Coral Reef Emissions of Atmospheric Dimethylsulfide and the Influence on Marine Aerosols in the Southern Great Barrier Reef, Australia

• Published in: Journal of geophysical research. Atmospheres 2020-04, Vol.125 (7), p.n/a
• Main Authors: Jackson, R. L., Gabric, A. J., Woodhouse, M. T., Swan, H. B., Jones, G. B., Cropp, R., Deschaseaux, E. S. M.
• Format: Article
• Language: English
• Subjects: Aerosol concentrations; Aerosols; Atmospheric aerosols; Atmospheric data; Barrier reefs; Boundary layers; Coral bleaching; coral reef; Coral reefs; Corals; Daylight; Dimethyl sulfide; dimethylsulfide; Emissions; feedback; Gases; Geophysics; Irradiance; Low tide; Low wind speeds; Marine aerosols; Marine invertebrates; Negative feedback; Ocean temperature; Ocean warming; Oxidation; Phytoplankton; Sea surface; Sea surface temperature; Solar irradiance; Stress (physiology); Sulfates; Surface temperature; Surveys; thermal stress; Trace gases; Waterfowl; Wind speed
• ISSN: 2169-897X; 2169-8996
• DOI: 10.1029/2019JD031837

Variability in atmospheric dimethylsulfide (DMSa) and the potential influence on atmospheric aerosols was investigated at Heron Island in the southern Great Barrier Reef (GBR), Australia. This work compiles previously published DMSa data (reported in Swan, Jones, Deschaseaux, & Eyre, 2017, https://doi.org/10.1007/s00216‐017‐0385‐8), with additional surveys of DMSa, atmospheric particle number concentration, and other oceanic and atmospheric data sets. DMSa was higher in summer (mean 3.2 nmol m−3/78 ppt) than winter (mean 1.3 nmol m−3/32 ppt), reflective of seasonal shifts in phytoplankton biomass and emissions from corals in the southern GBR. Seasonally extreme spikes in DMSa were detected during low tide and low wind speed, supporting findings that the coral reef can be an important source of DMSa above background oceanic emissions. A significant link was present between DMSa and aerosol concentration (ranging from 0.5 to 2.5 μm) during calm, daylight hours, when conditions were optimal for the local oxidation of DMSa to sulfate aerosol precursors. This link may reflect condensational growth of existing fine particles (< 0.5 μm), which is the dominant pathway by which biogenic trace gases influence aerosols in the marine boundary layer. Aerosol concentration significantly correlated with reduced surface solar irradiance and sea surface temperature, which is potential evidence of a local negative feedback mitigating coral physiological stress. These findings provide a step toward a better understanding of the processes influencing DMSa and aerosol concentrations and of the consequences for the local radiative balance over coral reefs; an increasingly important topic with ongoing ocean warming and coral bleaching. Key Points Coral reefs are an important source of atmospheric dimethylsulfide A significant link exists between atmospheric dimethylsulfide and marine aerosols in the southern Great Barrier Reef Marine aerosols reduced surface solar irradiance and sea surface temperature, potentially mitigating coral physiological stress