Project 4: Arsenic and Manganese Mobility: Land Use, Redox Shifts

项目 4：砷和锰的流动性：土地利用、氧化还原变化

• 批准号: 7932378
• 负责人: CHARLES F HARVEY
• 金额: $ 26.3万
• 依托单位: HARVARD SCHOOL OF PUBLIC HEALTH
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-12 至 2014-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7932378
• 关键词: Address; Adopted; Affect; Agriculture; Area; Arsenic; Attention; Automobile Driving; Bangladesh; Basic Science; Biochemical; British; Cessation of life; Characteristics; Chemicals; Chemistry; Complex; Consumption; Data; Diffuse; Environment; Epidemiology; Equilibrium; Evolution; Flushing; Future; Geology; Hand; Hour; In Situ; Incidence; Injection of therapeutic agent; Iron; Irrigation; Laboratories; Location; Malignant Neoplasms; Manganese; Metals; Methods; Minerals; Mining; Monitor; Nervous System Physiology; Oxidants; Oxidation-Reduction; Oxides; Oxygen; Pattern; Precipitation; Prevalence; Process; Pump; Research; Resolution; Rice; Seasons; Site; Skin Cancer; Soil; Source; Steam; Sulfides; Superfund; Surface; Surveys; System; Technology; Time; Toxin; Tritium; Water; Withdrawal; Work; contaminant transport; cost; drinking; drinking water; evaporation; hydrology; iron oxide; land use; oxidation; programs; remediation; research study; residence; response; sensor; solute; toxic metal

Tens of millions of people in the Ganges Delta continue to drink groundwater that is dangerously contaminated with arsenic and manganese. We estimate that in Bangladesh, if consumption of contaminated water continues, the prevalence of arsenicosis and skin cancer will be approximately 2 million and 100,000 cases per year, respectively, and the incidence of death from cancer induced by arsenic will be approximately 3,000 cases per year4. Although less attention has been given to manganese, dangerous levels of manganes are also common in Bangladesh's groundwater. In their landmark survey of groundwater chemistry, the BritisH Geological Survey2 found that manganese and arsenic are the two contaminants that routinely exceed safe concentrations in Bangladesh, and recent epidemiological work has shown that manganese may damage the neurological function of Bangaldeshi children5. Bangladesh is an ideal field site for studying processes that mobilize toxic metals into the environment under geochemical reducing conditions. The anoxic groundwater conditions of Bangladesh contrast to the Ta Creek site of Project 2, where mining has exposed large quantities of minerals to rapid oxidation. In Bangladesh, construction of irrigated rice fields and ponds has introducing large inflows of anoxic, organic-ric water. This shift has occurred over the last forty years and, with the advent of irrigation pumping, the residence time of groundwater is now also on the order of decades to a century. Consequentially, the effects of these chemical alterations to recharge water are now moving through the groundwater system and driving biogeochemical process that can be observed to both mobilize and sequester toxic metals. In this proposed Superfund Basic Research Program (SBRP), our research will address how land use and groundwater transport control arsenic and manganese concentrations in drinking water. These questions lie z the intersection of hydrology and biogeochemistry and are key unresolved questions for understanding metal mobilization in the environment. Over the last decade, we have gained a nuanced understanding of the static geochemical characteristics of arsenic-contaminated aquifers and have characterized the rapid microbialmediated response to chemical perturbations in sediment incubation experiments. However, remarkably little known about basic aspects of hydrogeology that are vital for understanding the evolution of groundwater chemistry along flow paths. Although water-balance data exist from an agricultural perspective6, we do not know how the solute fluxes that drive manganese and arsenic mobility enter the aquifer, what patterns groundwater flow follows, or how solutes mix across different flow paths. Little is known about deeper groundwater flow, and indeed, basic issues such as the significance of regional flow7"9 and groundwater pumping 10~12 are still controversial. At our field area, we have recently quantified the seasonal hydrologic cycle by which aquifers are recharged and discharge. In this project, we will build on this water balance to characterize the locations and biogeochemical conditions where arsenic and manganese are mobilized as we as the subsequent transport of these toxins through the complex transient three-dimensional pattern of streamlines that deliver them to drinking-water wells. As part of our effort, we will work to advance two technologies that have the potential for widespread application. We will develop new methods for using sensors to monitor shifting biogeochemical conditions, and we will experiment with new methods for in-situ remediation of arsenic and manganese. A network of probes will be constructed to monitor, at high temporal resolution, changing soil conditions over hours, seasons and years. We will focus on practical issues of limiting drift and biofouling and will integrate the geochemical probes with our successful network of vadose-zone hydraulic sensors. Our in situ remediation experiments will focus on push-pull well-injection methods that use oxidizing agents to create "filters" around well screens to adsorb arsenic by coating aquifer sediments with precipitated manganese and iron oxides.

恒河三角洲的数千万人继续饮用地下水 被砷和锰污染。我们估计在孟加拉国，如果被污染的消费 水继续，砷和皮肤癌的患病率将约为200万和100,000 每年的病例分别为砷引起的癌症死亡的发生率大约 每年3,000例4。尽管对锰的关注较少，但危险的锰水平 在孟加拉国的地下水中也很常见。在他们对地下水化学的里程碑式调查中，英国 地质调查2发现，锰和砷是通常超越安全的两种污染物 孟加拉国的浓度以及最近的流行病学工作表明，锰可能会损害 Bangaldeshi儿童的神经功能5。 孟加拉国是研究动员有毒金属进入环境的过程的理想场地 在地球化学还原条件下。孟加拉国的缺氧地下水与TA形成鲜明对比 项目2的Creek遗址，其中采矿使大量矿物接触到快速氧化。在 孟加拉国，灌溉稻田和池塘的建造引入了大量缺氧，有机-RIC的流入 水。这种转变发生在过去的四十年中，随着灌溉抽水的出现 现在，地下水的停留时间也处于数十年到一个世纪的秩序。因此，效果 这些化学改动以充电水正在通过地下水系统移动并驾驶 可以观察到动员和隔离有毒金属的生物地球化学过程。 在拟议的超级基础研究计划（SBRP）中，我们的研究将解决土地使用和 地下水运输控制饮用水中的砷和锰浓度。这些问题谎言z 水文学与生物地球化学的交集，是理解金属的关键尚未解决的问题 在环境中动员。在过去的十年中，我们对静态有细微的理解 砷污染的含水层的地球化学特征，并表征了快速微生物中介的 对沉积物孵化实验中化学扰动的反应。但是，很少 关于水文地质学的基本方面的了解，这对于理解地下水的演变至关重要 沿流动路径的化学。尽管从农业的角度存在水平数据，但我们却不 知道如何驱动锰和砷流动性的溶质通量进入含水层，什么样式 地下水流遵循，或者如何在不同流动路径上混合混合。关于更深层次的知之甚少 地下水流，甚至是基本问题，例如区域流的意义7” 9和地下水 泵送10〜12仍然存在争议。在我们的现场区域，我们最近量化了季节性水文学 含水层充电并放电的循环。在这个项目中，我们将以这种水平为基础 表征我们在我们的位置和生物地球化学条件的特征 随后这些毒素通过复杂的瞬态三维模式的转运 流线将它们运送到饮用水井。 作为我们努力的一部分，我们将努力推进两种具有广泛潜力的技术 应用。我们将开发使用传感器来监视转移生物地球化学条件的新方法， 我们将尝试使用新方法，以实地修复砷和锰。一个网络 将构建探针以在高时间分辨率下监测，在数小时内改变土壤条件， 季节和几年。我们将专注于限制漂移和生物污染的实际问题，并将 通过我们成功的Vadose-Zone液压传感器网络进行地球化学探针。我们的原位修复 实验将集中于使用氧化剂在周围创建“过滤器”的推扣孔注射方法 通过涂层含有沉淀的锰和氧化铁的含水层沉积物，筛选到吸附砷。