Paper Title
Spatio-Temporal Variations and Distribution of Potentially Toxic Elements in Lower Danube Water in Relation to Hydrological Regime

Abstract
Given the international and cross-border nature of the Danube River, this study investigated the spatio-temporal variations and distribution of potentially toxic elements (PTEs) in Lower Danube River between Calarasi and Braila (km 375-km 175) as a case study. Approximately 1500 samples were taken and processed from 10 monitoring sites by intensive monitoring program which took place during the period 2011-2017, in the area where hydrotechnical works have been done in order to improve navigation conditions. The potentially toxic elements (Cr, Cu, Zn, As, Co, Pb, Cd, Fe, Mnand Ni) were analyzed according to the standards in force and in relation to hydrological regime (Q) and water pH. The obtained results for potentially toxic elements values were compared to the value of Class I according to the national legislation, M.O. 161/2006. Based on the obtained results by evaluating the quality of potentially toxic elements, the water quality in the Lower Danube River achieved a good-moderate chemical status and corresponds to Class II and Class III of surface water quality. Keywords - Danube River, Potentially Toxic Elements, Water.