"Collaborative Research: Hydrological Controls over Biogeochemistry and Microbial Community Structure and Function across Terrestrial/Aquatic Interfaces in a Polar Desert"

“合作研究：极地沙漠中陆地/水生界面生物地球化学和微生物群落结构和功能的水文控制”

• 批准号: 0723643
• 负责人: John Barrett
• 金额: $ 3.89万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-12-24 至 2008-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0723643&HistoricalAwards=false
• 关键词: Collaborative; Research; Hydrological; Controls; over

Aquatic-terrestrial transition zones are crucial environments in understanding the biogeochemistry of landscapes. In temperate watersheds, these areas are generally dominated by riparian zones, which have been identified as regions of special interest for biogeochemistry because of the increased microbial activity in these locations, and because of the importance of these hydrological margins in facilitating and buffering hydrologic and biogeochemical exchanges between terrestrial and aquatic ecosystems. In the Antarctic Dry Valleys, terrestrial-aquatic transition zones are intriguing landscape features because of the vast importance of water in this polar desert, and because the material and energy budgets of dry valley ecosystems are linked by hydrology. Hydrological margins in aquatic-terrestrial transition zones will be studied in the Dry Valleys of Antarctica to answer two overarching questions: (1) what are the major controls over hydrologic and biogeochemical exchange across aquaticterrestrial transition zones and (2) to what extent do trends in nutrient cycling (e.g. nitrogen cycling) across these transition zones reflect differences in microbial communities or function vs. differences in the physical and chemical environment (e.g., redox potential)? The hydrologic gradients that define these interfaces provide the opportunity to assess the relative influence of physical conditions and microbial biodiversity and functioning upon biogeochemical cycling. Coordinated hydrologic, biogeochemical, and molecular microbial studies will be executed within hydrologic margins with the following research objectives: to determine the role of sediment characteristics, permafrost and active layer dynamics, and topography on sub-surface water content and distribution in hydrologic margins, to determine the extent to which transformations of nitrogen in hydrological margins are influenced by physical conditions (i.e., moisture, redox potential and pH) or by the presence of specific microbial communities (e.g., denitrifiers), and to characterize the microbial community structure and function of saturated zones. This proposed research will provide an improved understanding of the interaction of liquid water, soils, microbial communities, and biogeochemistry within the important hydrologic margin landscape units of the dry valleys. Dry valleys streams and lakes are unique because there is no influence of higher vegetation on the movement of water and may therefore provide a model system for understanding physical and hydrological influences on microbial ecology and biogeochemistry. Hence the findings will contribute to Antarctic science as well as the broader study of riparian zones and hydrologic margins worldwide. Graduate students and undergraduate students will be involved with fieldwork and research projects. Information will be disseminated through a project web site, and outreach activities will include science education in local elementary, middle and high schools near the three universities involved.

水陆过渡区是了解景观生物地球化学的关键环境。在温带流域，这些区域通常以河岸带为主，这些区域已被确定为生物地球化学特别感兴趣的区域，因为这些位置的微生物活动增加，并且因为这些水文边缘在促进和缓冲水文和生物地球化学方面的重要性陆地和水生生态系统之间的交流。在南极干谷，陆地-水生过渡区是令人着迷的景观特征，因为水在这片极地沙漠中极其重要，而且干谷生态系统的物质和能量预算与水文联系在一起。将在南极洲干谷研究水陆过渡带的水文边际，以回答两个首要问题：（1）水陆过渡带水文和生物地球化学交换的主要控制因素是什么；（2）水陆过渡带的趋势在多大程度上发生变化？这些过渡区的养分循环（例如氮循环）反映了微生物群落或功能的差异与物理和化学环境（例如氧化还原电位）的差异？定义这些界面的水文梯度提供了评估物理条件和微生物多样性以及生物地球化学循环功能的相对影响的机会。将在水文边缘内进行协调的水文、生物地球化学和分子微生物研究，研究目标如下：确定沉积物特征、永久冻土和活动层动力学以及地形对水文边缘地下水含量和分布的作用，确定水文边界中氮的转化受物理条件（即湿度、氧化还原电位和 pH 值）或特定微生物群落（例如，反硝化菌），并表征饱和区的微生物群落结构和功能。这项拟议的研究将更好地了解干旱山谷重要水文边缘景观单元内液态水、土壤、微生物群落和生物地球化学的相互作用。干谷溪流和湖泊是独一无二的，因为高等植被对水的运动没有影响，因此可以提供一个模型系统来了解物理和水文对微生物生态和生物地球化学的影响。因此，这些发现将有助于南极科学以及对全球河岸带和水文边缘的更广泛研究。研究生和本科生将参与实地考察和研究项目。信息将通过项目网站传播，外展活动将包括在所涉及的三所大学附近的当地小学、初中和高中进行科学教育。