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

Nevada System Of Higher Education, Desert Research Institute, Reno NV

Investigators

Abstract

ABSTRACT Edwards OPP-0520556 The 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.