DISSERTATION RESEARCH: Dynamics of labile organic matter fractions in arctic soils

论文研究：北极土壤中不稳定有机物组分的动态

• 批准号: 0909747
• 负责人: John Moore
• 金额: $ 1.32万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0909747&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Dynamics; labile; organic

The proposed doctoral dissertation research will determine the extent to which soil aggregates, a foundation of soils, provide stabilization for soil organic matter (SOM) in the Arctic. Warming has been linked to changes in carbon cycling in the Arctic. Cold temperatures and anoxic conditions inhibit microbial activity and reduce decomposition, resulting in an accumulation of carbon-rich organic matter, straining an already nitrogen-limited system. Nutrient additions have changed the plant community and depleted soil carbon; however, mechanisms behind carbon loss are not understood. It is not known which OM fractions are most susceptible to degradation in Arctic soils, and 2) where are they located within the soil matrix. These factors are important to understanding mechanisms behind carbon loss in Arctic soils, which may be due, in part, to shifts in the physical stability of soil aggregates. In other words, soils with greater proportions of macroaggregates contain more carbon.Soils have been collected from long-term nutrient addition experiments at the Arctic LTER site on the Alaskan North Slope, and were separated into four size classes of aggregates. These aggregates will be separated into sub-structural elements as well as free OM, which will reveal if SOM is protected within aggregates and which fractions are susceptible to degradation. The project will also link current conceptual models of soil carbon stabilization to the Arctic. The graduate student will interact with the K-12 community by providing research opportunities for teachers through existing workshops, internships, and a Teacher-in-Residence program.

拟议的博士论文研究将确定作为土壤基础的土壤团聚体在多大程度上为北极土壤有机质(SOM)提供稳定。气候变暖与北极地区碳循环的变化有关。寒冷的温度和缺氧条件抑制了微生物的活动，减少了分解，导致富碳有机物的积累，使本已有限的氮素系统变得紧张。养分的添加改变了植物群落，耗尽了土壤碳；然而，碳损失背后的机制尚不清楚。目前尚不清楚哪些OM组分在北极土壤中最容易降解，以及2)它们位于土壤基质中的什么位置。这些因素对于理解北极土壤碳流失背后的机制很重要，这可能部分是由于土壤团聚体物理稳定性的变化。换言之，大团聚体比例越大的土壤含有更多的碳。土壤是在阿拉斯加北坡的北极LTER站点进行的长期养分添加试验中收集的，并被分为四个大小类别的团聚体。这些团聚体将被分成亚结构元素和游离有机质，这将揭示有机质是否在团聚体中受到保护，以及哪些组分容易降解。该项目还将把目前土壤碳稳定的概念模型与北极联系起来。研究生将通过现有的研讨会、实习和教师入驻计划为教师提供研究机会，从而与K-12社区进行互动。