农业面源污染负荷的产生及土壤背景参数的影响

Agricultural non-point source (NPS) pollution comes from inorganic pollutants, such as nitrogen, phosphorous or pesticide and organic pollutants in field soil. During rainfall events, these pollutants enter surface water and groundwater through overland runoff and underseepage, finally contaminate the receiving waters. Diffused pollution is now paid importance throughout the world. Long-time research results from developed countries, especially USA, indicate that water quality degradation is mainly caused by NPS pollution, among which agricultural NPS pollution is the most important. In our country, development of agricultural resources has almost exceeded the limitation because of the press of increasing population. In order to increase the product yield, the consumption of fertilizer and pesticide has been raised year after year, which inevitably adds their content in soil. It will not only result in the increment of residual chemical matter in soil, but also contaminate the receiving waters through erosion and overland runoff during rainfall events. Presently, the control of NPS pollution is focused by environmental managers. And the vital basis of water pollution control and integrated catchment management is the quantifying assessment methods of NPS pollution load and the corresponding impacts to water environment..This project made systematic and in-depth studies on the transportation and transformation principles of phosphorous and nitrogen from agricultural NPS in soil and receiving water, quantitative approaches for agricultural and urban NPS pollutant load assessment, and the effects of NPS pollutant load on surface and groundwater. And the corresponding quantitative methods were presented: prediction model for potential erosion of nutrients under the effect of soil background parameters; agricultural NPS pollutant loading model in river plain area; urban NPS pollutant loading model; one-dimension surface water receiving model, one-dimension groundwater receiving model on vertical penetration..The artificial neural network was applied for the first time in the prediction of potential erosion of phosphorous from agricultural NPS pollution. It was presented that radial basic function (RBF) using multivariable interpolation is better than back propagation (BP) in fitting. Because of the randomicity and universality of the generation of NPS, the spatial and temporal distribution of NPS pollution has been averaged in modeling for a long time, which brought uncertainties in prediction and affected the possibility of real time forecasting. It was put forward firstly that spatial and temporal distribution of pollutant load should carried out based on the concept of width of attached land area in runoff generation and confluence theory. This method has improved the simulation accuracy, and made it possible for real time simulation of surface water environment. .

农业面污染源是水体污染的主要污染源之一，其污染负荷定量化研究是控制农业面源污染的重要基础工作。本项目将通过室内、外实验，研究农田中的土粒、氮素、磷素、杀虫剂，在不同土壤性质、不同土壤水份分布等背景参数影响下，随农田地表径流而产生的污染负荷，建立农业面源产污模型。为控制农业面源污染提供科学依据。