改性沸石对土壤铅、锌赋存形态的影响

通过室内土壤培养实验，研究改性沸石对污染土壤中Pb、Zn赋存形态的影响。结果表明，土壤中的Pb主要是以Fe—Mn氧化物结合态存在，土壤zn主要以残渣态存在。添加天然沸石和改性沸石不同程度地降低土壤酸提取态Pb、zn的含量，提高土壤残渣态Pb、zn的含量。与CK处理相比，添加4种沸石导致土壤酸提取态Pb含量降低8．7％-40．3％，土壤酸提取态zn含量降低10．5％-49．8％（培养1个月）。硝酸钾改性沸石比天然沸石更能显著地降低土壤酸提取态Pb、zn的含量，而氢氧化钠改性沸石和硝酸钾改性沸石比天然沸石更能显著地降低土壤酸提取态的zn含量。培养1、2和3月后，不同沸石处理导致土壤残渣态zn比率分别比CK处理提高14．4％～23．5％、19．6％～23．7％和1．9％-11．1％。研究结果表明，天然沸石经过一定方法改性后，是固定污染土壤Pb、zn的潜在改良剂。

Effects of modified zeolite on fractionation of Pb and Zn in contaminated soil

An indoor soil column cultivation experiment was carried out to investigate the effects of modified zeolite on fractionation of Pb and Zn in contaminated soil. The results showed that the main chemical form of Pb was Fe-Mn oxide form, while Zn dominated as the residue form. Addition of natural zeolite and modified zeolite could decrease the concentrations of HOAc-soluble Pb and Zn and increase the concentrations of residue Pb and Zn. Compared with the control, the four zeolites could decrease the concentrations of HOAc-soluble Pb by 8.7% -40.3% and the concentrations of HOAc-soluble Zn by 10.5% -49.8% after one month incubation. KNO3 modified zeolite could significantly reduce the concentrations of HOAc-soluble Pb and Zn than natural zeolite. While NaOH modified zeolite and KNO3 modified zeolite could significantly reduce the concentrations of HOAc- soluble Zn than natural zeolite. After 1,2 and 3 months incubation, addition of natural zeolite and modified zeo- lite could significantly increase the residue Zn fraction by 14.4% ~ 23.5% , 19.6% - 23.7% and 1.9% - 11.1% , respectively compared with control treatment. The results indicated that modified zeolite could promote Pb and Zn transforming from HOAc-soluble state to residue form, thereby they were the potential materials to fix Pb and Zn in the soil.