Project Details
Projekt
Iodine Biogeochemistry in the Southern Ocean
Applicant
Dr. Peter Leslie Croot
Subject Area
Oceanography
Term
from 2008 to 2011
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 74811330
Iodine is potentially a key element for climate change as iodine emissions from the ocean strongly influence the formation of new aerosol particles with impacts on cloud formation and radiative balances. The source and mechanism of iodine emissions from the ocean is poorly understood as are other more fundamental aspects of iodine biogeochemistry in seawater such as the cycling between the major iodine species; iodate and iodide. In the proposed work we will investigate the biogeochemistry of iodine in the poorly studied waters of the Southern Ocean. Central to this work will be investigations into the underlying mechanism behind the distribution and speciation of iodine species in the Atlantic sector of the Southern Ocean. The field work component of this project will be performed during Polarstern ANTXXIV-3 ZERO&DRAKE in cooperation with the IPY project GEOTRACES. During this cruise the speciation and distribution of iodine species will be examined across gradients of iron concentration and phytoplankton abundance in seawater; ranging from an open ocean region along the prime meridian, the Weddell Sea and Drake Passage and near several Antarctic islands. Laboratory work will focus on kinetic aspects of the speciation of iodide, in particular the reduction of iodate by abiotic and biotic mechanism, at the ambient temperatures found in Southern Ocean waters. The proposed work will be performed using state of the art techniques for the determination of iodine species in seawater that can be performed at sea: (1) Cathodic stripping voltammetry for the measurement of iodide. (2) Long path length spectrophotometry for the determination of iodate. Further to this culture experiments with Southern Ocean diatom species will examine and identity processes important for the reduction of iodate and oxidation of iodide. The accumulated data will be incorporated into a comprehensive model for iodine biogeochemistry in the Southern Ocean.
DFG Programme
Infrastructure Priority Programmes
