Study On Biopurification Of Water And Ecological Culture Model In Intensive Fishpond

Pond culture is the most important aquaculture model in China. With the process of industrialization, the sources of pond water are polluted, besides, more and more material input are introduced to fish pond, this led to eutrophy in pond water and brought negative effect to the water environment. Therefore, not only controlling exogenous pollution and endogenous pollution are necessary, but also improving self-purification of pond water is important. This study was designed to constract a fish-rice complex of ecosystem, discussed the rice field purification to intensive fishpond water and reparie effect of water quality; establishing a fish-vegetable culture model to explore a new aquaculture model to discuss the floating beds purification, so as to exploit in-situ repaire and ex-situ repaire of water techniques on pond's water. The main research results were as follows:1. The TN?TP?NH4+?NO3-?NO2- pourification in the recycling water aquaculture pond.Results showed that rice had high absorbing and filtering capacity, the N and P purifification were obvious:After 10 days, the NO3- concentration in recycling water pond was 0.0397 mg/L, the control ponds NO3- concentration was 0.0806 mg/L, it relative declined 50.74%; After 20 days, the NH4+ concentration in recycling water pond was 0.0642 mg/L, the control ponds NH4+ concentration was 0.2717 mg/L, it relative declined 76.37%; After 30 days, the NO2- concentration in recycling water pond was 0.0009 mg/L, the control ponds NO2- concentration was 0.0108 mg/L, it relative declined 91.67%; After 50 days, the TN concentration in recycling water pond was 0.3437 mg/L, the control ponds TN concentration was 0.8820 mg/L, it relative declined 63.07%. The efficicienty purification of rice field closely correlated with the N and P concentration.2. Ex-situ repaire of fishpond water by Fish-rice complex of ecosystem.This test conducted in 3 ponds and a rice field, ponds and rice field area were 2000 m2, they were arranged a "?" shape and constructed a fish-rice compound ecosystem. The results showed that:?The fish-rice compound ponds water quality improved, fish disease decreased, the retained profits increased 50% than traditional culture ponds.?The without fertilizing potash fertilizer, base fertilizer rice field had better removing effectively and had no significant difference between groups (P<0.05), the rice field removal rate of TN, NO2-, NH4+, TP, PO43-were 50%,70%,45%,47%,29%.?The efficicienty purification of rice field closely correlated with the N and P concentration, but had no effect of rice growth period.?Fertilization on rice field had no influence on purification on pollutant, proper fertilizer could increase rice production.3. In-situ repaire of intensive fishpond water by Ipomoea aquatica Forsskal floating-beds.Conducting 7.5% coverage of Ipomoea aquatica Forsskal on a fish pond (7000 m2) to test the application effect of floating beds on aquaculture.The results showed that:?Ipomoea aquatica Forsskal grown well on the surface of ponds, the specific yields was 16423.0 g/m2, and the floating plants removed 29672.1 g nitrogen and 3454.7 g phosphorus.?The water quality in the treatment pond was more shable than the control'sm the concentration of NH4+?NO2- in test pond was lower than control's. Howere, it observed that the test pond's TP and PO43- concentration were higher than control pond's. In experimental period, the PO43-/TP ratio were 31.2% and 33.8% (floral region and open water region) in test pond. This ratio was 18.0% in the control ponds.?Through nearly 10 months of feeding and management, the net yield of experiment pond was 37379.7 yuan, there was 1.92 times than control's.?With in the test ponds,35.0% of the input N and 34.6% of the input P were converted to the harvested fish, besides, the were 5.4% of input N and 2.6% of input P converted to the harvested plants. They were higher than the control's pond.