| Pesticide is very important in agriculture production. But excessive use of high toxin pesticide will induce many environment problems. At present the primary concern of farmers is how to increase their income, but they don't care about the pollution of the pesticides; in the other hand, many farmers drink groundwater and use groundwater to cook, so to study the groundwater pollution from pesticides is very important. In the international case, especially in America and Europe, ground water pollution from pesticide leaching has been studied for many years and advanced kinds of measures. But in China, further concern is needed. This article uses PEARL(Pesticide Emission Assessment of Regional and Local area) model to simulate the fate of a pesticide in the soil-plant system. And the results conclude which pesticide is safe to the groundwater, which one is dangerous.PEARL is a one-dimensional, dynamic, multi-layer model that describes the fate of a pesticide and relevant transformation products in the soil-plant system. The model is linked with SWAP (Soil Water Atmosphere Plant) model. They are combined into same software package. SWAP model describes the process of water, whereas PEARL is pesticide added. So SWAP is the basis. From 2000 PEARL becomes the new official tool in Dutch pesticide registration procedures.Pesticides can enter the system by direct application or by atmospheric deposition. PEARL and SWAP describe the following processes: Transient state soil water flow, potential evapotranspiration, interception of water, water uptake by plant roots, evaporation of water from the soil surface, lateral discharge, heat flow, pesticide application, dissipation of pesticide from the crop canopy, convective and dispersive transport of pesticide in the liquid phase, diffusion of pesticide through the gas and liquid phases, equilibrium sorption and non-equilibrium sorption, first-order transformation kinetics, uptake of pesticide by plant roots, and volatilization of pesticide at the soil surface.The two research sites are located in Shengli and Xibei village of Sichuan province. It took one year to collect basic data because this is the first time of PEARL implicated in China. The following data were concluded: crop (root depth, plant cover and plant high at the transplant, biggest, and harvest time), daily weather information(humidity, evaporation, precipitation, wind speed, min and max temperature from 1997 to 2001), groundwater level (chose 9 wells in the two village), soil (soil texture at different soil type), pesticide (application time, original soil environment, transference range, diffusion in soil and atmosphere).Input all data in PEARL model. KOM-DT50 graphs and substance concentration in the percolate are selected to analyze.The theory of KOM-DT50 graph(KOM: the pesticide absorbability of soil; DT50: half-life of pesticide)is: if a pesticide has high KOM and short DT50,it is safe to the groundwater; if a pesticide with low KOM and long DT50, it is dangerous to the groundwater. If we know KOM and DT50 of pesticides, we can judge is it safe or dangerous from KOM-DT50 graph.11 most frequently used pesticides are selected to analyze in the KOM-DT50 graph:Youshatian-garlic: The curve of 10mg/m3 is chose to analyze. Copper Hyrdoxide, Dimethoate, Fenaminosulf. Imidachloprid, Phoxim, Streptomycin sulfate, Triazophos and Trichlorfon are safe; Metalaxyl, Carbendazim and Oxadixyl are dangerous.Nitian-garlic: The curve of 10mg/m3 is chose to analyze, copper Hyrdoxide, Dimethoate, Fenaminosulf, Imidachloprid, Phoxim, Streptomycin sulfate, Triazophos, Trichlorfon and Metalaxyl are safe; Carbendazim and Oxadixyl are dangerous.Shatian-garlic: The curve of 10mg/m3 is chose to analyze, copper Hyrdoxide, Phoxim, Streptomycin sulfate and Triazophos are safe; Dimethoate, Fenaminosulf, Trichlorfon, Metalaxyl, Imidachloprid, Carbendazim and Oxadixyl are dangerous.The conclusion is: soil type influences the pesticides leaching strongly. Shatian is the most dangerous soil type, Youshat...
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