10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Field Collected and Synthesized Proteinaceous Material as Ice Nucleating Particles in Immersion Freezing
NADINE BORDUAS-DEDEKIND, Robert O. David, Kristopher McNeill, Zamin Abdulali Kanji, ETH Zürich
Abstract Number: 1533 Working Group: Unraveling the Many Facets of Ice Nucleating Particles and Their Interactions with Clouds
Abstract Organic aerosols represent a subset of atmospheric particles able to act as cloud condensation nuclei (CCN) and, as more recently found, ice nucleating particles (INPs). CCN and INPs affect the ratio of water and ice in mixed-phase clouds, leading to an impact on Earth’s radiative balance. In this work, we use dissolved organic matter (DOM) as a proxy for organic aerosols and lake spray aerosols in ice nucleation experiments. DOM is a complex mixture of terpene-derived compounds, proteinaceous material, lignin, organic acids and some ions. As the dominant IN mechanism in mixed-phase clouds is immersion freezing, we investigated the ability of DOM to act as INPs, using our homebuilt DRop freezing Ice Nucleation Counter Zurich (DRINCZ). We use field collected DOM from American rivers and find that the DOM, despite coming from different locations, shows consistent freezing around –12 °C. We are currently extending these results to field collected snow samples in Switzerland. In addition, we identify the material within DOM responsible for its INP activity. Preliminary results suggest the importance of proteinaceous material and so current work includes synthesis of discrete proteins of different sizes to probe their ice nucleating potential. A laboratory-based chemical perspective to the ability of proteinaceous material to nucleate ice will be presented.