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Subproject 3.6

Aerosol-ocean interaction: Oceanic import of dust

The deposition of Saharan dust into the Oceans significantly influences marine biochemical cycles due to the addition of key nutrient such as iron or phosphorus. The bioavailability of these nutrients depends on a variety of factors, including the atmospheric processing of the dust particles during their transport and also the actual seawater chemical processes.

However, the processes that influence their bioavailability are still not well understood. To improve our understanding of these processes that control nutrient availability, trace metal analysis together with dust deposition flux measurements are very necessary. With the permanent research sites CVAO and CVOO on and near the Cape Verde island São Vicente a new quality and quantity of scientific data including aerosol chemical and trace metal composition was obtained within the previous SOPRAN phases. This dataset allows investigation of inter-annual and seasonal variability of the deposition of dust and of nutrients such as iron, as well as their effects on the oceanic processes and delivers measurement data for model validation.

In the third phase of SOPRAN we shall continue the long term sampling of the chemical and microphysical parameters of aerosol particles that are necessary in assessing the impact of dust to the ocean ecosystem. This will include the further quantification of the amount of iron and soluble iron that is deposited into the Northern tropical Atlantic and the understanding of the factors that control the aerosol iron and trace metal solubility in marine aerosol particles such as photochemistry, aerosol pH, organic acid complexation, and aging.



Fig.1
:
Saharan dust storm at Cape Verde Atmospheric Observatory 7th of February 2012


PI's: H. Herrmann, A. Wiedensohler
Contact: Kanneh Wadinga Fomba (fomba@tropos.de)
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