9630572 Morel The dynamic relationship between the trace metal chemistry and microbiology of terrestrial and marine surface waters will be explored in this study. The principal investigator will conduct both field and laboratory studies to determine how two trace metals, copper and cadmium, are taken up by marine and freshwater phytoplankton and bacterioplankton, bound to biochelators, and released back into the water. The field work will be carried out in coastal salt ponds on Cape Cod and in Swiss alpine lakes where other scientists already have established programs to study trace metal biogeochemistry. Laboratory experimentation will help quantify the rates of these various processes. Besides improving current understanding of the role of plankton biochemical pathways impacting the trace metal chemistry of surface waters, these studies should also provide insight into how metal concentrations and chemical speciation are related in a two-way cause-and-effect relationship to planktonic species composition.