Trace metal and metal isotope biogeochemistry

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The primary aim of my research program is to increase our understanding of the biogeochemical cycles that are important for life on Earth through the use of trace metal and stable isotope geochemistry. Besides the inherent importance of metals in the environment (i.e., in their roles as nutrients or toxins), the chemistry of metals is often linked to, or plays a controlling role in, important environmental processes. Understanding metals in the environment is especially important in a changing world where human activities are perturbing many natural cycles and will have impacts on our food sources, health, and climate. New analytical advancements have opened the door for investigation of stable isotope fractionation of many metals. Isotopic signatures are powerful tools for identifying sources and sinks and for understanding biogeochemical cycling. My research program combines research on metal biogeochemistry with innovative studies of natural metal isotopic variations. The two primary objectives of my research program are (1) Metal Contaminants in the Environment and (2) The Marine Biogeochemistry of Trace Metals. The main focus of (1) will be the study of mercury. Mercury is a globally distributed and highly toxic pollutant. Much of the natural cycle of Hg is not well understood and new approaches are necessary to better track Hg sources and transformations in the environment. Dr. B.A. Bergquist recently demonstrated that Hg isotopes undergo unique isotopic fractionation that provides an indelible fingerprint for directly tracking and understanding Hg cycling in the environment. These findings pave the way for tracing the mobility and bioccumulation of the Hg in the environment. One of the goals of (2) will be to improve our understanding of the sources and biogeochemical cycling of iron in ocean. Iron is a vital micronutrient in the ocean and plays a fundamental role in climate change by influencing the carbon cycle of the ocean. Dr. Bergquist's research program combines both concentration and speciation studies of Fe with Fe isotopic signatures to gain insight into the sources and cycling of Fe in the ocean.