RII Track-4: Microscale processes controlling speciation and transformation of phosphorus in soils

非技术描述磷(P)在经常竞争的食物需求和保护水质中起着关键作用。切萨皮克湾是国家瑰宝，也是国会修复的第一个河口。提高对通往海湾的流域中磷的组成和含量的了解，将提高我们预测磷从森林、农业和城市来源向海湾水域移动的潜在风险的能力。这个项目的科学发现将有助于切萨皮克湾项目、美国地质调查局和美国环境保护署在海湾恢复计划中开展数十年的工作。PI和特拉华大学的一名研究生将与加州理工学院的科学家合作，使用一套复杂的仪器来确定土壤和水中磷的具体形式和浓度。这项工作将大大提高目前对控制切萨皮克湾流域P的环境命运的复杂过程的理解，并将使PI能够采用在国内机构无法获得的技术。技术描述跨时空尺度变化的土壤和水体中磷形态与过程之间的多尺度相互作用需要能够提供磷结构信息的先进和创新分析方法工具箱，这些分析方法可以将结构与化学反应性和转化途径联系起来。本研究旨在探讨土壤中不同磷库的形成、转化及其向开阔水域迁移的机制。它将利用先进的分析技术，包括空间分辨电子微探针分析（EMPA）、二次离子质谱分析（纳米SIMS和磁性SIMS）和激光烧蚀同位素质谱仪（LA-IRMS）。此外，轻同位素系统学的一系列理论和实验发展将被应用于识别和解释土壤短期和长期孵育以及土壤时间序列研究中磷的微观形态、物理化学关联和磷酸盐氧同位素的原位分布及其相互关系。该奖学金将最大限度地提高PI在几种新型同位素技术方面的研究生产力和领导地位，所获得的知识和经验将在未来催化新的研究前沿。该项目的研究结果将提供给美国农业部合作推广部以及其他州和地方机构，以便他们共同努力，尽量减少农业土壤中的养分流失，并帮助实现减少污染物的目标。

Non-technical DescriptionPhosphorus (P) plays a pivotal role in the often-competing demands of food and safeguarding water quality. Chesapeake Bay is a national treasure and the nation's first estuary targeted by Congress for restoration. Improved understanding of the composition and the amount of P in the watershed leading to the Bay will enhance our ability to predict the potential risk of movement of P from forest, agricultural, and urban sources to the Bay waters. Scientific findings from this project will contribute to decades of work conducted by the Chesapeake Bay Program, US Geological Survey, and US Environmental Protection Agency in the Bay restoration plan. The PI and a graduate student from the University of Delaware (UD) will work with scientists at the California Institute of Technology to use a suite of sophisticated instrumentation that will determine the specific forms and concentrations of P in soils and waters. This work will greatly improve the current understanding of the complex processes that govern the environmental fate of P in the Chesapeake Bay watershed, and will enable the PI to employ techniques that are not available at the home institution.Technical DescriptionMulti-scale interactions among forms of P and processes in soils and waters that vary across spatial and temporal scales call for a toolbox of advanced and innovative analytical methods capable of providing P structural information, which can connect the structure to chemical reactivity and transformation pathways. This research aims to identify the mechanisms of formation and transformation of different P pools in soils and its transport to open waters. It will utilize advanced analytical techniques, including spatially resolved electron microprobe analysis (EMPA), secondary ion mass spectrometry (nanoSIMS and magnetic SIMS), and laser ablation isotope mass spectrometer (LA-IRMS). In addition, a series of theoretical and experimental developments in light isotope systematics will be applied to identify and interpret microscale P speciation, physico-chemical association and in situ distribution of phosphate oxygen isotopes and their interrelationship in short- and long-term soil incubation as well as in soil chronosequence studies. This fellowship will maximize the PI's research productivity and leadership in several novel isotope techniques, and the knowledge and experience gained will catalyze new research fronts in the future. Findings from the project will be provided to the UD Cooperative Extension and other state and local agencies for their collective efforts to minimize the loss of nutrients from agricultural soils and to help achieve pollutant reduction goals.