Technology Research Center for Pollution Control and Remediation of Northwest Soil and Groundwater, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, People's Republic of China.
College of Ecology, Lanzhou University, Lanzhou 730000, People's Republic of China; Center for the Pan-third Pole Environment, Lanzhou University, Lanzhou 730000, People's Republic of China.
Sci Total Environ. 2024 Apr 10;920:170959. doi: 10.1016/j.scitotenv.2024.170959. Epub 2024 Feb 15.
Immobilization stands as the most widely adopted remediation technology for addressing heavy metal(loid) contamination in soil. However, it is crucial to acknowledge that this process does not eliminate pollutants; instead, it confines them, potentially leaving room for future mobilization. Presently, our comprehension of the temporal variations in the efficacy of immobilization, particularly in the context of its applicability to arid farmland, remains severely limited. To address this knowledge gap, our research delves deep into the roles of iron-oxidizing bacteria (FeOB) and organic fertilizer (OF) in the simultaneous immobilization of arsenic (As) and cadmium (Cd) in soils. We conducted laboratory incubation and field experiments to investigate these phenomena. When OF was combined with FeOB, a noteworthy transformation of available As and Cd into stable species, such as the residual state and combinations with Fe-Mn/Al oxides, was observed. This transformation coincided with changes in soil properties, including pH, Eh, soluble Fe, and dissolved organic carbon (DOC). Furthermore, we observed synergistic effects between available As and Cd when treated with bacteria and OF individually. The stabilization efficiency of As and Cd, as determined by the Toxicity Characteristic Leaching Procedure, reached its highest values at 33.39 % and 24.67 %, respectively, after 120 days. Nevertheless, the formation of iron‑calcium complexes was disrupted due to pH fluctuations. Hence, long-term monitoring and model development are essential to enhance our understanding of the remediation process. The application of organic fertilizer and the use of FeOB in calcareous soil hold promise for the restoration of polluted soil and the maintenance of soil health by mitigating the instability of heavy metals(loid).
固定化是目前广泛应用于土壤重金属（类）污染治理的修复技术。然而，需要注意的是，该技术并不能彻底消除污染物，而是将其固定在土壤中，为后续的再次释放留下隐患。目前，我们对于固定化技术效果的时间变化，尤其是其在干旱农田中的适用性，仍缺乏深入了解。为了弥补这一知识空白，我们深入研究了铁氧化菌（FeOB）和有机肥（OF）在土壤砷（As）和镉（Cd）同时固定化过程中的作用。我们通过实验室培养和野外试验来研究这些现象。当 OF 与 FeOB 结合使用时，土壤中有效态的 As 和 Cd 显著转化为稳定的形态，如残渣态和与 Fe-Mn/Al 氧化物结合的形态。这一转化与土壤性质的变化有关，包括 pH、Eh、可溶性 Fe 和溶解有机碳（DOC）。此外，我们还观察到细菌和 OF 单独处理时，有效态 As 和 Cd 之间存在协同作用。毒性特征浸出程序（TCLP）测定的 As 和 Cd 的稳定效率在 120 天后分别达到最高值 33.39%和 24.67%。然而，由于 pH 的波动，铁钙络合物的形成受到了干扰。因此，需要进行长期监测和模型开发，以加深我们对修复过程的理解。在石灰性土壤中应用有机肥和使用 FeOB 有望通过减轻重金属（类）的不稳定性来恢复污染土壤并维护土壤健康。
