good effect on controlling the number of algae under the proportion of 3:1,and when the proportion of silver carp and Bighead is 3:1,the difference between the density of60g/m3 and the density is 80g/m3 is not big.Therefore,it is suggested to further study the purification effect of silver carp and bighead carp at low density at 3:1,which is beneficial to reduce the cost while effectively controlling the reservoir. |
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