Collaborative Research: MIDGE: Minimally Invasive Direct Glacial Exploration of Biogeochemistry, Hydrology and Glaciology of Blood Falls, McMurdo Dry Valleys

最近在南极冰盖下发现了广泛的液态水和微生物生态系统，引起了人们对南极冰下环境研究的极大兴趣。了解冰下水文学，长期孤立的生命的持续存在以及冰下生境的演变和稳定性需要一个综合的跨学科方法。麦克默多干谷血福尔斯生物地球化学、水文学和冰川学的合作项目-微创直接冰川勘探将综合地球物理测量、分子微生物生态学和地球化学分析，以探索被称为血福尔斯的独特南极冰下系统。血福尔斯是一种高盐的冰下卤水，支持着活跃的微生物群落。冰下盐水从泰勒冰川表面的裂缝中释放出来，为南极冰下生态系统提供了一个可访问的门户。最近的地球化学和分子分析支持血液福尔斯中盐和微生物的海洋来源。上一次海洋沃茨淹没麦克默多干谷的这一部分是在晚第三纪，这表明盐水是古老的。尽管如此，还没有从冰下源头到血福尔斯收集到直接的样本，而且人们对这种盐水的来源或它被密封在泰勒冰川下面的时间所知甚少。在血液福尔斯附近收集的雷达剖面描绘了冰下基底中可能存在的断层，这可能有助于解释盐水释放的局部性和偶发性。然而，目前还不清楚是什么触发了盐水只在血福尔斯裂缝处的间歇性释放，或者盐水在到达地表时发生了多大程度的改变。MIDGE项目的目的是确定血液福尔斯盐水释放的机制，评估冰沟内地球化学和微生物群落的变化，并评估血液福尔斯沃茨水是否对泰勒冰川（南极洲研究最多的极地冰川之一）的热和应力状态产生明显影响。冰川结构和盐水释放机制的地球物理研究将使用地质雷达、全球定位系统和小型被动地震网络。MIDGE将与国际合作者、来自德国FH亚琛应用科学大学的“冰鼹鼠”团队（由德国航空航天中心资助）一起，开发和部署创新的微创技术，用于清洁进入和从血液福尔斯排水系统深处取回盐水样本。这些技术将允许收集远离地表（高达数十米）的盐水样本，用于地球化学分析和微生物结构功能实验。钻探过程中固有的化学和生物材料对原始冰下环境的污染令人关切; MIDGE将提供关于热电探测器在清洁获取和取回代表性冰下样本方面的功效的数据。南极冰下环境为研究微生物生命的生存性和适应性提供了极好的机会，是冰行星体上生命栖息地的潜在陆地类似物。MIDGE项目为热水和机械钻探提供了一种便携、多功能、清洁的替代方法，将使人们能够探索冰下水文和生态系统功能，同时在开发冰下系统微创和清洁取样技术方面取得重大进展。

Recent discoveries of widespread liquid water and microbial ecosystems below the Antarctic ice sheets have generated considerable interest in studying Antarctic subglacial environments. Understanding subglacial hydrology, the persistence of life in extended isolation and the evolution and stability of subglacial habitats requires an integrated, interdisciplinary approach. The collaborative project, Minimally Invasive Direct Glacial Exploration (MIDGE) of the Biogeochemistry, Hydrology and Glaciology of Blood Falls, McMurdo Dry Valleys will integrate geophysical measurements, molecular microbial ecology and geochemical analyses to explore a unique Antarctic subglacial system known as Blood Falls. Blood Falls is a hypersaline, subglacial brine that supports an active microbial community. The subglacial brine is released from a crevasse at the surface of the Taylor Glacier providing an accessible portal into an Antarctic subglacial ecosystem. Recent geochemical and molecular analyses support a marine source for the salts and microorganisms in Blood Falls. The last time marine waters inundated this part of the McMurdo Dry Valleys was during the Late Tertiary, which suggests the brine is ancient. Still, no direct samples have been collected from the subglacial source to Blood Falls and little is known about the origin of this brine or the amount of time it has been sealed below Taylor Glacier. Radar profiles collected near Blood Falls delineate a possible fault in the subglacial substrate that may help explain the localized and episodic nature of brine release. However it remains unclear what triggers the episodic release of brine exclusively at the Blood Falls crevasse or the extent to which the brine is altered as it makes its way to the surface. The MIDGE project aims to determine the mechanism of brine release at Blood Falls, evaluate changes in the geochemistry and the microbial community within the englacial conduit and assess if Blood Falls waters have a distinct impact on the thermal and stress state of Taylor Glacier, one of the most studied polar glaciers in Antarctica. The geophysical study of the glaciological structure and mechanism of brine release will use GPR, GPS, and a small passive seismic network. Together with international collaborators, the 'Ice Mole' team from FH Aachen University of Applied Sciences, Germany (funded by the German Aerospace Center, DLR), MIDGE will develop and deploy innovative, minimally invasive technologies for clean access and brine sample retrieval from deep within the Blood Falls drainage system. These technologies will allow for the collection of samples of the brine away from the surface (up to tens of meters) for geochemical analyses and microbial structure-function experiments. There is concern over the contamination of pristine subglacial environments from chemical and biological materials inherent in the drilling process; and MIDGE will provide data on the efficacy of thermoelectric probes for clean access and retrieval of representative subglacial samples. Antarctic subglacial environments provide an excellent opportunity for researching survivability and adaptability of microbial life and are potential terrestrial analogues for life habitats on icy planetary bodies. The MIDGE project offers a portable, versatile, clean alternative to hot water and mechanical drilling and will enable the exploration of subglacial hydrology and ecosystem function while making significant progress towards developing technologies for minimally invasive and clean sampling of icy systems.