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.

恒河三角洲数千万人继续饮用危险的地下水 被砷和锰污染。我们估计，在孟加拉国，如果消费受污染的 水继续供应，砷中毒和皮肤癌的患病率将分别约为200万和10万 每年分别有 1 例，砷诱发癌症的死亡发生率约为 每年 3,000 例4。尽管人们对锰的关注较少，但锰的危险水平 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发现锰和砷是两种经常超标的污染物 孟加拉国的锰浓度较高，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。 孟加拉国是研究有毒金属进入环境的过程的理想场所 在地球化学还原条件下。孟加拉国的缺氧地下水状况与塔吉克斯坦形成鲜明对比 项目 2 的 Creek 场地，这里的采矿活动使大量矿物质暴露在快速氧化之下。在 孟加拉国，灌溉稻田和池塘的建设引入了大量缺氧、有机污染物 水。这种转变发生在过去四十年里，随着灌溉泵的出现， 地下水的停留时间现在也在几十年到一个世纪的数量级。由此可见，影响 这些补给水的化学变化现在正在通过地下水系统并驱动 可以观察到动员和隔离有毒金属的生物地球化学过程。 在这个拟议的超级基金基础研究计划（SBRP）中，我们的研究将解决土地利用和 地下水输送控制饮用水中砷和锰的浓度。这些问题都在z 水文学和生物地球化学的交叉点，是理解金属的未解决的关键问题 环境中的动员。在过去的十年中，我们对静电有了细致入微的了解。 砷污染含水层的地球化学特征，并表征了快速微生物介导的 沉积物孵化实验中对化学扰动的响应。然而，非常少 了解水文地质学的基本方面，这对于了解地下水的演变至关重要 沿着流动路径的化学反应。尽管从农业角度来看存在水平衡数据6，但我们并不 了解驱动锰和砷迁移的溶质通量如何进入含水层，以什么模式 地下水流动，或者溶质如何在不同的流动路径中混合。更深层次的知识却知之甚少 地下水流，以及区域流7"9和地下水的重要性等基本问题 抽10~12仍有争议。在我们的现场区域，我们最近量化了季节性水文 含水层的补给和排水循环。在这个项目中，我们将在水平衡的基础上 描述砷和锰的移动位置和生物地球化学条件 这些毒素随后通过复杂的瞬态三维模式进行运输 将它们输送到饮用水井的流线。 作为我们努力的一部分，我们将努力推进两项有潜力广泛应用的技术 应用。我们将开发使用传感器监测不断变化的生物地球化学条件的新方法， 我们将试验砷和锰原位修复的新方法。一个网络 将建造探测器以高时间分辨率监测数小时内土壤状况的变化， 季节和年份。我们将重点关注限制漂移和生物污垢的实际问题，并将整合 地球化学探测器与我们成功的渗流区液压传感器网络。我们的原位修复 实验将集中于推拉井注入方法，该方法使用氧化剂在周围创建“过滤器” 通过用沉淀的锰和铁氧化物涂覆含水层沉积物来吸附砷的井筛。