Tracing the Sources of Atmospheric Phosphorus Deposition to a Tropical Rain Forest in Panama Using Stable Oxygen Isotopes

A. Gross*, B. L. Turner, T. Goren, A. Berry, A. Angert

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Atmospheric dust deposition can be a significant source of phosphorus (P) in some tropical forests, so information on the origins and solubility of atmospheric P is needed to understand and predict patterns of forest productivity under future climate scenarios. We characterized atmospheric dust P across a seasonal cycle in a tropical lowland rain forest on Barro Colorado Nature Monument (BCNM), Republic of Panama. We traced P sources by combining remote sensing imagery with the first measurements of stable oxygen isotopes in soluble inorganic phosphate (δ18OP) in dust. In addition, we measured soluble inorganic and organic P concentrations in fine (<1 μm) and coarse (>1 μm) aerosol fractions and used this data to estimate the contribution of P inputs from dust deposition to the forest P budget. Aerosol dry mass was greater in the dry season (December to April, 5.6-15.7 μg m-3) than the wet season (May to November, 3.1-7.1 μg m-3). In contrast, soluble P concentrations in the aerosols were lower in the dry season (980-1880 μg P g-1) than the wet season (1170-3380 μg P g-1). The δ18OP of dry-season aerosols resembled that of nearby forest soils (∼19.5‰), suggesting a local origin. In the wet season, when the Trans-Atlantic Saharan dust belt moves north close to Panama, the δ18OP of aerosols was considerably lower (∼15.5‰), suggesting a significant contribution of long-distance dust P transport. Using satellite retrieved aerosol optical depth (AOD) and the P concentrations in aerosols we sampled in periods when Saharan dust was evident we estimate that the monthly P input from long distance dust transport during the period with highest Saharan dust deposition is 88 ± 31 g P ha-1 month-1, equivalent to between 10 and 29% of the P in monthly litter fall in nearby forests. These findings have important implications for our understanding of modern nutrient budgets and the productivity of tropical forests in the region under future climate scenarios.

Original languageAmerican English
Pages (from-to)1147-1156
Number of pages10
JournalEnvironmental Science and Technology
Issue number3
StatePublished - 2 Feb 2016

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Publisher Copyright:
© 2015 American Chemical Society.


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