滨海旱作盐化潮土铵氮吸附特性研究

Characteristics of Ammonium Nitrogen Adsorption on Salinized FluvoAquic Soils in Coastal Dry Croplands

苏北滨海地区盐碱性土壤通过耕作措施进行了长期改良,探讨铵氮在该类型土壤中的吸附特性对防控盐碱土区域氮素流失风险具有重要意义。选取苏北平原滨海地区典型盐化潮土,开展了铵氮吸附特性室内模拟研究,描述吸附等温过程,探讨初始浓度和p H的影响,揭示铵氮吸附的动力学和热力学特征。结果表明:铵氮平衡吸附变化满足Langmuir吸附等温式,以单分子层电性吸附模式为主;吸附过程符合Elovich方程;溶液初始浓度越大、p H越高、温度越低,铵氮吸附量越大,但吸附速率降低;热力学参数估算显示该吸附是放热过程,初始浓度增加,吸附需克服的能垒越高。

In the coastal area of northern Jiangsu Province, the salinized fluvo-aquic soil has been amended for a long period through implementing of cultivating measures. It is pivotal to elucidate the characteristics of ammonium nitrogen adsorption on the salinized fluvo-aquic soil for control of nitrogen loss risk. Typical salinized fluvo-aquic soil samples were collected to conduct the laboratory experiments on ammonium nitrogen adsorption. The processes of adsorption isotherm were described,and effects of initial concentration and p H were revealed. Subsequently, kinetic and thermodynamic characteristics were illu-minated. Results showed that equilibrium adsorption of ammonium nitrogen is in accordance with Langmuir isotherm, indicat-ing the adsorption mode is mainly the single molecular layer electrical adsorption. The adsorption process fits the Elovich e-quation well. Increases in the initial concentration and p H of solutions and decrease in temperature could enhance the adsorp-tion amount of ammonium nitrogen, while suppress adsorption rates. The thermodynamic parameter estimation reveals that the adsorption is an exothermic process. Higher energy barrier needs to be overcome as initial concentration rises.