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

合作研究：极地沙漠陆地/水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: 0336970
• 负责人: Cristina Takacs-Vesbach
• 金额: $ 16.07万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0336970&HistoricalAwards=false
• 关键词: Collaborative; Research; Hydrologic; 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-陆过渡带是理解景观地球化学的关键环境。在温带流域，这些地区通常以河岸带为主，河岸带已被确定为生态地球化学特别感兴趣的区域，因为这些地方的微生物活动增加，而且这些水文边缘在促进和缓冲陆地和水生生态系统之间的水文和生态地球化学交换方面具有重要意义。在南极干旱河谷，陆地-水生过渡区是有趣的景观特征，因为水在这一极地沙漠中具有巨大的重要性，而且干旱河谷生态系统的物质和能量收支与水文学有关。将在南极洲干谷研究水陆过渡区的水文边缘，以回答两个首要问题：（1）在水-陆过渡带中，水文和地球化学交换的主要控制因素是什么？（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的差异（例如，氧化还原电位）？定义这些界面的水文梯度提供了评估物理条件和微生物生物多样性的相对影响以及生物地球化学循环的功能的机会。将在水文边界内进行协调的水文、生物地球化学和分子微生物研究，研究目标如下：确定沉积物特性、永久冻土和活动层动态以及地形对水文边界内次表层水含量和分布的作用，确定水文边界内氮转化受物理条件（即，水分、氧化还原电位和pH）或特定微生物群落的存在（例如，微生物群落结构和功能的饱和带。这项拟议的研究将提供一个更好的了解的液体水，土壤，微生物群落和地球化学的重要水文边缘景观单元的干旱河谷内的相互作用。干旱的山谷、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，用于了解物理和水文对微生物生态学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更广泛的研究河岸带和水文边缘世界各地。研究生和本科生将参与实地考察和研究项目。信息将通过一个项目网站传播，推广活动将包括在三所有关大学附近的当地小学、初中和高中进行科学教育。