Abstract：
An overexploitation of earth resources results in acid deposition in soil, which adversely impacts soil ecosystems and biodiversity and affects conventional heavy metal remediation using immobilization. A series of column experiments was conducted in this study to compare the cadmium (Cd) retention stability through biotic and abiotic carbonate precipitation impacted by simulated acid rain (SAR), to build a comprehensive understanding of cadmium speciation and distribution along soil depth and to elucidate the biogeochemical bacteria-soil-heavy metal interfaces. The strain of Sporosarcina pasteurii DSM 33 was used to trigger the biotic carbonate precipitation and cultivated throughout the 60-day column incubation. Results of soil pH, electrical conductivity (EC), and quantitative CdCO3/CaCO3 analysis concluded that the combination of biotic and abiotic soil treatment could reinforce soil buffering capacity as a strong defense mechanism against acid rain disturbance. Up to 1.8 ± 0.04 U/mg urease enzyme activity was observed in combination soil from day 10, confirming the sustained effect of urease-mediated microbial carbonate precipitation. Cadmium speciation and distribution analyses provided new insights into the dual stimulation of carbonate-bound and Fe/Mn-bound phases of cadmium immobilization under microbially induced carbonate precipitation (MICP). As confirmed by the microbial community analysis, outsourcing urea triggered diverse microbial metabolic responses, notably carbonate precipitation and dissimilatory iron metabolism, in both oxygen-rich topsoil and oxygen-depleted subsurface layers. The overall investigation suggests the feasibility of applying MICP for soil Cd remediation under harsh environments and stratagem by selecting microbial functionality to overcome environmental challenges.
摘要：
地球资源的过度开发导致土壤中的酸沉积，这对土壤生态系统和生物多样性产生了不利影响，并影响了使用固定化的常规重金属修复。在这项研究中进行了一系列的柱实验，以比较受模拟酸雨（SAR）影响的通过生物和非生物碳酸盐沉淀的镉（Cd）保留稳定性，全面了解镉的形态和沿土壤深度的分布，并阐明生物地球化学细菌-土壤-重金属界面。使用SporosarcinapasteuriiDSM33菌株触发生物碳酸盐沉淀，并在整个60天的柱孵育中进行培养。土壤pH值的结果，电导率(EC)，和定量CdCO3/CaCO3分析得出的结论是，生物和非生物土壤处理相结合可以增强土壤的缓冲能力，这是对抗酸雨干扰的强大防御机制。从第10天开始，在组合土壤中观察到高达1.8±0.04U/mg的脲酶活性，证实了脲酶介导的微生物碳酸盐沉淀的持续作用。镉的形态和分布分析为微生物诱导的碳酸盐沉淀（MICP）下镉固定的碳酸盐结合和Fe/Mn结合相的双重刺激提供了新的见解。微生物群落分析证实，外包尿素引发了不同的微生物代谢反应，特别是碳酸盐沉淀和异化铁代谢，在富氧表层和贫氧表层。总体调查表明，通过选择微生物功能来克服环境挑战，在恶劣的环境和策略下将MICP应用于土壤Cd修复的可行性。
