Trace metal marine geochemistry: speciation and coastal processes

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Trace elements in seawater play important roles as nutrients, as tracers of ocean processes, and as contaminants.  Their biogeochemical cycling has implications for research in diverse areas such as the carbon-cycle, climate-change, ocean ecosystems, and environmental contamination.  Despite the recognized importance of trace elements, our ability to use this information is limited by uncertainties concerning their sources, sinks, internal cycling and chemical speciation within the ocean.  My research focuses on determining the distributions of selected trace elements (Al, Ga, Ti, Zr, Hf, Mn, Cu, Cd, Zn, Pb) in the Northeast Pacific, and in some cases their chemical speciation, to assess the sources, sinks, and internal cycling of these elements.  The aim is to evaluate the physical, chemical and biological processes regulating their distributions. This includes characterization of some of the metal-binding ligands which strongly influence trace element speciation in the oceans. Over the next few years I will focus on characterizing coastal sources and transport processes, including fluvial input, shelf exchange, upwelling and transport in mesoscale eddies.  Many of the elements of interest are known to have coastal sources, but the detailed origins and magnitudes of these sources are not known.  Rivers supply dissolved metals and suspended sediments to seawater and the continental shelf in this region, some metals are mobilized from the shelf sediments via diagenetic processes.  Eddies may carry these metals from the coastal region out into the subarctic gyre, an area where primary production is known to be limited by iron.  I propose to look at the effect of these sources on the distribution of selected trace metals in the northeast Pacific.  I also propose to look at the structure, abundance and distribution of the strong metal-binding organic ligands in various estuarine and coastal regimes, as well as in laboratory phytoplankton cultures.