| In recent years,Biological floating bed technology has been applied more and more widely in pond.This study adopts a new floating bed made of ceramsite,analyze the effect of comprehensive application of floating bed in pond.Finally,this study will be aimed to offer more scientific basis for aquaculture and water pollution control.The results are as follows:(1)The effects of the ceramsite floating beds on water quality were explored:From May to October in 2014,6 traditional intensive fish ponds(400m2)ware divided into two groups,Ceramsite ecological floating beds were applied in one group as the test group which with 5% coverage of the ceramsite floating beds,the other group was the control group.The results show that:water quality has been effectively controlled,mean value of the water physicochemical parameters:Transparency(SD) was 23.18 cm,CODMn was19.48mg/L,NH4+-N、NO2--N and TN ware 1.54 mg/L、0.026 mg/L and 7.16 mg/L,TP and IP ware 0.55mg/L and 0.17 mg/L.Statistical analysis showed that,the pond were significantly lower than the control group.(2)The dynamics of phytoplankton community structure and planktonic bacteria in culture ponds were studied. During the period of the investigation, a total of 189 species of phytoplankton that belonged to 8 phyla and 115 genera were identified. The mean number of phytoplankton and biomass to the floating bed group and control group showed as follows: the floating bed group was 284×106ind/ml and 234.1mg/L;the control group,288×106ind/ml and 349.3mg/L. According to the correlation analysis, there was a insignificant difference in the quantity of phytoplankton between two groups,but there was a significant difference in the ranges of biomass between the two groups. From the quantity of phytoplankton,the contribution of Chlorophyta and Cyanophyta was over 90%. From the ranges of biomass,Chlorophyta was the absolute advantage. There were significant differences in total bacterial count(BN), AWCD and diversity index between the floating bed group and control group. Throughout the breeding process,the mean of the total bacteria number and microbial activity in the pond of the floating bed showed as follows:4.02×106/ml and 0.76. Significantly higher than the control group pond. Meanwhile, the microbial richness index, evenness index and dominance index were significantly higher than those of the control group.(3)The ceramsite floating bed water purification mechanism was explored:The variation of activities of proteinase, urease, phosphatase and dehydrogenase in floating bed area 、substrate and roots of the plant and their correlation with purification efficiency of wastewater were studied. The results showed that the four enzymatic activities increased and then decreased gradually which were varied with the seasons. According to the correlation analysis,there were significant correlation between enzyme activities of floating bed area and roots of the plant; For the roots of the plant,the variations of phosphatases activities were irrelevant to the removal contribution of TP、IP and CODMn, the variations of urease activities were irrelevant to the removal contribution of TN and NO2--N, the variations of proteinase activities were irrelevant to the removal contribution of CODMn, and the variations of dehydrogenase activities were irrelevant to the removal contribution of CODMn and TN. As for the floating bed area, the variations of phosphatases activities were also irrelevant to the removal contribution of TP、IP and CODMn, the variations of urease activities were irrelevant to the removal contribution of TN and NH4+-N, the variations of proteinase activities were irrelevant to the removal contribution of CODMn,but there were no significant correlation between dehydrogenase activities which was in the floating bed area and removal rates of CODMn and TN.(3)The comprehensive benefits in pond culture in the process of ceramsite floating bed was explored:Pond effect has been strengthened,survival rate of Carassius auratus in the treatment pond was 92.3%, and fish size 321.4g each, Carassius auratus production reached 11112.8kg/hm2, Total fish production reached 14415.2 kg/hm2,significantly higher than that of the control pond. Floating bed group pond input-output ratio is 1.13, the control group was only 1.01.the impact on the surrounding environment has been reduced,in the end of breeding.Compared to the traditional culture, floating bed group nitrogen emissions has been reduced by 20.5% and 17.6% reduction of phosphorus.In addition, pond floating bed after finishing, nitrogen, phosphorus of sediment than that of the control group were decreased by 22.9%, 11.9%.In conclusion, as a new farming methods ceramsite floating bed cultivation mode can improve water quality, improve fish survival and growth rates, increasing farming income and energy-saving emission reduction. |
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