ECOLOGICAL RISK ASSESSMENT OF HEAVY METALS IN SURFACE SEDIMENTS FROM THE DANUBE RIVER

Surface sediment samples were collected monthly from ten sites along the Danube River between Km 347 and Km 182, during May 2012 August 2014, in order to assess heavy metal pollution status and adverse biological effects. Concentrations of six elements (Cu, Cr, Ni, Zn, Pb and Cd) were determined using AAS technique. Statistical analyses were performed using the following software package: Minitab 16 and JMP 9 (SAS). The general profile of mean metal concentration in sediments for the study area was Zn>Cr>Cu>Ni>Pb>Cd. Pearson correlation coefficient revealed a strong relationship between Cu-Zn, Ni-Zn and Cd-Zn. The contamination factor (CF), geoaccumulation index (Igeo), pollution load index (PLI) and potential ecological risk index (RI) - calculated using adapted background concentrations of heavy metals - were used to assess the ecological risk associated with the studied heavy metals in surface sediments. Also, the measured concentrations of heavy metals were compared with sediment quality guidelines values (TEL - threshold effect level and PEL - probable effect level). The obtained data showed that in all sampling sections the mean concentrations of Cu and Ni ranged between TEL and PEL references values and therefore, Cu and Ni in sediments may cause harmful biological effects on aquatic life.