金山湖底泥重金属稳定化处理效果及机制研究

采用氧化钙和过氧化钙及二者混合物对底泥中的重金属进行稳定化试验,研究了稳定化后底泥中重金属迁移情况,并对底泥重金属稳定化技术的机制进行初步探讨.酸雨淋溶试验结果表明,底泥经CaO、CaO CaO2、CaO2稳定化后, pH=2.9时, Zn迁移到第3层,其首层迁移量分别为96、97和93mg/kg,而空白试验中Zn迁移至第6层,首层迁移量为128mg/kg; pH:5.0时, Zn迁移到第3层,其首层迁移量分别为87、90和89mg/kg,而空白试验中Zn迁移至第5层,首层迁移量为112mg/kg,这说明稳定化底泥中Zn的迁移速度和首层迁移量均有降低,3种稳定化药剂能够降低其在土壤中的迁移能力;淋溶液pH值对Zn的迁移能力有影响, pH较高能够减缓Zn在土壤中的迁移速度,降低其首层迁移量; Ni和Cd的酸雨淋溶试验也可得出同样结论.重金属稳定化机制试验结果表明,经上述3种药剂稳定化处理后,底泥pH值由6.76分别上升到8.33、8.15和8.21, TOC含量分别降低5%、10.9%和13.1%; Zn、Ni和Cd的稳定态含量分别增加10.6%、1.7%和4.5%,这是导致重金属迁移能力下降的主要原因;由此可见,3种药剂对同一金属的稳定化作用无明显差异;从不稳定态向稳定态转化的比例来看,稳定化药剂对不稳定态金属的稳定能力次序为: Zn>Cd>Ni.

Effect and Mechanism of Heavy Metal Stabilization Treatment of Sediment in Jinshan Lake

The heavy metal stabilization treatment (by mixture of CaO, CaO2, CaO and CaO2) of sediment in Jinshan Lake were investigated through soil column experiment, including the transport and transformation of heavy metal in sediment after stabilization, and the mechanism of heavy metal stabilization treatment technology. In the simulated acid rain experiment under a pH of 2.9, Zn in the sediment stabilized by CaO, CaO+ CaO2, CaO2, respectively, transferred to the third layer with the first layer's migrating quantities of 96, 97 and 93 mg/kg, while in another experiment under a pH of 5.0, Zn transferred to the third layer with the first layer's migrating quantities of 87, 90 and 89 mg/kg, respectively. In the blank experiments under pH 2.9 and 5.0, Zn transferred to the sixth and fifth layer with the first layer migrating quantities of 128 and 112 mg/kg, respectively. The above results were concluded to be: 1) both migrating velocity and first layer's migrating quantity of Zn decreased in stabilized sediment; 2) the three tested ways could reduce it migrating capability in soil; 3) pH of leached solution could affect the migrating capability of Zn and high Ph would lead to the decrease of Zn in soil. For Ni and Cd, the similar conclusion could also be gained. The results of metal transporting mechanism experiments with CaO, CaO + CaO2, CaO2 showed that: 1) pH of the sediment increased from 6.76 to 8.33, 8.15 and 8.21; 2) TOC content decreased with a range of 5%, 10.9% and 13.1%; 3) fixedness part contents of Zn, Ni and Cd increased 10.6%, 1.7% and 4.5%, respectively, which is the important reason leading to the decrease of metal transporting capability. The transformation proportion of heavy metal from labilization to stabilization showed that the stabilization capability of heavy metal followed the sequence: Zn > Cd > Ni.