The introduction of the MC-ICP-MS has allowed for the rapid growth and development of a new area of research – heavy element stable isotope geochemistry. These instruments allow for the precise determination of natural variations in the isotopic compositions of a range of heavy elements, where prior, knowledge of such variation was limited because of the lower ionization efficiency of the thermal-ionization source. With these new analytical capabilities, it is possible to undertake the challenge of deciphering the processes that produce these fractionations and use these isotopic tools in a variety of scientific fields.
Dominique has used the fingerprinting capability of Pb isotopes as a tracer of pollution. Combined with transitional isotope systems (Cd and Zn), she has mapped the dispersion of refinery plumes into neighbouring towns and the environment ((Deboudt et al., 1999; Franssens et al., 2004; Mattielli et al., 2009; Shiel et al., 2010). A study on bivalves resulted in high Cd contents in oysters from the west coast of North America being related to natural sources, signifying the importance of upwelling on Cd contents (Shiel et al., 2012).
Whereas in comparison to some key locations in France, historical pollution events with long persistence in rivers, sediments and ponds, are shown to be directly correlated to the high Cd contents in oysters (Shiel et al., 2013).
These results demonstrate the usefulness of Cd and Zn isotopes as environmental tracers and the methods developed through the research will be applied to further study the environment. For example, Dominique is now working on using Zn and Mo isotopes to study the mobility and fate of metals in mining waste rock piles.
Recently, Dominique has begun a study of the trace metal contents and Pb isotopic compositions of honey in the Greater Vancouver area. This study will trace whether the source of metals is natural or related to human impact, and is in collaboration with a non-profit organization (Hives for Humanity: http://hivesforhumanity.com/) that supports local sustainable economies and at-risk communities. Dominique has also analysed Pb concentrations and isotopes in tree rings to trace the history of lead pollution in Vancouver over the last 200 years.