Combining Hg stable isotopes and speciation to evaluate fate and transport of mercury in heterogeneous environments

Abstract:

Mercury (Hg) is a global pollutant and has a highly dynamic biogeochemistry in the environment due to its fast reactivity and complex changes in chemical speciation. Hg has seven stable isotopes which undergo mass dependent fractionation (MDF) during abiotic and biotic transformations. In addition, photochemical transformations can generate significant mass independent fractionation (MIF). A large range in MDF and MIF has been observed across a wide array of environmental and biological samples making the combination of Hg molecular speciation and Hg isotopic signatures a very promising and valuable approach to further understand the complexities in Hg sources, and subsequent patterns of fate and transport. The relationship between Hg stable isotope signatures and the chemical form of Hg can be used effectively in heterogeneous environments and throughout food webs, thus providing several important insights into Hg biogeochemical cycling and exposure regimes. This presentation examines the importance of experimental and high resolution analytical investigations to understand Hg isotopic fractionation pathways and highlights some of our recent scientific advances related to the use of Hg isotopes in biogeochemical and ecological studies.