Ammonium-rich pore water will release from clayey sediments into adjacent aquifers during aquitards compaction, which can adversely affect groundwater quality. Differences in the rate of groundwater exploitation can lead to differences in the rate of compaction of aquitards, which may, to some extent, affect the release of chemical components of the pore water from the aquitard. However, the effect of the compaction rate of aquitards on the process of ammonium release from clayey sediments is poorly understood. Three groups of indoor compaction experiments were conducted to identify the effect of compaction rate on ammonium release from clayey sediments during compaction. The results showed that the compaction rate and sediment liquid limit exert a clear controlling effect on the release rate and internal change process of ammonium in clayey sediments. The increase in the ammonium release rate was approximately proportional to the increase in the compaction rate. When the moisture content of the clayey sediments exceeds the liquid limit, the ammonium concentration in pore water increases mainly due to the mineralization of organic matter containing nitrogen and the dissolution of the carbonate-bound ammonium. When the moisture content drops to the liquid limit, the ammonium concentration in pore water begins to decrease. Because the increase in the compaction rate weakened sediment mineralization and accelerated pore water release, the main forms of ammonium released from the sediment change from organic sulfide-bound ammonium and carbonate-bound ammonium to carbonate-bound ammonium and ion-exchanged ammonium. The results of this study have important significance for the management of groundwater quality in groundwater exploitation areas.

中文翻译：

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压实率对粘土沉积物铵释放影响的定量表征

在弱透水层压实过程中，富含铵的孔隙水将从粘土沉积物释放到邻近的含水层中，这会对地下水质量产生不利影响。地下水开采速度的差异会导致弱透水层压实速度的差异，从而在一定程度上影响弱透水层孔隙水化学成分的释放。然而，弱透水层的压实率对粘土沉积物中铵释放过程的影响知之甚少。进行了三组室内压实实验，以确定压实速率对压实过程中粘土沉积物铵释放的影响。结果表明，压实率和沉积物液限对粘土沉积物中铵的释放速率和内部变化过程有明显的控制作用。铵释放率的增加与压实率的增加大致成正比。当粘土沉积物的含水量超过液限时，孔隙水中的铵浓度增加，主要是由于含氮有机质的矿化和碳酸盐结合铵的溶解。当含水率下降到液限时，孔隙水中的铵浓度开始下降。由于压实率的增加减弱了沉积物矿化作用，加速了孔隙水的释放，沉积物释放的铵主要形态由有机硫化物结合铵和碳酸盐结合铵转变为碳酸盐结合铵和离子交换铵。本研究结果对地下水开采区地下水水质管理具有重要意义。