Understanding the nature of atmospheric acid processing of mineral dusts in supplying bioavailable phosphorus to the oceans

Stockdale, A., Krom, M.D., Mortimer, R.J.G. ORCID: 0000-0003-1292-8861, Benning, L.G., Carslaw, K.S., Herbert, R.J., Shi, Z., Myriokefalitakis, S., Kanakidou, M. and Nenes, A., 2016. Understanding the nature of atmospheric acid processing of mineral dusts in supplying bioavailable phosphorus to the oceans. Proceedings of the National Academy of Sciences of the United States of America. ISSN 0027-8424

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Abstract

Acidification of airborne dust particles can dramatically increase the amount of bioavailable phosphorus (P) deposited on the surface ocean. Experiments were conducted to simulate atmospheric processes and determine the dissolution behaviour of phosphorus compounds in dust and dust precursors oils. Acid dissolution occurs rapidly (seconds to minutes) and is controlled by the amount of H + ions present. For H + <10-4 mol per gram dust, 1-10% of the total phosphorus is dissolved, largely as a result of dissolution of surface-bound forms. At H + >10-4 mol per gram of dust, the amount of phosphorus (and Ca) released follows a power law dependent on the amount of H + consumed until all inorganic phosphorus minerals are exhausted and the final pH remains acidic. Once dissolved, phosphorus will stay in solution due to slow precipitation kinetics. Dissolution of apatite-P, the major mineral phase in dust (79-96%), occurs whether CaCO 3 is present or not, though the increase in dissolved phosphorus is greater if CaCO 3 is absent or if the particles are externally mixed. The system was modelled adequately as a simple mixture of apatite-P and calcite. Phosphorus dissolves readily by acid processes in the atmosphere in contrast to iron, which dissolves slower and is subject to re-precipitation at cloud water pH. We show that acidification can increase bioavailable phosphorus deposition over large areas of the globe, and may explain much of the previously observed patterns of variability in leachable phosphorus in oceanic areas where primary productivity is limited by this nutrient (e.g. Mediterranean).

Item Type: Journal article
Publication Title: Proceedings of the National Academy of Sciences of the United States of America
Creators: Stockdale, A., Krom, M.D., Mortimer, R.J.G., Benning, L.G., Carslaw, K.S., Herbert, R.J., Shi, Z., Myriokefalitakis, S., Kanakidou, M. and Nenes, A.
Publisher: National Academy of Sciences
Date: 7 December 2016
ISSN: 0027-8424
Identifiers:
NumberType
10.1073/pnas.1608136113DOI
Divisions: Schools > School of Animal, Rural and Environmental Sciences
Depositing User: Linda Sullivan
Date Added: 09 Dec 2016 16:21
Last Modified: 09 Jun 2017 14:09
URI: http://irep.ntu.ac.uk/id/eprint/29319

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