CCA-방부목재 성분금속(크롬, 구리 및 비소)의 토양 내 경쟁적 흡착

초록

Metals released from CCA (chromated copper arsenate)-treated wood are potentially toxic to humans and the environment. Competitive sorption of the metals onto soils is important to evaluate their mobility and bioavailability since the soils contaminated with the CCA metals may contain more than one metal species. The objective of this study was to examine sorption characteristics and competitive sorption of the metals on three different types of soils (sandy soil, sandy clay loam, and loam) for the fate and mobility of the metals after their release to the soil system. Batch kinetic experiments were carried out to determine sorption of the metals by the soils. The kinetic results indicated strongly kinetic behavior where the rates of the metals was relatively rapid, usually less than 24 hrs. Based on the results of competitive sorption isotherm experiments using the three types of soils, the presence of copper and arsenic reduced the sorption of chromium in all three soils, which indicates the competitive sorption between the metals. However, it was found that no signigicant competitive effect of arsenic with other metals was observed in the multi-solute system possibly due to different chemical forms such as oxyanions among the metals. The competitive isotherm of chromium with the presence of copper and arsenic in multi-solute system fitted the Langmuir one-site model better than Linear and Freundlich sorption models. The Langmuir model equation fitted the chromium sorption data of the multi-solute system for the soils with good correlation coefficient (R2 ranged from 0.86 ~ 0.99), while the correlation between the sorption data of chromium and the Freundlich sorption model equation varied widely (R2 ranging from 0.02 ~ 0.99). This study indicates that competition between the metals in soils contaminated with CCA-treated wood should be considered in transport and fate models predicting the metals (especially, chromium and copper) when released from the treated wood onto soils.

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