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沟渠系统“过程拦截”是现阶段农业非点源污染控制和管理的重要手段.针对当前农田排水沟渠水体-底泥-植物系统内各介质间非点源溶质迁移转化机制不清的现状,本研究以天然沟渠为对象,以非点源溶质氮为例,通过2014年3月~2015年2月现场监测试验,分析了农田排水沟渠水体及底泥中非点源溶质氮的分布特征.结果表明,沿沟渠纵向,试验沟渠水体中总氮质量浓度、底泥中总氮含量均呈现一定程度递减趋势,表现出沟渠系统对非点源溶质的净化作用;水体中总氮质量浓度、底泥中总氮含量在沟渠横断面分布存在较大不均匀性,其分布特征与断面形态、流量变化过程、流速分布等因素有关,其中水体中总氮质量浓度均衡度为76.89%,底泥中总氮含量均衡度为57.04%;试验期内,水体中总氮质量浓度呈“凹”形变化、底泥中总氮含量呈“凸”形变化,二者表现出相逆的变化趋势.
Ditch system “process interception ” is an important means of agricultural non-point source pollution control and management at present.According to the current unclear status of non-point source solute transport and transformation mechanism of various media in the farmland drainage ditch water body-sediment-plant system In this study, natural ditches were taken as an object, and non-point source solute nitrogen was taken as an example. Through field monitoring experiments from March 2014 to February 2015, the distribution characteristics of non-point source solute nitrogen in farmland drains and ditches were analyzed The results showed that along the longitudinal direction of the ditch, the total nitrogen concentration in the ditch water and the total nitrogen in the sediment all showed a decreasing trend, showing the purifying effect of the ditch system on the non-point source solute. The total nitrogen concentration, The distribution of total nitrogen in the sediment is quite heterogeneous in the cross-section of the ditches. The distribution characteristics of the total nitrogen in the sediment are related to the morphology of the cross-section, the change of flow rate and the distribution of flow velocity. The balance of total nitrogen in the sediment is 76.89% The total nitrogen content in the sediment was 57.04%. During the experiment period, the total nitrogen concentration in the water body was “concave” and the total nitrogen content in the sediment changed “convex” The trend of change.