磷对土壤As(V)固定与活化的影响

P和As的化学性质相近,在土壤中存在竞争吸附的关系,因而土壤中P浓度增加可能会影响As的固定和活化。本文通过等温吸附和浸提实验,模拟施P对黄棕壤中As固定和活化的影响。实验结果表明,提高溶液P浓度能够减少土壤对As的吸持能力,并增加As从土壤中的解吸量。在P浓度较低的情况下,这种影响尤其显著,As的解吸量与P浓度成极显著的线性相关关系。因此,不能忽视施用P肥对土壤As活化和迁移的影响。持续增加溶液的P浓度时,这种影响的程度逐渐减弱,可能与土壤中存在不同类型的吸附位有关。

EFFECT OF PHOSPHORUS ADDITION ON SOIL ARSENIC ADSORPTION AND MOBILIZATION

Arsenic and phosphorus are similar in chemical properties and compete with each other for sorption sites in soil. Effect of phosphorus on adsorption of arsenate in yellow-brown soil was evaluated in a batch experiment. Solutions different in P concentration were also used to extract As from the As contaminated soil. The results showed that when P concentration was low, the rise in P concentration might significantly reduce As adsorption but increase As extraction from the soil. When P concentration further increased, the changes in As adsorption and desorption became not so distinct. Sorption of As (V) even in the presence of high concentrations of P may be attributed to presence of sorption sites specific for As (V) and P and other sites that are common for both. Results of this study indicate that application of phosphate-containing fertilizer to As-contaminated soils may increase soil As solubility, phytoavailability and potential of leaching to groundwater.