中文摘要：

采用平衡法研究了红壤胶体、砖红壤胶体、潮土胶体和褐土胶体在不同pH值条件下DNA吸附与解吸特征.结果表明,在NaCl和KCl电解质体系中,4种土壤胶体在吸附过DNA后,溶液pH值均有不同程度的增加,pH增加的幅度为红壤胶体〉砖红壤胶体〉潮土胶体〉褐土胶体;NaCl电解质体系〉KCl电解质体系.土壤胶体对DNA的吸附量均随着pH值的升高而降低,在pH为2～4,不同胶体对DNA的吸附量保持最大值,约为13.1～14.8μg·mg^-1当平衡溶液pH值从4.2开始上升至8.6,在NaCl体系中,砖红壤胶体和红壤胶体上DNA的吸附量下降幅度约5.5μg·mg^-1而在KCl体系中,DNA的吸附量下降幅度约2.1μg·mg^-12种电解质体系,潮土胶体与褐土胶体上DNA的吸附量下降幅度约为8.3～12.2μg·mg^-1DNA吸附量下降幅度为恒电荷土壤（潮土和褐土）胶体〉可变电荷土壤（红壤和砖红壤）胶体.用NaOAc和NaH2PO4对土壤胶体吸附DNA的解吸时,可变电荷土壤胶体与恒电荷土壤胶体解吸规律有明显差异.在3种溶液pH值为3、5和7时,可变电荷土壤（红壤和砖红壤）胶体上NaOAc解吸率约10%～24.5%,NaH2PO4解吸率约23.5%～40.2%;而恒电荷土壤（潮土和褐土）胶体上,NaOAc解吸率约为72.3%～85.9%,NaH2PO4解吸率约8.8%～21.6%.这表明可变电荷土壤胶体吸附DNA时键合作用较大,恒电荷土壤胶体静电引力较大,这是DNA在不同电荷类型土壤胶体表面的吸附差异.

英文摘要：

The characteristics of adsorption and desorption of DNA by Red soil colloid, Latosol colloid, Chao colloid and Cinnamon colloid at different pH values were studied using a batch method. It showed that there was an increase of solution pH after adsorption of DNA by the four soil colloids in both NaCl and KCl electrolyte systems. The increasing ranges of pH values were in order of Red soil colloid 〉 Latosol colloid 〉 Chao colloid 〉 Cinnamon colloid, and NaCl electrolyte system 〉 KCl electrolyte system. The amounts of DNA adsorption on soil colloids decreased with the increase of pH value. The maximum amounts of DNA adsorption in different colloids were about 13.1-14.8μg·mg^-1 when pH values were 2-4. The decreasing ranges of the amounts of DNA adsorption were about 5.5μg·mg^- 1 in NaCl electrolyte system and 2.1 μg·mg^-1 in KCl electrolyte system in Red soil colloid and Latosol colloid after the rising of equilibrium solution pH from 4.2 to 8.6, whereas the remarked decreasing ranges of the adsorption amounts of DNA were about 8.3-12.2 μg·mg^-1 on Chao colloid and Cinnamon colloid in two electrolyte systems. The decreasing ranges of DNA adsorption were in order of the constant charge （Chao soil and Cinnamon） colloids 〉 the variable charge （Red soil and Latosol ） colloids. The differences of desorption on the variable and the constant charge colloids are very significant while the DNA adsorbed was desorbed with NaOAc solution and Nail2 PO4 solution. The desorption percent desorption of DNA as NaH2PO4 desorbent was 23.5%-40.2% larger on the variable charge colloids than 8.8%-21.6% on the constant charge of colloids at the three different solution pH values of 3, 5 and 7, while that as NaOAc desorbent was 72.3 %-85.9 % larger on the constant charge colloids than 10%-24.5 % on the variable charge colloids. These results implied that the ligand exchange played a more important role in DNA adsorption on the variable charge colloids, and electrostatic interactions did on the constant charge collo