农田生态系统中除草剂阿特拉津的环境行为及其模型研究进展

阿特拉津是世界范围内广泛使用的除草剂,在曾经使用阿特拉津的国家的地下水、河流和湖泊中已经检测到阿特拉津的残留,长期暴露在该有机污染物的环境中,势必对动物的生殖与繁衍及人体的健康产生不良影响。介绍了阿特拉津国内外的研究情况,着重评述了阿特拉津的吸附机制与影响因素、化学降解、生物降解、生态毒理学评价以及模型对其环境行为的描述,目的旨在帮助理解田间阿特拉津迁移机制及其如何污染地下水。农田生态系统中阿特拉津的迁移规律决定其环境行为,它是进行环境和健康风险评价的基础,目前应用较多的迁移模型是经典的对流-扩散方程,该模型已广泛运用于水-土系统中化学物质的迁移,且室内模拟的实验结果能较好解释田间现象,因此,开展阿特拉津在稳定流场饱和/非饱和室内土柱中的混合置换实验及批量平衡吸附实验,可获得反映阿特拉津迁移的穿透曲线特性及阿特拉津吸附性能的分配系数,结合数学模型拟合阿特拉津在土壤中非平衡迁移曲线,用拟合参数预测不同深度土壤中阿特拉津浓度变化和累积淋溶量动态规律,应该是今后研究工作的重点。

Research advance of environmental fate of herbicide atrazine and model fitting in farmland ecosystem

Among the postemergent herbicides,atrazine(2-chloro-4-ethylamino-6-isopropylamino-1,3,5-s-triazine) is the most commonly applied worldwide to control broadleaf and grassy weeds on both agricultural and non-agricultural land.It is,unfortunately,also very widely detected in surface water,subsurface water,and groundwater in the countries where it has been used.Due to long-term and chronic exposure to groundwater supplies,the presence of atrazine in groundwater underlying agricultural regions causes the potential animal reproductive and human health problems.This paper introduces advances in the domestic and international use of atrazine.It also provides a key review concerning atrazine's absorptive mechanism and influential factors(such as pH,soil organic matter,temperature,agricultural management practice,etc.),its chemical and biological degradation,its eco-toxicological assessment,and its closeness of fit with the CXTFIT mathematical model.The primary objectives for introducing progress in atrazine research are two fold.First,an evaluation of the potential for atrazine to contaminate groundwater requires an understanding of transport mechanisms that occur in the field,and second an understanding of the behavior of atrazine is required for the evaluation of environmental and health risks. Analytical solutions to the classical convection-dispersion equation(CDE),or alternative equations,have been widely used as models of chemical transport in the soil-water system.Although such models are limited to steady-state water flow conditions in homogeneous soils,they are especially useful for interpreting laboratory experiments.In fact,valuable information has been gained through their use.Transport regulation also governs the environmental behavior of atrazine in a farmland ecosystem.Physical and chemical nonequilibrium conditions can accelerate contaminant transport and have important consequences on the fate of atrazine.Under steady-state and saturated or unsaturated flow rate conditions,miscible displacement experiments and equilibrium adsorption batch experiments in a soil column indoors can be conducted to acquire breakthrough curves(BTCs) that reflect the characteristics of atriazine transport and to depict the partitioning coefficient of atrazine adsorption to a soil.Also application of a mathematical model to atrazine transport in the farmland ecosystems' soils can be used to fit nonequilibrium BTCs in order to acquire atrazine's quantitative cognition of the transport mechanism.Then parameters that the mathematical model simulates can be applied to predict the concentration variability and determine the amount of atrazine leached at different depths of the farmland ecosystems' soils.This should be key to future research work.