冻融作用对旱地土壤中不同吸附形态铵根离子的影响

摘要

[Objective] This study aimed to investigate the effect of freeze-thaw action on ammonium adsorption in dryland soil. [Method] The indoor simulation test was conducted to study the effect of freeze-thaw action on the total adsorbed amount of ammonium (water extract) and strongly-adsorbed amount of ammonium (0.01 mol/L KCl solution extract) in the dryland soil of Sanjiang Plain. [Result] Compared with linear equation, Freundlich equation could better fit the total adsorbed amount of ammonium in dryland soil ( R2 > 0. 99, SE 0.99,SE < 0. 54) the strongly-adsorbed amount of ammonium increased significantly after FTT. When the initial concentration of NH4+ increased from 0 mg/L to 200 mg/L, the adsorbed amount increased linearly from -2. 36 mg/kg to 28.81 mg/kg for FTT and from -4.25 mg/kg to 25.12 mg/kg for UFTT. The freeze-thaw action reduced the concentration of NH4+ in soil solution when the NH4+ in strong adsorption state reached the balance, therefore, it helped to reduce the leaching of ammonium ions in soil. Freeze-thaw action mainly influenced the NH4+ adsorbed in soil in ion exchange form. [Conclusion] This study provides theoretical bases for the control of excessive soil nitrogen from entering into water body and the prevention of water entrophiuation.%[目的]探讨冻融作用对土壤中不同吸附形式铵根离子的影响.[方法]通过室内模拟试验,研究了冻融作用时三江平原旱地土壤吸附铵根离子总量(水浸提)、强吸附态量(0.01 mol/L KCl溶液浸提)的影响.[结果]冻融处理和非冻融对照处理下,相比线性方程,旱地土壤吸附的铵根离子总量能更好的由Freundlich方程拟合(R2＞0.99,SE＜1.69).冻融作用对铵根离子的总吸附量基本没有影响:当土壤中加入的NH4+初始浓度从0 mg/L升高到200mg/L时,冻融条件下NH4+总吸附量从-0.52 mg/kg升高到39.0mg/kg；非冻融条件下NH4+总吸附量从-0.70mg/kg升高到38.5 mg/kg.土壤中强吸附态NH4+的吸附等温线呈线性(R2＞0.99,SE ＜0.54),强吸附态NH4+的吸附量经过冻融过程后有明显增加,当土壤中加入的NH4+初始浓度从0 mg/L升高到200 mg/L时,冻融条件下NH4+强吸附态含量从-2.36 mg/kg呈线性升高到28.81mg/kg；非冻融条件下NH4+强吸附态量从-4.25mg/kg呈线性升高到25.12 mg/kg.由于冻融作用降低了强吸附态NH4+吸附解吸达到平衡时土壤溶液中NH4+的浓度,因而有利于降低土壤中铵根离子的淋失.冻融作用主要影响的是以离子交换形式吸附于土壤的NH4+.[结论]该研究为控制土壤氮素过量输入水体,防治水体富营养化奠定了理论基础.