紫色土中砷、磷的吸附-解吸和竞争吸附

采用批培养法研究了As、P在三峡库区典型土壤紫色土中的吸附-解吸特点及竞争吸附对As、P迁移活化的影响.结果表明：3种紫色土中As、P的吸附-解吸特点相似，等温吸附均符合Langmuir和Freundlich方程，As在酸性、中性和石灰性紫色土中的最大吸附量分别为1428.6、1250.0和1111.1 mg·kg^-1；P在酸性、中性和石灰性紫色土中的最大吸附量分别为322.6、357.1和434.8 mg·kg^-1；As、P吸附动力学过程为先快后慢，均符合一级动力学方程与Elovich方程，快速吸附段符合一级动力学方程，为交换吸附；慢速吸附阶段满足Elovich方程，可能属于深层吸附或专性吸附.As、P竞争吸附试验表明，As、P共存时P的吸附速度和吸附量均增强，而As的吸附速度和吸附量均降低，表明As的存在能明显增强紫色土对P的吸附作用，P的存在则明显抑制紫色土对As的吸附.

Adsorption-desorption and competitive adsorption of arsenic and phosphorus in purple soil.

A batch incubation test was conducted to study the characteristics of arsenic (A s) and phosphorous (P) adsorption-desorption as well as the effects of the comp etitive adsorption of the two elements on their translocation and activation in three kinds of purple soil, the typical soil in Three Gorges Area. In the test a cid, neutral, and calcareous purple soils, As and P adsorption-desorption had t he similar characteristics, with their isothermal adsorption conformed to Langmu ir and Freundlich equations. The maximum adsorption of As in the acid, neutral, and calcareous purple soils was 14286, 12500, and 11111 mg·kg-1, an d that of P was 3226, 3571, and 4348 mg·kg-1, respectively. The ads orption of As and P was fast at the beginning and slowed down then. The kinetics corresponding to the fast process was of first order, and that to the slow proc ess was of Elovich type. The mechanism for the fast process might be exchange ad sorption, and that for the slow process might be specific adsorption. When the A s and P coexisted, the adsorption rate and quantity of P increased while those o f As decreased, implying that the existence of As could promote the adsorption o f P in purple soil, while the existence of P would restrain the adsorption of As.