Key Laboratory of Surficial Geochemistry of Ministry of Education, School of Earth Sciences and Engineering, Hydrosciences Department, Nanjing University, Nanjing 210023, China.
Key Laboratory of Surficial Geochemistry of Ministry of Education, School of Earth Sciences and Engineering, Hydrosciences Department, Nanjing University, Nanjing 210023, China.
Environ Pollut. 2019 Nov;254(Pt A):112940. doi: 10.1016/j.envpol.2019.07.108. Epub 2019 Jul 20.
Predicting the cotransport of functional microorganisms and heavy metals in porous media is essential to both bioremediation and pollutant risk assessment. In this study, batch and column experiments were conducted to explore the cotransport behaviors of functional bacteria (FA1) and heavy metals (Pb/Cd) in saturated sand media under different conditions. The sorption capacity of heavy metals on FA1 was much greater than that of the sand, while both FA1 and sand showed stronger affinity to Pb than Cd. The surface properties, especially zeta potential, of the bacteria and sand were altered by metal adsorption. As a result, the co-existence of Pb decreased the transport of FA1 more significantly than that of Cd, and the influence was more significant with higher heavy metal concentration. On the other hand, the co-existence of FA1 inhibited the mobility of Pb and Cd in most scenarios, except when the cotransport concentration of Pb was 5 mg L, and the inhibition was more pronounced for Pb than Cd. Increase in metal concentrations decreased the FA1-associated Pb/Cd in effluents due to the remarkable decrease in FA1 mobility, and free soluble Pb/Cd became the major migration species. In addition, due to stronger attractive forces and affinity between Pb and FA1, nearly all presorbed-Pb by sand was remobilized by FA1 and transported mainly in FA1-associated form other than soluble Pb. Findings from this study indicated that the cotransport of biocolloids and heavy metals are highly sensitive to the ion type and concentration, and evaluation of their transport in the subsurface should be carefully carried out to avoid inaccurate estimations.
预测功能微生物和重金属在多孔介质中的共迁移对于生物修复和污染物风险评估都至关重要。本研究通过批实验和柱实验，探讨了功能菌（FA1）和重金属（Pb/Cd）在不同条件下在饱和砂介质中的共迁移行为。重金属在 FA1 上的吸附容量远大于在砂上的吸附容量，而 FA1 和砂对 Pb 的亲和力都强于 Cd。金属吸附改变了细菌和砂的表面性质，尤其是 zeta 电位。结果表明，Pb 的共存使 FA1 的迁移显著减少，而 Cd 的迁移减少较少，且重金属浓度越高影响越显著。另一方面，在大多数情况下，FA1 的共存抑制了 Pb 和 Cd 的迁移，除了 Pb 的共迁移浓度为 5mg/L 时，且对 Pb 的抑制作用比 Cd 更明显。由于 FA1 迁移性显著降低，金属浓度的增加降低了流出物中与 FA1 相关的 Pb/Cd，而自由溶解的 Pb/Cd 成为主要迁移物种。此外，由于 Pb 与 FA1 之间更强的吸引力和亲和力，几乎所有被砂预吸附的 Pb 都被 FA1 重新迁移，并主要以 FA1 相关的形式而不是可溶 Pb 迁移。本研究结果表明，生物胶体和重金属的共迁移对离子类型和浓度高度敏感，在进行地下水中的迁移评估时应谨慎进行，以避免不准确的估计。
