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

铁（Fe）是地球上第四丰富的元素，也是所有生命（从微生物到人类）的关键营养素。铁矿物是我们生活中重要的一部分：它们是我们脚下土壤的一部分;我们汽车上的铁锈;我们电脑中的硬盘驱动器;以及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大部分红色，黄色，绿色和黑色的原因，它们通过生物驱动的氧化三价铁（Fe 3+）和还原亚铁（Fe 2+）之间的氧化还原循环深刻地影响着我们的水，空气和土壤的质量。这些铁矿物捕获土壤和沉积物中的大部分有机碳（C），也可以在厌氧呼吸中取代氧气，在缺氧土壤和沉积物中将有机物质氧化和矿化为CO2。对碳驱动的气候变化的日益关注为更好地理解控制土壤和沉积物中碳（C）储存的Fe和C过程之间的耦合提供了强大的动力。这项工作的研究成果将通过提供对陆地对气候变化的反应以及水质保护（如砷释放）和工程水处理系统的重要见解而造福社会。该项目将为来自高中（HS）和本科（UG）水平科学代表性不足的群体的个人提供真实的研究经验。这将是accom-plished通过参与长期UG研究人员在项目中，提供HS初中和高中生从学校历史上低大学入学的机会，参加正宗的夏季研究活动，并提供直接的教师，学生指导HS和UG学生的一部分？规模问题？夏季土壤研究所Summer Soil Institute本研究项目的总体目标是了解铁和有机碳土壤和沉积物之间复杂的氧化还原动力学。在还原环境中，溶解的Fe 2+可以催化铁氧化物重结晶成具有相似或截然不同化学性质的新矿物相。这一过程，Fe 2+催化的重结晶，已被观察到的纯Fe相，但尚未被探索作为一种途径，动员（或螯合）有机C。此外，有机碳的存在也可能会改变重结晶过程中的Fe反应性和同位素分馏的重要影响。研究人员将研究Fe 2+催化的重结晶如何影响有机碳和铁矿物的反应性。为此，研究人员将进行一系列Fe同位素示踪实验，以量化从一系列Fe氧化物和天然有机物多样性合成的模型Fe-C组合中Fe2+催化重结晶的程度。氧化铁对微生物和化学溶解的敏感性的变化将被测量，沿着与铁同位素分馏，以及铁-碳组合重结晶后的碳可用性。

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.