Adsorption/Desorption Behavior of NH4-N under Surface Water-Groundwater Interaction and Its Impact on N Migration and Transformation
The migration and transformation of NH4-N are influenced by the interactions between surface water and groundwater.However,the mechanisms remain poorly understood.Continuous monitoring of the water level and its hydrochemical composition was conducted in the Shahu site.Column experiments and reactive transport modeling were applied to identify the migration and transformation of NH4-N under conditions of both surface water recharge and groundwater discharge.In this study it indicates that most injected NH4-N is adsorbed on shallow sediment.Infiltration of surface water enhances desorption of NH4-N from sediment particle and subsequent nitrification reactions.In contrast,adsorption of NH4-N on sediment is favored during discharge of NH4-N containing groundwater.Simulating results emphasize the crucial role of cation exchange in NH4-N mobility.Alterations in the hydrogeochemical environment during surface water-groundwater interactions impact the NH4-N adsorption/desorption behaviors and associated biogeochemical reactions.
ammonium nitrogenion exchangereactive transport modelingsurface watergroundwaterJianghan Plainhydrogeology