Concentration of heavy metals (Cd, Cr, Zn, and Pb) in muscle and liver tissues of common carp (Cyprinus carpio L., 1758) from coastal waters of Golestan Province

Concentrations of four heavy metals (Cd, Cr, Zn, and Pb) in the common carp (Cyprinus carpio) were assessed in winter, spring and summer seasons of the years 2008. Four coastal areas in the west and east, Gomishan Marsh and Gorgan Bay including 11 sites were sampled. After biometrical measurements of the fish, specimens of muscle (104) and liver (36) tissues were immediately frozen and transferred to laboratory for assessment of heavy metal concentration. Dry ash method and atomic absorption spectrometer (AAS) of Perkin Almer (400 model, German) were used to assess metals concentration. In the process, analysis of variance (ANOVA) and Tukey-test were implemented. Heavy metals concentration in kidney tissue was higher than muscle tissue. In carp muscle tissue, level of zinc was highest and the next categories were those of lead, cadmium and chromium, respectively. A significant difference was observed between chromium concentrations in muscle tissue of Cyprinus carpio with sex (P<0.05). The concentrations of heavy metals in liver tissues were higher than those of the muscle tissues and in all cases; they were lower than mean allowable concentrations of international standards (WHO, UK, MAFF and NHMRC).