氧化木糖无色杆菌(Achromobacte rxylosoxidans)LAX2对Cu、Pb和Cd复合污染土壤的生物矿化修复研究

The remediation of complex Cu, Pb and Cd polluted soil through biomineralization by Achromobacte rxylosoxidans LAX2

我国土壤重金属复合污染较为突出,是目前亟待解决的土壤环境问题之一.本文研究了一株氧化木糖无色杆菌LAX2对Cu、Pb和Cd共存体系的生物矿化作用及其复合污染土壤的矿化修复作用.结果表明,菌株LAX2的发酵液、无菌发酵液和菌体细胞对3种重金属的去除能力大小顺序均为Pb^(2+)>Cd^(2+)>Cu^(2+).X-射线衍射、扫描电镜、红外光谱和能谱分析表明,3种重金属共存时菌株LAX2发酵液可诱导形成PbCO_3和CdCO_3晶体,而Cu不能单独成矿,混合矿物晶体呈长杆状.菌株LAX2发酵液能够明显降低黑钙土和白浆土中Cu、Pb和Cd的有效态含量,矿化修复30 d后,黑钙土中Cu、Pb、Cd的有效态含量分别降低了48.0%、71.4%、62.8%,白浆土中Cu、Pb、Cd的有效态含量分别降低了42.0%、63.2%、53.6%;碳酸盐结合态和铁锰氧化物结合态含量明显增加,可交换态和有机物结合态含量明显降低.矿化修复后的土壤中重金属的浸出毒性随修复时间的增长而降低,黑钙土中Cu、Pb、Cd浸出量分别降低了90.3%、93.2%、92.8%,白浆土中Cu、Pb、Cd浸出量分别降低了82.5%、86.1%、84.3%.以上结果说明,菌株LAX2可通过碳酸盐矿化作用固定土壤中的复合重金属,且在相同条件下对黑钙土的修复效果好于白浆土.

The soil pollution by complex heavy metals, which is one of the soil environmental problems needed to be urgently solved, is particularly severe in China. In this study, the biomineralization of Cu, Pb and Cd in coexisting system and the remediation of soil polluted by complex Cu, Pb and Cd through biomineralization by Achromobacter xylosoxidans LAX2. The results indicated that the removal of heavy metals by fermentation broth, sterile fermentation broth, and bacterial cells was in the same order of Pb2＋ 〉Cd2＋ 〉Cu2＋. X-ray diffraction, scanning electron microscope analysis, infrared spectrum and energy spectrum analysis showed that LAX2 fermentation broth could induce the formation of PbCO3 and CdCO3 minerals when Cu, Pb and Cd coexsiting, while no Cu carbonate minerals was formed, and the crystal of the mixed minerals was long rod-shaped. Strain LAX2 fermentation broth could significantly reduce the content of available Cu, Pb and Cd in Cheruozem and Albic soils. After 30 d of remediation by biomineralization, the content of available Cu, Pb and Cd in Chernozem and Albic soils were reduced by 48.0% and 42.0%, 71.4% and 63.2%, 62.8% and 53.6%, respectively; the content of carbonate bound and Fe-Mn oxides bound increased significantly, and the content of exchangeable and organic matter bound decreased significantly. The leaching toxicity of heavy metals in soil remedied by biomineralization was reduced with the increasing of remediation time, and the leaching content of Co, Pb and Cd in Chernozem and Albic soils were 90.3% and 82.5%, 93.2% and 86.1%, 92.8% and 84.3% respectively. The above indicated that strain LAX2 could immobilize complex heavy metals in soil by carbonate mineralization, and more heavy metals were immobilized in chernozem soil than that in Albic soil under the same conditions.