The Role of Dust on Snow and Other Aeolian Inputs in Soil Formation and Biogeochemical Cycling in Barren, Alpine Catchments

迫切需要提高我们对高海拔集水区的生物地球化学循环和地表水质量如何对尘埃和其他风沙沉积事件作出反应的理解。气温上升和粉尘排放、冰川融化以及最近冰川融化土壤中惊人的高微生物活动相结合，代表了贫瘠的高山集水区地质、生物和水文过程之间的新联系。众所周知，粉尘沉积为贫瘠的高山地区提供了重要的盐基阳离子，也可能影响土壤阳离子交换池、土壤pH值和流域阳离子的输出，在产生贫瘠土壤方面可能比基岩风化更重要。此外，风沙沉积日益被认为是高海拔生态系统碳和磷等营养物质的重要来源，这些输入可能会推动生物过程，如那些增强硝化作用和影响水质的过程。定义该项目的一个重要假设是，在贫瘠的高山集水区，尘埃和其他大气输入是土壤形成和生物地球化学过程(如硝化作用)的重要途径。该项目将评估风沙沉积的来源和化学质量，并使用新的光谱技术、稳定同位素和阳离子分析、土壤化学和矿物学分析以及生物有效性实验，研究贫瘠、高海拔土壤的风化和生物地球化学循环的初始阶段。假说将在科罗拉多前锋山脉的绿湖四号(GL4)流域得到验证，在那里，风沙沉积、土壤微生物过程和硝化作用将作为相互作用的过程在一项跨学科调查中进行研究，这些因素在过去几十年中一直被独立研究。考虑到全球范围内前所未有的冰川融化速度，这项研究将产生的生物地球化学过程的改进代表与全球范围内碳和磷有限的山区集水区相关。鉴于这项研究的全球相关性，将在美国的其他关键区观测站以及国际高山观测站进行部分活动。通过研究风沙干湿沉积、微生物群落组成、微生物过程速率以及河流和土壤水质，以及通过进行融雪-生物地球化学耦合模拟而获得的新见解，将进一步提高预测气候变化的高海拔流域生物地球化学循环和水文变化的能力。这个项目将支持研究生参与跨学科的研究，包括地球化学、生物学和水文学研究。此外，该项目将吸引高中生参加圣弗拉恩数学、工程和科学成就(MESA)计划，该计划旨在提高拉丁裔学生的成绩。MESA学生将开发他们自己的暑期研究项目，由PIs和研究生指导，并通过这个项目提供津贴支持。每年在北极和高山研究所(INSTAAR)开放日期间，也会有更多的MESA学生访问加州大学校园，这是INSTAAR为K-12学生举办的为期一天的实验室参观和实地演示。

There is an urgency to improve our understanding of how biogeochemical cycling and surface water quality in high-elevation catchments are responding to dust and other aeolian deposition events. The combination of increasing temperatures and dust emissions, melting glaciers, and surprisingly high amounts of microbial activity in recently deglaciated soils represent a new connectivity between geologic, biological, and hydrologic processes in barren, alpine catchments. Dust deposition, known to supply barren, alpine areas with important base cations, may also influence the soil cation exchange pool, soil pH, and export of cations from the watershed and may be more important than bedrock weathering in generating barren soils. Additionally, aeolian deposition is increasingly being recognized as an important source of nutrients, such as carbon and phosphorus, to high‐elevation ecosystems, and these inputs may drive biological processes, such as those that enhance nitrification and influence water quality. An overarching hypothesis that defines this project is that dust and other atmospheric inputs are important pathways to soil formation and biogeochemical processes, such as nitrification, in barren, alpine catchments. This project will evaluate the provenance and chemical quality of aeolian deposition and investigate the initial phases of weathering and biogeochemical cycling in barren, high-elevation soils using novel spectroscopic techniques, stable isotope and cation analyses, soil chemistry and mineralogy analyses, and bioavailability experiments. Hypotheses will be tested in the Green Lakes Four (GL4) catchment of the Colorado Front Range, where aeolian deposition, soil microbial processes, and nitrification, which have been studied independently over the last few decades, will be studied as interacting processes in an interdisciplinary investigation. Given unprecedented rates of glacier melting worldwide, the improved representation of biogeochemical processes that this research will produce is relevant for C- and P- limited mountain catchments on a global scale. Given the global relevance of this research, a subset of activities will be conducted at other Critical Zone Observatory sites in the US as well as at international alpine sites. New insights gained from investigating aeolian wet and dry deposition, microbial community composition, rates of microbial processes, and stream and soil water quality, and from conducting coupled snowmelt-biogeochemical modeling will further improve the capability to forecast changes in the biogeochemical cycling and hydrology of high-elevation watersheds with a changing climate. This project will support graduate students to participate in interdisciplinary research that spans geochemical, biological, and hydrologic studies. In addition, this project will engage high school students participating in the St. Vrain Math, Engineering, and Science Achievement (MESA) Program, which seeks to improve achievement by Latino students. MESA students will develop their own summer research projects, mentored by the PIs and graduate students and supported with stipends through this project. A larger group of MESA students will also visit the CU campus annually during the Institute for Arctic and Alpine Research (INSTAAR) Open House, a day of lab tours and field demonstrations for K-12 students hosted by INSTAAR.