ACCUMULATION OF LEAD (Pb) IN SCARDINIUS ERYTHROPHTHALMUS AND CERATOPHYLLUM DEMERSUM FROM FRESHWATER ECOSYSTEM BIOSPHERE RESERVE SREBARNA, BULGARIA

Concentration of heavy metals in Scardinius erythrophthalmus (L., 1758) found in Biosphere Reserve "Srebarna" (Northeastern Bulgaria) was examined in 25 fish individuals from every age group and season. The concentration of heavy metals was investigated by mineralization and subsequent atomic absorption spectrophotometry (according to the requirements of the methodology of the pollutants). To ensure the comparability of results the following standards were complied: 1. Sample collection and storage - ISO 5667-3/4:1995; etc. Fish sampling and analysis were carried out in compliance with National Program for Biomonitoring of Bulgaria (MEW, 1999). Particular the concentrations of Pb in Scardinius erythrophthalmus, Ceratophyllum demersum (L.), sediments and water were studied. Bioconcentration factor (BCF=C fish tissues;macrophytes/C water;sediments) for Pb in the tissues of fish and macrophytes were estimated and discussed. Biomagnification factors (BMF=C fish tissues/C macrophites) for Pb in the tissues of fish were estimated and discussed. The chemical analysis showed accumulation of Pb mainly in the fish bones as compared to the accumulation of the respective metal in the fish muscles. Biomagnification factors of Pb in Scardinius erythrophthalmus compared to Ceratophyllum demersum were evaluated. The mean concentration of Pb in the muscles of Scardinius erythrophthalmus was established to greatly exceed the reference values for lead in fish meat from Regulation ? 31 of 29 July 2004 on the maximum levels of pollutants in food.