地下水中铵态氮的迁移转化过程

Transport and Transformation of Ammonium in Groundwater

铵态氮进入地下水的主要途径是土壤淋失,通过室内土柱淋滤实验研究铵态氮在土壤中的迁移转化过程,测定不同时间和不同深度土壤中铵态氮及其转化物硝态氮和亚硝态氮的浓度变化,分析了影响铵态氮迁移转化的因素。实验表明:在土壤饱和、持续淋滤条件下,土柱中随采样深度的增加,铵态氮穿透时间延长,依次滞后;通过硝化能力分析,土柱上层发生了轻微的硝化反应,土柱底部发生了反硝化反应,导致硝态氮的浓度衰减。研究认为在铵态氮的迁移转化过程中,当入渗铵态氮浓度较低时,影响铵态氮迁移转化的显著因素是土壤对铵态氮的吸附;当入渗铵态氮浓度较大时,影响铵态氮迁移转化的显著因素是生物作用导致的铵态氮的硝化,以及土壤的渗透系数、弥散度等因素。

The primary sources of ammonium in groundwater are leak and leaching in soil.Through soil-column leaching experiments in laboratory,characteristics of NH4＋-N migration and transformation in different types of soils were studied and concentrations of NO3——N,NO2——N,NH4＋-N in solution sampled from different depths in the soils-column at different times were detected to research the influence factor on ammonium nitrogen transport and transformation.The column test showed that under the saturated conditions,the NH4Cl was continuous injected to soil-column,the lower level of the soil,the longer of breakthrough time of ammonium.By analyzing nitrification ability,it was found that slight nitration reaction occurs on the upper layer of the soil column and denitrification reaction occurs on the bottom of the soil column,which makes the concentration of NO3——N to lower.In the process of ammonium nitrogen transport and transformation,when the infiltration ammonium concentration is low,the main factor that affects ammonium transport and transformation is the adsorption properties.When the infiltration ammonium concentration is high,the main factors are nitration of ammonium nitrogen by biological actions,dispersivity and permeability of the soil.