不同盐碱化土壤对NH4+吸附特性研究

为探求NH₄⁺在不同盐碱化土壤中吸附特性的变化规律，采用平衡吸附法分别从吸附行为与影响因素探究氮素在轻度、中度、重度盐碱化土壤中的吸附效果。结果表明： 3种供试土壤对NH₄⁺的吸附量随盐碱化程度的加深而增大，平衡吸附量为：重度盐碱化土壤 > 中度盐碱化土壤 > 轻度盐碱化土壤，吸附过程符合Langmuir吸附模型；准二级动力学方程能更好地描述不同盐碱化程度土壤对铵态氮吸附过程，吸附平衡时间为720 min；3种供试土壤对铵态氮的吸附反应均是自发、放热及混乱度增加的过程；背景液pH（3.0~9.0）范围内，3种供试土壤对铵态氮的吸附量随pH值上升而增大；添加不同浓度的Na⁺、Ca²⁺、Al³⁺溶液，3种供试土壤对铵态氮的吸附量随离子浓度的增加而减少。研究表明，提高溶液pH值能增强盐碱土对铵态氮的吸附能力；温度、离子价态增加则不利于吸附，土壤盐碱化程度提高，对铵态氮的吸附能力有所增强，限制了铵态氮的迁移，污染风险有所降低。

NH4+ adsorption characteristics of different saline soils

The equilibrium adsorption method was used to investigate the effects of mild, moderate, and severe saline-alkaline soils on nitrogen adsorption and influencing factors to explore the changing law of NH₄⁺ adsorption characteristics in different salinized soils. The results showed that the adsorption capacity of NH₄⁺ in soils with three different degrees of salinization increased with the depth of salinization. The equilibrium adsorption capacity was:severe salinized soil > moderately saline soil > lightly saline soil. The adsorption process conformed to the Langmuir adsorption model; the Pseudo-second-order kinetic model better describes the adsorption process of ammonium nitrogen on soils with different degrees of salinization, and the adsorption equilibrium time was 720 min. The adsorption reaction of three types of test soils on ammonium nitrogen were processes of spontaneous, exothermic, and chaotic increase; In the pH range (3.0~9.0)of the background liquid, the adsorption of ammonium nitrogen by the three types of test soils increased as pH increased. The adsorption of ammonium nitrogen in soil with different degrees of salinization decreased with increasing ion concentration with the addition of different concentrations of Na⁺, Ca²⁺, and Al³⁺ solutions. Increasing the pH of the solution could enhance the ammonium nitrogen adsorption capacity of saline-alkali soil, and the increase in temperature and ion valence was not conducive to adsorption, because the degree of soil salinization was increased, and the adsorption capacity for ammonium nitrogen was enhanced. This limited the migration of ammonium nitrogen reducing the risk of pollution.