School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China.
Int J Environ Res Public Health. 2019 Jan 18;16(2):268. doi: 10.3390/ijerph16020268.
Cadmium (Cd) is a highly toxic metal that can affect human health and environmental safety. The purpose of this study was to research the removal of Cd from an environmental perspective. In this article, four highly urease-active strains (CZW-2, CZW-5, CZW-9 and CZW-12) were isolated from an abandoned mine and their phylogenetic trees were analyzed. The maximum enzyme activities, the mineralized precipitate and the removal rates of these strains were compared. The results showed that CZW-2 had the highest urease activity at 51.6 U/mL, and the removal rates of CZW-2, CZW-5, CZW-9 and CZW-12 after 120 h were 80.10%, 72.64%, 76.70% and 73.40%, with an initial concentration of Cd of 2 mM in the Cd precipitation experiments. XRD (X-ray diffractometer), EDS (Energy dispersive spectrometer) and FTIR (Fourier transform infrared spectroscopy) analysis indicated that the mineralized precipitate was CdCO₃. SEM (Scanning electron microscopy) analysis revealed that the diameter of the oval-shaped mineralized product ranked from 0.5 to 2 μm. These strains were used to remedy Cd-contaminated soil, and five different fractions of Cd were measured. Compared with the control, the results of spraying pre-cultured strains containing 2% urea to remove Cd from contaminated soils showed that the exchangeable fraction of Cd decreased by 53.30%, 27.78%, 42.54% and 53.80%, respectively, whereas the carbonate-bound fraction increased by 55.42%, 20.27%, 39.67% and 34.36%, respectively, after one month. These data show that these strains can effectively reduce the bioavailability and mobility of Cd in contaminated soils. The results indicate that biomineralization based on the decomposition of substrate urea can be applied to remedy heavy contaminated soil and water.
镉 (Cd) 是一种剧毒金属，会影响人类健康和环境安全。本研究旨在从环境角度研究镉的去除。本文从废弃矿山中分离出四株高脲酶活性的菌株（CZW-2、CZW-5、CZW-9 和 CZW-12），并对其进行了系统发育树分析。比较了这些菌株的最大酶活性、矿化沉淀和去除率。结果表明，CZW-2 的脲酶活性最高，为 51.6 U/mL，在 Cd 沉淀实验中，初始 Cd 浓度为 2 mM 时，CZW-2、CZW-5、CZW-9 和 CZW-12 的去除率在 120 h 后分别为 80.10%、72.64%、76.70%和 73.40%。XRD（X 射线衍射仪）、EDS（能谱仪）和 FTIR（傅里叶变换红外光谱仪）分析表明，矿化沉淀为 CdCO₃。SEM（扫描电子显微镜）分析表明，椭圆形矿化产物的直径在 0.5 至 2 μm 之间。将这些菌株用于修复 Cd 污染土壤，并测量了 Cd 的五个不同形态。与对照相比，向污染土壤中喷洒含有 2%尿素的预培养菌株以去除 Cd 后，结果表明交换态 Cd 分别减少了 53.30%、27.78%、42.54%和 53.80%，而碳酸盐结合态 Cd 分别增加了 55.42%、20.27%、39.67%和 34.36%，一个月后。这些数据表明，这些菌株可以有效降低污染土壤中 Cd 的生物有效性和迁移性。结果表明，基于基质尿素分解的生物矿化可应用于修复重污染土壤和水。
