Adsorption of Cadmium by Soil Colloids and Minerals in Presence of Rhizobia

Experiments were conducted to study the adsorption of Cd on two soil colloids (red soil and yellowbrown soil) and three variable-charge minerals (goethite, noncrystalline Fe oxide and kaolin) in the absence and presence of rhizobia. The tested strain Rhizobium fredii C6, tolerant to 0.8 mmol L-1 Cd, was selected from 30 rhizobial strains. Results showed that the isotherms for the adsorption of Cd by examined soil colloids and minerals in the presence of rhizobia could be described by Langmuir equation. Within the range of the numbers of rhizobial cells studied, the amount of Cd adsorbed by each system increased with increasing rhizobial cells. Greater increases for the adsorption of Cd were found in red soil and kaolin systems.Rhizobia influence on the adsorption of Cd by examined soil colloids and minerals was different from that on the adsorption of Cu. The presence of rhizobia increased the adsorption af~nity of soil colloids and minerals for Cd, particularly for the goethite and kaolin systems. The discrepancies in the influence of rhizobia on the adsorbability and affinity of selected soil colloids and minerals for Cd suggested the different interactions of rhizobia with various soil components. It is assumed that bacterial biomass plays an important role in controlling the mobility and bioavailability of Cd in soils with kaolinite and goethite as the major colloidal components, such as in variable-charge soil.

作 者： HUANG Qiaoyun WU JIANMEI Chen Wenli LI Xueyuan   作者單位： HUANG Qiaoyun,WU JIANMEI,LI Xueyuan(Department of Resources, Environment and Agrochemistry, Huazhong Agricultural University, Wuhan 430070 China)

Chen Wenli(Department of Microbiology, Huazhong Agricultural University, Wuhan 430070 ChinaReceived July 23, 2000; revised August 17, 2000) 

刊 名： 土壤圈(意譯名)  ISTIC SCI 英文刊名： PEDOSPHERE AN INTERNATIONAL JOURNAL  年，卷(期)： 2000 10(4)  分類號：   關(guān)鍵詞： cadmium adsorption   iron oxide   kaolin   rhizobia   soil colloid