农田气象条件下阿特拉津在土壤中淋溶动态的数值模拟

阿特拉津(Atrazine)是我国华北地区夏玉米田常用的除草剂,而夏玉米生育期又是该地区的主要降雨时段,对这一时段Atrazine在田间尺度的淋溶风险进行评价,对保护浅层地下水环境具有重要意义。以北京市通州区永乐店试验站一块27 m×27 m的农田为背景,通过田间采样、测试分析土壤样品并收集2001年的气象数据,基于简化土壤水三维流场的柱模型假设,在同时考虑土壤水力学参数、Atrazine运移和吸附参数空间变异性的情况下,对该农药在农田尺度下淋溶动态的空间分布进行了数值模拟。在此基础上,对夏玉米不同生育期耕层20 cm深度处的土壤水负压、水流通量和Atrazine浓度的空间变异结构进行了地质统计学分析。结果表明,在整个夏玉米生育期内这三个参量的半方差模型基本上为球状模型,它们的变程多在8~10 m。本研究案例对布设农田尺度土壤水分和Atrazine动态监控网具有一定的参考意义。

NUMERICAL SIMULATION OF ATRAZINE LEACHING IN SOILS UNDER AGRICULTURAL METEOROLOGICAL CONDITION

Atrazine is an herbicide commonly used on summer maize throughout North China,where the growing period of summer maize coincides with the rainy season.It is,therefore,of great significance to protection of the shallow groundwater environment to assess leaching risk of atrazine at filed scale.In this study,with a small agricultural plot (27 m 27 m) at Yongledian Experimental Station,Tongzhou District,Beijing as background,soil samples were collected and analyzed for soil physicochmical propert ies and the meteorological data of the year of 2001 were gathered.On such a basis and the assumption of column model,numerical simulations of the spatial distribution of atrazine leached dynamics at field scale were conducted with spatial variability of the soil hydraulic parameters and the atrazine transport and adsorption parameters taken into account.And then geostatistical analysis was carried out of spatial variance structure of soil water negative pressure,water flux and atrazine concentration at 20 cm depth during the growing stage of summer maize.Results show that,variograms of the three variables during the summer maize growing season were basically spherical models,and most variograms had ranges about 8 to 10 m.This approach of the study can be used as reference in designing and laying out a monitoring network for water movement and atrazine transport at field scale.