Zhang Li, Wang Wenjun, Yue Caili, Si Youbin
Anhui Province Key Laboratory of Farmland Ecological Conservation and Pollution Prevention, College of Resources and Environment, Anhui Agricultural University, Hefei 230036, China.
Anhui Province Key Laboratory of Farmland Ecological Conservation and Pollution Prevention, College of Resources and Environment, Anhui Agricultural University, Hefei 230036, China.
Sci Total Environ. 2024 Apr 15;921:171060. doi: 10.1016/j.scitotenv.2024.171060. Epub 2024 Feb 18.
Bioremediation based on microbial-induced carbonate precipitation (MICP) was conducted in cadmium and lead contaminated soil to investigate the effects of MICP on Cd and Pb in soil. In this study, soil indigenous nitrogen was shown to induce MICP to stabilize heavy metals without inputting exogenous urea. The results showed that applying Bacillus pasteurii coupled with CaCl reduced Cd and Pb bioavailability, which could be clarified through the proportion of exchangeable Cd and Pb in soil decreasing by 23.65 % and 12.76 %, respectively. Moreover, B. pasteurii was combined separately with hydroxyapatite (HAP), eggshells (ES), and oyster shells (OS) to investigate their effects on soil heavy metals' chemical fractions, toxicity characteristic leaching procedure (TCLP)-extractable Cd and Pb as well as enzymatic activity. Results showed that applying B. pasteurii in soil significantly decreased the heavy metals in the exchangeable fraction and increased them in the carbonate phase fraction. When B. pasteurii was combined with ES and OS, the content of carbonate-bound Cd increased by 114.72 % and 118.81 %, respectively, significantly higher than when B. pasteurii was combined with HAP, wherein the fraction of carbonate-bound Cd increased by 86 %. The combination of B. pasteurii and biogenic calcium effectively reduced the leached contents of Cd and Pb in soil, and the TCLP-extractable Cd and Pb fractions decreased by 43.88 % and 30.66 %, respectively, in the BP + ES group and by 52.60 % and 41.77 %, respectively, in the BP + OS group. This proved that MICP reduced heavy metal bioavailability in the soil. Meanwhile, applying B. pasteurii and calcium materials significantly increased the soil urease enzyme activity. The microstructure and chemical composition of the soil samples were studied, and the results from scanning electron microscope, Fourier transform infra-red spectroscopy, and X-ray diffraction demonstrated the MICP process and identified the formation of CaCO, CaCdCO, and PbCO in heavy metal-contaminated soil.
基于微生物诱导碳酸钙沉淀（MICP）的生物修复技术被应用于镉和铅污染土壤，以研究MICP对土壤中镉和铅的影响。在本研究中，土壤中的固有氮被证明可诱导MICP来稳定重金属，而无需添加外源尿素。结果表明，施用巴氏芽孢杆菌与氯化钙可降低镉和铅的生物有效性，这可通过土壤中可交换态镉和铅的比例分别降低23.65%和12.76%得到证明。此外，将巴氏芽孢杆菌分别与羟基磷灰石（HAP）、蛋壳（ES）和牡蛎壳（OS）结合，以研究它们对土壤重金属化学形态、毒性特性浸出程序（TCLP）可提取的镉和铅以及酶活性的影响。结果表明，在土壤中施用巴氏芽孢杆菌可显著降低可交换态部分的重金属含量，并增加碳酸盐相部分的重金属含量。当巴氏芽孢杆菌与ES和OS结合时，碳酸盐结合态镉的含量分别增加了114.72%和118.81%，显著高于巴氏芽孢杆菌与HAP结合时，其中碳酸盐结合态镉的比例增加了86%。巴氏芽孢杆菌与生物源钙的组合有效降低了土壤中镉和铅的浸出含量，在BP + ES组中，TCLP可提取的镉和铅部分分别降低了43.88%和30.66%，在BP + OS组中分别降低了52.60%和41.77%。这证明了MICP降低了土壤中重金属的生物有效性。同时，施用巴氏芽孢杆菌和钙材料显著提高了土壤脲酶活性。研究了土壤样品的微观结构和化学成分，扫描电子显微镜、傅里叶变换红外光谱和X射线衍射的结果证明了MICP过程，并确定了重金属污染土壤中CaCO、CaCdCO和PbCO的形成。
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