Melnikov A. Migration of heavy metals in the Ukrainian part of the Danube delta ecosystem

Thesis for the degree of Candidate of Technical Sciences in specialtiy 21.06.01 "Ecological safety". – Scietific Research Institution “Ukrainian Scietific Research Institute of ecological problems”, Kharkiv, 2021. The dissertation is devoted to the study of heavy metals migration in the system water – bottom sediments – biota (higher aquatic plants, cladocerans) of the Danube delta and the development on their basis, recommendations for improving heavy metal pollution of surface water bodies monitoring. Methods for investigating the content of heavy metals (atomic absorption and atomic fluorescence spectrometry), sampling points in the Ukrainian part of the delta of the Danube is specified. Additionally biomonitoring observations on other water bodies, in particular near the Zmievskaya and Burshtynskaya TPPs are carried out. Scientifically based methods of active biomonitoring using crustaceans of the Chydoridae family and passive biomonitoring using submerged higher aquatic plants are developed. The results of the Danube water and bottom sediments of the pollution within Ukraine by heavy metals are investigated. Total content and concentration of dissolved forms of heavy metals in water are analyzed. The time trends of changes in the metal content in the Danube water are estimated. Particular attention is paid to the study metal contents relationships. A correlation analysis is carried out and relationships of the content of heavy metals in bottom sediments are obtained. The main features of monitoring pollution by heavy metals of water and bottom sediments are indicated. The heavy metals content in higher water plants patterns had been used of assessing of the water bodies pollution by heavy metals. The accumulation of lead23 and cadmium in Cladocera genus Chydorus sp. was observed; the main features of the obtained patterns are indicated. Active biomonitoring of the lead and cadmium content in the Danube water within Ukraine according to the developed methodology is provided. Satisfactory results were obtained. Some aspects of biomonitoring using higher aquatic plants and Cladocera are formulized. On the basis of theoretical and experimental investigation the recommendation of water bodies pollution by heavy metals monitoring is developed. Key words: the Ukrainian part of the Danube river, surface waters, heavy metals, bottom sediments, higher aquatic plants, cladocerans, migration, correlation analysis, recommendations.