Biotic ligand model development for Zn and Pb in estuarine and marine waters: interactive influences of salinity and dissolved organic carbon

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Metal mining and smelting plays a key role in the Canadian economy (3.2% of the national GDP, 368,000 jobs). Canada is a major producer of both lead and zinc, the majority of which is sold for export. Both metals may be hazardous to the aquatic environment, and regulatory pressures, particularly in Europe and the U.S.A., are threatening these markets. The current regulatory guidelines often rely on the Precautionary Principle (PP) rather than sound science, and favour a blanket approach; there is a critical need for science-based regulatory tools that can be applied on a site-specific basis so as to avoid arbitrary application of the PP. Regulatory focus at present is on the marine and estuarine environment. Our team consists of an aquatic toxicologist, an environmental chemist, and a foreign collaborator (Brazil) with specific expertise in the collection of marine DOC (dissolved organic carbon). As we helped to develop the Biotic Ligand Model (BLM), which has proven to be very effective in countering application of the PP in freshwater environments, our team has been recruited by two industry-supported metal research organizations (International Lead Zinc Research Organization, ILZRO, & International Zinc Association, IZA) to generate data for development of marine/estuarine BLMs for Pb & Zn,. The research will focus on the organisms which are most sensitive to metals, the early life stages of mussels, sea urchins, and oysters (48-72h development tests), and will examine the interactive influences of two major water quality variables, salinity and DOC. A critical tissue residue approach will be evaluated. Two M.Sc. research projects will focus on (i) the physiological mechanisms behind Pb and Zn toxicity to mussel embryos and (ii) chemical characterization of marine DOCs and their interactions with metals, and visiting Brazilian graduate students will contribute to a field validation exercise. The ultimate products will be new science-based models that can be used as risk assessment and regulatory tools by by government and industry on a worldwide basis.