Collaborative Research: A Novel Tracer Approach to Estimate the Atmospheric Input of Trace Elements into the Global Ocean

大气向全球海洋输入的许多化学物质等于或超过来自河流的化学物质，因此构成了这些元素的重要预算组成部分。此外，微量元素的大气输入在海洋生物地球化学过程中起着关键作用。然而，对这种投入的评估是困难的，因为对海洋沉积速率的测量很少，而且容易受到时间和空间变异性问题的影响。由于缺乏直接测量，海洋界必须依赖大气输送和沉积模式，而这些模式本身在降雨量和气溶胶去除参数化方面约束很差。因此，间接方法，例如使用从大气输送到海洋的天然放射性核素，经常用于估计大气输入。在该项目开发的一项新应用中，迈阿密大学和佛罗里达州立大学的研究人员将测量地表水和低层大气中的7Be，同时测量气溶胶和雨水中的微量元素，7Be是一种宇宙射线产生的放射性同位素，它与对流层中的粒子有关，随后沉积到海洋表面。由于其相对较短的半衰期（53.3天），可以合理地将上层海洋中7Be的衰变库存等同于大气中由于干湿沉积而产生的7Be通量。这提供了大气中化学物质的浓度与其在海洋中的沉积之间的关键联系。这些物种包括许多GEOTRACES项目感兴趣的元素，如Al， Mn, Fe, Cu， Zn和Cd。这些重要的微量元素（TEs）的大气通量可以通过将大气通量（由其海洋库存决定）乘以气溶胶和湿沉积中的TE/7Be比率来估计。更广泛的影响：这项研究将直接解决国际GEOTRACES科学计划的关键目标之一：“开发和改进海洋表面的化学示踪剂，用于量化大气沉积”。提供大气向海洋输入的相关微量元素的估计的能力将对化学海洋学和其他领域作出广泛贡献，包括了解人为对海洋的影响以及te的大气输入在海洋生态中所起的作用。这个项目的结果将有利于其他国际倡议，如SOLAS计划，在这项工作中产生的数据将可用于气溶胶沉积和大气输入模型的地面真实性。研究生的教育和培训是这项研究的重要组成部分。pi定期教授本科生和研究生课程，并将他们实地考察的结果纳入讲座材料，以激励下一代地球科学家。FSU化学和/或生物学专业的本科生（男性，女性，少数民族）将通过年度REU补充申请参与研究。随着它们的发展，结果将在国家/国际科学会议上提出，并在同行评议的期刊上发表。根据NSF/OCE的要求及时提交数据。

The atmospheric input of numerous chemical species into the global ocean equals or exceeds that from river sources and thus constitutes an important budgetary component for these elements. In addition, the atmospheric input of trace elements plays a key role in ocean biogeochemical processes. Assessment of this input is difficult however because measurements of deposition rates to the ocean are rare and susceptible to problems of temporal and spatial variability. Given the dearth of direct measurements, the ocean community must rely on atmospheric transport and deposition models which themselves are poorly constrained as to rainfall amounts and aerosol removal parameterization. Thus indirect methods, such as the use of natural radionuclides delivered to the ocean from the atmosphere are often used to estimate atmospheric inputs. In a novel application developed in this project, researchers at the University of Miami and Florida State University will use measurements of 7Be in the surface waters and in the lower atmosphere, coupled with trace element measurements in aerosols and rain, to provide estimates of the atmospheric input of relevant trace elements into the subtropical North Atlantic. 7Be is a cosmic ray produced radioisotope that becomes associated with particles in the troposphere and subsequently deposited to the surface ocean. Because of its relatively short half-life (53.3 days) it is reasonable to equate the inventory of 7Be decay in the upper ocean to the flux of 7Be from the atmosphere due to wet plus dry deposition. This provides a key linkage between the atmospheric concentration of chemical species and their deposition to the ocean. Such species include many of interest to the GEOTRACES program such as Al, Mn, Fe, Cu, Zn, and Cd. The atmospheric flux of these important trace elements (TEs) can then be estimated from multiplying the 7Be atmospheric flux (determined by its ocean inventory) by the TE/7Be ratios in aerosols and wet deposition. Broader Impacts: This research will directly addresse one of the critical objectives in the International GEOTRACES Science Plan: "Develop and refine chemical tracers in the surface ocean for quantification of atmospheric deposition". The ability to provide estimates of the atmospheric input of relevant trace elements to the ocean will contribute widely to the field of chemical oceanography and elsewhere, including understanding anthropogenic impacts on the oceans and the role atmospheric input of TEs plays in ocean ecology. The results of this project will benefit other international initiatives such as the SOLAS program, and data generated in this work will be available to allow ground-truthing of models of aerosol deposition and atmospheric input. Education and training of graduate students are essential components of this research. The PIs regularly teach undergraduate and graduate classes and incorporate the results of their fieldwork into lecture materials to motivate the next generation of Earth scientists. Undergraduate FSU chemistry and/or biology majors (males, females, minorities) will be involved in the research via annual requests for REU supplements. As they evolve, results will be presented at national/international scientific meetings, and published in peer-reviewed journals. The data will be submitted in a timely manner according to the requirements of NSF/OCE.