离子强度和SO2-4对土壤吸附Al的影响

研究了离子强度和SO4^2-对土壤吸附Al的影响，结果表明：在所研究的pH范围内，随着NaCl支持电解质浓度的提高，土壤对Al的吸附量基本保持不变，并且当pH＜3．9时，即土壤表面净电荷为正时，土壤对Al的吸附量仍然很大，超过最大吸附量的50％，而用CaCl2作支持电解质时，当pH＜4．5时，在溶液中CaCl2浓度最高的情况下，Al的吸附量最小，在其余两种浓度条件下则基本相等；当pH＞4．5时，Al的吸附量几乎不受CaCl2浓度变化的影响。SO4^2-的加入对土壤吸附Al没有影响。这些都说明土壤吸附Al的作用机制主要为专性吸附。

SORPTION OF ALUMINUM BY SOIL AS AFFECTED BY IONIC STRENTH AND SULFATE

The influence of ionic strength and sulfate on the sorption of aluminum by soil was investiga- ted.It was shown that the supporting electrolyte of NaCl under three concentrations affected Al sorption insignificantly within the range of pH studied,suggesting the specific adsorption of aluminum on soil by formation surface inner-sphere complexes.The mechanism was also confirmed by the existence of aluminum sorption even the solution pH below the ZPNC of the soil studied where the net charge of soil surface was positive and electrostatic adsorption disappeared.As for CaCl 2,it inhibited aluminum sorption when the largest amount of Ca 2+ added and solution pH below 4.5,while which eliminated after solution pH raised above 4.5 due to the extreme affinity of soil for aluminum hydrolysis products.The effect of sulfate on aluminum sorption was not detected which may attribute to the high selection of soil for aluminum and the weak bond between Al and SO 2- 4.