Assessment and remdiation of As enrichments in groundwater

天然或人为富集砷的地下水在包括美国在内的世界许多地区构成严重的健康危害。这个项目建立在越来越多的人认识到砷对铁氧氢氧化物的高亲和力是调节地下水中溶解砷浓度的关键因素的基础上。As对Fe-oxyhydroxides的特殊亲和力已在不久的将来被开发为推荐值10马克/升，需要更好地了解不同的处理方案和地下水成分对处理效果的影响。它们(I)作为减少地下水的动员：来自美国超级基金在Winthrop， ME和Vineland，新罕布什尔州（项目）和孟加拉国（项目5）的现场材料将用于量化在氧化和还原条件下溶解相和特定相之间的As交换。在第一组实验中，通过还原溶解对砷的潜在综合释放将通过从覆盖一系列氧化还原条件的存档含水层材料中提取羟胺来确定。将还原溶解释放的As和FE的空间格局与含水层中氧的分布进行比较。在第二组实验中，将对选定地点的新鲜含水层岩心进行孵育，以量化砷和铁交换（吸附或解吸）的速率。在第三组实验中，最先进的表面分析技术将用于表征砷在一系列代表自然环境的条件下在模型铁氧化物表面的结合。主题（二）从还原性地下水中去除砷：氯化铁共沉淀处理是一种通常用于去除水中砷的有效技术。另一种从地下水中去除砷的方法很有前途，但尚未得到充分评价，它依赖于铁屑的吸附特性。这种方法被发现是非常有效的，但尚未充分评估依赖于铁屑的吸附性能。这种方法被发现在温斯洛普，ME，超级基金站点非常有效，并将在新泽西州Vineland的另一个站点进行测试。利用表面光谱学对铁屑去除砷的机理进行了探讨。本主题下的另一个目标是开发切实可行的方法，减少砷修复的规模，从而满足美国和孟加拉国家庭井用户的需求。我们将把重点放在以氢氧铁为基础的处理上，尽可能利用地下水中的天然铁含量。将与当地政府研究人员合作，探索孟加拉国现有除铁装置的除砷潜力。在美国和孟加拉国，还将研究将铁片作为共沉淀铁的替代来源来处理来自家庭电池的水的潜力。

Groundwater naturally or anthropogenically enriched in As poses serious health hazards in many parts of the world, including the US. This project builds on the growing realization that the particular high affinity of As for Fe-oxyhydroxides is a key factor regulating dissolved As concentrations in groundwater. The particular affinity of As for Fe-oxyhydroxides has been exploited for recommended value to 10 mug/L in the near future, a better fundamental understanding of different treatment options and the influence of groundwater composition on the efficacy of treatment is needed. Them (I) As mobilization into reducing groundwater: Field material from US Superfund sites at Winthrop, ME and Vineland, NH (Project) and Bangladesh (PROJECT 5) will be used to quantify the exchange of As between the dissolved and the particular phase under oxic and reducing conditions. In a first set of experiments, the potential integrated release of As by reductive dissolution will be determined with hydroxylamine extraction from archived aquifer material covering a range of redox conditions. The spatial patterns of As and FE released by reductive dissolution will be compared to the oxygen distribution in the aquifers. In a second set of experiments, fresh cores of aquifer from selected sites will be incubated to quantify the rate of As and Fe exchange (adsorption or desorption). In a third set of experiments, state-of-the-art surface analytical techniques will be used to characterize arsenic binding at model Fe oxide surfaces under a range of conditions representative of the natural environment. Theme (II) As removal from reducing groundwater: Co-precipitation treatment with ferric chloride is an effective technique commonly used for the removal of arsenic form water. A different approach for removing As from groundwater that is promising but has not yet been fully evaluated relies on the adsorptive properties of Fe filings. This method was found to be very effective but has not yet been fully evaluated relies on the adsorptive properties of Fe filings. This methods was found to be very effective at the Winthrop, ME, Superfund site and will be tested at another site in Vineland, NJ. The mechanisms of As removal by Fe filings will also be probed using surface spectroscopy. Another objective under this theme is to develop practical ways of reducing the scale of As remediation and hereby meet the needs of users of domestic wells in the US and Bangladesh. We will focus on Fe-oxyhydroxide-based treatment using, whenever possible, the natural Fe content of groundwater. The As- removal potential of existing Iron Removal Units in Bangladesh will be explored in collaboration with local government researchers. The potential of filings as an alternative source of Fe for co-precipitation to treat water from domestic cells in the US and Bangladesh will also be examined.