(PH092) Change of copper associated with gills of common carp evaluated by a sequential extraction procedure.

Tao, Shu1, Liu, Guojin1, Pan, Bo1, 1 College of Environmental Science, Laboratory for Earth Surface Processes, Peking University, Beijing, China

ABSTRACT- Dynamic changes in copper speciation and its binding status to fish gills was investigated by exposing common carp (Cyprinus carpio) to a copper concentrated solution for seven hours. Copper speciation in the bulk solution and fish gill microenvironment was calculated using general chemical equilibrium modeling. A sequential extraction procedure using distilled water, magnesium dichloride (1.0 mol/l), and acetic acid (10%) was used to characterize the copper associated with the fish gills. Copper residual in the gill tissue was measured after the sequential extraction. Changes in total copper concentration, pH and dissolved organic carbon in both the bulk solution and the fish gill microenvironment were recorded during the experimental period. The dominant copper species in the bulk solution were Cu(OH)n, Cu2+, Cu-mucus, and CuSO4, while Cu-mucus was the dominant species in the fish gill microenvironment. Forty-three percent of the copper associated with the gills was readily water extractable, with an additional 22% exchangeable through cation or proton activity. Only 35% of the copper accumulated within the gill tissues. The binding of copper to the fish gills reached apparent equilibrium after three hours of exposure. Further, the amount of water extractable copper within the gills showed significant correlation to the concentration of copper complexed with free mucus in the gill microenvironment.

Key words: copper, fish gill, sequential extraction, mucus

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