147-13 Iron fertilization potentials of differing types of atmospheric dust

Session: Climate, Ocean and Environmental Changes Through Earth History: From Marine and Terrestrial Proxies to Model Assessments (Posters)

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Abstract:

Iron sourced from atmospheric dust has long been noted as an important factor in controlling primary production in large swaths of the ocean. As a key micronutrient, iron is a co-factor in marine biogeochemical cycling and plays an important role in nitrogen fixation, as well as increasing growth rates that improve the efficiency of the biological pump. However, recent studies have noted that mineral dusts are not equal in terms of the bioavailability of iron, and thus may have differing fertilization potentials; for example, some suggest that volcanic ash and glacial dusts deliver more soluble and bioavailable iron compared to desert dust. In this study, we empirically test the fertilization potentials of different types of eolian-marine dust from two modern through upper Pleistocene marine sediment cores that span the last three glacial-interglacial cycles (~400 ky). Both cores are from offshore settings isolated from fluvio-deltaic or deepwater fan contributions, thus preserving a mostly pristine eolian record. One core from offshore southern California contains marine-deposited dust sourced predominantly from inland hot deserts, together with combustion aerosols, while a core from offshore Patagonia contains marine-deposited dusts derived predominantly from glacial and volcanic sources. We will integrate sedimentological and geochemical datasets to gain a wholistic picture of the fertilization potential for these primary dust types. Here we will utilize iron speciation as a proxy for bioavailable iron and then utilize lipid biomarker analysis to provide insights on the phytoplankton diversity and abundance, to ultimately create first-order constraints on the fertilization effects of these differing dust types. Sedimentological datasets such as particle size will aid in differentiating the occurrence of dust throughout these cores. Ultimately, we hope to provide better insight into the role of dust deposition within the larger carbon cycle, and dust’s ability to stimulate organic carbon burial in the near-time geologic record.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8762

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