Tracing natural and anthropogenic sources of aerosols to the Atlantic Ocean using Zn and Cu isotopes

Packman, Hollie, Little, Susan H., Baker, Alex R. ORCID: https://orcid.org/0000-0002-8365-8953, Bridgestock, Luke, Chance, Rosie J., Coles, Barry J., Kreissig, Katharina, Rehkämper, Mark and van de Flierdt, Tina (2022) Tracing natural and anthropogenic sources of aerosols to the Atlantic Ocean using Zn and Cu isotopes. Chemical Geology, 610. ISSN 0009-2541

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Abstract

Anthropogenic activities have significantly enhanced atmospheric metal inputs to the ocean, which has potentially important consequences for marine ecosystems. This study assesses the potential of Zn and Cu isotope compositions to distinguish between natural and anthropogenic atmospheric inputs of these metals to the surface ocean. To this end, the isotopic compositions of Zn and Cu in aerosols collected from the eastern tropical Atlantic Ocean on the GEOTRACES GA06 cruise are examined. Enrichment factors and fractional solubility measurements indicate the presence of a significant anthropogenic component in the aerosols collected furthest from the North African dust plume for both Zn and Cu. The mean δ65CuNIST SRM 976 for the fully digested aerosols is +0.07 ± 0.39 ‰ (n = 9, 2 SD), which is indistinguishable from the lithogenic value, and implies that Cu isotopes are not an effective tracer of aerosol sources in this region. The mean δ66ZnJMC-Lyon value for the aerosols that underwent a total digestion is +0.17 ± 0.22 ‰ (n = 11, 2 SD). The aerosols leached with ammonium acetate have similar Zn isotope compositions, with a mean of +0.15 ± 0.16 ‰ (n = 7, 2 SD). The aerosols were collected in a region with prevalent mineral dust but, despite this, exhibit isotopically lighter Zn than lithogenic Zn with δ66Zn ≈ +0.3 ‰. When coupled with the previously published Pb isotope data, the aerosols exhibit coupled Zn-Pb isotope systematics that are indicative of mixing between mineral dust (δ66Zn = +0.28 ‰ and 206Pb/207Pb = 1.205) and anthropogenic emissions (δ66Zn = −0.22 ‰ and 206Pb/207Pb = 1.129). This demonstrates the potential of Zn isotopes to trace atmospheric Zn inputs from anthropogenic sources to the surface ocean.

Item Type: Article
Additional Information: Acknowledgements: The authors gratefully thank Peter Morton and William Landing for the personal distribution of ATD. All members of the MAGIC research group at Imperial College London are thanked for their support. H.P. was supported by the Natural Environment Research Council DTP “Science and Solutions for a Changing Planet” [grant number NE/L002515/1 ] at Imperial College London . S.H.L is supported by a NERC Independent Research Fellowship (NE/P018181/2). Sample collection was supported by the UK Natural Environment Research Council (NERC) through grant NE/G016585/1. Publisher Copyright: © 2022
Uncontrolled Keywords: aerosols,anthropogenic contribution,copper,isotopic composition,trace metals,zinc,geology,geochemistry and petrology ,/dk/atira/pure/subjectarea/asjc/1900/1907
Faculty \ School: Faculty of Science > School of Environmental Sciences
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Depositing User: LivePure Connector
Date Deposited: 08 Sep 2022 15:30
Last Modified: 25 Sep 2022 03:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/87979
DOI: 10.1016/j.chemgeo.2022.121091

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