Bringing the ocean into the laboratory to probe the chemical complexity of sea spray aerosol.

The prodn., size, and chem. compn. of sea spray aerosol (SSA) particles strongly depend on seawater chem., which is controlled by phys., chem., and biol. processes. Despite decades of marine environment studies, a direct relationship has yet to be established between ocean biol. and physicochem. SSA properties. The ability to establish such relationships is hindered because SSA measurements are typically dominated by overwhelming background aerosol concns., even in remote marine environments. This work describes a newly developed approach to reproduce SSA chem. complexity a lab. setting, comprising a unique ocean/atm. facility equipped with actual breaking waves. A mesocosm expt., performed with natural seawater using controlled phytoplankton and heterotrophic bacteria concns., showed SSA size and chem. mixing state are acutely sensitive to the aerosol prodn. mechanism and to the type of biol. species present. The largest redn. in SSA hygroscopicity occurred as heterotrophic bacteria concns. increased, whereas phytoplankton and chlorophyll-a concns. decreased, directly corresponding to a change in mixing state in the smallest size range (60-180 nm). Using this newly developed approach to generate realistic SSA, systematic studies can now be performed to advance the fundamental understanding of the effect of ocean biol. on SSA chem. mixing state, heterogeneous reactivity, and resulting climate-relevant properties. [on SciFinder(R)]