Workshop proposal: Recovering Uncompromised Samples of Aquifer Sands with In-Situ Groundwater from up to 300-m Depth in South and Southeast Asia

地下水含水层是全球约20亿人的主要饮用水来源。然而，公众对长期暴露于天然的地源污染物越来越关注，这些污染物可以从未受污染的沉积物释放到地下水中。未经处理的地下水的天然成分目前被认为是严重的健康问题，包括南亚和东南亚的氟、锰，特别是砷。控制这些潜在有毒成分释放的地下水和沉积物性质往往在垂直和横向上都有很大的变化。这种高度的空间变异性，加上缺乏在不接触钻井液或大气氧气的情况下同时对地下水和含水层砂子进行采样的技术，是造成生物地球化学和水文因素难以分离的一个关键原因。克服这一限制的一个有希望的方法是增加一个原位冷冻组件，在用现有绳索钻探工具收集的岩芯底部形成一个塞子，该工具是由国家科学基金会部分支持的非营利性公司DOSECC(地球的钻井、观测和采样？S大陆地壳公司)开发的。这项提议是为了补充国际大陆科学钻探计划现有的研讨会赠款，以开发必要的采样技术，并制定在未来十年部署新技术的科学计划。通过类比于物理学中的大型实验，独特技术的可获得性可以促进地球科学家社区内的合作水平，这种合作水平比过去理解复杂环境问题(如南亚和东南亚的地下水砷问题)的不同努力更适合。受影响地区的缓解工作继续受到从低砷深层含水层抽水的可持续性的不确定性的阻碍，这些含水层越来越多地被用来向数百万村民提供安全饮用水。拟议的技术将有助于减少这种不确定性，并可随后用于与地下水质量有关的其他问题的研究。

Groundwater aquifers are the main source of drinking water for about 2 billion people worldwide. There is, however, growing public health concern about chronic exposure to natural, geogenic contaminants that can be released from uncontaminated sediment to groundwater. Natural constituents of untreated groundwater currently recognized to be of significant health concern include fluoride, manganese, and particularly arsenic in South and Southeast Asia. The groundwater and sediment properties that regulate the release of these potentially toxic constituents are often highly variable both vertically and laterally. This high degree of spatial variability combined with a lack of technology for sampling groundwater and aquifer sands simultaneously without exposure to drilling fluid or atmospheric oxygen are a key reason that contributing biogeochemical and hydrological factors have been difficult to isolate. A promising avenue for overcoming this limitation is the addition of an in situ freezing package to form a plug at the bottom of a core collected with existing wire-line drilling tools developed by DOSECC (Drilling, Observation and Sampling of the Earth?s Continental Crust Inc.), a not-for-profit corporation supported in part by the National Science Foundation. This proposal is a request to supplement an existing workshop grant from the International Continental Scientific Drilling Program to develop the necessary sampling technology and to generate a science plan for deploying the new technology over the next ten years. By analogy to large experiments in physics, the availability of unique technology could foster the level of collaboration within a community of geoscientists that is better suited than disparate efforts of the past to understanding a complex environmental issue such as the groundwater arsenic problem in South and Southeast Asia. Mitigation in the affected region continues to be hampered by uncertainty concerning the sustainability of pumping from deep low-arsenic aquifers that are increasingly tapped to provide safe drinking water to millions of villagers. The proposed technology will contribute to reducing this uncertainty and could subsequently be deployed for research on other issues related to groundwater quality.