SusChEM: Redox and mineral controls maximizing Phosphorus mobility and bioavailability

了解磷在环境中的行为对社会至关重要，因为磷作为肥料在促进农业生产中发挥着核心作用。然而，磷也是水环境中的一种污染物，人类在水和沉积物中富集磷可促进有害藻华。 全世界的磷储量是有限的，特别是在美国，水资源的保护也是一个日益重要的关注领域，以促进可持续的清洁饮用水，健康的渔业和经济上至关重要的娱乐资源。这些问题需要更好地了解如何P是，可以，在不同的地质和工程设置动员。磷与其他元素，特别是铁，锰和碳的相互作用，往往控制磷的流动性，了解这种相互作用，因此，制定战略，更可持续的农业和水质的关键。这个研究项目？的目标是发展一个概念框架的环境条件，最大限度地提高磷的流动性在沉积物-水系统。 该项目将与调查湖泊水质的NSF-EPSCoR计划相结合。关于这些主题的研究将与推广机会相结合，教导当地学童和利益攸关方负责任的营养管理以及如何更好地保护水资源。磷通常在沉积物-水系统中分配在矿物质、溶解物和有机物池之间。确定不同的磷物种池变化的氧化还原条件的响应时间是了解沉积物-水系统中磷的流动性和生物有效性的驱动因素的主要障碍。静态模型描述P分区和流动性之间的这些池是大量的，但没有捕捉到关键因素。 沉积物-水界面（SWI）附近的氧化还原条件是浅水淡水和海洋系统中P和相关氧化还原活性元素（特别是Fe、Mn、S、N）反应性的关键控制因素，并且可以在昼夜、季节和更混沌的事件时间尺度上波动。该项目的中心假设是，特定的P池的流动性是最大化的氧化还原条件的变化在SWI在短（分钟至小时）的时间跨度，这些氧化还原振荡的持续时间和严重程度驱动的分区和行为的P（和Fe）物种随着时间的推移在SWI附近。 要测试这一点，需要一个全面的调查P形态和流动性，耦合场和实验室的方法，旨在阐明这个复杂的系统的驱动程序和动力学。 具体的磷池和相关元素的分析将利用先进的技术，以检查不同的磷形式在不同的池在不断变化的氧化还原条件下的分配。 具体而言，使用环境伏安技术对天然和人工SWI氧化还原动力学进行高分辨率原位监测，并结合一套有针对性的分析来描述沉积物-水P池的氧化还原驱动演化，包括：1）沉积物磷的矿物组成和可提取性; 2）磷和铁的形态;酶消化和核磁共振技术测定有机磷形态将为建立沉积物-水系统中磷形态和迁移率的分子模型提供必要的数据。

Understanding phosphorus (P) behavior in the environment is critical to society, as P often plays a central role in promoting productive agriculture as a fertilizer. Yet phosphorus is also a contaminant in aquatic environments, where human-derived enrichment of P in water and sediment can promote harmful algal blooms. Worldwide reserves of P are limited, especially in the U.S., and sustaining agricultural production will require the recovery and recycling of P. The protection of water resources is also an increasingly critical area of concern to promote sustainable clean drinking water, healthy fisheries, and economically vital recreational resources. These issues require improved understanding of how P is, and can be, mobilized in different geological and engineered settings. P interaction with other elements, especially iron, manganese, and carbon, often controls P mobility, and understanding this interaction is therefore key to developing strategies for more sustainable agriculture and water quality. This research program?s goal is to develop a conceptual framework of the environmental conditions that maximize phosphorus mobility in sediment-water systems. The project will integrate with NSF-EPSCoR program investigating lake water quality. Research on these topics will be integrated with outreach opportunities to teach local schoolchildren and stakeholders about responsible nutrient management and how to better protect water resources.Phosphorus is generally partitioned in sediment-water systems between mineral, dissolved, and organic pools. Determining the response times for different pools of P species to changing redox conditions is a major hurdle in understanding the drivers of phosphorus mobility and bioavailability in sediment-water systems. Static models describing P partitioning and mobility between these pools are voluminous but do not capture key factors. The redox conditions near the sediment-water interface (SWI) are a critical control on the reactivity of P and associated redox-active elements (Fe, Mn, S, N especially) in shallow freshwater and marine systems, and can fluctuate on diel, seasonal, and more chaotic event-based timescales. The central hypothesis of this project is that the mobility of specific P pools is maximized by changes in redox conditions at the SWI over short (minutes to hours) time spans, and that the duration and severity of these redox oscillations drives the partitioning and behavior of P (and Fe) species over time near the SWI. To test this requires a comprehensive investigation of P speciation and mobility that couples field and laboratory approaches designed to elucidate the drivers and dynamics of this complex system. Analysis of the specific P pools and related elements will utilize advanced techniques to examine the partitioning of different P forms in different pools under changing redox conditions. Specifically, high-resolution in-situ monitoring of natural and manipulated SWI redox dynamics using environmental voltammetric techniques, combined with a suite of targeted analyses to describe the redox-driven evolution of sediment-water P pools including: 1) sediment P mineralogical composition and extractability, 2) P and Fe speciation, and 3) enzyme digestion and NMR techniques to determine organic P speciation will provide the data needed to develop a molecular-based and temporally constrained model of P speciation and mobility in sediment-water systems.