太行山低山丘陵区典型剖面土壤优先流形成机制及其对氮迁移通量的影响

农田包气带水氮迁移过程对土壤优先流的响应机制是水氮循环领域关注的热点问题。受山区岩土二元结构、含水层渗透性强的影响，包气带累积氮素易受到降水条件变化的影响以优先流形式发生快速淋失，影响山区水环境安全。太行山低山丘陵区是华北平原地下水的重要补给源区，农业过量施肥使得包气带累积大量氮素，严重威胁地下水安全。本项目拟选择代表太行山低山丘陵区典型农林生态系统的太行山站为研究基地，以刺槐林、农田和石榴林三种植被类型的典型土壤剖面为研究对象。基于野外原位观测，结合同位素示踪、水文地球化学及田间染色示踪方法，在识别优先流发育特征及影响因素的基础上，研究优先流对降水等水文条件变化的响应关系，揭示山区典型剖面土壤优先流形成机制及影响因素，阐明水文条件变化下典型剖面优先流对氮素迁移通量的影响。这不仅有助于认识降水等水文条件变化下山区包气带水氮迁移过程，也对山区和下游平原区地下水保护及水氮综合管理有重要意义。

The response mechanism of water and nitrogen migration to preferential flow in farmland of vadose zone have attained worldwide attention. Nitrogen stock in the vadose zone is easily affected by the different precipitation conditions and leached by preferential flow due to the dual soil-rock system and high permeability of aquifers, which affects water environment safety in the mountain area. The hilly region of Taihang Mountain recharge the aquifer systems of the North China Plain. Intensive fertilizer application for agriculture resulted in the increasing nitrogen storage, which poses a major threat in the future. In this project, the Hilly Ecosystem Experimental Station of Chinese Academy of Sciences was selected as the study area to study the formation mechanism of perferential flow and its controlled factors and coupling the characteristics of preferential flow pathways. The hydrological and geochemical observations in situ field, stable isotopes of water and dyeing tracer method will be combined to identify the response of hydrological processes and nitrogen migration flux to precipitation. This study will provide the implication on the management of agricultural land use and water resources of the Taihang Mountain and water environment safety of mountain and plain area. It also will be essential to understand the mechanism of water and nitrogen in regions with different precipitation conditions.