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UBC Theses and Dissertations

Role of heavy metals and organic matter on sorption and mobility of polycyclic aromatic hydrocarbons in soil : implications for remediation Saeedi, Mohsen


Polycyclic aromatic hydrocarbons (PAHs) are a group of abundant contaminants in contaminated sites having many adverse effects on human health and the ecosystem. Due to the many common sources of PAHs and heavy metals, many sites are contaminated by both groups. Co-presence of these contaminants can affect their sorption/desorption in the soil environment, affecting their fate, transport, and remediation processes. This research project advanced the understanding of sorption behavior of PAHs co-existing with heavy metals in soil. Three types of artificially blended clay and clay minerals (kaolinite, kaolinite+sand, kaolinite+sand+bentonite) and a real spiked clayey soil sample were investigated. The synergistic effect of organic matter (humic acid) with heavy metals on enhancing the sorption of PAHs was tested and confirmed for the first time. Different single and combined solutions were used to enhance the desorption of PAHs from the soil. Two non-ionic surfactants (Triton X-100 and Tween 80) with EDTA showed the capability to simultaneously remove these PAHs (acenaphthene, fluorene and fluoranthene) and these prominent heavy metals (Ni, Pb, and Zn) from the soil sample. Results also showed that the co-presence of metal contaminants and soil organic matter can decrease the mobility and desorption of PAHs with the results that the efficiency of soil washing/flushing remediation could decrease in such cases. Our findings also show that the rate of desorption of PAHs is reduced by the co-presence of organic matter and heavy metals in soil. This affects the cost and time of remediation of sites contaminated by mixed heavy metals and PAHs. Our findings were confirmed through column soil flushing of a real natural soil sample by combined enhancing solutions.

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