Collaborative Research: Climate effects on Mn oxidation states in soils and Mn/SOM interactions

本研究旨在了解元素锰在土壤有机质(SOM)降解中所起的作用。在土壤中，锰以多种化学形式存在，这取决于土壤中的氧气有效性和酸度；其中一些形式比其他形式更活跃地推动土壤有机质的降解。这项拟议的研究将结合使用高科技工具来评估锰的形态，并通过实验来评估这些形态与土壤有机质以及与土壤细菌和真菌的种群和活性的相互作用。该项目还将为本科生和研究生提供研究培训机会，并提供机会扩大未被充分代表的群体成员对科学的参与，包括向夏威夷原住民进行社区宣传。SOM是生物圈中最大的潜在活性碳(C)池，但其中大部分C的周转速度很慢，因为它具有化学顽固性和/或物理保护。MN可以抑制这种顽固性，通过与其三种氧化状态相关的多条途径推动SOM的分解。该项目将评估锰的氧化状态如何随降雨变化，以及不同的锰的氧化状态如何驱动SOM的分解。实地考察工作将在夏威夷群岛明确定义的降水梯度上进行，在这种梯度上，生态系统过程的大多数潜在控制可以保持相对恒定，而气候变化很大(从年降水量300毫米/年到3200毫米/年)，并以明确的方式进行；它还利用国家生态观测网(NEON)和其他站点的信息来评估锰氧化态及其在除降水之外其他因素不同的广泛地点的影响，以检验降水是锰氧化态的主要驱动因素及其对土壤有机质稳定性的影响的假设。该项目将建立在与夏威夷原住民社区组织(Ulu Mau Puanui[UMP])正在进行的伙伴关系的基础上，该组织正在恢复同一田野地点的传统农业系统，并将在该研究项目中使用。参与该项目的科学家和学生将与UMP合作制定课程，接触到每年访问该网站的600多名学习者中的许多人(其中约一半是夏威夷原住民)；该项目还将与夏威夷原住民科学家合作，评估锰在夏威夷传统农业系统中的作用。该项目将包括本科生和研究生，他们属于科学界代表性较低的群体。最后，该项目将参加怀俄明大学一个成熟的暑期项目，以扩大未被充分代表的群体成员对科学的参与。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This research project seeks to understand the role that the element manganese (Mn) plays in driving the degradation of soil organic matter (SOM). Mn takes multiple chemical forms in the soil, depending on oxygen availability and acidity in the soil; some of these forms are more active in driving the degradation of SOM than others. This proposed research will use a combination of high-technology tools to evaluate the forms of Mn, and experiments to evaluate the interactions of these forms with SOM and with the populations and activity of soil bacteria and fungi. The project will also afford research training opportunities for undergraduate and graduate students and opportunities to broaden participation of members of underrepresented groups in science, including community outreach to Native Hawaiians. SOM is the largest pool of potentially active carbon (C) in the biosphere, but much of that C turns over slowly because it is chemically recalcitrant and/or physically protected. Mn can override this recalcitrance, driving SOM breakdown through multiple pathways that relate to its three oxidation states. This project will evaluate how the oxidation state of Mn varies as a function of rainfall, and how the different oxidation states of Mn drive the decomposition of SOM. Fieldwork will take place on a well-defined precipitation gradient in the Hawaiian Islands, on which most potential controls of ecosystem processes can be held relatively constant while climate varies widely (from 300 mm/yr annual precipitation to 3200 mm/yr) and in well-defined ways; it also draws upon information from National Ecological Observatory Network (NEON) and other sites to evaluate Mn oxidation states and their implications in a broad range of sites that differ in other factors in addition to precipitation, as a test of the hypothesis that precipitation is the dominant driver of Mn oxidation states and its consequences to SOM stability. This project will build upon an ongoing partnership with a Native Hawaiian community organization (Ulu Mau Puanui [UMP]) that is restoring a traditional agricultural system at the same field sites will be used in this research project. Scientists and students in this project will work with UMP to develop curricula and to reach many of the 600+ learners (about half of whom are Native Hawaiian) who visit the site each year; it will also collaborate with Native Hawaiian scientists to evaluate the role of Mn in traditional Hawaiian agricultural systems. The project will include undergraduate and graduate students who belong to underrepresented groups in science. Finally, the project will take part in a well-established summer program at the University of Wyoming to broaden participation of members of underrepresented groups in science.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.