Mobilization of arsenic by dissolved organic matter from iron oxides, soils and sediments
Mobilization of arsenic by dissolved organic matter from iron oxides, soils and sediments
复制标题
DOI：
10.1016/j.scitotenv.2005.01.027
复制
发表时间：
2006-02-01
影响因子：
9.8
通讯作者：
Blodau, C
中科院分区：
文献类型：
--
作者：
Bauer, M;Blodau, C
含水层的砷污染与溶解有机物（DOM）的输入有关。根据这一建议，本研究的目的是量化 DOM 对与合成氧化铁和来自不同地球化学环境（土壤、浅层含水层、湖泊沉积物）的天然样品结合的砷的解吸和氧化还原转化的化学影响。在批量实验中，与无机溶液相比，使用含有 25-50 mg/L 两种不同类型 DOM（纯化泥炭腐植酸和来自泥炭排水的 DOM）的溶液作为提取剂。 DOM 溶液能够从所有固相中调动砷。铁氧化物的动员（最大值：53.3%）大于天然样品的动员（最大值：2.9%）。萃取剂的动员效果按HCl > NaH2PO4 > DOM > NaNO3 的顺序降低。因此，DOM 解决方案主要针对弱吸附的砷。动员在 24-36 小时内完成，并且 DOM 在孵育过程中被吸附，表明对吸附位点的竞争。不同 DOM 类型和浓度观察到相同的模式。添加 DOM 导致 (a) 水溶液中砷的还原（最大 7.8%）和氧化（6.4%）增强，以及（b）土壤样品水相中亚砷酸盐的出现（5.5%）。作为砷从固相释放的主要机制，我们确定了砷和有机阴离子之间对吸附位点的竞争，而氧化还原反应可能不太重要。这项研究的结果表明，DOM 的吸附具有从土壤和沉积物中吸收砷的强大潜力。 (c) 2005 Elsevier B.V. 保留所有权利。
The arsenic contamination of aquifers has been linked to the input of dissolved organic matter (DOM). In light of this suggestion, the aim of this study was to quantify chemical effects of DOM on desorption and redox transformations of arsenic bound to synthetic iron oxide and natural samples from different geochemical environments (soils, shallow aquifer, lake sediment). In batch experiments, solutions containing 25-50 mg/L of two different types of DOM (purified peat humic acid and DOM from a peat drainage) were used as extractants in comparison to inorganic solutions. DOM solution was able to mobilize arsenic from all solid phases. Mobilization from iron oxides (maximum: 53.3%) was larger than from natural samples (maximum: 2.9%). The mobilization effect of extractants decreased in the order HCl > NaH2PO4 > DOM > NaNO3. DOM solutions, therefore, mainly targeted weakly sorbed arsenic. Mobilization was complete within 24-36 h and DOM was sorbed during incubation indicating competition for sorption sites. The same patterns were observed for different DOM types and concentrations. Addition of DOM lead to (a) enhanced reduction (maximum 7.8%) and oxidation (6.4%) of arsenic in aqueous solution and (b) the appearance of arsenite in aqueous phase of soil samples (5.5%). As the primary mechanism for the arsenic release from solid phases we identified the competition between arsenic and organic anions for sorption sites, whereas redox reactions were probably of minor importance. The results of this study demonstrate that sorption of DOM has a strong potential to mobilize arsenic from soils and sediments. (c) 2005 Elsevier B.V. All rights reserved.