Anion Transport Involving Competitive Adsorption during Transient Water Flow in an Andisol
Anion Transport Involving Competitive Adsorption during Transient Water Flow in an Andisol
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安迪溶胶中瞬态水流期间涉及竞争吸附的阴离子传输
DOI：
10.2136/sssaj1996.03615995006000050011x
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发表时间：
1996
影响因子：
2.9
通讯作者：
S. Green
中科院分区：
文献类型：
--
作者：
H. Katou;B. Clothier;S. Green
含有allophane和其他结晶性差的物质的和二醇，携带可变的表面电荷，并吸附其他惰性阴离子，如Cl -和no3 -。本研究的目的是预测不稳定水流过程中阴离子的组分依赖、延迟转运。采用不同浓度（0.00462 ~ 0.115 mol L -1）的cacl2、Ca(no3) 2和cacl2 -Ca(no3) 2混合溶液，在坎农岱底土（hyc Hapludand）柱上进行了一维吸收实验。由于土壤对Cl -和no3 -的非线性竞争性吸附，观察到阴离子渗透的阻滞取决于入侵溶液的总浓度和组成。与Cl -相比，硝酸根离子对吸附位点的亲和性较小（选择系数Kv = 0.51），而在Cl -存在时，硝酸根离子的渗透力更大。土壤对Cl -和no3 -的吸附远远超过同时对so4 -的解吸。这表明so42 -被强烈吸附，与入侵阴离子的交换反应仅在有限的范围内进行。因此，对单价阴离子的吸附很大程度上是由于土壤的阴离子交换能力随着体积溶液离子强度的增加而增加。建立了一种涉及竞争吸附的阴离子传输近似理论，其中总单价阴离子吸附服从langmuir型方程，通过Kv分配给Cl -和no3 -的吸附。利用从独立的稳态浸出实验中确定的吸附参数，该理论成功地描述了测量到的阴离子含量曲线。
Andisols containing allophane and other poorly crystalline materials, carry variable surface charge, and adsorb otherwise inert anions such as Cl - and NO 3 - . The objective of this study was to predict composition-dependent, retarded transport of anions during unsteady water flow in an Andisol. One-dimensional absorption experiments in Kannondai subsoil (Hydric Hapludand) columns were conducted with CaCl 2 , Ca(NO 3 ) 2 , and mixed CaCl 2 -Ca(NO 3 ) 2 solutions at different concentrations (0.00462-0.115 mol L -1 ). Because of nonlinear, competitive adsorption of Cl - and NO 3 - by the soil, the observed retardation of anion penetration depended on the total concentration and composition of the invading solution. Nitrate ion had a smaller affinity to the adsorption sites than Cl - (the selectivity coefficient Kv = 0.51) and showed a greater penetration in the presence of Cl - . The adsorption of Cl - and NO 3 - much exceeded the concurrent SO 4 2- desorption from the soil. This suggests that SO 4 2- was so strongly adsorbed that exchange reaction with the invading anions proceeded only to a limited extent. Thus, the adsorption of the monovalent anions was largely due to the increase in the anion exchange capacity of the soil in response to an increase in the ionic strength of the bulk solution. An approximate theory was developed for anion transport involving competitive adsorption in which total monovalent anion adsorption, obeying a Langmuir-type equation, is allocated via Kv to the adsorption of Cl - and NO 3 - . Employing the adsorption parameters determined from separate steady state leaching experiments, the theory successfully described the measured anion content profiles.