Atmospheric inputs of natural and anthropogenic substances and their impact on ocean biogeochemistry and climate have been subject of major debate. Enhanced atmospheric deposition of anthropogenic nitrogen, iron, and phosphorus to the ocean surface may induce low-level ocean fertilization, in turn increasing marine 'new' productivity and sequestering additional atmospheric CO2 into the ocean. Recent changes in anthropogenic and climatic conditions may result in enhanced nutrients deposition to the open ocean, with impacts on marine productivity, CO2 drawdown, N2O production and the emissions of marine organic compounds. Atmospheric inputs of other toxic substances, e.g., lead, cadmium, and persistent organic pollutants, into the ocean are also of concern. This session will address the atmospheric deposition fluxes, impact of nutrients and toxic substances to the ocean, emissions and fate of gases and aerosols emitted from the ocean surface, and major uncertainties limiting our understanding and evaluation of these impacts on marine biogeochemistry and climate. We welcome new findings from both measurement programmes and atmospheric and oceanic models.

This session arises from the work of GESAMP Working Group 38 on ‘Atmospheric Deposition of Nitrogen and its Impact on Marine Biogeochemistry’.