稻田空间分布格局对三峡库区农业小流域径流氮排放的影响

发布时间：2018-05-16 16:45

  本文选题：三峡库区 + 面源污染　； 参考：《西南大学学报(自然科学版)》2017年06期

【摘要】：对三峡库区涪陵段两个毗邻集水域的汇水口径流进行了持续1年的高频(每日)采样监测,以对比分析稻田空间分布格局对径流氮素质量浓度和输出强度的影响.所选择的两个集水域稻田面积比例相近,但其中一个(记为A)的稻田分布零散,破碎度高,另一个(记为B)的稻田则连片分布在其末(底)端,破碎度低.结果表明两集水域不同作物生长季径流氮素的输出均以硝态氮为主(占总氮的60%~81%).对比两个集水域,A在全年和不同作物生长季的径流氮素平均质量浓度都相应地高于B.同样,集水域A的年径流量(1 431 m3/hm2)显著高于集水域B(840 m3/hm2),因而前者径流总氮的年输出通量(16.1kg/hm2)远大于后者(5.21kg/hm2).鉴于两个集水域的气候、土壤类型、地形地貌和农田耕作管理方式相同,单位土地面积的施肥量以及稻田面积比例也相近,只是稻田空间分布格局迥异,汇水口径流氮素的质量浓度和输出通量的差异显然是由于集水域末端连片分布的人工湿地—稻田比零散分布的稻田对集水域内的径流及随其迁移的氮素有更佳的拦截和净化作用所致.
[Abstract]:The high frequency (daily) sampling of two adjacent catchments in Fuling section of the three Gorges Reservoir area was carried out for one year to compare and analyze the effect of the spatial distribution pattern of paddy field on the nitrogen concentration and output intensity of runoff. The proportion of rice field area in the two collected waters was similar, but one rice field (A) was scattered and the fragmentation was high, while the other (B) rice field was distributed at the end (bottom) end of rice field with low degree of fragmentation. The results showed that the output of nitrogen in runoff of different crop growing seasons was mainly nitrate nitrogen (accounting for 60% of total nitrogen). The average nitrogen concentration in runoff of two catchment waters was higher than that of B. Similarly, the annual runoff of catchment A is 1 431 m3 / hm 2) significantly higher than that of BX 840 m 3 / hm 2, so the annual output flux of total nitrogen in runoff of the former is much higher than that of the latter (5. 21 kg / hm 2 路hm 2). In view of the same climate, soil type, landform and farmland tillage management, the fertilization amount per unit land area and the proportion of rice field area are similar, but the spatial distribution pattern of rice field is very different. The difference of mass concentration and output flux of nitrogen in the catchment is obviously due to the fact that the constructed wetland with continuous distribution at the end of the catchment water is better than the scattered paddy field in runoff and nitrogen transport in the catchment area. As a result of interception and purification.
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