不同pH条件和P-Se交互作用对茶园土壤Se(Ⅳ)吸附行为的影响

Effects of pH and Phosphate on Se(Ⅳ) Adsorption by Tea Garden Soil

为了给生产上采取增施磷肥措施提高茶园土壤硒的有效性提供理论依据,通过实验室模拟实验,研究了不同pH条件和P-Se交互作用对茶园土壤Se(Ⅳ)吸附行为的影响。结果表明,在吸附液3种pH条件下Se(Ⅳ)的吸附平衡时间无明显变化。当吸附液pH=3时土壤对Se(Ⅳ)的吸附量显著高于pH=5和pH=7的处理,而后两者之间差异较小。P-Se交互作用不仅延长了Se(Ⅳ)达到吸附平衡所需的时间,而且导致其平衡吸附量显著下降。茶园土壤对Se(Ⅳ)的吸附动力学曲线用双常数方程和Elovich方程拟合效果较好,而Langmuir方程、Freundlich方程和Temkin方程均可较好地描述Se(Ⅳ)的吸附热力学特征。P对土壤中Se(Ⅳ)吸附行为的影响与两者的摩尔浓度比以及添加顺序有关,在3种不同添加顺序下,Se(Ⅳ)吸附量的大小为先加Se后加P>Se与P同时加入>先加P后加Se,且当P/Se摩尔浓度比>1时,土壤对Se(Ⅳ)的吸附量呈现明显的下降趋势。

Chemical behaviors of Se in soils influence Se availability to plants. The effects of pH and phosphate on Se （ Ⅳ ） adsorption by tea garden soil were investigated. The results showed that the time required to achieve adsorption equilibrium of Se （ Ⅳ ） did not show differences when pH values increased from 3 to 7. Adsorption capacity of Se（ Ⅳ ） was higher at pH 3 than at pH 5 and pH 7. No significant differences in adsorption were found between pH 5 and pH 7. The presence of phosphate not only increased the time for Se（ Ⅳ ） to reach adsorption equilibrium, but also remarkably decreased the Se （ Ⅳ ） adsorption. Adsorption kinetics of Se （ Ⅳ ） followed Elovich and double-constant equations, while adsorption isotherms could be explained by Langmuir, Freundlich, and Temkin models. The effects of P on Se（ Ⅳ ） adsorption were affected by P/Se molar ratios and addition sequences. At P/Se molar ratio〉1, Se（ Ⅳ ） adsorption decreased significantly. Adsorption of Se（ Ⅳ ） was in order of Se addition prior to P〉Se and P together〉P prior to Se. These findings could provide useful information for enhancing plant availability of Se in tea garden soil.