Copper Speciation and Accumulation in the Gill Microenvironment of Carp (Cyprinus carpio) in the Presence of Kaolin Particles

Abstract

Carp were exposed to copper adsorbed on kaolin particles at various concentrations (0–2.4 mg/L), and net accumulation due to elevated adsorbed copper in the surrounding water was observed. Copper speciation in the water and fish gill microenvironment was modeled in the presence and absence of kaolin using a chemical speciation program (MINTEQA2). The adsorption affinity constants of kaolin for copper at various pH values used in the speciation calculations were experimentally determined, and the quantitative relationship between the affinity constant and pH was modeled. Copper accumulations in fish gills exposed to kaolin-adsorbed copper was then observed. The results indicate that desorption occurred in the fish gill microenvironment due to both mucus competition of copper and slight increase in water pH. Furthermore, the available copper species increased as a result of desorption, causing a net accumulation of Cu by the gills.