Investigating interactions between mineral-associated and dissolved soil organic matter to improve understanding of soil carbon retention under intermittent flooding

研究矿物相关有机质和溶解土壤有机质之间的相互作用，以提高对间歇性洪水下土壤碳保留的了解

• 批准号: RGPIN-2021-03250
• 负责人: Kallenbach, Cynthia
• 金额: $ 2.55万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=743307
• 关键词: Investigating; interactions; between; mineral; associated

The long-term goal of my research program is to understand how soil organic matter (SOM) is impacted by the interactions of soil microbial communities and plants under global change and land-use management. SOM governs key ecosystem services such as regulating climate change through carbon (C) stored within SOM. Maintaining and increasing global SOM stocks is a global priority yet also a consistent challenge due to climate change stressors that often accelerate SOM mineralization. The prevailing thinking is that SOM is protected from microbial mineralization via strong chemical interactions that attached organic matter to soil minerals, limiting microbial access. Thus, the mineral-associated organic matter pool (MAOM) is considered the most relevant fraction of SOM for understanding long-term SOM retention and C sequestration. However, this overlooks emerging evidence that this MAOM pool is vulnerable to loss, easily disassociating from minerals into dissolved organic matter (DOM) where it can then be leached or respired by microbes. This often occurs during flood events when oxygen depletion releases MAOM from its chemical protective bonds into DOM. In Eastern Canada, increases in flood intensity and duration are expected with climate change, necessitating a more complete understanding of SOM vulnerability and retention following flood events. A more accurate framework that considers the complex biophysical controls on the exchanges between MAOM and DOM during flood events is needed to understand the mechanisms controlling soil C storage. Over the next five years my goal is to gain insights into how biophysical controls affect the exchanges between MAOM and DOM under intermittent flooding and to apply the knowledge gained to better understand flooding impacts on the net balance of persistent SOM. To address this, I will integrate insight from across three short-term objectives: 1. Determine how soil structure impacts sorption and solubilization of SOM during flood events and consequently the net balance of MAOM. 2. Evaluate the influence of microbial growth responses to flooding and the subsequent outcomes on DOM-MAOM exchanges and C loss. 3. Explore how rhizosphere processes counter-act or amplify flooding effects on DOM-MAOM exchange. My program will generate much needed fundamental knowledge of MAOM and DOM exchange and SOM retention, providing a more complete picture of SOM under intermittent flooding and agricultural management scenarios, priority goals for Canadian governments and land resource managers, including the agri-food sector. Novel outcomes from this program will explain how plant roots, soil microbial communities, and the soil physical environment impact MAOM vulnerability to flooding. My program will train 7 HQP who will gain expertise in molecular chemical and microbial techniques, isotope biogeochemistry, and designing and implementing experiments, positioning them to become leaders in the field of soil biogeochemistry.

我的研究计划的长期目标是了解土壤有机物（SOM）如何受到在全球变化和土地利用管理下土壤微生物群落和植物相互作用的影响。 SOM控制关键的生态系统服务，例如通过SOM中存储的碳（C）调节气候变化。维持和增加全球SOM库存是全球优先事项，但由于气候变化压力源通常会加速Someralization，这也是一致的挑战。流行的思想是，通过将有机物附着在土壤矿物质上的强大化学相互作用，可以保护SOM免受微生物矿化的保护，从而限制了微生物的通道。因此，与矿物相关的有机物池（MAOM）被认为是SOM最相关的部分，用于理解长期的SOM保留和C隔离。但是，这忽略了新的证据表明该毛姆很容易遭受损失，很容易从矿物分解为溶解的有机物（DOM），然后可以被微生物浸出或呼吸。这通常发生在洪水事件中，当氧耗尽将MAOM从其化学保护键中释放到DOM中。在加拿大东部，随着气候变化的影响，预计洪水强度和持续时间会增加，因此需要对洪水事件后对SOM脆弱性和保留率有更全面的了解。 一个更准确的框架需要在洪水事件期间对MAOM和DOM之间的交流进行复杂的生物物理控制，以了解控制土壤C储存的机制。在接下来的五年中，我的目标是深入了解生物物理控制如何影响间歇性洪水泛滥下的MAOM和DOM之间的交流，并运用所获得的知识以更好地了解洪水对持续的SOM净额的影响。 为了解决这个问题，我将整合三个短期目标的见解：1。确定土壤结构如何影响洪水事件期间SOM的吸附和溶解，从而影响MAOM的净平衡。 2。评估微生物生长对洪水的影响以及随后的结果对DOM-MAOM交换和C损失的影响。 3。探索根际过程如何对抗或放大洪水对DOM-MAOM交换的影响。我的计划将对MAOM和DOM Exchange和SOM保留产生急需的基本知识，并在间歇性的洪水和农业管理方案，加拿大政府的优先目标和土地资源经理（包括农业食品部门）提供了更完整的SOM图片。该计划的新成果将解释植物根，土壤微生物群落和土壤物理环境如何影响毛姆对洪水的脆弱性。我的计划将培训7 HQP，他将获得分子化学和微生物技术，同位素生物地球化学以及设计和实施实验的专业知识，并将其定位为成为土壤生物地球化学领域的领导者。