浅层排水系统降雨过程氮磷垂直迁移数值仿真

发布时间：2018-12-13 13:16

【摘要】：浅层排水系统是一种快速排出农田积水的有效设施,但其同时也改变了水分及面源污染物如氮磷在农田系统迁移的速度和途径.为了对浅层排水农田系统中的氮磷垂直迁移过程有全面了解,利用有限元分析技术对已监测的浅层排水系统单元土壤柱进行数值仿真.结果表明,在5 h 4 mm/h降雨结束后,降雨量没有达到使地表到排水管道之间土壤层完全饱和,从而使随之溶解的氮磷污染物不足以渗透到排水管,导致没有氮磷的流失.降雨时间延长至10 h后,降雨量使土壤层达到饱和,从而使溶解的污染物产生流失,其中硝酸盐的流失量明显大于磷酸盐,硝酸盐流失量为9~10 mg/L,磷酸盐流失量为0.05~0.1 mg/L.在24 h降雨事件后,排水管中硝酸盐质量分数达最大值.在降雨时间不断增加的过程中,硝酸盐流失呈指数增长,而磷酸盐只是线性增长,形成该现象的原因与污染物的本身性质有关.
[Abstract]:Shallow drainage system is an effective facility for rapid discharge of water from farmland, but it also changes the speed and path of water and non-point source pollutants such as nitrogen and phosphorus migration in farmland system. In order to understand the vertical transport process of nitrogen and phosphorus in shallow drainage farmland system, the finite element analysis technique was used to simulate the soil column of shallow drainage system unit. The results showed that after 5 h and 4 mm/h of rainfall, the rainfall did not reach the saturation of soil layer between the surface and the drainage pipe, so that the dissolved nitrogen and phosphorus pollutants were not enough to penetrate into the drainage pipe, resulting in the loss of nitrogen and phosphorus. When the rainfall time was extended to 10 hours, the soil layer was saturated by rainfall, resulting in the loss of dissolved pollutants, in which the loss of nitrate was obviously greater than that of phosphate, and the loss of nitrate was 9 ~ 10 mg/L,. Phosphate loss of 0. 05 ~ 0. 1 mg/L. After 24 h rainfall, the nitrate content in the drainage pipe reached the maximum. In the process of increasing rainfall time, nitrate loss increases exponentially, while phosphate increases linearly. The reason for this phenomenon is related to the nature of pollutants.
【作者单位】：城市水资源与水环境国家重点实验室(哈尔滨工业大学);伊利诺伊大学香槟分校农业与生物技术工程学院;
【基金】：国家自然科学基金(51179041) 水体污染控制与治理科技重大专项(2013ZX07201007) 城市水资源与水环境国家重点实验室自主课题(2014TS05)
【分类号】：X52

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