| The aim of this study was to research the effect of Salix saposhnikovii on the depuration of polluted water and nutritional requirements for the growth of Wolffia globosa.Experiments1:In order to analyze the purification effects of Salix saposhnikovii which were planted under different time, we planted Salix saposhnikovii in two groups, including half year group(HY group) and half month group(HM group), in static simulated wetland environment. The removal rates of the NH4-N, NO3were tested and the results showed that Salix saposhnikovii have significantly high removal rates of nitrogen in polluted water. After one day, the removal rate of NH4-N in the half year, in the half month group and in the control group was91%,67%,59.5%. The removal rate of HY group were significantly larger than control group(P<0.05). After one day, the removal rate of NO3-N in the half year group, half month group and in the control group were45.6%、26.5%、26.5%.In order to analyze the purification effects of Salix saposhnikovii which were planted in different amount, we planted Salix saposhnikovii in three groups, including three trees group, six trees group and nine trees group. After one day, the removal rate of NH4-N in the three trees group, six trees group, nine trees group and the control group were77%、95.5%、97%、39.5%. At the same time, the removal rate of NO3-N in the three trees group, six trees group, nine trees group and the control group were30.9%、51.5%、75%、22.1%.The removal rate of NH4-N in all of experiment groups were significantly larger than control group(P<0.05).The more shrub willow was planted, the more removal rate of NO3-N in the experimental group. The result showed that the removal rate of Nitrogen by the six trees group was best. The best planting density was17trees/m2(6tree/box) and the shortest purification time was one day.Experiments2:The aim of this study was to research the effect of Salix saposhnikovii on the survival and growth of juvenile Procambarus clarkii, including the Procambarus clarkii’s survival rate, the increase of body length and the coefficient of variation in body length. What’s more, the Procambarus clarkii’s survival rate and the purification rate of ammoniacal nitrogen were also analyzed after that the bigger Procambarus clarkii were put into two levels of waste water with shrub willow. The results showed that the Procambarus clarkii’s survival and the increase of body length were significantly more than control group (P<0.05) cultured under the common laboratory condition with aerated water, besides the coefficient of variation in the Procambarus clarkii’s body length were not significantly (Experiment I).In Experiment IIa, the Procambarus clarkii’s survival rate and the purification rate of ammoniacal nitrogen in the group with shrub willow were significantly than control group(P<0.05) while the concentration of ammoniacal nitrogen in the wastewater was2mg/L. In Experiment lIb, the Procambarus clarkii’s survival in the group with Salix saposhnikovii were significantly more than control group(P<0.05)except that the purification rate of ammoniacal nitrogen were not significantly while the concentration of ammoniacal nitrogen in the wastewater was l0mg/L. The studies concluded that:Salix saposhnikovii can significantly improve the survival and growth of juvenile Procambarus clarkii. And the range of purification in ammoniacal nitrogen by shrub willow was between2mg/L to1Omg/L.Experiments3:This study was to analyze the nutrient demand (several nutrient element demand) for the growth of Wolffia globosa with the aim to provide references for the improvement on the formula of nutrient solution for the cultivation of Wolffia globosa. The basic conditions of the pond were simulated in the greenhouse, and nutrient solution was added to cultivate Wolffia globosa. The main element compositions of the experimental water, wild water and dried Wolffia globosa were detected by inductively coupled plasma spectrometer(ICP) and element analyzer, in order to study the nutrient demand for Wolffia globosa’s growth. And the absorption of N, P, K and consumption of P for the growth of Wolffia globosa were also analyzed. The Wolffia globosa biomass of the experimental group which cultivated by adding nutrient solution increased over time, and after2weeks, the average capacity was significantly more than initial capacity; and the average capacity of the control group without nutrient solution was significantly lower than initial capacity, indicating that the addition of nutrient solution has obvious effect on the growth of Wolffia globosa. However, the biomass of the experimental group was no longer increase after2weeks, indicating that there are some inhibitory factors in the incubators of the experimental group. The element detection results were as follows:the content proportions of N, P and K were3.8:1:2.8,11.5:1:17and5.2:1:6.8in the experimental water, wild water and drying Wolffia globosa, respectively. The N, P, K in the water of experimental group was not exhausted, while the contents of Ca and Zn in three experimental incubators were below the limit of detection (ND). And the contents of Mn in incubators No.1-3were ND,0.05mg/L and0.38mg/L. The inhibitory growth of Wolffia globosa is closely related with the absence of Ca, Mn and Zn in the nutrient solution. The experimental results provided valuable parameters for the improvement on the formula of the original nutrient solution.Experiments4:This study was to research several nutrient elements demand for Wolffia globosa’s growth in hydroponic conditions. Methods:nutrient solution was added to cultivate Wolffia globosa. We analyze the growth of Wolffia globosa and detect the nutrients of water in the end of growth cycle by ICP. Results:Biomass of Wolffia globosa increases over time, and the K values of nutrition groups which have nutrient solution are much higher than those control groups which don’t have nutrient solution. The Ca, Ba, Sr in the water of experimental group was lower than the control group. Through analysis the ICP report, we found that the inhibitory growth of Wolffia globosa is closely related with the absence of Ca. Furthermore, when Ca is absence in the water, Wolffia globosa could use Ba, Sr instead. |
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