CAREER:Mineralogical and Biogeochemical Control of Phosphorus Transformation during Soil Development

土壤中磷的循环和生物有效性决定了生态系统的结构和功能。在土壤形成过程中的特定土壤发育阶段，磷的化学组成为评估当代磷、碳和其他养分的循环以及确定磷有效性的变化可能如何影响不同的生态系统过程，如初级生产力提供了有用的背景。在这个项目中，PI和他的团队将研究长期生态系统发展过程中土壤中磷成分的变化及其与有机碳循环的耦合。这项拟议的工作将改变目前对磷的动态及其与陆地生态系统碳循环的耦合的理解。这项工作对磷肥在农业上的利用也具有重要的意义，有助于加深对磷肥施用后磷素去向的认识。拟议的教育工作将通过开发课程、课程和STEM活动以及培养地球科学教师，对怀俄明州各级学生的地球科学教育产生广泛影响。这项建议的研究、教育和推广部分是协同发展的，以最大限度地影响PI以及现有的校园推广组织。广受欢迎的Walker和Syers模型描述了土壤形成或土壤发育过程中的P转化，是基于操作上定义的P组分，通过化学提取来衡量，而不是P的形态。因此，它在描述磷与矿物和有机物相互作用的磷的生物地球化学转化方面有很大的局限性。此外，由于模型没有考虑风尘沉降是半干旱环境中另一个重要的P输入，因此该模型是在湿润环境中发展起来的，对半干旱生态系统的适用性有限。因此，迫切需要开发基于磷形态的模型，以准确描述湿润和半干旱生态系统中的磷转化。在这个项目中，P-X-射线吸收光谱将被用来确定土壤、Walker和Syers模型的P库和风尘中的P形态。将检查对比气候条件和/或母材料的时间序列。提出了一种基于P-物种形成的生态系统发育转化模型。为了深入了解通过与矿物相互作用促进有机磷和碳的耦合循环，将利用光谱分析和生物化学分析来表征与不同大小土壤颗粒相关的土壤有机质中磷的形态。这一奖项反映了NSF的法定使命，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，被认为是值得支持的。

Phosphorus (P) cycling and bioavailability in soils shapes ecosystem structure and function. At a given soil developmental stage during soil formation, the P chemical composition provides a useful context for evaluating contemporary cycling of P, carbon and other nutrients, and for determining how changes in P availability might affect diverse ecosystem processes, such as primary productivity. In this project, the PI and his team will address transformation of P composition in soils and its coupling to organic carbon cycling during long-term ecosystem development. The proposed work will transform the current understanding of P dynamics and its coupling to carbon cycling in terrestrial ecosystems. This work also has important implications for P utilization in agriculture and will advance the understanding of P fate after P fertilizer application. The proposed education work will have broad impacts on Earth Science education of various levels of students in the state of Wyoming through developing courses, curriculum and STEM activities, and preparing earth science teachers. The research, education and outreach components of this proposal have been developed synergistically to maximize the impact on the PI's, as well as existing on-campus outreach organizations.The well-received Walker and Syers model describing P transformation during pedogenesis or soil development is based on operationally-defined P fractions as measured by chemical extractions, rather than P speciation. Thus, it has significant limitations in describing P biogeochemical transformation involving P interactions with minerals and organics. Moreover, the model was developed from humid environment and has limited applicability to semi-arid ecosystems as the model does not consider aeolian dust deposition as another important P input in the semi arid environment. There is, therefore, a great need to develop P speciation-based models that can accurately describe P transformation in both humid and semi-arid ecosystems. In this project, P X-ray absorption spectroscopy will be used to determine P speciation in soils, the P pools of the Walker and Syers model, and aeolian dust. Chronosequences in contrasting climate conditions and/or parent materials will be examined. A P-speciation based transformation model during ecosystem development will be proposed. To gain insights into coupled cycling of organic P and carbon facilitated by interacting with minerals, P speciation in soil organic matter associated with soil particles of different size regimes will be characterized using spectroscopic and biochemical analyses. Results are expected to have significant implications for understanding P cycling and bioavailability in terrestrial ecosystems.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.