Geochemistry and Microbiology of the Extreme Aquatic Environment in Lake Vida, East Antarctica

Abstract: Lake Vida is the largest lake of the McMurdo Dry Valleys, with an approximately 20 m ice cover overlaying a brine of unknown depth with at least 7 times seawater salinity and temperatures below -10 degrees C year-round. Samples of brine collected from ice above the main water body contain 1) the highest nitrous oxide levels of any natural water body on Earth, 2) unusual geochemistry including anomalously high ammonia and iron concentrations, 3) high microbial counts with an unusual proportion (99%) of ultramicrobacteria. The microbial community is unique even compared to other Dry Valley Lakes. The research proposes to enter, for the first time the main brine body below the thick ice of Lake Vida and perform in situ measurements, collect samples of the brine column, and collect sediment cores from the lake bottom for detailed geochemical and microbiological analyses. The results will allow the characterization of present and past life in the lake, assessment of modern and past sedimentary processes, and determination of the lake's history. The research will be conducted by a multidisciplinary team that will uncover the biogeochemical processes associated with a non-photosynthetic microbial community isolated for a significant period of time. This research will address diversity, adaptive mechanisms and evolutionary processes in the context of the physical evolution of the environment of Lake Vida. Results will be widely disseminated through publications, presentations at national and international meetings, through the Subglacial Antarctic Lake Exploration (SALE) web site and the McMurdo LTER web site. The research will support three graduate students and three undergraduate research assistants. The results will be incorporated into a new undergraduate biogeosciences course at the University of Illinois at Chicago which has an extremely diverse student body, dominated by minorities.

摘要：维达湖是麦克默多干谷中最大的湖泊，其上方覆盖着约20米厚的冰盖，下方为深度未知的卤水，该卤水盐度至少为海水的7倍，全年水温均低于-10℃。从主水体上方冰层中采集的卤水样本具备三大特征：其一，其一氧化二氮含量为全球天然水体之最；其二，地球化学特征异常，氨与铁浓度显著偏高；其三，微生物总数较高，且超微细菌（ultramicrobacteria）占比达99%，比例非同寻常。即便与其他干谷湖泊相比，该微生物群落仍独具特色。本研究计划首次进入维达湖厚冰层下方的主卤水体，开展原位测量，采集卤水柱样本，并从湖底获取沉积岩芯以开展详细的地球化学与微生物学分析。研究成果将助力表征该湖泊当前与过往的生命活动，评估现代及历史沉积过程，并阐明维达湖的演化历史。本研究将由多学科团队实施，旨在揭示与长期隔离的非光合微生物群落相关的生物地球化学过程。本研究将围绕维达湖环境的物理演化背景，探讨微生物的多样性、适应机制及演化过程。研究成果将通过学术论文、国内外学术会议报告、南极冰下湖泊探索（Subglacial Antarctic Lake Exploration, SALE）网站以及麦克默多长期生态研究站点（McMurdo LTER）网站进行广泛传播。本研究将资助3名研究生与3名本科研究助理。相关成果将融入伊利诺伊大学芝加哥分校一门全新的本科生物地球科学课程，该课程的学生群体极具多样性，以少数族裔学生为主。