砂土混合基质对雨水径流中磷素的吸附特性

基质吸附是生物滞留设施去除雨水径流磷素的主要途径之一。以体积比2:1砂土混合基质为研究对象，探讨砂土混合基质吸附雨水径流中磷的作用效果及机制，分析竞争吸附对磷吸附的影响。结果表明：相比于原状表层土，砂土混合基质中砂砾、粉粒和粘粒占比分别为原状土的4.18倍、0.28倍和0.35倍，工程砂和原状土混合可提高基质渗透性能；砂土混合基质磷吸附符合Freundlich和Langmuir模型，最大静态吸附量为2 470.733 mg/kg，以化学吸附为主，且不易解吸；雨水径流中Cl-、SO42-和NO3-的竞争吸附对砂土混合基质磷吸附的影响可忽略不计。砂土混合基质可促进雨水下渗，并强化磷污染控制。

Adsorption Properties of Sand-soil Mixed Matrix to Phosphorus in Rainwater Runoff

Matrix adsorption is one of the main ways for bioretention facilities to remove phosphorus from stormwater runoff. Taking the sand-soil mixed matrix with a volume ratio of 2:1 as the research object, the effect and mechanism of the sand-soil mixed matrix adsorbing phosphorus in rainwater runoff were discussed, and the influence of competitive adsorption on phosphorus adsorption were analyzed. The results show that compared with the undisturbed topsoil, the proportions of gravel, powder and clay in the sand-soil mixed matrix are 4.18, 0.28 and 0.35 times that of the undisturbed soil, respectively. The mixing of engineering sand and undisturbed soil can improve the permeability of the matrix. Phosphorus adsorption on the sand-soil mixed matrix conforms to the Freundlich and Langmuir models, with the maximum static adsorption capacity of 2 470.733 mg/kg, which is dominated by chemical adsorption and is not easy to desorb. The influence of Cl- SO42-, and NO3- in rainwater runoff on the adsorption of phosphorus by the sand-soil mixed matrix is negligible. The sand-soil mixed matrix can promote rainwater infiltration and strengthen the control of phosphorus pollution.