title: Understanding the nature of atmospheric acid processing of mineral dusts in supplying bioavailable phosphorus to the oceans.
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 behavior of P compounds in dust and dust precursor soils. Acid dissolution occurs rapidly (seconds to minutes) and is controlled by the amount of H+ions present. For H+< 10-4mol/g of dust, 1-10% of the total P is dissolved, largely as a result of dissolution of surface-bound forms. At H+> 10-4mol/g of dust, the amount of P (and calcium) released has a direct proportionality to the amount of H+consumed until all inorganic P minerals are exhausted and the final pH remains acidic. Once dissolved, P will stay in solution due to slow precipitation kinetics. Dissolution of apatite-P (Ap-P), the major mineral phase in dust (79-96%), occurs whether calcium carbonate (calcite) is present or not, although the increase in dissolved P is greater if calcite is absent or if the particles are externally mixed. The system was modeled adequately as a simple mixture of Ap-P and calcite. P dissolves readily by acid processes in the atmosphere in contrast to iron, which dissolves more slowly and is subject to reprecipitation at cloud water pH. We show that acidification can increase bioavailable P deposition over large areas of the globe, and may explain much of the previously observed patterns of variability in leachable P in oceanic areas where primary productivity is limited by this nutrient (e.g., Mediterranean).
authors.affiliation: School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom; tony@biogeochemistry.org.uk.
authors.forename: Anthony
authors.identifier: 0000-0002-1603-0103
authors.initials: A
authors.lastname: Stockdale
authors.affiliation: School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom.|Department of Marine Biology, Haifa University, Haifa 3498838, Israel.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Krom
authors.affiliation: School of Animal, Rural and Environmental Sciences, Nottingham Trent University, Brackenhurst Campus, Southwell, Nottinghamshire NG25 0QF, United Kingdom.
authors.forename: Robert J G
authors.initials: RJ
authors.lastname: Mortimer
authors.affiliation: School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom.|German Research Center for Geosciences, GFZ, 14473 Potsdam, Germany.
authors.forename: Liane G
authors.initials: LG
authors.lastname: Benning
authors.affiliation: School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom.
authors.forename: Kenneth S
authors.identifier: 0000-0002-6800-154X
authors.initials: KS
authors.lastname: Carslaw
authors.affiliation: School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom.
authors.forename: Ross J
authors.initials: RJ
authors.lastname: Herbert
authors.affiliation: School of Geography and Earth Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom.
authors.forename: Zongbo
authors.initials: Z
authors.lastname: Shi
authors.affiliation: Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, Heraklion, Greece, GR-71003.
authors.forename: Stelios
authors.identifier: 0000-0002-1541-7680
authors.initials: S
authors.lastname: Myriokefalitakis
authors.affiliation: Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, Heraklion, Greece, GR-71003.
authors.forename: Maria
authors.initials: M
authors.lastname: Kanakidou
authors.affiliation: School of Earth & Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332.|School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332.|Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Athens, Greece, GR-15236.|Institute of Chemical Engineering Sciences, Foundation for Research and Technology-Hellas, Patras, Greece, GR-26504.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Nenes
mesh_terms: D001272:Atmosphere / Q000737:chemistry*; D002118:Calcium / Q000032:analysis; D002119:Calcium Carbonate / Q000032:analysis; D057486:Carbon Cycle; D004391:Dust / Q000032:analysis*; D005843:Geography; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry; D008903:Minerals; D009584:Nitrogen; D009792:Oceans and Seas; D010087:Oxides / Q000737:chemistry; D010710:Phosphates / Q000032:analysis; D010758:Phosphorus / Q000032:analysis*; D012623:Seawater / Q000737:chemistry*; D012995:Solubility; D013499:Surface Properties
chemical_list: D004391:Dust; D008903:Minerals; D010087:Oxides; D010710:Phosphates; D010758:Phosphorus; D007501:Iron; D002119:Calcium Carbonate; D009584:Nitrogen; D002118:Calcium
keywords: atmospheric processing; desert dusts; ocean macronutrients