DISSERTATION RESEARCH: Landscape Patterns in the Biodegradability of DOC and DON Within and Among Arctic Hillslopes

溶解的有机物是苔原土壤和溪流中发现的植物和微生物的重要能量和营养来源。随着北极气候变暖，目前储存在极冷或冻土中的碳的命运将受到微生物矿化（向大气释放碳）和植物生产力（在植物和土壤中储存碳）的平衡的控制，而这两者都受到溶解有机物可用性的影响。微生物分解特定溶解有机化合物的能力（生物降解性）和土壤颗粒对溶解有机物质的稳定性是控制溶解有机物质运输的两个主要因素。然而，高纬度流域溶解有机质的生物降解性和稳定性的景观格局尚未得到很好的研究。相关的论文研究主要集中在北极流域矿质土壤组分对溶解有机质的稳定作用。本项目提出的研究将通过表征溶解有机质的化学成分（对生物可降解性的重要控制）来研究溶解有机质的生物可降解性的空间格局，并确定阿拉斯加北极地区山坡内和山坡间微生物溶解有机质的分解率。除了列入出版物外，研究结果还将通过北极长期生态研究数据库传播。这项研究将增加我们对碳和营养物质如何在冻土带中移动的理解，特别是考虑到区域气候变暖所预期的变化。

Dissolved organic matter is an important source of energy and nutrients for plants and microorganisms found in tundra soils and streams. As the arctic climate warms, the fate of carbon currently stored in very cold or frozen soils will be controlled by the balance of microbial mineralization (release of carbon to the atmosphere) and plant productivity (storage of carbon in plants and soils), both of which are influenced by the availability of dissolved organic matter. Two major controls on dissolved organic matter transport are the ability of microbes to decompose specific dissolved organic compounds (biodegradability), and stabilization of dissolved organic matter by soil particles. However, landscape patterns in biodegradability and stabilization of dissolved organic matter have not been well studied in high-latitude watersheds. Related dissertation research has focused on the stabilization of dissolved organic matter by mineral soil components in arctic watersheds. The research proposed in this project will examine spatial patterns of dissolved organic matter biodegradability by characterizing the chemical composition of dissolved organic matter (an important control on biodegradability), and determining rates of microbial dissolved organic matter decomposition within and among hillslopes in arctic Alaska. In addition to inclusion in publications, the results will be disseminated through the Arctic Long Term Ecological Research database. This study will increase our understanding of how carbon and nutrients move in the tundra, especially in view of changes expected from regional climate warming.