Future Secular Changes & Remediation of Groundwater Arsenic in the Ganga River Basin

地下水中的砷正在对印度次大陆的人类健康造成严重的有害影响。在供养着5亿多人口的恒河流域，数千万人暴露在地下水砷中，导致每年15 000多人过早死亡，发病率增加，经济生产力下降。虽然已经实施了许多补救/缓解计划，以减少地下水砷暴露，但存在可能部分抵消这些努力的压力。这些变化包括：[i)人口增加和生活富裕造成的对地下水的依赖程度增加，加上地表水水库补给的减少；(Ii)我们假设未来地下水砷长期增加可能源于(A)地表衍生有机碳的进入，据信这与微生物介导的生物地球化学过程密切相关；或(B)在有管理的含水层补给(MAR)中注入含氧水，导致含砷黄铁矿被氧化溶解；在本项目中，我们将量化城市或农村浅层含水层对氧气或有机碳供应增强刺激的地下水砷长期增加的脆弱性。这项研究将以印度和英国高度互补的研究和水资源管理调查团队现有的核心研究以及野外和实验室基础设施为基础，结合对恒河/霍格利上游、中部和/或下游不同沉积类型的自然实验室的独特实地研究，以及对比自然补给和河岸过滤(RBF)等管理含水层补给系统。我们将评估在地表水-地下水相互作用的关键区域，包括潜水带，控制砷动员的生物地球化学过程。我们将建立在现有详细的实地水文地质知识的基础上，这些知识大部分是由项目合作伙伴建立的，并辅之以对关键示踪剂的进一步采样和分析，包括氟氯化碳、SF6、氚和来源指标、有机生物标记物(包括新出现的有机污染物)和氧化还原物种比率。我们对这些系统的了解将被纳入活性污染输送模型，以(I)促进对未来50年恒河流域地下水砷危害的预测；(Ii)为补救技术和方法的选择提供信息，包括间接方法，例如改善近地表城市和农村有机碳源的管理。建立可行的框架，审议解决办法的尽职调查、长期维护和可持续性，以及利用社区参与办法实现技术的社会融合，将是项目外联和知识转让的一个关键要素。研究结果将为印度其他地区和全球地下水脆弱性的风险评估和补救/缓解提供信息，包括在许多官方发展援助国家和英国。我们已经建立了一个广泛和包容的网络，由研究人员、非政府组织、政府组织和其他利益相关者组成，他们对缓解人类活动对印度脆弱地下水中砷和其他污染物浓度长期上升的影响有着强烈的兴趣。该网络将致力于传播关于这些危害的危害、风险和潜在补救/缓解的知识，并推动进一步的联网、整合、知识转让和共同筹资，以更好地了解控制这些重大公共卫生风险的自然和人为过程以及减轻这些风险的有效方法。合作伙伴在这一研究和水资源管理领域拥有实质性和互补性的记录，并将通过工作人员的时间和/或实验室和外地基础设施为该项目带来大量共同资金。

Arsenic in groundwater is causing severe detrimental impacts on human health in the Indian sub-continent. In the Gangetic River Basin, which supports a population of over 500 million people, tens of millions of people are exposed to groundwater arsenic, resulting in more than 15,000 premature deaths each year, as well as enhanced morbidity and reduced economic productivity. Whilst many remediation/mitigation schemes have been implemented to reduce groundwater arsenic exposure, there exist pressures that may partly counteract these efforts. These include: [i] increased reliance on groundwater arising from increased population and affluence coupled with decreased recharge of surface water reservoirs, and [ii] future secular increases in groundwater arsenic which we hypothesise may arise from (a) ingress of surface-derived organic carbon, thought to be strongly implicated in the microbially-mediated biogeochemical processes leading to arsenic mobilisation; or (b) injection of oxygenated waters in managed aquifer recharge (MAR) leading to oxidative dissolution of arsenic-bearing pyrite In this project, we will quantify the vulnerability of shallow urban or rural aquifers to secular increases in groundwater arsenic stimulated by enhanced oxygen or organic carbon supplies. Efficiently and effectively building on existing core research and field and laboratory infrastructure of the highly complementary team of India and UK research and water resource management investigators, this study will combine unique field studies of sedimentologically distinct natural laboratories in the upper, mid and/or lower Ganga/Hooghly as well as contrasting naturally recharging and managed aquifer recharging systems such as river bank filtration (RBF). We will evaluate the biogeochemical processes controlling arsenic mobilisation in key zones, including the hyporheic zone, of surface water-groundwater interactions. We will build upon existing detailed hydrogeological knowledge of the field areas, much built up by the project partners , supplemented by further sampling and analysis of key tracers including CFCs, SF6, tritium, and indicators of provenance, organic biomarkers, including emerging organic contaminants, and redox species ratios. Our developed understanding of these systems will be incorporated into reactive contaminated transport models to (i) facilitate the prediction of groundwater arsenic hazards in the Ganga River Basin over the next 50 years; (ii) inform selection of remediation technologies and approaches, including indirect approaches, such as improving management of near surface urban and rural organic carbon sources. Establishing workable frameworks for considering due diligence, long-term maintenance and sustainability of solutions, social integration of technology using community participatory approaches will be a key element of project outreach and knowledge transfer. The results will inform risk assessment and remediation/mitigation of groundwater vulnerability both elsewhere in India and globally, including in many ODA countries and the UK.We have established a broad and inclusive network of researchers, NGOs, government organisations and other stakeholders with strong interests in mitigating the impacts of human activity on secular increases in the concentration of arsenic and other contaminants in vulnerable groundwaters in India. This network will aim to both transfer knowledge of the hazard, risk and potential remediation/mitigation of these hazards as well as drive for further networking, integration, knowledge transfer and co-funding to better understand the natural and anthropogenic processes controlling these critical public health risks and effective ways to mitigate against them. The partners have substantive and complementary track-records in this area of research and water resource management and will bring significant co-funding to the project, through staff time and/or lab & field infrastructure.