BGD

Biogeosciences Discussions

BGD

Biogeosciences Discuss.

1810-6285

Göttingen, Germany

10.5194/bg-2020-283

Extraterrestrial dust as a source of bioavailable Fe for the ocean productivity

Gowda

Rudraswami N.

https://orcid.org/0000-0002-3375-9860

¹ Pandey

Mayank

¹ Genge

Matthew J.

² Fernandes

Dafilgo

https://orcid.org/0000-0002-6857-7901

CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India

Department of Earth Science and Engineering, Imperial College London, SW7 2AZ, UK

Ministry of Earth Sciences

PMN-MOES

11 09 2020

2020 1 23

2020

This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/

This article is available from https://bg.copernicus.org/preprints/bg-2020-283/

The full text article is available as a PDF file from https://bg.copernicus.org/preprints/bg-2020-283/bg-2020-283.pdf

Bioavailable Fe is an essential nutrient for phytoplankton that allows organisms to flourish and drawdown atmospheric CO2 affecting global climatic condition. In marine locales remote from the continents extraterrestrial-dust provides an important source of Fe and thus moderates primary productivity. Here we provide constraints on partitioning of extraterrestrial Fe between seawater and sediments from observations of dissolution and alteration cosmic spherules recovered from the deepsea sediments and Antarctica. Of the ~ 3000–6000 t/a extraterrestrial dust that reaches Earth surface, ~ 2–5 % material survives in marine sediments whilst the remainder is liberated into seawater. Both processes contributes ~ (3–10) × 10−8 molFe m−2 yr−1. Also, Fe contribution due to evaporation of survived particle is estimated to be ~ 10 % of Fe contribution to meteoric smoke. Changes in extraterrestrial-dust flux vary not only the amount of Fe by up to three orders of magnitude, but also the partitioning of Fe between surface and abyssal waters depending on entry velocity and evaporation.