Light-enhanced primary marine aerosol production from biologically productive seawater

Abstract

Physical and biogeochemical processes in seawater controlling primary marine aerosol (PMA) production and composition are poorly understood and associated with large uncertainties in estimated fluxes into the atmosphere. PMA production was investigated in the biologically productive NE Pacific Ocean and in biologically productive and oligotrophic regions of the NW Atlantic Ocean. Physicochemical properties of model PMA, produced by aeration of fresh seawater under controlled conditions, were quantified. Diel variability in model PMA mass and number fluxes was observed in biologically productive waters, increasing following sunrise and decreasing to predawn levels overnight. Such variability was not seen in oligotrophic waters. During daytime, surfactant scavenging by aeration in the aerosol generator without replenishing the seawater in the reservoir reduced the model PMA production in productive waters to nighttime levels but had no influence on production from oligotrophic waters. Results suggest bubble plume interactions with sunlight-mediated biogenic surfactants in productive seawater significantly enhanced model PMA production.

The influence of marine microbial activities on aerosol production: A laboratory mesocosm study

“…Longer bubble residence times imply slower bubble terminal rise velocities and thus smaller bubble sizes. Furthermore, smaller bubble sizes equate to a larger concentration of bubbles and a greater bubble bursting rate when all other parameters, such as bubbling air flow, are kept constant [ Keene et al , ; Long et al , ]. Burns and Zhang [] showed that the size of bubbles in aerated seawater decreased in the presence of Triton X‐100.…”

“…The addition of peptone and yeast extract is also expected to decrease the surface tension, as observed for proteose‐peptone and yeast extract [ Innocente et al , ; Lima et al , ]. In light of these studies and the fact that aerosol flux increases over time due to growth of phytoplankton and bacteria as was directly observed in the present study and inferred in the field [ Long et al , ], we suggest that biological activity mediates bubble surface tension and the amount and nature of surfactants which in turn alters bubble production in terms of size and concentration and thus alters SSA particle production.…”

“…When the SML is disrupted by, e.g., breaking waves and winds, it has been observed that biological and organic material, including microgels, TEP, phytoplankton, bacteria, cellular fragments, and other organic matter, can be dispersed at depth or aerosolized [ Sieburth , ; Bezdek and Carlucci , ; Kuznetsova et al , ; Lewis and Schwartz , ; Aller et al , ; Massel , ; Bigg and Leck , ; Wurl and Holmes , ; Leck and Bigg , ; de Leeuw et al , ; Feng et al , ]. In addition to material concentrated at the uppermost surface layer, a background pool of organic matter in subsurface waters can be scavenged by rising bubbles, brought to the surface and then aerosolized [ Lewis and Schwartz , ; Modini et al , ; Long et al , ; Quinn et al , ]. A recent global modeling study has highlighted the importance of these biogenically produced compounds, especially those which are surface‐active, to the contribution of organic aerosol mass in SSA [ Burrows et al , ].…”

Calcium enrichment in sea spray aerosol particles

“…The seawater samples in the chamber were not changed between each replicate run, so differences in the surfactants present at the water surface in subsequent replicate experiments due to bubble scavenging of surfactants cannot be ruled out [Long et al, 2014]. Three replicate experiments were conducted using artificial seawater (Sigma Aldrich, S9883; mass fraction: 55% chloride (Cl − ), 31% Na + , 8% sulfate (SO 2− 4 ), 4% Mg 2+ , 1% K + , 1% Ca 2+ , < 1% other; rehydrated to an absolute salinity of 35 g kg −1 using DIW).…”

Primary marine aerosol physical flux and chemical composition during a nutrient enrichment experiment in mesocosms in the Mediterranean Sea

“…The Mediterranean Sea is a highly oligotrophic basin (Bosc et al, 2004;MERMEX group, 2011) with seasonal blooms in the northwest of the basin (D'Ortenzio and Ribera d 'Alcalà, 2009;Siokou-Frangou et al, 2010) and high UVB solar radiation in the stratified surface water during summer time (Sempéré et al, 2015). Additionally, the warm water temperatures of the Mediterranean Sea (compared to colder locations such as the North Atlantic Ocean) could also impact the PMA flux (Jaeglé et al, 2011;Long et al, 2014;Ovadnevaite et al, 2014). In this study, we performed a mesocosm experiment in the Mediterranean Sea to study an artificial bloom, different from the natural bloom period studied in the Schwier et al (2015) study, and tracked the physical and chemical properties of primary marine aerosol that allows us to discuss the parameterization of organic material in PMA provided in earlier works.…”