This study evaluated the current status and leaching properties of deposited tailings from both banks in the upper region of the Nakdong river. The deposited tailings samples were collected at 80 points over 55 km from Gumunso, Taebaek-si. The estimated volume of deposited tailings was 3,668 m 3 , with an exposed tailings area of 1,468 m 2 . The chemical results showed that the average concentrations of As, Cd, Pb, and Zn in the tailings were 3,518, 15.39, 2,616, and 2,307 mg/kg, respectively. Results of the KSLP showed that the Cd and Pb in the tailings exceeded environmental standards, and Zn was relatively high. According to sequential extraction of the tailings, As dominated Fraction 3, whereas relatively high proportions of Cd existed in Fractions 1 and 2. In addition, the deposited tailings were re-lost in the form of particles via physical separation and crushing due to natural weathering.
This study evaluated the environmental impact of As and heavy metals occurring upstream of the Andong dam. In sediments, the concentrations of heavy metals were found to be higher in the dry season than in the wet season, with the highest concentration occurring near the smelter. Moreover, As concentrations in some tributaries, such as Songjeongricheon, Golpocheon, and Gacheon, were higher than those in the Nakdong River. The concentrations of heavy metals in water samples did not exceed the Korean environmental standards. However, some tributaries showed relatively high As concentrations in the dry season. In suspended sediments, As and heavy metals were detected in the wet season, and particulate transport was identified as their major dispersion mechanism. In conclusion, the abandoned metal mines, smelter, and deposited-tailings were the source of the pollutants, which accumulated on the river bed in the dry season and were carried into the Andong dam in the wet season, via streams.
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