5Castillo M M,Allan JD,Brunzell S.Nutrient concentrations and discharge in a midwenstern agricultural catchment[J].Environ.Qual,2000,29(4):1142-1153.
6'D F Acton.The health of our soils toward sustainable agriculture in Canada[J].Saskatchewan Land Resource Unit Saskatoon,SK S7N 5A8,2001,110-135.
7Zhung W,Wang XJ.Modeling for point non-point source effluent trading:perspective of non-point sources regulation in China[J].The Science of the Total Environment,2002,292(3):167-176.
8Bohler Troud,Karatzas Kostas.Providing multimodal access to environmental data-customiable information services for disseminating urban air quality information in APNEE:Computers[J].Environment and urban systems,2002,26(11):39-61.