Scientists from Florida State University, the University of Hawaii, and the University of Washington will continue the trace metal component of the CLIVAR/CO2 Repeat Hydrography Program with cruises in the Indian Ocean (I8S/I9N, I6S, I7N or S4P). The researchers will use their clean rosette/GoFlo system to collect trace metal profiles at 1' spacing (12 depths to 1000 m). These samples will be analyzed on board for dissolved Al and Fe using Flow Injection Analysis. Subsamples will be collected and acidified for shore-based analysis of dissolved Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb using either isotope dilution inductively coupled plasma mass spectrometry (ICPMS) and/or standard additions ICPMS. The colloidal fraction of these samples will be obtained using tangential flow ultrafiltration (<1000Da) and the low molecular weight fraction will be analyzed for Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb. In addition, suspended matter filters will be analyzed for particulate Al, Fe, and other trace elements. Besides seawater samples, aerosol samples also will be collected using a MOUDI (micro-orifice uniform deposit impactor) cascade impactor to obtain size-fractionated aerosol samples that will be analyzed for total aerosol Al and Fe, and ultrapure water soluble aerosol Al, Fe, other trace elements, and major ions.
In terms of broader impacts, results from basin scale sections of dissolved and particulate trace elements combined with the total and soluble aerosol trace element data will improve our understanding of global ocean biogeochemical cycles, as well as improve the predictive capabilities of coupled ocean/atmospheric carbon cycle models. Two graduate students from Florida State University, one post-doc and one graduate student from the University of Hawaii, and one graduate student from the University of Washington will be supported and trained as part of this project.
