AsFePO - A model concept for in situ investigation of arsenic and phosphate adsorption to predefined iron minerals and to characterize transformation processes of iron minerals

AsFePO - 用于原位研究砷和磷酸盐对预定铁矿物的吸附并表征铁矿物转化过程的模型概念

• 批准号: 230271102
• 负责人: Dr. Harald Neidhardt
• 金额: --
• 依托单位: Forschungsbereich Geographie
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/230271102?language=en
• 关键词: AsFePO; model; concept; situ; investigation

Shallow groundwater of the huge deltaic systems of Asia like the Red River Delta in Vietnam is often enriched in inorganic arsenic (As), threatening the health of millions of residents. The massive abstraction of groundwater in these areas locally causes an irreversible mixing of arsenic-free groundwater resources with arsenic-rich groundwater. Increased concentrations of competitive anions, especially phosphate (PO43-), decrease the immobilization capacity of the sediments. During transport, the mobility of dissolved As in local aquifers is strongly influenced by adsorption to sedimentary and ubiquitously occurring iron(oxyhydr)oxides. Additionally, arsenic-rich groundwater is often enriched in reduced iron (Fe2+) as well, which is capable to react with iron(oxyhydr)oxides, thereby inducing mineral transformations. Such transformations permanently affect the arsenic adsorption and immobilization capacity of the sediments.Within the scope of this research project, the underlying mechanisms related to As transport and the resulting threat to arsenic-free groundwater resources will be characterized in cooperation with the Swiss Federal Institute of Aquatic Science and Technology (Eawag). The research concept aims at assessing the complex interactions within the arsenic-iron-phosphate-system under field conditions at a study site next to the Red River. First, filtration experiments using local groundwater enriched in As and PO43- will be used to determine the As adsorption capacity of different and previously geochemically characterized iron(oxyhydr)oxides. In a second step, sample carrier containing As loaded iron(oxyhydr)oxides will be introduced into surface near aquifer parts of the study site (via existing groundwater monitoring wells). These samples will be exposed to local groundwater characterized by increased As, Fe2+ and PO43- concentrations for the following nine months. Using the in situ exposition of predefined iron(oxyhydr)oxides, it will be possible to distinguish potential mineral transformations and their influences on the As immobilization capacity of the respective iron(oxyhydr)oxides.By combining the results and outcomes of the field experiments, new and important conclusions regarding the mobility of As can be drawn. The data can be used to create a hydrochemical transport model describing reactive As transport within the investigation area. In addition, the results of the in situ exposition experiments will allow to draw conclusions in respective to the long term As immobilization capacity of different iron(oxyhydr)oxides, which is an essential information regarding in situ decontamination techniques.

亚洲巨大的三角洲系统的浅层地下水，如越南的红河三角洲，经常富含无机砷(As)，威胁着数百万居民的健康。这些地区大量抽取地下水，导致无砷地下水资源与富砷地下水不可逆转地混合在一起。竞争阴离子浓度的增加，特别是磷酸盐(PO43-)的浓度增加，降低了沉积物的固定能力。在迁移过程中，在当地含水层中溶解的砷的迁移性受到沉积和普遍存在的铁(氧)氧化物吸附的强烈影响。此外，富含砷的地下水通常还富含还原铁(Fe2+)，能够与铁(氧)氧化物反应，从而引起矿物转化。在本研究项目的范围内，将与瑞士联邦水产科学与技术研究所(Ewag)合作，描述与砷迁移相关的潜在机制以及由此对无砷地下水资源的威胁。这项研究的概念旨在评估红河旁边的一个研究地点在野外条件下砷-铁-磷-系统内的复杂相互作用。首先，将利用富含砷和PO43-的当地地下水进行过滤实验，以确定不同的、以前具有地球化学特征的铁(水氧)氧化物对砷的吸附能力。第二步，将装载有铁(氧)氧化物的样品载体引入研究场地含水层部分附近的地表(通过现有的地下水监测井)。这些样本将在接下来的九个月里暴露在以As、Fe2+和PO43-浓度升高为特征的当地地下水中。利用预定义的铁(水合)氧化物的原位展示，将有可能区分潜在的矿物转化及其对各个铁(水合)氧化物固定砷能力的影响。通过结合现场实验的结果和结果，可以得出关于砷的移动性的新的重要结论。这些数据可用于建立水化学传输模型，将反应性描述为调查区域内的传输。此外，现场展示实验的结果将使我们能够得出关于不同铁(氧)氧化物的固定能力的长期结论，这是关于现场去污技术的基本信息。