Over the past decades, emission reductions for air pollution abatement resulted in changes in precipitation, cloud and aerosol chemical composition, and in atmospheric deposition of anthropogenically derived nutrients to the ocean, affecting atmospheric acidity and atmospheric deposition to ecosystems.
Atmospheric acidity is central to many processes in the atmosphere and the Earth system: atmospheric chemistry, biogeochemical cycles, atmospheric deposition, ecosystems, human health, and climate. Atmospheric deposition impacts on marine productivity, oceanic carbon dioxide uptake and emissions to the atmosphere of climate active species. These oceanic emissions of reactive species and greenhouse gases influence atmospheric chemistry and global climate, and induce potentially important chemistry-climate feedbacks. Thus, air-sea fluxes of biogeochemically active constituents have significant impacts on global biogeochemistry and climate.
Despite the wide range of important effects of atmospheric acidity and air-sea exchanges, scientific knowledge gaps remain. Understanding atmospheric acidity’s levels, its spatial and temporal variability and controlling factors in the precipitation and the suspended atmospheric media, aerosols and clouds, and its multiple impacts, is an open scientific topic for research. We also still lack understanding of many of the physical and biogeochemical processes linking atmospheric deposition, atmospheric acidity, nutrient availability, marine biological productivity, and the biogeochemical cycles governing air-sea fluxes of these climate active species. Atmospheric inputs of other toxic substances, e.g., lead, cadmium, copper, and persistent organic pollutants, into the ocean are also of concern.
To address these current knowledge gaps, in this session we welcome new findings from laboratory, in-situ and remote sensing observations and atmospheric and oceanic numerical models, on the status of atmospheric acidity, the factors that affect its levels, its wide range of impacts, on atmospheric deposition of nutrients and toxic substances to the ocean, their impacts on ocean biogeochemistry, on the air-sea fluxes of climate active species and potential feedbacks to climate.
This session is jointly sponsored by GESAMP Working Group 38 on ‘The Atmospheric Input of Chemicals to the Ocean’, the Surface Ocean-Lower Atmosphere Study (SOLAS), and the International Commission on Atmospheric Chemistry and Global Pollution (iCACGP).