Research On Transport And Transformation Law Of Agricultural Nonpoint Source Pollution

As point source pollution is controlled strictly in developed country, nonpoint source pollution research has been paid more and more attention. It has been researched since 1980's in home, and now it becomes a research hotpot. Based on the developed research at home and outside, this paper research the transport and transformation law of nonpoint pollution by using the large-scale box of state key laboratory of Hydrology-Water Resources and Hydraulic Engineering of Hohai University. There have been 9 artificial rains and more than 3300 times water and soil chemic analyze experimentation in the time of one and a half year. The researches are useful in the study of agricultural non point pollution and offer scientific help to control agricultural nonpoint pollution and eutrophication of Taihu Lake. The content can be summarized as follows:1) According to the research status of nonpoint pollution at present, design alarge-scale box plan and apply it to study of nonpoint pollution.2) According to the soil character, setup a runoff erode model based on the theory of unit runoff power. Test the model with measured produces and process of the ninth rain, the different of the calculate value and the measured value less than 10%.3) Research the law of transport and transformation of nitrogen. Indicate thecharacter of nitric cycle and the nitric study level presently. There is an absorbent water layer outside of the soil particle which is meaningful to the release of nutriment. Derive the adsorption isotherm from the principle of phase equilibrium. At last deduce a concentration formula of runoff based on the nutrition balance on the interface of absorbent water layer. Infiltration is calculated with Green-Ampt model. Regress the load of nitrate, ammonium and total nitrogen by MQ equation. Put forward a concept of soil alive index, measure the value of tested soil and apply it to calculate mineralization of nitrogen, compare the result with measured value. Conclude the factors influencing nitrogen transport and transformation.4) Research the law of transport and transformation of phosphor. Indicate the character of phosphoric cycle and the phosphoric study level presently. Calculate the concentration of dissolved phosphate in runoff, compare the result with measured value. Regress the load of dissolved phosphate and total phosphor by MQ equation. Calculate phosphoric enrichment ratio. Total phosphoric load in the runoff is compared with that in the sand, compare fertilization effect with the two boxes. Calculate mineralization of phosphor with soil alive index. Conclude the factors influencing phosphor transport and transformation.