Heavy metal contamination in dusts and stream sediments in the Taejon area, Korea

Abstract

Associated with the rapid pace of urbanization and industrialization is the increase of automobile emissions, factory emissions, and industrial wastewater. Heavy metal contamination from these point sources has received much attention in the Taejon area, Korea. In order to investigate the degree of heavy metal contamination, 81 road dusts, 79 house dusts, 40 indoor dusts of subway stations and 21 stream sediments have been analyzed for Cd, Cu, Pb and Zn. Copper, Pb and Zn levels in road dusts from the control area are lower than average levels, while those from the traffic and industrialized areas including the city center and highway junctions are relatively high. In particular, the highest Pb concentration in road dust, 161 mu g g(-1), is noted in dust samples from Yusung Highway Junction. The Pollution Index of multi-element contamination levels in road dust is found to correlate with a calculated Urbanization and Industrialization Index. Elevated levels of Cu, Pb and Zn are also noted in house dusts near the Yusung Highway Junction and industrialized areas. The age of property is found to influence the Pb levels in house dusts, with older houses (>15 years) having significantly higher concentrations than newer properties (>15 years). Levels of heavy metals in indoor dusts from subway stations in the city center range up to 4470 mu g g(-1) Cu and 660 mu g g(-1) Pb. Elevated levels of Cd, Cu, Ph and Zn are found in stream sediments from the Taejon industrialized area. The highest Zn concentration of 387 mu g g(-1) is found in the sediment close to the Sintanjin Industrial Complex. A sequential extraction procedure applied to stream sediments indicates a high percentage of easily exchanged metals. The exchangeable phase of the metals may originate not from parent materials but from wastewaters and exist in an adsorbed phase on the surfaces of sediments. These metals are easily dissolved into the water by reactions, and relative amounts of dissolved phase metals are in the order Cu = Zn > Pb. (C) 1998 Elsevier Science B.V. All rights reserved.