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Impact of marine biogeochemistry on the chemical mixing state and cloud forming ability of nascent sea spray aerosol
Author(s) -
Collins Douglas B.,
Ault Andrew P.,
Moffet Ryan C.,
Ruppel Matthew J.,
CuadraRodriguez Luis A.,
Guasco Timothy L.,
Corrigan Craig E.,
Pedler Byron E.,
Azam Farooq,
Aluwihare Lihini I.,
Bertram Timothy H.,
Roberts Gregory C.,
Grassian Vicki H.,
Prather Kimberly A.
Publication year - 2013
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/jgrd.50598
Subject(s) - aerosol , sea spray , cloud condensation nuclei , supersaturation , sea salt aerosol , seawater , mesocosm , biogeochemical cycle , biogeochemistry , environmental chemistry , chemistry , particle (ecology) , environmental science , atmospheric sciences , oceanography , sea salt , nutrient , geology , organic chemistry
The composition and properties of sea spray aerosol, a major component of the atmosphere, are often controlled by marine biological activity; however, the scope of impacts that ocean chemistry has on the ability for sea spray aerosol to act as cloud condensation nuclei (CCN) is not well understood. In this study, we utilize a mesocosm experiment to investigate the impact of marine biogeochemical processes on the composition and mixing state of sea spray aerosol particles with diameters < 0.2 µm produced by controlled breaking waves in a unique ocean‐atmosphere facility. An increase in relative abundance of a distinct, insoluble organic particle type was observed after concentrations of heterotrophic bacteria increased in the seawater, leading to an 86 ± 5% reduction in the hygroscopicity parameter ( κ ) at 0.2% supersaturation. Aerosol size distributions showed very little change and the submicron organic mass fraction increased by less than 15% throughout the experiment; as such, neither of these typical metrics can explain the observed reduction in hygroscopicity. Predictions of the hygroscopicity parameter that make the common assumption that all particles have the same bulk organic volume fractions lead to overpredictions of CCN concentrations by 25% in these experiments. Importantly, key changes in sea spray aerosol mixing state that ultimately influenced CCN activity were driven by bacteria‐mediated alterations to the organic composition of seawater.