Speciation and Leaching Potential of Heavy Metals in Sediments of Nakdong River

Experimental studies were performed to investigate speciation and leaching potential of heavy metals(Cu, Cd, Pb Zn, Ni) in ten sediment samples collected from Nakdong River. Acid Volatile Sulfide (AVS) andSimultaneously Extractable Metals (SEM) measurements were used to estimate heavy metals that can beleached under anaerobic conditions. Sequential Extraction Procedure (SEP) and Toxicity CharacteristicLeaching Procedure (TCLP) were used to characterize speciation and leaching potential of heavy metalsunder aerobic conditions. The results show that total concentrations of Cu, Zn and Ni were relatively high inthe sediments from points Seongseo industrial complex stream (upper stream) (D), Seongseo industrialcomplex stream (midstream) (E), Dalseo stream (F), and Nakdong river estuary (J), and that Cdconcentrations were higher in all sampling points except for Goriung Bridge (G) and Soosan Bridge (H).SEM and AVS analyses reveal that samples from points Ilsun Bridge (A), Namgumi Bridge (C), and SoosanBridge (H) have potential of heavy metals leaching, although leachable concentrations are relatively low.The leaching potential of heavy metals in other points was low because of higher concentrations of AVSthan SEM. SEP results show that more than 50% of Cu, Zn and Ni were present in residual fraction, whichmeans these metals are less amenable to leaching in anaerobic conditions. On the other hand, more than50% of Pb and Cd were extracted during the first through third step of the SEP, which means substantialfraction of these metals can be leached upon changing of redox conditions. TCLP tests predict that leachingpotential of heavy metals was generally low, which is consistent with the results obtained by AVS and SEMmeasurements.