The influence of Fe on the distribution and kinetic speciation of Zn, Cd, Co and Ni in the Southern Ocean
Dr. Peter Leslie Croot
National University of Ireland
Department of Earth and Ocean Sciences
Iron is the key limiting nutrient in the Southern Ocean and has a strong control on phytoplankton productivity and macronutrient biogeochemistry. However there are other key trace bio-elements (Cd, Co, Ni and Zn) which also may influence secondary aspects of phytoplankton productivity in the Southern Ocean. Central to this work will be investigations into the distribution and speciation of these bio-elements in the context of iron availability in the Southern Ocean. The principal field work will be carried out during Polarstern ANTXXIV-3 ZERO&DRAKE as part of the IPY project GEOTRACES. During this cruise the speciation and distribution of Cd, Co, Ni and Zn will be examined across gradients of iron concentration/bioavailabilty in seawater; ranging from an open ocean region along the prime meridian, the Weddell Sea and Drake Passage and near to Antarctic islands. Laboratory work will focus on kinetic aspects of the speciation of these elements at the ambient temperatures found in Southern Ocean waters. The proposed work will be performed using state of the art techniques: (1) Competitive ligand exchange with detection by cathodic stripping voltammetry for the measurement of Co2+, Ni2+ kinetics and speciation. (2) Anodic stripping voltammetry for the measurement of Cd2+ and Zn2+ kinetics and speciation. (3) Flow injection analysis with chemiluminescence detection for the measurement of Co in Southern Ocean waters. (4) Standard solvent extraction methods with graphite furnace atomisation for the measurement of Co, Ni, Cd and Zn in seawater. The accumulated data will be incorporated into a comprehensive model for trace metal biogeochemistry in the Southern Ocean.
Förderung von 2007 bis 2012