Qu Chenchen, Chen Wenli, Fein Jeremy B, Cai Peng, Huang Qiaoyun
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China.
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China.
J Hazard Mater. 2021 Mar 5;405:124081. doi: 10.1016/j.jhazmat.2020.124081. Epub 2020 Sep 23.
Mineral-organic interfacial reactions strongly influence the adsorption, distribution and bioavailability of metal cations in soil systems. The molecular binding mechanisms and distribution of Cd onto goethite, humic acid, Pseudomonas putida cells, and their composites at different mass ratios were studied through the combination of bulk adsorption coupled with EXAFS, ITC and SCM. In binary and ternary composites, the energetics of the overall adsorption of Cd was dominated by the entropy of Cd adsorption onto the organic fraction. The formation of a type-B HA bridging complex >FeOH-HACOOCdOH enhanced Cd adsorption by 10-30% at low Cd concentrations, and more than 93.5% of the adsorbed Cd was bound onto HA fraction. In ternary systems, the component additivity over-estimated Cd adsorption onto bacteria by ~21.8%, likely due to site blocking effects. Models involving the masking of phosphoryl sites and HA bridging reactions can simulate the distribution of Cd in the composites. Our modelling suggests that HA is the main scavenger of Cd under a range of environmental conditions, and that bacteria become important in affecting the distribution of Cd under lower pH settings. This study demonstrates the impact of iron oxide-HA-bacteria interactions on the fate and distribution of Cd in soils and associated environments.
矿物-有机界面反应对土壤系统中金属阳离子的吸附、分布和生物有效性有强烈影响。通过批量吸附结合EXAFS、ITC和SCM，研究了不同质量比下镉在针铁矿、腐殖酸、恶臭假单胞菌细胞及其复合物上的分子结合机制和分布。在二元和三元复合物中，镉总体吸附的能量学主要由镉吸附到有机部分的熵主导。在低镉浓度下，B型腐殖酸桥联复合物>FeOH-HACOOCdOH的形成使镉吸附增加了10%-30%，且超过93.5%的吸附镉与腐殖酸部分结合。在三元体系中，组分加和法高估了镉在细菌上的吸附约21.8%，可能是由于位点阻断效应。涉及磷酰位点掩蔽和腐殖酸桥联反应的模型可以模拟镉在复合物中的分布。我们的模型表明，在一系列环境条件下，腐殖酸是镉的主要清除剂，而在较低pH值条件下，细菌对镉分布的影响变得重要。本研究证明了氧化铁-腐殖酸-细菌相互作用对土壤及相关环境中镉的归宿和分布的影响。
