In the fall of 2010, the US GEOTRACES North Atlantic Section cruise began its survey of the distribution of trace metals and isotopes across a basin where there is an enhanced influence from atmospheric deposition. Due to damages to the ship's (R/V Knorr) propulsion system, the cruise was halted at an early stage when less of a third of the cruise track was completed. The completion of this section has been rescheduled for the fall of 2011.
With support through this Grant for Rapid Response Researcher, a GEOTRACES researcher at the University of Alaska at Fairbanks will be able to continue participation in this expedition to complete work originally proposed and funded by NSF through an ARRA award. This work addresses the guiding mission of GEOTRACES: "to identify processes and quantify fluxes that control the distributions of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions". Iron is a key trace element in the GEOTRACES program, and this study investigates the fractional solubility of aerosol Fe using a novel field approach. Results will improve our understanding of how aerosol deposition affects the surface distribution of Fe in the North Atlantic. Information obtained from this work will also help establish how changing environmental conditions (e.g. increased dust flux) may affect the distribution and speciation of Fe.
The continuation of the GEOTRACES North Atlantic section cruise will traverse over surface waters with significantly different chemical and biological characteristics, and with aerosol deposition from natural and anthropogenic sources. This portion of the cruise offers the complementary setting needed to complete the investigation of factors affecting aerosol Fe dissolution in the North Atlantic.
Broader Impacts. Essential information concerning the dissolution of Fe in seawater will be generated and incorporated into the GEOTRACES database. This project presents a unique approach for investigating the fractional solubility of aerosol Fe in seawater that will result in important information for models of global carbon cycling and climate change that incorporate the aeolian supply of Fe. The project will support an early-career, female principal investigator at the University of Alaska Fairbanks (UAF), and helps build research infrastructure at UAF. An undergraduate student at UAF will receive support from this study. Information gained from this research will be incorporated into materials for web dissemination and public outreach events.
The purpose of this Rapid Response Grant was to provide funds for covering unforeseen expenses which arose as a result of the breakdown and incapacitation of the Research Vessel Knorr in the early stages of the original US GEOTRACES North Atlantic Section expedition during fall 2010. This grant enable the participation of the principal investigator on the continuation expedition of the US GEOTRACES North Atlantic Section during the following year (fall of 2011). As a result the principal ivestigator was able to successfully complete on-board work funded through an American Recovery and Reinvestment Act (ARRA) award. The study conducted on-board involved comparison of several leaching protocols for extracting the soluble fraction of iron found in open ocean atmospheric aerosols. Constraining the soluble fraction of this aerosol-derived micronutrient is essential for quantifying the aeolian input of iron available to biota in the open ocean. At present this fraction is not well constrained, and the factors contributing to the observed variability are not well understood. Findings from on-board experiments will be included in the ARRA's grant report. This project supported an early-career, female principal investigator at the University of Alaska Fairbanks (UAF), and helped build research infrastructure at UAF, an EPSCoR institution. An graduate student at UAF participated in pre-expedition logistics and learned about various aspects necessary for the preparation for an oceanographic expedition.
