黄土高塬沟壑区不同坡位和植被下的土壤硝态氮特征研究

发布时间：2018-06-05 09:00

本文选题：植被类型 + 黄土坡地　；参考：《环境科学学报》2017年06期

【摘要】：地形和植被会改变水分在土壤中的运移,进而影响土壤中硝态氮(NO_3~--N)的分布,并可能导致对水体污染的差异.在黄土高塬沟壑区黑河流域选取3个样点,采集刺槐林和草地在不同坡位(上、中和下坡位)的6 m深土样,分析了坡位和植被对NO_3~--N迁移的影响,并初步评估了其对地表水及地下水污染的潜在风险.不同坡位及植被条件下,土壤中硝态氮均没有出现累积,在表层土壤达到最大值后逐渐减小.2种植被下NO_3~--N达到稳定时的深度约为200 cm,稳定浓度均为下坡位上坡位中坡位,但在同一坡位的稳定浓度均有草地高于刺槐林的特点,说明坡位及植被覆盖类型均会影响NO_3~--N在土壤中的分布.整个流域地表水NO-3含量枯水期及汛期分别为(6.90±2.10)mg·L~(-1)和(5.84±2.86)mg·L~(-1),而坡地表层土壤(0~20 cm)中可移动态NO_3~-为(29.55±6.59)mg·L~(-1),明显大于地表水中的浓度,很有可能随径流流失造成地表水氮素污染.地下水枯水期和汛期的NO_3~-含量分别为(24.61±23.72)mg·L~(-1)和(15.70±10.78)mg·L~(-1),而坡地深层土壤(200 cm)中NO-3为(0.78±0.16)mg·L~(-1),由于浓度较低,对地下水造成污染的可能性较小.
[Abstract]:Topography and vegetation will change the movement of water in soil, and then affect the distribution of NO3- N in soil, which may lead to the difference of water pollution. In the Heihe River Basin of the Loess Plateau and gully region, the samples of 6 m deep soil from Robinia pseudoacacia forest and grassland in different slope positions (upper, middle and lower) were collected, and the effects of slope position and vegetation on no _ 3--N migration were analyzed. The potential risk of surface water and groundwater pollution was preliminarily evaluated. Under different slope positions and vegetation conditions, no accumulation of nitrate nitrogen in soil was observed. After the topsoil reached the maximum value, the depth of NO3- N under planting cover was about 200 cm, and the stable concentration was at the middle slope position in the upper slope position of the downhill position, and the concentration of nitrate nitrogen in the soil decreased gradually after the surface soil reached the maximum value, and the depth of NO3- N under the soil cover was about 200 cm. But the stable concentration in the same slope was higher than that in the Robinia pseudoacacia forest, indicating that both the slope position and the vegetation cover type would affect the distribution of NO3- -N in the soil. The contents of no-3 in the surface water of the whole basin were 6.90 卤2.10)mg / L ~ (-1) and 5.84 卤2.86)mg / L ~ (-1) respectively during the dry season and flood season respectively, while the movable no _ 3 ~ (3 +) was 29.55 卤6.59)mg / L ~ (-1) in the topsoil soil of sloping land, which was obviously higher than that in the surface water, and it was very likely that the surface water could be polluted by nitrogen with runoff. The contents of NO3- in groundwater during dry season and flood season are 24.61 卤23.72)mg / L ~ (-1) and 15.70 卤10.78)mg / L ~ (-1), respectively, while in the deep soil of sloping land, the content of no ~ (- 3) is 0.78 卤0.16)mg / L ~ (-1), so the possibility of groundwater pollution is low because of its low concentration.
【作者单位】：西北农林科技大学资源环境学院;西北农林科技大学黄土高原土壤侵蚀与旱地农业国家重点实验室;
【基金】：国家自然科学基金(No.51179161) 中央高校基本科研业务费专项(No.2452015105)~~
【分类号】：S153.6;X52

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