Collaborative Research: CAS-MNP: Sea ice-ocean exchange of Arctic microplastics: linking small scales to the large-scale system

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Microplastics, defined as plastic pieces smaller than 5 millimeters, are a massive litter problem in the world’s oceans. The Arctic Ocean, while remote, is not immune; recent work has found microplastics in all components of the Arctic system, including within the floating sea ice cover. While marine microplastics are ubiquitous, the physical characteristics of the polar oceans, including sea ice, lead to effects unique to the polar regions. For example, microplastics may have an impact on climate by darkening the usually bright white sea ice and its overlying snow cover, which would result in an increase in the absorption of sunlight and thus in warming and melting. Furthermore, the presence of sea ice affects where microplastics are found within the Arctic, as sea ice and the underlying ocean transport microplastics differently. This project is addressing both of these processes. As microplastics are a global problem with potential impact on the health of the marine ecosystem, understanding the way sea ice and microplastics interact is crucial for informing strategies to deal with this pollution in the future. In this interdisciplinary research project, laboratory studies and numerical models are being used together to make progress in understanding the interactions between Arctic sea ice and microplastics. The researchers are developing new laboratory techniques to understand the exchange of microplastics between sea ice and the ocean during uptake and release, including the effect of marine gels on this process. They are also measuring the effects of the optical properties of microplastics on the mass balance of sea ice. Based on those laboratory insights, they are developing and testing parameterizations for including microplastics in open-source, community sea ice, ocean, and climate models. Both one-dimensional (i.e., vertical column) and three-dimensional (i.e., full sea ice/ocean-coupled) models are being modified from existing code and run. Hindcast and future simulations are being performed to assess the impact of including microplastic ice-ocean exchange parameterizations on the large-scale distribution of microplastics in the Arctic Seas and their impact on climate.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.