The U.S. GEOTRACES North Atlantic zonal section cruise was scheduled for 15 October through 5 December 2010. Because of a major irresolvable mechanical failure of the ship's propulsion system, the expedition had to be terminated in the Cape Verde Islands on 4 November after completing about one third of the planned track. This required on-the-spot changes in return travel for all sea-going investigators as well as in shipping arrangements for all their samples and equipment. The funds requested in this proposal address the PI's need to cover salary costs to prepare for the cruise and shipping costs to get his supplies to the ship and back to his home institution after the cruise. The dissolved and colloidal trace elements determined as part of this study (Cd, Fe, Mn, and Zn) would improve coupled ocean/atmosphere carbon and nutrient cycling models and yield new insights on the role of the atmosphere in depositing metals to surface waters and their transfer to the interior ocean.
The award funds shipping of sampling equipments to and from the US Atlantic GEOTRACES cruise in 2011. This cruise was the continuation of the 2010 US Atlantic GEOTRACES cruise which was terminated due to the mechanical problems of the ship. In this project, we collected ~1000 seawater samples to determine dissolved trace metals iron, maganese, zine, copper and cadmium in oceanic waters. These elements are important essential micronutrients for planktonic alage in oceanic waters and important tracers for various biogeochemical processes in the ocean. The study of these elements in oceanic waters help understand ocean productivity, fishery, atmospheric carbon dioxide levels and climate change. The US GEOTRACES project aims to map these elements throughout the global ocean. Our 2010 and 2011 Atlantic cruises are part of such effort. So far, we have successfully completed these two cruises, obtained the samples that were shipped to our laboratory in the University of Miami. We are in the process of analyzing these samples. Our preliminary results show that there are large enrichment of dissolved iron in subsurface oceans that has low dissolved oxygen and high surface productivity. We also observed a substantial hydrothermal source of iron and maganese to deep ocean near mid-Atlantic ridge. We will report our results in 2012 fall AGU meeting in San Francisco.