Biogeochemistry of Victoria Land Coastal Ponds: Role in Terrestrial Ecosystem Organic Carbon Dynamics and Structure

自1993年以来，南极陆地生态系统中的生态系统结构、过程和功能联系一直是麦克默多干河谷麦克默多长期生态研究(LTER)基地的重点。这个生态系统有一个现代组成部分，将土壤、冰川、溪流和冰盖湖泊之间的有机碳动态联系在一起，加上在该地区沉积古有机碳的古代冰川事件的遗产。土壤水库含有泰勒河谷72%的季节性未冻结和生物可利用的有机碳，其中很大一部分可能是来自古代气候事件的顽固碳。LTER的中心主题之一是了解有机碳运输方面的生态系统要素与影响初级生产的过程之间的联系，但尚未调查的一个潜在的大量不稳定的、可用于生物利用的有机碳来源是麦克默多干河谷大部分地区，特别是沿海附近的大量小池塘。这些池塘的表面积相对较大，当它们在地貌上移动位置时，似乎会产生大量搁浅的微生物垫子。这些池塘的暂时性使有机物质易于运输，并可能是麦克默多干河谷生态系统中其他成分的现代不稳定碳的重要来源。虽然它们的确切程度尚不清楚，但初步估计沿海池塘水库可能至少占干旱河谷土壤水库碳的11%。因此，这些池塘可能会显著影响干旱山谷生态系统的碳循环，如果要为这片极地沙漠制定完整的碳收支，就必须考虑这些池塘。该项目将(1)确定沿海池塘水库的范围，(2)评估水库作为一个整体的生产力，以及(3)在干旱山谷地区陆地生态系统的有机碳动态和总体结构中，确定沿岸池塘水库是源还是汇。这项工作的大部分将侧重于从影响有机碳生产和养分循环的因素方面了解这些池塘的生物地球化学。这项研究的结果将更详细地了解现代生态系统组成部分之间的联系，为极地沙漠生态系统内的生物地球化学循环提供见解，并可能确定有助于维持极端环境中生命的机制。这项研究还将涉及诺克斯维尔市学校的学生，他们主要来自非洲裔美国人社区。K-5年级的学生将通过互联网参与问答环节，年龄较大的学生将设计生态实验并了解科学方法。数据分析将在科学和数学课程中使用，以帮助培养分析技能，并将这些技能置于学生的相关背景中。

Ecosystem structure, processes, and functional linkages in the Antarctic terrestrial ecosystem have been the focus of the McMurdo Long-Term Ecological Research (LTER) site in the McMurdo Dry Valleys since 1993. This ecosystem has a modern component linking the organic carbon dynamics between the soils, glaciers, streams and ice-covered lakes plus a legacy to ancient glacial events that deposited paleo-organic carbon within the region. The soil reservoir contains 72% of the seasonally unfrozen and biologically available organic carbon within Taylor Valley and a substantial fraction of this carbon may be recalcitrant carbon derived from ancient climatic events. While one of the central themes of the LTER is to understand the linkages between ecosystem elements in terms of the transport of organic carbon and processes affecting primary production, one potentially large source of labile, and hence bioavailable, organic carbon that has not been investigated is the abundant small ponds found in most areas of the McMurdo Dry Valleys, especially near the coast. These ponds have a relatively large surface area, and they seem to generate a large amount of stranded microbial mat as they shift position on the landscape. The transient nature of these ponds renders the organic matter vulnerable to transport and possibly represents a significant source of modern, labile carbon to the other components in the McMurdo Dry Valleys ecosystem. While their exact extent is unknown, a preliminary estimate suggests that the coastal pond reservoir may constitute at least 11% of the carbon to the Dry Valleys soil reservoir. Therefore, these ponds may significantly impact the carbon cycle of the Dry Valleys ecosystem and they must be considered if a complete carbon budget is to be developed for this polar desert. This project will (1) determine the extent of the coastal pond reservoir, (2) assess how productive the reservoir is as a whole and (3) to determine if coastal pond reservoir is a source or sink within the organic carbon dynamics and overall structure of the terrestrial ecosystem in the dry valleys region. Much of this work will focus on understanding the biogeochemistry of these ponds in terms of the factors affecting organic carbon production and nutrient cycling. The results of this study will provide a more detailed understanding of the linkages between modern ecosystem components, provide insights into the biogeochemical cycling within polar desert ecosystems and possibly identify mechanisms that help sustain life in extreme environments. This study will also involve Knoxville city school students from predominantly African-American neighborhoods. The K-5 students will be involved in question and answer sessions over the Internet and the older students will design ecological experiments and become introduced to the scientific method. Data analysis will be used in science and math classes to help develop analytical skills and to place the skills in a relevant context for the students.