| Mercury pollution has emerged as a global problem that poses significant human health and environmental risks. Elemental mercury, mostly emitted from coal fired power plants and municipal waste incinerators, is the predominant species of mercury in the atmosphere and is a particular concern. Through a series of complex biological processes, elemental mercury is converted to monomethyl and/or dimethyl mercury, which are both highly toxic and can bioaccumulate by up to a factor of 105--107 in the aquatic food chain. By better understanding mercury's chemical speciation pathways and atmospheric transport mechanisms, new and improved control technologies can be developed---to capture it at source---and the ecological impact radically reduced.;In the past decade, as mercury pollution has come under increasing scrutiny by public policy analysts and environmental regulators, nanoscale science and engineering has emerged as an enabling technology and driven tremendous technological change in the field of sensors. In this thesis, use is made of the unique optical properties of gold nanoparticles to develop an environmental sensor capable of detecting elemental mercury at sub ppm levels in aquatic and atmospheric environments. The electron confinement and inner field enhancement that occurs in gold nanoparticles give rise to a strongly absorbing Lorentzian type surface plasmon resonance (SPR) band in the visible spectrum that makes them particularly suited to this application. Several types of gold particle, varying in size, shape, stability, and surface constitution, are investigated and exposed to mercury whilst in solution, i.e., in colloidal form, and immobilized to the surface of transparent quartz substrates using organosilane functional molecules, e.g., aminopropyl-trimethoxysilane (APTMS). UV-vis spectroscopy and TEM imaging are used to characterize changes to the morphology of the gold particles after exposure to mercury, and shifts in the SPR maximum position (wavelength and absorbance) are used to quantify the amount of mercury present.;Gold nanoparticles have been demonstrated to be a viable medium to detect elemental mercury. A detection limit of sub ppm mercury has been achieved in both atmospheric and aquatic environments and the foundation set for the development of a sensitive, real-time, in-situ, inexpensive mercury detector. |
