土壤溶液中镉的化学形态及化学平衡研究  

CHEMICAL SPECIES AND EQUILIBRIA OF CADMIUM IN SOIL SOLUTIONS

作　　者：熊礼明[1] 

机构地区：[1]中国科学院南京土壤研究所,210008

出　　处：《环境科学学报》1993年第2期150-156,共7页Acta Scientiae Circumstantiae

摘　　要：据土壤溶液的实际情况建立简便的平衡模式,研究了红壤、黄棕壤、黄潮土三种典型土壤溶液中Cd的化学形态和化学平衡.结果表明,溶液中Cd的主要形态为Cd^(2+)、CdCl^+和CdSO_4~6.黄潮土还有一定量的CdHCO_3^+,其它形态Cd很少,其中游离Cd^(2+)占绝大部分.红壤最高,黄棕壤次之.红壤施石灰后游离Cd^(2+)下降,CdSO_4~6增加;添加氯化物后,溶液pH下降,大量Cd进入溶液中,CdCl^+比例明显升高.溶液中Cd的形态分布与土壤Cd的生物有效性有一定关系.此外,溶解度图证明,供试土壤中不可能有Cd的矿物生成.Cd在固液相间的平衡受吸附解吸反应控制.A simple chemical equilibrium model was developed to speciate Cd in soil solutions of red earth, yellow-brown earth and yellow fluro-aquic soil peviously amended with Cd. Results showed that Cd2+, CdCl+, and CdSO40 were the dominant species of Cd in soil solution. Limimg the red earth reduced free Cd2+ and increased CdSO40 in the species composition. Adding chlorides decreased soil pH and desorbed Cd from solid matrix, and CdCl+ and CdCl20 rised dramatically. Solubility diagram suggested that the soil solution was far undersaturated with respect to all Cd minerals hence Cd activity in soil solution was controlled by sorption-desorption equilibrium of Cd between soil solid and solution phases.

关 键 词：土壤 溶液 化学形态 化学平衡 镉 

分 类 号：X144[环境科学与工程—环境科学]