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本文提出了吸附势(logK_a)和解吸势(logK_d或相对解吸势logK_(dr))两个有关吸附和解吸的强度概念,并进行了理论推导和实验验证。logK_a和logK_d或logK_(dr)是影响土壤或胶体吸附和解吸因素的综合反应。实验证实logK_a可用于表征土壤胶体对Cd的相对选择性,并且对胶体吸附Cd有着良好的预测性;logK_(dr)可用于表征土壤胶体对Cd的相对固定能力,并可用于估测Cd的污染程度。盆栽试验表明,随着土壤胶体logK_a的增加,或logK_(dr)的降低,稻草或糙米中Cd的含量下降。可以预期,吸附势和解吸势不但在土壤物理化学,土壤环境化学研究中,而且在植物营养化学、水化学、以及界面化学等方面有可能获得实际应用。
In this paper, two concepts about the adsorption and desorption strengths of logK_a and desorption (logK_d or relative logK_ (dr)) are proposed, and the theoretical derivation and experimental verification are made. logK_a and logK_d or logK_ (dr) are the combined reactions that affect soil or colloidal adsorption and desorption. The results showed that logK_a could be used to characterize the relative selectivity of soil colloids to cadmium and to predict the adsorption of Cd on colloids. LogK_ (dr) could be used to characterize the relative immobilty of soil colloids to cadmium and to estimate Cd pollution degree. Pot experiments showed that the content of Cd in rice straw or brown rice decreased with the increase of log K_a or the decrease of log K_ (dr). It is expected that adsorption potential and desorption potential are likely to be applied not only in soil physico-chemical and soil-environment chemistry but also in plant nutrition chemistry, hydrochemistry and interfacial chemistry.