Humic acid controls cadmium stabilization during Fe(II)-induced lepidocrocite transformation
Humic acid controls cadmium stabilization during Fe(II)-induced lepidocrocite transformation
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腐殖酸在 Fe(II) 诱导纤铁矿转化过程中控制镉的稳定性
DOI：
10.1016/j.scitotenv.2022.160624
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发表时间：
2022
影响因子：
9.8
通讯作者：
Jiangtao Qiao
中科院分区：
文献类型：
--
作者：
Hongling Bu;Qinkai Lei;Hui Tong;Chengshuai Liu;Shujie Hu;Wenpo Xu;Yujie Wang;Manjia Chen;Jiangtao Qiao
Fe（II）对氧化铁的非生物还原是影响土壤铁循环的关键过程之一。Lepidocrocite（Lep）天然存在于凉爽和温带地区的厌氧，粘土，非石灰性土壤中，然而，鲜为人知的是共沉淀腐殖酸（HA）对Fe（II）诱导的Lep转化及其后果的影响重金属固定。在这项研究中，Fe（II）诱导的Lep-HA共沉淀物的相变进行了分析，作为C/Fe比的函数，并进一步研究了其对随后的Cd（II）浓度动态溶解和固体形式的影响。结果表明，在Fe（II）诱导Lep转化过程中，普遍形成了次生Fe（II）磁铁矿，进而改变了Cd（II）的迁移和分布。随着C/Fe比的增加，共沉淀的HA导致Fe固相转变减少。磁铁矿被发现是一个次要的矿物在0.3 C/Fe比Lep-HA共沉淀，而只有Lep被观察到在C/Fe比为1.2，使用X射线衍射（XRD）和穆斯堡尔谱。基于XRD、扫描电子显微镜（SEM）、穆斯堡尔谱、X射线光电子能谱（XPS）和傅里叶变换红外光谱（FTIR）的结果，新形成的磁铁矿可能通过表面络合物、掺入或结构取代来吸附Cd（II）。HA的存在有利于Cd（II）的结合，并影响Lep向磁铁矿的矿物学转化，进而诱导Cd（II）向新生次生矿物中的分配。这些结果提供了深入的了解镉（II）在响应腐殖物质和铁（oxyhydr）氧化物在厌氧环境中之间的反应的行为。
Abiotic reduction of iron (oxyhydr)oxides by aqueous Fe(II) is one of the key processes affecting the Fe cycle in soil. Lepidocrocite (Lep) occurs naturally in anaerobic, clayey, non-calcareous soils in cooler and temperate regions; however, little is known about the impacts of co-precipitated humic acid (HA) on Fe(II)-induced Lep transformation and its consequences for heavy metal immobilization. In this study, the Fe(II)-induced phase transformation of Lep-HA co-precipitates was analyzed as a function of the C/Fe ratio, and its implications for subsequent Cd(II) concentration dynamic in dissolved and solid form was further investigated. The results revealed that secondary Fe(II)-bearing magnetite commonly formed during the Fe(II)-induced transformation of Lep, which further changed the mobility and distribution of Cd(II). The co-precipitated HA resulted in a decrease in the Fe solid phase transformation as the C/Fe ratios increased. Magnetite was found to be a secondary mineral in the 0.3C/Fe ratio Lep-HA co-precipitate, while only Lep was observed at a C/Fe ratio of 1.2 using X-ray diffraction (XRD) and Mössbauer spectroscopy. Based on XRD, scanning electron microscopy (SEM), Mössbauer, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) results, newly formed magnetite may immobilize Cd(II) through surface complexes, incorporation, or structural substitution. The presence of HA was beneficial for binding Cd(II) and affected the mineralogical transformation of Lep into magnetite, which further induced the distribution of Cd(II) into the newly formed secondary minerals. These results provide insights into the behavior of Cd(II) in response to reaction between humic matter and iron (oxyhydr)oxides in anaerobic environments.