摘要
本文运用非饱和土壤中水分运动和溶质运移基本理论,建立了非饱和土壤中农药运移的数值模拟模型。模型中考虑了农药在土壤中迁移与转化的主要过程:附土壤水分的对流;水动力弥散;土壤吸附及生物化学降解等。模型得到了室内土柱中灭幼脲-Ⅲ号杀虫剂淋溶试验的验证。文中分析了各种因素对该农药存土壤中迁移的影响,并且对两种不同的农药进行了比较。研究表明,在本文所研究的条件下影响农药在土壤中迁移与转化的主要因素是土壤吸附和农药在土壤中的降解。
It is desirable to be able to estimate the fate of a pesticide applied to the agricultural fields. The widespread nature of pesticides contamination makes the problem difficult because it is not as a 'point source' that can be isolated and controlled. The fate is determined by a number of environmental processes, many of which operate in the unsaturated zone of soil. A mathematical simulation technique has been developed to evaluate pesticide leaching potential.A model of the pesticide transport and transfer in the unsaturated soil is presented The model is described according to the basic principles of water and solute movement under transient condition, in consideration of pesticide advection, diffusion, dispersion, sorption and degradation. A hybrid finite-differencing procedure provided substential flexibility of initial and boundary conditions. The water conductivity and diffusion rate of the unsaturated soil sample were measured. The regularities of adsorption and degradation of CCU [1-(4-chlorophenyl)-3-(2-cholobenzoyl)urea] in the soil sample were studied by the experiments in laboratory. The model has been tested for CCU using data from the leaching experiments of soil columns in laboratory. The influence factors, such as initial soil water contents, rainfall, irrigation, pesticide adsorption and degradation were analyzed. The transport and transfer regularities of two kind of pesticides in the same soil under unsaturated condition were compared.The results indicate that the leaching depth of CCU in both of the two kind soil was samll, and CCU had a little threat to groundwater, but it could cause the pollution by the erasion of top soil. Adsorption and degradation had more influnce than the other factors under the conditions in the study. Adsorption and degradation determine the transport and transfer in unsaturated soils.The modeling approach can provide reliable and useful estimations of the pesticide transport and transfer in unsaturated soil. It also can be expanded to predict the fate of pesticide under field condition and to provide fundamental insights into the management processes.
出处
《土壤学报》
CAS
CSCD
北大核心
1992年第4期383-391,共9页
Acta Pedologica Sinica
关键词
农药
迁移与转化
数学模型
Pesticide, Transport and transfer, Mathematical simulation
