摘要
为探究锌、镉及铵态氮在土壤中的运移特征,该文通过室内土柱混合置换试验,分析了不同pH值和离子强度对锌、镉、铵态氮(Zn2+、Cd2+、NH4+)在土壤中运移的影响;获得了示踪剂Br和Zn2+/Cd2+/NH4+的穿透曲线(breakthrough curves,BTCs),并对试验结果进行了模拟。研究表明:Zn2+/Cd2+/NH4+在土壤中运移时,运移速度:NH4+>Zn2+>Cd2+,pH值越高,Zn2+/Cd2+/NH4+的出流时间越晚,峰值越低;离子强度越大,出流时间越早,峰值越高。描述溶质运移的非平衡两点模型(two-site model,TSM)能够较好地模拟Zn2+/Cd2+/NH4+在土壤中的运移,pH值越高,模拟得到的分配系数Kd值越大(以Zn2+为例,由3.853增大到4.386),f值越小(以Zn2+为例,由0.231减小到0.006),分形系数β值很小且无明显变化规律;离子强度越大,模拟得到的分配系数Kd值越小(以Zn2+为例,由4.023减小到到3.381),f值及分形系数β值均很小且无明显变化规律。该研究对深入了解Zn2+/Cd2+/NH4+在土壤中的运移机理、提出污染土壤修复措施提供科学依据。
In order to make a thorough inquiry of Zn,Cd,NH4＋ transportation in soils,the effect of pH and ionic strength on Zn,Cd,NH4＋ transport in soils were studied,through a stable flow miscible displacement experiment.Breakthrough curves（BTCs） of the tracer bromide（Br） and Zn^2＋/Cd^2＋/NH4＋ were obtained in these soil column experiments.With the software HYDRUS-1D,the local equilibrium assumption（LEA） model was used to simulate the observed BTCs of Br.Then we estimated the porosity θ and dispersion coefficient D and got the soil column migration model parameters.Through adjusting the value of Kd,β,α,f,two-site model（TSM） was used to simulate the BTCs of Zn^2＋/Cd^2＋/NH4＋ with software HYDRUS-1D.Based on the analysis of BTCs observation,it turned out that transport velocity of Zn^2＋/Cd^2＋/NH4＋ is NH4＋Zn^2＋Cd^2＋ when they coexisted in migration.The higher the pH is,the later the flow time of Zn^2＋/Cd^2＋/NH4＋ is,and the lower peak value of relative concentration is.The flow time of NH4＋ was delayed by 8.08 pv to 9.72 pv and the peak value of the relative concentration dropped from 0.976 to 0.904.The flow time of Zn^2＋ was delayed by 12.89 pv to 15.45pv and the peak value of BTCs dropped from 0.548 to 0.448.The flow time of Cd^2＋ was delayed by 13.32pv to 16.44pv and the peak value of the relative concentration dropped from 0.315 to 0.235.So the rise of pH can increase the adsorption quantity of Zn^2＋/Cd^2＋/NH4＋ in soil and consequently block their transportation.On the other hand,the bigger the ionic strength is,the earlier the flow time of Zn^2＋/Cd^2＋/NH4＋ is,and the higher the peak value is.The flow time of NH^4＋ was advanced from 8.78 pv to 7.68 pv and the peak value of the relative concentration rose from 0.933 to 1.013.The flow time of Zn^2＋ was advanced from 14.83 pv to 13.98 pv and the peak value of relative concentration rose from 0.496 to 0.542.The flow time of Cd^2＋ was advanced from 15.86 pv to 14.69 pv and the peak value of relative conc
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2013年第12期218-227,共10页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金项目(40771095
41171183)
水利部公益性行业科研专项经费项目(201201024)
