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【目的】探讨pH值对新疆典型草原黑钙土中胡敏酸(HA)、富里酸(FA)与Cd离子络合物稳定性的影响。【方法】采用Schuber提出的离子交换平衡法测定腐殖质-Cd复合体的络合稳定常数和配位数。【结果】在不同pH值条件下,HA与Cd结合形成的复合体络合稳定常数在1.45～7.88,而FA与Cd的络合稳定常数在1.29～5.53。络合稳定常数和配位数随着pH值的增大而增大,但是HA-Cd的络合稳定常数和配位数均比FA-Cd的络合稳定常数和配位数高。【结论】pH值显著地影响HA-Cd、FA-Cd的络合稳定常数和配位数。在不同pH值条件下,HA-Cd的络合稳定常数、配位数以及吸附率均大于FA-Cd的络合稳定常数、配位数以及吸附率。
【Objective】 The objective of this study was to investigate the effect of pH value on the stability of humic acid (HA), fulvic acid (FA) and Cd ion complexes in calcareous soil of Xinjiang steppe. 【Method】 The complex stability constant and coordination number of humus-Cd complex were determined by Schuber’s ion exchange equilibrium method. 【Result】 Under different pH conditions, the complex formed by HA and Cd complexed at a stability constant of 1.45 ~ 7.88, while the complex stability constant of FA and Cd was 1.29 ~ 5.53. The complexation stability constant and coordination number increased with the increase of pH, but the complexation stability constants and coordination numbers of HA-Cd were higher than those of FA-Cd. 【Conclusion】 pH value significantly affected the complexation stability constants and coordination numbers of HA-Cd and FA-Cd. Under different pH conditions, the complexation stability constant, coordination number and adsorption rate of HA-Cd were all greater than that of FA-Cd, and the complexation number and adsorption rate were all higher.