US GEOTRACES North Atlantic Section: Analysis of Key Trace Elements in Size-fractionated Marine Particles

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

GEOTRACES is an international program to study the global marine biogeochemical cycles of trace elements and their isotopes (TEIs). Its guiding mission is to "identify processes and quantify fluxes that control the distributions of key trace elements and isotopes [TEIs] in the ocean" (GEOTRACES Science Plan, 2006). Because particles in the ocean serve as important sources and/or sinks for many trace elements and isotopes, particulate TEIs are key parameters for GEOTRACES. Indeed, the composition and distribution of particles in the ocean is crucial to understanding all three themes identified by the Science Plan: 1) Fluxes and processes at ocean interfaces, 2) Internal cycling, and 3) Development of proxies for past change. In this project, researchers at the Woods Hole Oceanographic Institution will be supported to ensure the collection of high quality trace metal clean size-fractionated particles on the US North Atlantic GEOTRACES Atlantic section and the analysis of key trace elements and major particulate phases. They will analyze size-fractionated particles collected by battery operated in-situ filtration for all key trace elements listed in the Science Plan (Fe, Al, Zn, Mn, Cd, Cu), a suite of other trace elements of interest (e.g. Co, Ti, Ba), and major carrier phases (e.g. CaCO3, biogenic Si, and POC). The operation of battery operated in-situ filtration (McLane pumps) for short-lived radionuclides is already funded for the Atlantic GEOTRACES section. This project will coordinate closely with the short-lived radionuclide group to adapt McLane pumps for simultaneous sampling of size-fractionated particles for trace metal analysis and radionuclide collection. Broader Impacts: Inasmuch as this will be the first full ocean depth zonal section of size-fractionated particulates, the result should be a novel and comprehensive understanding of the distribution, composition, and dynamics of the particles that control much of the chemical distribution, carbon uptake, and the biological productivity of the ocean. Because of the importance of particles in so many processes affecting the cycling of TEIs, this dataset will be invaluable in conjunction with other parameters measured on the GEOTRACES Atlantic section. Many as yet unposed scientific questions will emerge from this unprecedented dataset, which will be made available through publication and electronically through the BCO-DMO data office at Woods Hole so that it can be mined in the future by anyone in the community exploring questions about particle distribution and composition. A summer undergraduate student will help with some sample analyses, as will a graduate student in the MIT-WHOI Joint Program in Oceanography.