锆、镧和镧锆改性沸石添加控制底泥磷释放的对比

本研究采用镧和锆作为改性剂制备了3种不同类型的改性沸石,即锆改性沸石(Zr MZ)、镧改性沸石(La MZ)和镧锆改性沸石(La Zr MZ),对比考察了其对水中磷酸盐的吸附作用,并对比研究了其添加对上覆水、间隙水和底泥中磷的影响.结果发现,3种改性沸石均可有效地吸附水中的磷酸盐,且La Zr MZ对水中磷酸盐的吸附性能明显优于La MZ和Zr MZ. 3种改性沸石添加均可有效地降低上覆水和间隙水中SRP的浓度.La MZ对底泥中潜在活性磷的钝化效果优于La Zr MZ,而后者又优于Zr MZ. 3种改性沸石添加均可以降低底泥中水溶性磷(WSP)、藻类可利用磷(AA-P)和铁氧化物-滤纸提取磷(Fe O-P)的含量,WSP和AA-P削减效应的排序为:La MZ La Zr MZ Zr MZ,Fe O-P削减效应的排序为:La Zr MZ Zr MZ La MZ. La Zr MZ和La MZ添加均可以降低底泥中易解吸磷(RDP)的含量,且削减效应的排序为:La MZ La Zr MZ. La Zr MZ和Zr MZ添加均可以降低底泥中Na HCO_3提取磷(Olsen-P)的含量,且削减效应的排序为:La Zr MZ Zr MZ.以上结果显示,镧、锆和镧锆改性沸石均可以有效控制水体内源磷向上覆水的释放;从吸附容量和生物可利性磷钝化效果看,镧锆联合改性沸石是一种非常有希望的用于控制水体内源磷释放的底泥改良材料.

Comparison of the Control of Sedimentary Phosphorus Release Using Zirconium-, Lanthanum-, and Lanthanum/Zirconium-Modified Zeolites as Sediment Amendments

In this study, the adsorption characteristics of phosphate on zirconium-modified zeolite (ZrMZ), lanthanum-modified zeolite (LaMZ) and lanthanum/zirconium-modified zeolite (LaZrMZ) were comparatively investigated, and the effect of ZrMZ, LaMZ, and LaZrMZ addition on the mobilization of phosphorus (P) in sediments was comparatively studied. Results showed that the phosphate adsorption capacity decreased in the order of LaZrMZ > LaMZ > ZrMZ. The addition of LaZrMZ, LaMZ, and ZrMZ in sediments all could effectively reduce the concentrations of soluble reactive P (SRP) in the overlying and pore waters. Furthermore, the addition of LaZrMZ, LaMZ and ZrMZ all could decrease the amount of mobile P in sediments, and the reduction rate decreased in the order of LaMZ > LaZrMZ > ZrMZ. The amendment of sediments with LaZrMZ, LaMZ, and ZrMZ all could lead to a decrease in the amount of water-soluble P (WSP), algal available P (AA-P) and iron oxide-filter paper extractable P (FeO-P) in the sediments. The reduction rate of WSP and AA-P decreased in the order of LaMZ > LaZrMZ > ZrMZ, and the reduction rate of FeO-P decreased in the order of LaZrMZ > ZrMZ > LaMZ. The addition of LaZrMZ and LaMZ both could reduce the content of readily desorbed P (RDP), and the reduction rate decreased in the order of LaMZ>LaZrMZ. The LaZrMZ and ZrMZ amendments both could decrease the concentration of NaHCO₃ extractable P (Olsen-P) in sediments, and the reduction rate decreased in the order of LaZrMZ>ZrMZ. The results of this study demonstrate that the addition of ZrMZ, LaMZ, and LaZrMZ in sediments all could effectively intercept the upward mobilization of sedimentary P to the overlying water, and LaZrMZ is a very promising amendment for the control of the internal P loading from the point of view of both phosphate adsorption ability and bioavailable P immobilization efficiency.