Tracing and constraining anthropogenic aerosol iron fluxes to the North Atlantic Ocean using iron isotopes.

ABSTRACT: Atmospheric dust is an important source of the micronutrient Fe to the oceans. Although relatively insoluble mineral Fe is assumed to be the most important component of dust, a relatively small yet highly soluble anthropogenic component may also be significant. However, quantifying the importance of anthropogenic Fe to the global oceans requires a tracer which can be used to identify and constrain anthropogenic aerosols in situ. Here, we present Fe isotope (?⁵⁶Fe) data from North Atlantic aerosol samples from the GEOTRACES GA03 section. While soluble aerosol samples collected near the Sahara have near-crustal ?⁵⁶Fe, soluble aerosols from near North America and Europe instead have remarkably fractionated ?⁵⁶Fe values (as light as -1.6‰). Here, we use these observations to fingerprint anthropogenic combustion sources, and to refine aerosol deposition modeling. We show that soluble anthropogenic aerosol Fe flux to the global surface oceans is highly likely to be underestimated, even in the dusty North Atlantic.

SUBMITTER: Conway TM 

PROVIDER: S-EPMC6570766 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature