Collaborative Research: Biogeochemistry of Trace Elements in the Western Pacific: Atmospheric Input and Upper Ocean Cycling

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ABSTRACTOCE-0117917OCE-0117655OCE-0117648While previous studies in the Atlantic Ocean and Arabian Sea have documented a direct relationship between atmospheric dust deposition and reactive trace element additions to surface waters, little is known about the effect that the Asian dust plume has on the distribution of reactive trace elements in surface waters of the western North Pacific. For this reason, PIs from the University of Hawaii, Old Dominion University and Florida State University will participate in a cruise to the central and western North Pacific during April/May 2002, a time period coincident with maximum Asian dust over that region. During this cruise the following four research objectives will be addressed: (1) quantify the areal extent and concentration of atmospheric dust in this region using dissolved Al concentrations in surface water samples and compare results with estimates obtained during field studies carried out as part of the ACE-ASIA program in 2001, as well as historical deposition models; (2) compare the solubility of bioactive trace metals in aerosols and rainwater along with their concentration and distribution in surface water samples versus Al values to assess the role that atmospheric deposition has in controlling/altering the upper ocean biogeochemical cycles of these elements; (3) ascertain the magnitude and pathways via which atmospheric inputs get incorporated into the thermocline and central waters of the North Pacific; and (4) provide baseline concentrations for trace metals. The PIs will collect surface samples while underway by pumping water onto the ship through a Teflon-lined, polyethylene tube mounted on a modified bathythermograph and vertical profiles at 8 stations that will encompass the key hydrographic regimes of the area. Samples (total, particulate, dissolved, colloidal) will be analyzed for the metals Ag, Al, Cd, Cu, Co, Fe, Mn, Ni, Pb, Zn and the metalloids As, Sb, Se. Aerosols and rainfall samples also will be collected and analyzed for metals/major ions and metals/metalloids, respectively. In addition, selected samples also will be analyzed for nutrients, salinity, oxygen, chlorophyll a, particulate organic carbon, particulate organic nitrogen, particulate organic sulfur, dissolved organic carbon and dissolved organic nitrogen.