Investigation on changes of heavy metals concentration in the Alluvial Sediments of Sungun Copper Mine, East Azerbaijan province, Iran

Abstract

To investigate the spatial distribution and vertical changes of heavy metals in the alluvial sediments of Sungun copper mine, sampling was performed in two stages. In the first stage twelve samples of alluvial sediments and mine tailings from depth of 0-5 cm and in the second stage 9 sediment samples from three depths of 0-50, 50-100 and 100-150 cm were collected. The samples were washed out using 0.1 N chloridric acids to prepare the extract which then was analyzed for Cu, Zn and Mn and also for Cu, Zn, Mn Cd and Al in the first and second stages, respectively. The tailing samples were digested by Aqua Regia to get the extract. Evaluation of the pollution indices showed that Cu in 80% of the samples was the main cause of pollution and the most polluted sample was the one collected from the end of Pakhir valley. The highest concentration of Zn was also detected in the same sample. Analyzing the tailing samples showed the highest Mn concentration which represented the tailing impact on the accumulation of heavy metals in the downstream sediments with concentration of 26.5 mg/kg. The results also represented the highest concentration of the metal in 0-50 cm depth. The maximum decrease of concentration was for Cu and the minimum of it was for Mn which was due to decrease of concentration of the materials in water during vertical movements through the sediment. Also heavy metals didn’t accumulate in coarse texture sediments and leached to the lower horizons and reached the finer grain sediments.