Total Dissolved Copper Determinations: Production by Natural Microbial Populations of Copper-complexing Ligands in a Major Harbor (Elizabeth River, VA)

The Elizabeth River is one of the regions of the Chesapeake Bay that has extremely elevated amounts of copper, which can be toxic at high concentrations. We found total dissolved copper concentrations of 15nM to 25nM in the water at the Norfolk Naval Base Station. The toxic and bioavailable form of copper is the free cupric ion (Cu(II)) which can amazingly be complexed into non-toxic strong organic (ligand) complexes (usually denoted CuL). Cu(II) causes mortality at concentrations at or slightly below 10-9.9 M (Sunda et. al 1990). Phytoplankton have proven in the laboratory to produce ligands which complex the free copper ions. Previous studies have shown that there was a greater ligand concentration than total dissolved copper concentration found in the Elizabeth River in previous years. The research currently underway will show whether natural microbial populations in a major polluted harbor (Elizabeth River) produce strong Cu-complexing ligands and will measure the levels of ligands versus the levels of toxic copper ions. The determination of total dissolved Cu concentrations is a necessary piece of that research.