Establishment and application of source/sink-based agricultural non-point source pollution model

Improving control standards of point (PSP) and non-point (NSP) source pollutions are recent highlights of water and environmental issues. Agricultural non-point source pollution (AGNSP) problems caused especially by heavy use of chemical fertilizers and pesticides are prominent in this regard. Quantitative research on pollution loads is the basis of control standard, evaluation and management of AGNSP. Using AGNSP and unit-load characteristics, an AGNSP model was developed that uses source/sinks modules determine the complex migration routes of pollutants. The source module was further divided into farmland irrigation drainage and farmland contaminant concentration estimation sub-modules. The sink module was also divided into farmland drainage and pollutant migration/transformation sub-modules. By integrating the modules, a complete AGNSP load model was therefore established. The integrated AGNSP model was tested in the Qingtongxia Irrigation District (QID) in upstream reaches of the Yellow River. The 2008 crop pattern was used in the developed AGNSP model to simulate AGNSP load and output in QID. Based on the simulation results, salinity, total phosphorus, total nitrogen, nitrate nitrogen and ammonia nitrogen in QID were 470 099 t, 98.17 t, 3 593 t, 2 122 t and 426 t, respectively. The application of the established AGNSP model indicated that the model presented preferable simulated results, and was practicable in the similar studies.