SusChEM: Collaborative Research: Influence of Fe2+- catalyzed recrystallization on Fe oxide reactivity and C stabilization

SusChEM：合作研究：Fe2 催化重结晶对 Fe 氧化物反应性和 C 稳定性的影响

• 批准号: 1451494
• 负责人: Thomas Borch
• 金额: $ 8.7万
• 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: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1451494&HistoricalAwards=false
• 关键词: SusChEM; Collaborative; Research; Influence; Fe2+

Iron (Fe) is the fourth most abundant element on Earth and a critical nutrient for all life (from microorganisms to humans). Iron minerals are an important part of our lives: they are part of the soil beneath our feet; the rust on our cars; the hard drives in our computers; and the rocks on Earth and Mars. These tiny, often nanoscale, particles are responsible for most of the red, yellow, green, and black colors around us and they profoundly influence the quality of our water, air, and soil through biologically-driven redox cycling between oxidized ferric iron (Fe3+) and reduced ferrous iron (Fe2+). These Fe minerals trap much of the organic carbon (C) in soils and sediments and can also take the place of oxygen in anaerobic respiration, oxidizing and mineralizing organic matter to CO2 in anoxic soils and sediments. Increasing concerns about carbon driven climate change provides strong motivation to better understand the coupling between Fe and C processes that govern storage of carbon (C) in soils and sediments. The research findings from this work will benefit society by providing important insights into terrestrial response to climate change, as well as water quality preservation (such as arsenic release), and engineered water treatment systems. This project will provide authentic research experiences for individuals from groups underrepresented in the sciences at the upper high school (HS) and undergraduate (UG) levels. This will be accom-plished by involving long-term UG researchers in the project; providing HS junior and seniors from schools with historically low-college enrollment opportunities to participate in authentic summer research activities; and providing direct faculty-student instruction for HS and UG students as part of a ?Scale-Matters? workshop and Summer Soil Institute. The overall goal of this research project is to understand the complex redox dynamics between Fe and organic C soils and sediments. In reducing environments, dissolved Fe2+ can catalyze Fe oxides to recrystallize into new mineral phases with similar or drastically different chemical properties. This process, Fe2+- catalyzed recrystallization, has been observed for pure Fe phases, but has yet to be explored as a pathway for mobilizing (or sequestering) organic C. Additionally, the presence of organic C is also likely to alter the recrystallization process with important implications for the Fe reactivity and isotope fractionation. The investigators will investigate how Fe2+- catalyzed recrystallization influences organic C and Fe mineral reactivity. To do this, the investigators will conduct a series of Fe isotope tracer experiments to quantify the extent of Fe2+- catalyzed recrystallization in model Fe-C assemblages synthesized from a range of Fe oxides and diversity of natural organic matter. Changes in Fe oxide susceptibility to microbial and chemical dissolution will be measured, along with Fe isotopic fractionation, and C availability following recrystallization of the Fe-C assemblages.

铁（Fe）是地球上第四大元素，也是所有生命（从微生物到人类）的关键养分。铁矿矿是我们生活的重要组成部分：它们是我们脚下的土壤的一部分；我们汽车上的生锈；我们的计算机中的硬盘驱动器；还有地球和火星上的岩石。这些微小的（通常是纳米级的颗粒）是我们周围的大多数红色，黄色，绿色和黑色的颗粒，它们通过生物学驱动的氧化还原循环在氧化铁（Fe3+）和减少的亚铁铁（Fe2+）之间深刻影响我们的水，空气和土壤的质量。这些FE矿物质在土壤和沉积物中捕获大部分有机碳（C），还可以代替氧气中的氧气呼吸，氧化和矿化有机物在缺氧土壤和沉积物中的二氧化碳中。对碳驱动气候变化的越来越关注，可以更好地了解控制土壤和沉积物中碳（C）储存的Fe和C过程之间的耦合。这项工作的研究结果将通过提供对陆地对气候变化以及水质保存（例如砷释放）和工程水处理系统的重要见解，从而使社会受益。该项目将为上高中（HS）和本科（UG）级别的科学群体中占人数不足的小组的个人提供真实的研究经验。这将通过参与该项目的长期UG研究人员来遵守；提供历史上低年度入学机会的学校的HS大三和老年人参加正宗的夏季研究活动；并为HS和UG学生提供直接的教师教学，作为？研讨会和夏季土壤研究所。该研究项目的总体目标是了解FE和有机C土壤和沉积物之间的复杂氧化还原动态。在还原环境中，溶解的Fe2+可以催化Fe氧化物，将具有相似或截然不同的化学性质的新矿物相结合。对于纯Fe阶段，已经观察到了该过程，Fe2+ - 催化的重结晶，但尚未探索作为动员（或隔离）有机物的途径。此外，有机c的存在也可能改变重新结合过程，对FE反应性和同位素分数的重要意义。研究人员将研究Fe2+催化的重结晶如何影响有机C和Fe矿物质反应性。为此，研究人员将进行一系列Fe同位素示踪剂实验，以量化Fe2+ - 催化的Fe-C C催化重结晶的程度，该模型是Fe-C组合中从一系列Fe氧化物和自然有机物的多样性中合成的。 Fe-C组合重结晶后，将测量Fe氧化Fe氧化物对微生物和化学溶解的易感性的变化，以及C的可用性。