HEAVY METALS CONCENTRATIONS IN AQUATIC ENVIRONMENT AND LIVING ORGANISMS IN THE DANUBE DELTA, ROMANIA

Abstract

A major role in terms of danger to the aquatic ecosystem is played by heavy metals, which stand out by their persistence and accumulability. In this study an overview on recent monitoring (2003-2005) of some heavy metals (Cu, Zn, Cd, Pb) analyzed in fish species, plants and benthic macro invertebrates from Danube Delta Biosphere Reserve.In the system of contamination classes elaborated by (Wachs B. 2000) , for the grading of the situation of ecosystems in term of heavy metal content, of all the various compartments, fish constitute the only critical part. The fish organs-in particular the muscles-show a very wide spread of concentration. Fish are very sensitive to cadmium and lead poisoning, but certain species, for example roach, perch and gibbel carp in aquatic ecosystem from Danube Delta was found with high concentration of cadmium and lead. The accumulation of contaminants in aquatic organisms can prove harmful to a number of fish species during sensitive stages within the lifecycle. Concentrations in aquatic plants was higher special in Ceratophyllum demersum Cd (1.89 mg/kg wet substance) and Pb (23,2 mg/kg w.s.).Variations of heavy metal concentrations from different sampling stations are discussed. Results indicate that the levels of lead and cadmium were highest concentration