冻融作用对旱地土壤中不同吸附形态铵根离子的影响

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,研究了冻融作用对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(R20.99,SE1.69)。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200 mg/L时,冻融条件下NH4+总吸附量从-0.52 mg/kg升高到39.0 mg/kg;非冻融条件下NH4+总吸附量从-0.70 mg/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(R20.99,SE0.54),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28.81 mg/kg;非冻融条件下NH4+强吸附态量从-4.25 mg/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。

Effect of Freeze-thaw Action on Ammonium Adsorption in Dryland Soil

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 < 1.69).The freeze-thaw action almost had no influence on the total adsorbed amount of ammonium that when the initial concentration of NH4+ increased from 0 mg/L to 200 mg/L,the total adsorbed NH4+ amount increased from-0.52 mg/kg to 39.0 mg/kg in freeze-thaw treatment(FTT),while that of the blank(UFTT) increased from-0.70 mg/kg to 38.5 mg/kg.However,the strongly-adsorbed amount of ammonium presented linear relationship with the concentration of NH4+(R2 > 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 entrophication.