Fate of Metals Associated with Marine Biogenic Debris

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The flux of biogenic debris has often been implicated as major vector in the vertical transport of metals in aquatic systems. However, efforts to model quantitatively these processes have been limited by an inadequate data base on the retention times of most metals in biogenic debris particularly under different conditions of microbial decomposition. This study includes a series of radiotracer experiments in which the retention times of thirteen metals will be measured in phytoplankton, copepods, appendicularians, and chaetognaths as well as zooplankton fecal pellets, crustacean molts, and larvacean houses under different condition of microbial degradation. Metal biokinetics and pathways in organisms will be studied for metals accumulated from dissolved and ingested sources. Metal compartmentalization in phytoplankton will be assessed to help understand the fate of ingested in herbivores. A simple model to quantify the roles that different forms of biogenic debris can play in mediating the flux of metals will be constructed and tested off the NE US coast. Decomposition of biogenic debris and metal flux in individual types of debris will be measured in material caught in sediment traps deployed for the SEEP program. Metal analyses will employ the X-ray microprobe facility of the National Synchrotron Light Source.