Program and Agenda

Abstract

232TH/230TH AT THE HAWAII OCEAN TIME-SERIES STATION ALOHA: A TOOL FOR IRON CYCLING

The role of iron as a micronutrient motivates an effort to understand the supply and removal of lithogenic trace metals in the ocean. In the subtropical North Pacific in particular, iron is a potentially limiting factor for diazotrophic nitrogen fixation and the biological productivity supported thereby. The long-lived thorium isotopes (232Th and 230Th) dissolved in seawater can be used to quantify the input of lithogenic metals attributable to the partial dissolution of aerosol dust. Thus, Th can help in disentangling the Fe cycle by providing estimates of its ultimate supply and turnover rate. By comparing Th-based lithogenic dissolved Fe fluxes with measured dissolved Fe inventories, we derive Fe residence times of 6 months for the surface ocean and 20 years for the whole water column. Iron is clearly very rapidly removed from seawater, due to some combination of biological uptake and chemical scavenging. We also critically examine a variety of factors relating to the use of 232Th/230Th as a lithogenic source-tracer, including colloidal content of the two Th isotopes, Fe/Th ratios in source material and the issue of seasonality.

ePoster:

Authors

Hayes, C. T., Massachusetts Institute of Technology, USA, cthayes@mit.edu

Boyle, E. A., Massachusetts Institute of Technology, USA, eaboyle@mit.edu

McGee, D., Massachusetts Institute of Technology, USA, davidmcg@mit.edu

Fitzsimmons, J. N., Massachusetts Institute of Technology, USA, jessfitz@mit.edu

Anderson, R. F., Lamont-Doherty Earth Observatory of Columbia University, USA, boba@ldeo.columbia.edu

Details

Poster presentation

Session #:049
Date: 2/27/2014
Time: 16:00 - 18:00
Location: Poster/Exhibit Hall

Presentation is given by student: No

PosterID: 2436