Abstract : LONG-TERM GOALS. To gain a better understanding of the role of colloidal organic macromolecules and inorganic colloidal microparticles in the cycling, speciation and bioavailability of trace elements in coastal waters. SCIENTIFIC OBJECTIVES. 1. Critically evaluate ultra-filtration methodology for the collection of colloidal matter from fresh, estuarine and sea water. 2. Investigate changes in the phase distribution of selected trace metals and metalloids in estuarine water along salinity transects. 3. Determine the importance of coagulation of colloidally bound trace metals (e.g., Ag, Hg, Se, As, Sb, Cd, Cu, Co, Ni, Pb, Zn, Fe) in estuarine waters. 4. Determine the bioavailability of colloidally bound trace elements and metalloids to penaeid shrimp. 5. Develop new analytical methods to establish binding of trace elements (e.g., Ag) with natural organic macromolecules and colloidal organic matter in the estuarine environment. 6. Evaluate microscopy imaging approaches to determine forms, shapes and sizes of natural organic macromolecules and inorganic microparticles (i.e., colloids).