Atmospheric P deposition to the subtropical North Atlantic: sources, properties, and relationship to N deposition
Article first published online: 14 FEB 2013
©2013. American Geophysical Union. All Rights Reserved.
Journal of Geophysical Research: Atmospheres
Volume 118, Issue 3, pages 1546–1562, 16 February 2013
How to Cite
2013), Atmospheric P deposition to the subtropical North Atlantic: sources, properties, and relationship to N deposition, J. Geophys. Res. Atmos., 118, 1546–1562, doi:10.1002/jgrd.50187., , , and (
- Issue published online: 1 APR 2013
- Article first published online: 14 FEB 2013
- Accepted manuscript online: 18 JAN 2013 09:07AM EST
- Manuscript Accepted: 11 JAN 2013
- Manuscript Revised: 9 JAN 2013
- Manuscript Received: 3 AUG 2012
 Biogeochemical studies show that the surface waters of the subtropical North Atlantic are highly phosphorus (P) stressed. Human activity may exacerbate phosphorus stress by enhancing atmospheric nitrogen (N) deposition and raising N/P ratios in deposition. However, the magnitude of this effect is unclear, in part, because atmospherically deposited phosphorus sources are not well known, particularly the contribution from organic phosphorus. Here we report measurements of phosphorus in aerosols and wet deposition at Miami and Barbados. African dust is the major aerosol P source at both Miami and Barbados, containing ~880 ppm total phosphorus and ~70 ppm soluble reactive phosphorus (SRP). Organic compounds contribute, on average, 28%–44% of soluble phosphorus in precipitation. Because of dust transport seasonality, phosphorus inputs to the North Atlantic are expected to be highly variable with 2–10 times more P deposition during summer than winter. Pollution is also an important contributor to total and soluble phosphorus in Miami aerosols and deposition. Estimated SRP deposition in Barbados and Miami is 0.21 and 0.13 µmol m−2 d−1 phosphorus, respectively. Inorganic nitrogen in excess of Redfield ratio expectations in deposition was very different between the sites, totaling 21–30 and 127–132 µmol m−2 d−1 nitrogen in Barbados and Miami, respectively; the high deposition rates at Miami are linked to pollutants. Including soluble organic nitrogen and phosphorus halved the estimates of excess nitrogen in Barbados wet deposition. Thus, the organic phosphorus fraction is important in the assessment of the magnitude of biogeochemical change of the North Atlantic caused by atmospheric deposition.