Enhanced Solubility and Ecological Impact of Atmospheric Phosphorus Deposition upon Extended Seawater Exposure

Atmospheric P solubility affects the amount of P available for phytoplankton in the surface ocean, yet our understanding of the timing and extent of atmospheric P solubility is based on short-term leaching experiments where conditions may differ substantially from the surface ocean. We conducted lon...

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Bibliographic Details
Published in:Environmental science & technology 2012-10, Vol.46 (19), p.10438-10446
Main Authors: Mackey, Katherine R. M, Roberts, Kathryn, Lomas, Michael W, Saito, Mak A, Post, Anton F, Paytan, Adina
Format: Article
Language:English
Subjects:
Aerosols
Atmosphere
Atmospheric aerosols
Environment
Environmental impact
Environmental science
Indian Ocean
Leaching
Mineral solubility
Models, Theoretical
Nitrogen
Oceans
Phosphorus
Phosphorus content
Phytoplankton - physiology
Plankton
Seawater
Seawater - chemistry
Solubility
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Summary:Atmospheric P solubility affects the amount of P available for phytoplankton in the surface ocean, yet our understanding of the timing and extent of atmospheric P solubility is based on short-term leaching experiments where conditions may differ substantially from the surface ocean. We conducted longer- term dissolution experiments of atmospheric aerosols in filtered seawater, and found up to 9-fold greater dissolution of P after 72 h compared to instantaneous leaching. Samples rich in anthropogenic materials released dissolved inorganic P (DIP) faster than mineral dust. To gauge the effect of biota on the fate of atmospheric P, we conducted field incubations with aerosol samples collected in the Sargasso Sea and Red Sea. In the Sargasso Sea phytoplankton were not P limited, and biological activity enhanced DIP release from aerosols, and aerosols induced biological mineralization of dissolved organic P in seawater, leading to DIP accumulation. However, in the Red Sea where phytoplankton were colimited by P and N, soluble P was rapidly consumed by phytoplankton following aerosol enrichment. Our results suggest that atmospheric P dissolution could continue over multiple days once reaching the surface ocean, and that previous estimates of atmospheric P deposition may underestimate the contribution from this source.
ISSN:0013-936X
1520-5851
DOI:10.1021/es3007996