傍河开采驱动下潜流带氮素迁移转化的生物地球化学特征

为研究傍河开采驱动下潜流带中"三氮"迁移转化规律和氧化还原分带，通过不同时期在傍河开采条件下采集潜流带土样和水样分析三氮的转化过程及特性，并结合溶解氧和氧化还原电位及硝酸根和亚硝酸根含量和优势菌来判断其迁移转化规律与机理。结果表明:河水在入渗的过程中，首先进入处于离岸-6~1.5 m处的氧化带，O₂与有机物发生反应释放出CO₂，随后到离岸1.5~17 m处的弱氧化环境的氧化还原过渡带，在硝化细菌和反硝化菌的作用下发生硝化反应和反硝化反应，最后到离岸17~350 m处缺氧环境的还原带中，在缺氧条件下反硝化反应。优势菌对水源地氧化还原作用分带具有响应联系特征。枯水期水位低能够更加快速降低水中溶解氧DO、氨氮、硝酸盐氮，所以枯水期的氧化还原距离短，丰水期的距离稍长。在傍河开采驱动下，水动力条件随着不同时期发生改变，河水向地下水补给过程中各方面均存在差异，而这一系列的差异影响了氮素在地下介质中的迁移转化。

BIOGEOCHEMICAL CHARACTERISTICS OF NITROGEN MIGROGEN MIGRATION AND TRANSFORMATION IN SUBSURFACE FLOW BELT DRIVEN BY RIVER COLLECTION

In order to study the migration, transformation and REDOX zoning of tri-nitrogen in subsurface flow zone driven by riverside mining, soil samples and water samples were collected from subsurface flow zone in different periods of riverside collection to analyze the transformation process and characteristics of tri-nitrogen, and the migration and transformation law and mechanism were determined by combining dissolved oxygen, redox potential, nitrate and nitrite content and dominant bacteria. The results showed that in the process of infiltration, the river water firstly entered the oxidation zone in -6~1.5 m offshore, O₂ reacted with organic matters to release CO₂, then went to the oxidation-reduction transition zone of weak oxidation environment in 1.5~17 m offshore, nitration and denitrification reactions occurred under the action of nitrifying bacteria and denitrifying bacteria, and finally entered into the reduction zone of anoxic environment in 17~350 m offshore, denitrification happened under anoxic condition. The dominant bacteria had some connection and response to Redox Zoning. Low water level in dry season was conducive to reduce DO, NH₃-N and NO₃--N more quickly, so the REDOX distance was shorter in dry season and longer in wet season. Driven by riverside collection, hydrodynamic conditions changed with different periods, and there were differences in various aspects in the process of river recharge to groundwater, which affected the migration and transformation of nitrogen into underground media.