中文摘要：

利用流动搅动法研究几种有机酸对土壤和矿物表面Cd的解吸动力学特征.结果表明,有机酸对Cd的解吸可能有质子的交换和溶解作用,以及有机配体与胶体表面对Cd的竞争作用.在40-50min内,红壤和针铁矿表面Cd的解吸达到稳态,而砖红壤和高岭土上并未达到稳态.柠檬酸、苹果酸、酒石酸和草酸对Cd的解吸率在红壤土上分别为86%,96%,93%和61%;在砖红壤上分别为86%,80%,69%和64%;在针铁矿上分别为94%,93%,86%和87%;在高岭土上分别为34%,41%,35%和42%.用双指数方程和一级动力学方程能更好地拟合Cd的解吸过程.不同有机酸解吸Cd的快反应速率常数为酒石酸、柠檬酸〉苹果酸〉草酸,慢反应速率常数为苹果酸〉柠檬酸、酒石酸〉草酸.除质子溶解作用外,有机配体与胶体表面对Cd的竞争力不同也是导致Cd解吸速率和解吸量差异的原因之一.

英文摘要：

The kinetic characteristics of Cd desorption by organic acids in minerals and soils were studied using a flow-stirred method. It showed that the mechanism of Cd desorption could be ion exchange and dissolution of H^＋ , and the competition of organic ligands with colloids for Cd when organic acids were added as exterior protons and organic anions. The kinetics of Cd desorption could be divided into fast and slow reactive steps. The fast reactive step would be close to quasi-equilibrium in 40-50 min in red soil and goethite, and did not reach the stead state in latosol and kaolinite during the reaction time. Percentage of Cd desorption for citric, malic, tartaric and oxalic acid were very different in soils and minerals. The fast reactive rate constants of Cd desorption by organic acids could be in order of tartaric and citric acid 〉 malic acid 〉 oxalic acid, and the slow reactive rate constants in sequence of malic acid 〉 citric acid and tartaric acid 〉 oxalic acid. Cd desorption could be well described by double exponential equation and the first order kinetics. Elovich equation and twoconstant equation also were fitted better than the parabolic diffusion. Except for H^＋ exchange and dissolution, the different organic ligands could compete with colloid surface for Cd and would lead to the difference of Cd desorption rate and amounts.