Clean-up method for the polluted soil sites by colloid particles and dissolved organic matter

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The purpose of this research is to evaluate the possibility of a new clean-up method for polluted soils, based on applying or enhancing colloid and dissolved organic matter(DOM) leaching through the soil. For this purpose, mobilization and transport of colloids and DOM through differently-structured soil systems, and poly aromatic hydrocarbon(PAH) sorption to different soil types were investigated. Mobilization and leaching of three natural soil constituents, inorganic colloidal matter(ICM), colloidal organic carbon(COC) and dissolved organic carbon(DOC) from a surface soil (loam) during repeated irrigation showed widely different leaching behavior and behaved differently in soil with and without continuous macropores. Both colloid mobilization and transport through macropores and PAH sorption to soil and soil constituents were found to be time-dependent and diffusion-limited processes, and new models to describe diffusion-limited colloid generation and mobilization and PAH sorption were proposed. The transport of externally applied colloid and DOM was examined for a loam soil and a sand. Almost 100% of the applied colloids leached through the loam soil, while around 32% leached and 68% was captured by sand. From the comparison of transport parameters of colloid and a tracer (Br), the velocity of colloid was 3〜4 times larger than the one of the tracer in a highly-structured loamy soil a the field scale. From the results, it is suggested that the possibility of applying the proposed clean-up method for polluted soil is most realistic for soils that are not highly-structured but still facilitates a significant colloid and DOM transport, with low-organic sandy or coarse-loamy soils being the most promising target group. But further investigation and tests at pilot and field scale are needed before any actual application.