Study On The Contents Of Total Nitrogen, Total Phosphorus And The Balance Of Nitrogen And Phosphorus In Three-dimensional Ecosystem Of Freshwater Pearl Culture

In this study,8,000acres of freshwater pearl farm in Qiaomai lake was investigated in the summer and winter from2010to2011. The pearl farms was divided into three regions, respectively is pearl farming area (southern edge area and central area), rice purification area and control area out of the farms. The TN, TP contents of the water, sediment, plants, rice samples and the algae, chlorophyll-a contents of the water which from the three regions, were analyzed. The results are as follows:(1) The nutrition index of sampling points in Pearl farming sites of Qiaomai lake were between50-63, the water is light eutrophication and moderate eutrophication state. The average of TN wasl.135mg/L in the water, change the value of the range of0.65-1.75mg/L. The annual average of TP was0.154mg/L, and changes in the value range of0.132-0.168mg/L. The algae, TN and TP concentration is related to positively. N, P is the main nutrient elements of the breeding farms algae growth, so, the areas with high content of TN, TP content the phytoplankton species is relatively high.(2) The sediment of TN, TP in terms of distribution space from the south to the north was on the decline. With seasonal fluctuations TN has no significant change, but compared with summer, TP content in the winter has a downward trend. The highest content of TP appear in the summer was1.64mg/g, and the lowest value in winter was0.26mg/g. TN, TP concentrations and chlorophyll a concentration was positively correlated in farm sediment.(3) Compared with the central of farms, the sediment repaired by the rice in breeding farms was reduced. The TN was reduction31.6%, TP was reduction45.1%, shows that after three-dimensional culture and rice cultivation on the ecosystem the TN, TP of sediment were repaired.(4) Under the polyculture mode, the total amount of farms nitrogen, phosphorus input were558kg/hm2,422.4kg/hm2, which feed the farms of nitrogen, phosphorus and the main form of income, the proportion of81.5%and94.7%. Breeding farms harvest aquaculture biological nitrogen expenditure accounted for66.1%of the nitrogen of the total expenditure, the main form of the farm nitrogen spending. Phosphorus spending while other means spending more, followed by breeding biological phosphorus expenditures, accounting for21.4%of the total.