Coupling fractionation and batch desorption to understand arsenic and fluoride co-contamination in the aquifer system
Coupling fractionation and batch desorption to understand arsenic and fluoride co-contamination in the aquifer system
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DOI：
10.1016/j.chemosphere.2016.08.075
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发表时间：
2016-12-01
期刊：
影响因子：
8.8
通讯作者：
Ramanathan, A. L.
中科院分区：
文献类型：
--
作者：
Kumar, Manish;Das, Nilotpal;Ramanathan, A. L.
目前的工作是尝试使用基于实验室的测定法来研究 As 和 F+ 的共价性，该测定法结合了分馏和批量溶解实验。对从印度阿萨姆邦布拉马普特拉河漫滩收集的沉积物和土壤样本进行了顺序提取程序（SEP），分为五个“操作定义的阶段”。土壤/沉积物样品中铁（氢）氧化物分数与总砷含量之间的高度相关性表明铁（氢）氧化物是砷的主要来源。 F- 是一种阴离子，有很高的潜力被吸附到带正电的表面上。 SEP 的研究结果用于通过控制土壤/沉积物的 Fe（氢）氧化物含量来设计批量解吸实验。在酸性、中性和碱性 pH 条件下，未处理和去除铁（氢）氧化物的样品中观察到了 As 和 F- 的解吸。研究发现，在碱性 pH 值下，未处理的样品中 As 和 F- 的释放量最高，而不含 Fe（氢）氧化物的样品中的浸出量较低。研究表明，土壤和沉积物中常见的 Fe（氢）氧化物部分对带负电荷的物质（例如 As、AsO43-（砷酸盐）和 AsO33-（亚砷酸盐）的 F- 氧阴离子）具有高亲和力。研究发现 Fe（氢）氧化物部分在 As 和 F- 的共同演化中起主要作用。根据采样地点地下水中存在的易浸出部分和砷，提出了两个吸附系数，以了解浸出污染的脆弱性。 (C) 2016 Elsevier Ltd. 保留所有权利。
The present work is an attempt to study As and F+ coevality using laboratory based assays which couples fractionation and batch dissolution experiments. Sequential extraction procedure (SEP) resulting into five "operationally defined phases", was performed on sediment and soil samples collected from the Brahmaputra flood plains, Assam, India. High correlation between the Fe (hydr)oxide fraction and total As content of the soil/sediment sample indicates the involvement of Fe (hydr)oxides as the principal source of As. F- being an anion has high potential to be sorbed onto positively charged surfaces. Findings of the SEP were used to design the batch desorption experiments by controlling the Fe (hydr)oxide content of the soil/sediment. Desorption of As and F- was observed under acidic, neutral and alkaline pH from untreated and Fe (hydr)oxide removed samples. Highest amount of As and F- were found to be released from untreated samples under alkaline pH, while the amount leached from samples with no Fe (hydr) oxide was low. The study showed that the Fe (hydr)oxide fraction commonly found in the soils and sediments, had high affinity for negatively charged species like F- oxyanions of As, AsO43- (arsenate) and AsO33- (arsenite). Fe (hydr)oxide fraction was found to play the major role in co-evolution of As and F-. Two sorption coefficients were proposed based on easily leachable fraction and As present in the groundwater of sampling location for understanding of contamination vulnerability from the leaching. (C) 2016 Elsevier Ltd. All rights reserved.