Support for this work came from postcruise funding made available to LCP, RWM, KMY, JWK, and TJB through the U.S. Science Support Program. Stable isotope analyses were also supported by NSF Grant OCE-9709807 to LCP, who acknowledges with thanks the laboratory assistance of K. Blair, H. Ensing, and L. Leist. The contributions of GHH were made possible with funding from the German Research Foundation (DFG) and from NSERC (Canada). Funding to RWM from NSF (EAR-9724282) supported the initial acquisition and use in this study of the ICP-ES facility at Boston University. Postcruise work undertaken by RBP was funded by the NERC (UK). We thank R.C. Thunell and an anonymous reviewer for their constructive and thorough reviews. This is a contribution from the Rosenstiel School of Marine and Atmospheric Science, University of Miami.