Heavy metals occurrence in lakes of the Danube Delta, Romania

Abstract

The results of investigations on contents of several heavy metals in aquatic environments within the Danube Delta, Romania, are presented.The distribution of these heavy metals in the delta lakes was studied taking into consideration hydrochemical characteristics of the water catchment areas and the potential sources of contamination. The water sampling was done during several field campaigns in 2019, 2020 and 2021. A total of 143 water samples from 25 lakes, were collected for quantification of heavy metals content in water of studied lakes. The total concentration of technophile elements was determined using the ICP-EOS method. The results of analyses showed that the content of Cd, Co, Cr, Cu, Ni, Pb and Zn (μg/L) in the water samples were mainly within the acceptable limits set for Quality Class I (Very Good) and II (Good). Incidentally, the content of Cd (μg/L) reaches or exceeds the limit set for Quality Class III (moderate). In conclusion, the degree of heavy metal contamination in the investigated waters of the Danube Delta lakes is acceptably low and consequently presents a low environmental risk to aquatic life. In addition, the results obtained in three consecutive years showed that the environmental state of lakes is relatively stable. The results obtained concerning the heavy metals content in the water of Danube Delta inter-distributary depressions lakes represent a baseline data set that will be used for planning future delta water quality monitoring.