Polar Expeditions To Investigate The Seasonality of Hg: Cryosphere, Hydrosphere, Atmosphere, Transport, Speciation

Mercury (Hg) is a global pollutant that accumulates in marine food webs, threatening ecosystem health and human populations dependent on seafood. In the rapidly changing Arctic, sea ice acts as a barrier, reservoir, and transporter of Hg, yet fundamental gaps remain on how much Hg it contains, when it is released, and how it impacts polar ecosystems. The project PETITS Hg CHATS will address these gaps by investigating the seasonal cycling and speciation of Hg in Arctic sea ice, combining archived samples, new seasonal field observations, and advanced modelling. The project will test four hypotheses on how ice age, seasonality, and Hg speciation influence storage, fluxes, and risks to polar ecosystems. Archived sea ice cores and newly collected samples from the TARA Polar Station expedition will be analysed for total Hg and methylmercury (MeHg), generating the most comprehensive dataset of its kind. Hg interpretation and fieldwork will incorporate the expertise and network of host Dr. Heimburger-Boavida. Novel Hg tracers will be incorporated into the open-source CICE+Icepack sea ice model with help from secondment supervisor Dr. Duarte, to simulate Hg biogeochemical behavior, transport and release, with model outputs compared to field data. The resulting datasets will be combined with biological indicators to assess the timing, mechanisms, and ecological consequences of Hg delivery from sea ice to the ocean. By doubling the number of published Hg sea ice cores and providing the first seasonal dataset for MeHg, this project will significantly advance understanding of contaminant dynamics in polar regions. Outcomes will inform international bodies such as AMAP and the Arctic Council, supporting risk assessments for fisheries, food security, and the Minamata Convention. PETITS Hg CHATS will also strengthen the researcher’s interdisciplinary expertise in biogeochemistry, polar fieldwork, and modelling, providing a strong foundation for an independent research career.