Airborne Algae: Emerging Atmospheric and Health Implications

MICKEY ROGERS, Robert Stanley, Pacific Northwest National Laboratory

     Abstract Number: 59
     Working Group: Aerosol-Ecosystem Interactions

Abstract
Microalgae are known to exist in aquatic and airborne environments, but the extent to which microalgae impact atmospheric processes and air qualities is still unknown. Previous work has explored the in situ surface abundance of marine algal blooms by utilizing surface microscopy and spectroscopy techniques (Brewster Angle Microscopy and Sum-Frequency Generation). Over the course of a bloom, algae produce surface-active molecules that temporally partition to the topmost interfacial layers of our oceans. Surface imaging and spectroscopic measurements showed morphological structural changes and heterogeneity in the interfacial film of Skeletonema marinoi at the ocean surface. Interfacial film thickness calculations quantified the average surface thickness of a productive bloom over time, revealing an ∼5 nm thick surface region in the late stages of the bloom. Knowing algal species are highly abundant at the water surface and persist in the atmosphere within aerosol means new airborne algal properties need considered. The atmosphere provides rather extreme conditions from the ocean including high acidity (as low as pH 2), high salinity (up to 4 M NaCl), and low temperatures (subzero-20ᵒC), yet algae are still able to survive. While atmospheric conditions are much different than the ocean, they are proposed to be more favorable for airborne algal cells to exist in aerosol with high surface-area to volume ratios, allowing for greater carbon contacting. Additionally, as warmer waters increase extreme weather events, the concentration of airborne algae and diversity of airborne algal species may increase, presenting new concerns to coastal communities during harmful algal blooms (HABs). Currently, airborne HAB species and toxins are the least-studied organisms in both aerobiological and phycological (the scientific study of algae) studies. New developments in science and policy should prioritize the health impacts of air quality and composition.