Gu Wenzhi, Cui Mengyao, Tian Chang, Wei Cuicui, Zhang Lixia, Zheng Dechong, Li Daping
Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Science, Chengdu 610041, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Science, Chengdu 610041, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Ecotoxicol Environ Saf. 2021 May 8;218:112263. doi: 10.1016/j.ecoenv.2021.112263.
For controlling heavy metal pollution, the utilization of carboxylic acids (CAs) combined with sulfate-reducing bacteria (SRB) for continuous and stable remediation of Cr (VI)-contaminated soil was comprehensively investigated. At pH 3, citrate and lactate had photocatalysis characteristics that enabled them to reduce high Cr (VI) concentrations. The reduction efficiencies of citrate and lactate were 99.16-100% and 80.78-87.00%, respectively. In the 40 mg L Cr (VI) treatment, the total Cr adsorption rate of soil was 61.39-68.31%; as the pH increased, the Cr species adsorption capacity of the soil decreased. Following the addition of exogenous 100 mg L Cr (VI), the Cr (VI) content of re-contaminated soil was reduced to 16.2734 ± 0.9505 mg L or 15.8618 mg kg by adding citrate or lactate. Then, using SRB via culture by mulching, addition of citrate or lactate markedly reduced the toxicity of Cr (VI). The respective citrate or lactate treatments had sulfur concentrations of sulfide from deep soil (high-sulfide layer) of 70.54 ± 17.59 and 98.85 ± 13.84 mg kg, respectively, and released Cr (VI) concentrations of 0.22 ± 0.25 and 3.64 ± 3.32 mg kg, respectively, due to oxidation upon air exposure. We used a two-stage remediation strategy for these treatments: First, CAs were used for photocatalytic reduction to reduce Cr (VI); next, CAs were utilized as carbon sources by SRB, which further reduced Cr (VI) and stabilized Cr species. In addition, citrate was more conducive than lactate to maintaining the stability of the soil microbial community. The results show that this method has potential in the remediation of Cr (VI)-contaminated soil.
为控制重金属污染，对利用羧酸（CAs）与硫酸盐还原菌（SRB）联合对铬（VI）污染土壤进行连续稳定修复进行了全面研究。在pH值为3时，柠檬酸盐和乳酸盐具有光催化特性，使其能够还原高浓度的铬（VI）。柠檬酸盐和乳酸盐的还原效率分别为99.16 - 100%和80.78 - 87.00%。在40 mg/L铬（VI）处理中，土壤对总铬的吸附率为61.39 - 68.31%；随着pH值升高，土壤对铬形态的吸附能力下降。添加外源100 mg/L铬（VI）后，通过添加柠檬酸盐或乳酸盐，再污染土壤中的铬（VI）含量分别降至16.2734±0.9505 mg/L或15.8618 mg/kg。然后，通过覆盖培养利用SRB，添加柠檬酸盐或乳酸盐显著降低了铬（VI）的毒性。各自的柠檬酸盐或乳酸盐处理中，深层土壤（高硫化物层）中硫化物的硫浓度分别为70.54±17.59和98.85±13.84 mg/kg，由于空气暴露氧化，释放的铬（VI）浓度分别为0.22±0.25和3.64±3.32 mg/kg。我们对这些处理采用了两阶段修复策略：首先，利用CAs进行光催化还原以降低铬（VI）；其次，CAs被SRB用作碳源，进一步降低铬（VI）并稳定铬形态。此外，柠檬酸盐比乳酸盐更有利于维持土壤微生物群落的稳定性。结果表明，该方法在铬（VI）污染土壤修复方面具有潜力。
