Contaminant transport in natural sediments: influence of soil organic matter and Fe/Al-oxyhydroxides on heavy metals (Cu, Zn) and nanoparticles (titanium dioxide)

Fisher-Power, Leanne (2018) Contaminant transport in natural sediments: influence of soil organic matter and Fe/Al-oxyhydroxides on heavy metals (Cu, Zn) and nanoparticles (titanium dioxide). Masters thesis, Memorial University of Newfoundland.

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Abstract

Contaminant transport in subsurface environments may be significantly influenced by contents of aquifer sediments, such as soil organic matter (SOM) and Fe/Al-oxyhydroxides, though their effects are not fully known. This thesis systematically explored the influences of SOM and Fe/Al-oxyhydroxides on two common groundwater contaminants, engineered nanoparticles (titanium dioxide nTiO2) and heavy metals (Cu and Zn), in two projects using the same natural sediment. Project 1 found dissolved SOM enhanced nTiO₂ transport by adsorbing onto nTiO₂ surface and stabilizing it in suspension, whereas solid SOM and Fe/Al-oxyhydroxides reduced transport by attracting nTiO₂ when surface charges were opposite. In project 2, Cu adsorption was strongly dependent on SOM and Fe/Al-oxyhydroxide content, with lesser effects for Zn. Depleted SOM decreased adsorption when pH was <6.5, whereas depleted Fe/Al-oxyhydroxides decreased adsorption when pH was >6.5. Both projects contributed to knowledge of the roles of SOM and Fe/Al-oxyhydroxides in governing contaminant transport in natural sediments.

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