Speciation and bioavailability of EDTA complexed copper in the microenvironment of fish gills

Carp were exposed to a synthetic solution with varied concentrations of Cu-EDTA and constant levels of other copper species and the amount of copper accumulated in the fish gills was measured. The distributions of copper species in both the bulk solution and the fish gill microenvironment were modeled using MINTEQA2. Under experimental conditions without EDTA, Cu(OH)2 was the most dominant species in the bulk solution while Cu-mucus dominated the gill microenvironment. When Cu-EDTA was added to the solution, copper accumulation in the fish gills increased significantly, suggesting a change in copper speciation. The amount of copper accumulated in the fish gills correlated positively to the concentration of Cu-mucus, rather than to free copper.