Atmospheric Input of Bioavailable Iron and Phosphorus to Arctic during the Past Century from Greenland Ice Cores

本项目的目标是利用沙漠研究所（DRI）最近开发的独特的实验室能力，开发高分辨率的连续记录，记录全新世晚期格陵兰岛的总铁（Fe）、总磷（P）、活性磷、可溶铁、可溶铁形态、铁富集（相对于地壳）和相关的大气通量。分析能力的基础是最近开发的连续流动分析微量元素系统，其中包括两个新的高分辨率电感耦合等离子体质谱仪的重大升级，这将产生唯一的亚年度分辨率冰芯铁和磷数据。科学价值：在整个第四纪地球气候的大规模变化伴随着排放，大气传输和沉积的灰尘衍生的铁和磷的变化。在最近几个世纪，气候变化，土地利用的变化，和工业活动已经改变了自然变异和大气中的铁和磷的化学和相关的水生和陆生生物地球化学循环。在世界许多地区，海洋浮游植物的净初级生产力（NPP）以及因此对大气碳（C）的去除和封存目前受到生物可利用铁的输入的限制（最近在南大洋的公海铁施肥实验证明）。最近对卫星测量结果的分析表明，近几十年来，净初级生产力显著下降，其中中高纬度地区下降幅度最大，并与大气铁沉降的减少有关。同样，大气沉积的磷可能会限制许多陆地生态系统的生产力。然而，没有可靠的高时间分辨率的可溶性铁或活性磷通量的记录。目标：1）通过对格陵兰岛6个冰芯的化学分析，研究了近百年来格陵兰岛可溶性铁和活性磷沉积的时空变化特征：2）通过对全铁、全磷、可溶性铁和活性磷的变化以及可溶性铁的形态分析，研究了生物有效铁、磷和全铁、磷通量的变化特征; 3）通过比较化学示踪剂，评估过去世纪中总铁和生物有效铁以及总磷和活性磷通量变化的可能原因（同时测量）生物质燃烧、粉尘输送、火山活动和工业活动与铁和磷通量的变化; 4）通过测量六个相距甚远的冰芯中的铁通量，评估中高纬度地区可溶性铁和活性磷通量的半球内模式;和5）评估可溶性铁通量的测量变化与观察到的NPP下降在过去的二十年。更广泛的影响：首席研究员将支持本科生，并致力于吸引代表性不足的群体。 他将在K-12班和高中任教，以吸引年轻学生对科学的兴趣，并将通过开发一个在线外展网站“虚拟冰芯”来向公众介绍冰芯研究，该网站将利用NSF资助的环境科学高级计算科学可视化实验室位于DRI。

ABSTRACTEdwardsOPP-0520556The goal of this project is to use recently developed, unique laboratory capabilities at the Desert Research Institute (DRI) to develop high-resolution, continuous records of total iron (Fe), total phosphorus (P), reactive P, soluble Fe, soluble Fe speciation, Fe enrichment (relative to the Earth's crust) and associated atmospheric fluxes to Greenland during the late Holocene. Analytical capabilities are based on recent development of a continuous flow analysis with trace elements system which includes major upgrades with two new high-resolution, inductively coupled plasma mass spectrometers that will yield the only sub-annual resolution ice core Fe and P data available. Scientific merit: Large-scale changes in the Earth's climate throughout the Quaternary have accompanied changes in the emission, atmospheric transport, and deposition of dust-derived Fe and P. During recent centuries, climate change, changes in land use, and industrial activities have altered the natural variability and chemistry of atmospheric Fe and P and related aquatic and terrestrial biogeochemical cycles. Net primary production (NPP) and, consequently, removal and sequestration of atmospheric carbon (C) by ocean phytoplankton in many regions of the world is currently limited by the input of bioavailable Fe (demonstrated by recent, open-ocean, Fe-fertilization experiments in the Southern Ocean). Recent analyses of satellite measurements show significant declines in NPP in recent decades, with the largest declines in middle to high latitudes and associated with a decrease in atmospheric Fe deposition. Similarly the atmospheric deposition of P may limit productivity in many terrestrial ecosystems. There are, however, no reliable high-temporal-resolution records of soluble Fe or reactive P fluxes. Objectives:: 1) Document temporal and spatial variability in soluble Fe and reactive P deposition to Greenland during the past 100 years by applying novel chemical analysis methods to six existing ice cores; 2) Distinguish changes in bioavailable Fe and P and total Fe and P fluxes by assessing variability of total Fe and P and soluble Fe and reactive P as well as speciation of soluble Fe; 3) Evaluate possible causes of change in total and bioavailable Fe and total and reactive P fluxes during the past century by comparing chemical tracers (measured simultaneously) of biomass burning, dust transport, volcanism, and industrial activity with changes in Fe and P fluxes; 4) Evaluate intra-hemispheric patterns of soluble Fe and reactive P fluxes in mid to high latitudes by measuring Fe fluxes in six widely separated ice cores; and 5) Evaluate measured changes in soluble Fe fluxes in relation to observed declines in NPP during the last two decades.Broader impacts: The Principal Investigator will support undergraduate students and is committed to attracting underrepresented groups. He will teach in K-12 classes and high schools to interest younger students in science and will inform the public about ice core research by developing an online outreach site, The Virtual Ice Core, which will utilize the NSF-funded Advanced Computing in Environmental Sciences Scientific Visualization Laboratory located at DRI.