Study On The Control Of Plain Reservoir Eutrophication By Silver Carp And Bighead Carp And Aquatic Plants

Plain reservoirs are relative to the mountain reservoirs, which are mainly built inthe plain areas, surrounded by the dam. Plain reservoirs are affected by geology,topography, climate and human activities. Plain reservoirs play an important role insolving local people’s production and living water, supplying urban water andagricultural water, improving the water environment.Eutrophication is becoming environmental and ecological issues which receiveda worldwide attention and eutrophication in plains reservoir is getting more and moreattention. Fish and aquatic plants have been widely used in the management ofeutrophication. We studied the purification effect of eutrophication by putting silvercarp and bighead carp which are in different densities and proportions into theeutrophication water. We analyzed the feeding habits of silver carp and bighead carp.We planted aquatic plants in nutrient-rich water.We got the main results as follows:Silver carp and bighead carp play an important role in purifying theeutrophication.In our study, the most appropriate density is50.3g/m3;and the mostappropriate proportion of silver carp and bighead carp is4:1.In this condition,theconcentration of Chla can be reduced from25.15μg/L to9.7μg/L; the concentration ofTN can be reduced from7.41mg/L to2.43mg/L; the concentration of TP can bereduced from0.392mg/L to0.091mg/L and the concentration of COD-Mncan beruduced from8.74mg/L to5.35mg/L.There are little differences in the removal ofalgae blooms by fish in different sediment conditions. If we put silver carp andbighead carp into water before eutrophication occurs instead of after, we can get ahigher removal rate of algae blooms.When the food reach into the digestive tract, Silver carp and bighead carp cannot get well use of the filter-feeding food. If the fish feces were re-cultured, there stillare a lot of varieties of algae alive. There are differences in feeding and digestibilitywhen silver carp and bighead carp are feeding on different algae.We studied the removal rate of water pollutants and the quality of removed pollutants per unit mass of aquatic plants of Acorus calamus, Eichhornia crssipes andPurple root of water hyacinth; We researched the effect of remove of differentconcentrations artificial nutrition by the three aquatic plants.We comprehensive studied the purification effects on different water pollutantsof different aquatic plants, the purification effects of Purple root of water hyacinth isbetter than that of Eichhornia crssipes and Acorus calamus.