Source Partitioning of Metal Contaminants Using Stable Isotope Fractionation

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The focus of my research program is the development of tools that can be used in the management of environments contaminated by inorganic substances such as cadmium (Cd), zinc (Zn), and mercury (Hg). Contaminated environments, particularly highly contaminated sites, tend to be complex, often resulting from multiple sources of emission. Because it isn't realistic or possible to eliminate all sources of potentially toxic metals, determining the relative contributions of various sources is necessary. This approach is called source partitioning and it is central to my research program. My goal is to use the stable isotope ratios of these metals to determine the relative contributions of the metals from multiple sources to a specific end receptor. Ideally the end receptor is a sentinel organism that integrates the various contamination sources and processes. Our primary test site for the next five years will be the Pearl River Estuary (PRE), which is one of the most contaminated sites on earth. There are three primary sources of metals to the PRE: effluents from e-waste processing, industrial sewage release and atmospheric deposition of materials primarily from coal combustion. Our initial work in the PRE consists of measuring variations in Cd, Zn, Cu and Ni isotope ratios in oysters (Crassostrea hongkongensis) from ten stations in the delta. At the same time we will collect samples for isotope analysis from the most likely sources of metals to the delta. With these data we can begin to examine the feasibility of source partitioning in this complex environment. The direct impact of this research will be the potential to reduce metal pollution to one of the earth's most contaminated environments by applying mitigation to the most important sources. In addition, the outcomes of this work will provide a significant improvement in our theoretical framework for metal contaminant source partitioning generally. Also this work will add to our technical ability to make valid measurements of metal isotope ratios in a variety of environmental media, which remains a challenge currently. Finally, my research will allow Canada to take a leading role in this emerging area and contribute on the international stage to mitigation of some of the most contaminated sites in the world.