Analysis of biogeochemical nutrient delivery to the Amazon and Atlantic Ocean from transported smoke and dust
EMSL Project ID
51900
Abstract
Atmospheric particles (e.g., aerosols) deposit key nutrients, such as iron (Fe) and phosphorus (P), to the open ocean and the Amazon Rainforest. These nutrients are important for biological functions and the cycling of nutrients that stimulate primary productivity. However, key uncertainties remain regarding the quantity and biological availability of nutrients found in aerosols emitted from different sources. We propose to perform spectroscopy, mass spectrometry, and microscopy to analyze atmospheric particles (collected on filters) to determine the concentration, source, and bioavailability of Fe- and P-containing particles. This data will be implemented into a biogeochemical module that is part of DOE’s Energy Exascale Earth System Model (E3SM). We will use samples collected at a gateway to the Amazon Basin and at a tower in Barbados that has documented the transport of atmospheric particles to the ocean for over 50 years. These two sites receive dust and smoke transported from Africa that are thought to fertilize the Atlantic Ocean and the Amazon Basin. We will focus on two key data products critically needed to improve current model predictions: (1) characterization of organic forms of Fe and P, and (2) Fe:Dust and P:Dust ratios—indicative of the nutrient content of transported dust—in addition to Fe:black carbon (BC) and P:BC ratios that are indicative of the nutrient content of smoke particles. Traditionally, dust has been thought to fertilize ecosystems through inputs of inorganic forms of Fe and P. However, we hypothesize that organic forms of nutrients, including smoke particles, are a major source of bioavailable Fe and P to the Amazon and Atlantic Ocean. Computer-controlled scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (CCSEM/EDX) will be used to determine the size, Fe and P content, and source of individual particles in our samples, two forms of secondary ion mass spectrometry (e.g., Nano-SIMS and TOF-SIMS) will be used to probe associations between organic compounds with Fe and P. Dust mineralogy and the oxidation state and phase of Fe-containing minerals will be investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Mössbauer spectroscopy. CCSEM/EDX combined with electron energy loss spectroscopy (TEM-EELS) and selected area electron diffraction (SAED) will be used to characterize BC in smoke and elucidate nutrient ratios (e.g., Fe:BC, P:BC) when combined with elemental information from EDX. The use of state-of-the-art EMSL instrumentation is critical for testing our hypothesis and for the overall success of this project. The CCSEM/EDX needed to distinguish different sources of aerosols, TOF-SIMS and Nano-SIMS needed to probe mineral-organic matter interactions, Mössbauer spectroscopy, XPS, and XRD needed to determine Fe bioavailability and dust mineralogy, and TEM-EELS and SAED needed to determine P:BC and Fe:BC ratios are only possible through a collaboration with EMSL. This work will improve our understanding of how aerosols fertilize ecosystems and impact the global carbon cycle through the sequestration of atmospheric carbon dioxide. This proposal also aligns with DOE’s interest in the cycling of elements and nutrients in terrestrial and aquatic ecosystems in addition to the improvement and validation of Earth System Models.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2021-10-01
End Date
2023-10-01
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
H.M. Royer, M.L. Pöhlker*, O.O. Krüger, E. Blades, P. Sealy, N.N. Lata, Z. Cheng, S. China, A. Ault, P.K. Quinn, P. Zuidema, C. Pöhlker, U. Pöschl, C.J. Gaston* “African Smoke Particles Act as Cloud Condensation Nuclei in the Wintertime Tropical North Atlantic Boundary Layer over Barbados” Submitted to Atmospheric Chemistry and Physics Discussions, https://acp.copernicus.org/preprints/acp-2022-341/