## 4 Metals
** \\ \hline \multirow{4}{*}{Belgrade section of the Danube River (from 1168 th to 1170 th river km), Serbia/October-November 2010} & \multirow{4}{*}{As, B, Ba, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, (C7-OES & Surface waters (ng/L): Al (77-18); As (1.1-1.6); Cd (0.03-0.18); Cu (2.8-10.1); Fe (120-308); Mn (ND-20); Zn} & \multirow{4}{*}{[108]} \\  & & & (0.03-0.18); Cu (2.8-10.1); Fe (120-308); Mn (ND-20); Zn \\ \cline{1-1}  & & & (3.8-10.5) & \\ \cline{1-1}  & & & Fish muscle (ng/kg DW); & \\ \cline{1-1}  & & & & Al (10-87.56); As (10-77.05); As (10-70.53); Cu (0.005-0.01); Ba & \\ \cline{1-1}  & & & (0.66-2.15); C (0.01-0.06); Mn (0.12-0.87); Cu (0.75-1.42); & \\ \cline{1-1}  & & & & (0.99-1.63); Zn (15.4-9.01) & \\ \hline \multirow{4}{*}{Danube and tributary on Serbian territory/2011 and 2013, during the same season (June-October)} & \multirow{4}{*}{Cl, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, (C7-OES & Surface Waters (ng/L): Al (77-18); As (1.1-1.6); Cd (0.03-0.18); Cu (2.8-10.1); Fe (120-308); Mn (ND-20); Zn} & \multirow{4}{*}{[108]} \\  & & & (0.001-0.07); Cr (0.1-11.41); Cu (0.07-27.8); Fe (0.81-1.44); & \\ \cline{1-1}  & & & & Hg(00-0.78); Mn (0.08-0.41); Ni (0.009-0.07); Pb \\ \cline{1-1}  & & & & (0.11-0.82) \\ \hline \multirow{4}{*}{Danube in the Belgrade region, Serbia/early autumn, 2012} & \multirow{4}{*}{Cu, Fe, Zn, Ni, Pb, Cd, Hg, As} & \multirow{4}{*}{AAS} & \multirow{4}{*}{[108]} \\  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \hline \multirow{4}{*}{Tsa River/July, August and September 2001} & \multirow{4}{*}{Cd, As, Hg, Cu, Zn, Cr, Pb, Ni} & \multirow{4}{*}{FAS with a hydride vapour system} & \multirow{4}{*}{[108]} \\  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \hline \multirow{4}{*}{Five sites along Yantra River, Bulgaria/2013-2018 (four times per year, one every three months)} & \multirow{4}{*}{Fe, Mn, Mg, Ca, Cd, Hg, As, Cu, Cr, Zn, Pb and Ni} & \multirow{4}{*}{[11]} \\  & & & & (method: ISO 011885) & (0.001-0.01); Pb (0.001-1.20); Hg \\ \cline{1-1}  & & & & (method: ISO 011885) & (0.001-0.815); Ca (0.002-14.90); As (1.06-10.1); Cr \\ \cline{1-1}  & & & & (0.11-1.78); Ni (0.22-0.14) & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \hline \multirow{4}{*}{Five sites along Yantra River, Bulgaria/2013-2018 (four times per year, one every three months)} & \multirow{4}{*}{Fe, Mn, Mg, Ca, Cd, Hg, As, Cu, Cr, Zn, Pb and Ni} & \multirow{4}{*}{[11]} \\  & & & & (method: ISO 011885) & (0.001-0.815); Ca (0.002-14.90); As (1.06-10.1); Cr \\ \cline{1-1}  & & & & (0.11-1.78); Ni (0.22-0.14) & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \hline \multirow{4}{*}{Tsa River/July, August and September 2001} & \multirow{4}{*}{Cd, As, Hg, Cu, Zn, Cr, Pb, Ni} & \multirow{4}{*}{[108]} \\  & & & & (3.75-158); Pb (0.6-32.50); Cd (0.15-10.1); Ni (0.7-11.1); & \\ \cline{1-1}  & & & & (3.0-0.08); Hg (0.002-0.09); & \\ \cline{1-1}  & & & & (0.00-0.08); Hg (0.002-2.09); As (0.002-0.09); Pb \\ \cline{1-1}  & & & & (0.00-0.08); Hg (0.002-2.09); As (0.0  
\begin{table}
\begin{tabular}{l l l l l} \hline \hline
**Sampling Site/Sampling Moment (Data)** & **Monitored Contaminants** & **Analytical Approach** & \multicolumn{2}{l}{**Relevant Environmental Concentrations Range for the Detected Compounds in Analyzed Matters**} \\ \hline  & & & Surface water (fg/L); C (2-6d; Mn (0.8-46e); Co \\  & & (0.02-10); Ni (0.05-87); Cu (0.2-12); As (0.02-6.9); Cd \\  & & (0.01-6.5); Pt (0.04-15.1); Hg (0.01-1.5); Zn (0.1-38); Fe \\  & & ICP-MS and AAS, method ISO & (1-264); Al (N2-991) \\  & & & Softments (mg/kg); Cr (ND-22); Mn (137-2273); Co \\  & & & (ND-29); Ni (2-80); Zn (0.08-56); As (ND-33); Cd \\  & & & (1-0.5); Pt (0.08-21.1); Hg (0.04-22); Zn (0.7-6.52); Fe \\  & & & (ND-14053); Al (37-30819) \\ \hline Two sites in low Danube region, Galist (km 150) and Tulcea (km 71)/ August 2010 & Cd, Cu, Zn, Pb & \multicolumn{2}{l}{AAS (air/active frame); GC with 2m (32.58-47); Pt (0.44-2.14)} \\  & & & Fish (DW-C) (0.01-0091); Cu (1.5-5.34); Zn (21.92-44) \\  & & & 5 fs); Pt (0.26-0.65) \\ \hline Danube River, South-Western part of &  
Surface waters were analyzed in 17 studies, sediments in 16, and biota (fish species, mollus, plankton, aquatic plants, and microalgae) in 15 studies.