模拟酸雨对微米和纳米羟基磷灰石稳定化污染土壤的铜和镉淋溶效应

Release of Cu and Cd From Contaminated Soil Amended by Nanoparticle and Microparticle Hydroxyapatite in the Condition of Acid Deposition

采用室内土柱淋溶试验,以1%的质量比向铜、镉复合污染土壤中添加微米羟基磷灰石(MHA)和纳米羟基磷灰石(NHA)稳定化培养72 h,并探讨模拟酸雨对稳定化修复土壤中Cu和Cd的释放影响,包括淋溶液的pH值、电导率(EC)、Cu和Cd浓度,以及Cu和Cd生物有效性的变化。结果表明,MHA处理淋溶液pH值最高,达7.78,其后依次为NHA和对照(CK)处理,且3种处理的pH值均高于模拟酸雨。MHA和NHA处理均增加了淋溶液EC值,MHA处理EC最高值是CK处理的10.41倍。与CK处理相比,MHA处理显著增加淋溶液Cu浓度,而NHA处理则降低Cu浓度;MHA和NHA处理均降低淋溶液Cd浓度。淋溶前MHA处理Cu和Cd的生物有效性降幅分别为75.0%和90.7%,NHA处理Cu和Cd生物有效性降幅分别为59.6%和52.2%,说明MHA处理稳定化效果比NHA处理更好。但是在模拟酸雨淋溶下,MHA处理Cu释放量更多,表明经MHA处理稳定的Cu和Cd在酸雨淋溶下易再次被活化。

Release characteristics of Cu and Cd from compound contaminated soil under simulated acid rain were studied through a leaching experiment for the untreated soil and hydroxyapatite amended soil with a rate of 1%.EC,pH,Cu and Cd concentration of leaching solution and before and after leaching of soil heavy metal bioavailability were analyzed.The result show that the leaching solution pH order is MHA〉NHA〉CK,higher than simulated acid rain pH.MHA and NHA treatments increase the leaching solution conductivity（EC）,especially for MHA with its leaching solution EC was 10.41 times as high as that of CK.Compared with CK,MHA significantly increased Cu concentration of the leaching solution,and had been maintained at a higher level,while the NHA decreased the Cu concentration of the leaching solution,but MHA and NHA both decrease Cd concentration of the leaching solution.Before leaching Cu and Cd bioavailability of MHA treated soil were reduced by 75.0% and 90.7%,respectively,while for NHA treatment the rates were 59.6% and52.2%,respectively,indicating that MHA can be more effective stabilization of Cu,Cd than NHA.But in MHA treatment Cu and Cd were activated more under simulated acid rain leaching comparing with NHA,showing that MHA stabilized Cu and Cd can easily be reactivated under acid rain condition in south China.