Atmospheric Trace Metal Deposition near the Great Barrier Reef, Australia

Michal Strzelec,Robyn Schofield,Andrew R Bowie,Robert G Ryan,Morgane M G Perron,Melanie Gault-Ringold,Melita D Keywood,Philip W Boyd,Bernadette C Proemse,Jason Ward,Zoran D Ristovski,Joel Alroe,Ruhi S Humphries

doi:10.3390/atmos11040390

Abstract

Aerosols deposited into the Great Barrier Reef (GBR) contain iron (Fe) and other trace metals, which may act as micronutrients or as toxins to this sensitive marine ecosystem. In this paper, we quantified the atmospheric deposition of Fe and investigated aerosol sources in Mission Beach (Queensland) next to the GBR. Leaching experiments were applied to distinguish pools of Fe with regard to its solubility. The labile Fe concentration in aerosols was 2.3–10.6 ng m−3, which is equivalent to 4.9%–11.4% of total Fe and was linked to combustion and biomass burning processes, while total Fe was dominated by crustal sources. A one-day precipitation event provided more soluble iron than the average dry deposition flux, 0.165 and 0.143 μmol m−2 day−1, respectively. Scanning Electron Microscopy indicated that alumina-silicates were the main carriers of total Fe and samples affected by combustion emissions were accompanied by regular round-shaped carbonaceous particulates. Collected aerosols contained significant amounts of Cd, Co, Cu, Mo, Mn, Pb, V, and Zn, which were mostly (47.5%–96.7%) in the labile form. In this study, we provide the first field data on the atmospheric delivery of Fe and other trace metals to the GBR and propose that this is an important delivery mechanism to this region.

Highlights

IntroductionAn important component of this system is the land-atmosphere-ocean transport of minerals and micronutrient trace elements vital to biology [1,2,3]
Oceans play an essential role in Earth’s climate through the uptake of atmospheric CO2 .An important component of this system is the land-atmosphere-ocean transport of minerals and micronutrient trace elements vital to biology [1,2,3]
To differentiate between aerosols transported from the sea during the day and those transported from the land at night, a short 12-h sampling period was applied from 6 a.m.–6 p.m. and 6 p.m.–6 a.m

Summary

Introduction

An important component of this system is the land-atmosphere-ocean transport of minerals and micronutrient trace elements vital to biology [1,2,3] Included in this is the iron (Fe) biogeochemical. Atmosphere 2020, 11, 390 cycle, in which Fe-rich aerosols are delivered to the oceans as a result of the deposition of mineral dust, biomass burning, and anthropogenic emissions. Trace micronutrients, such as Fe, are essential for the biogeochemical functioning of marine ecosystems [4,5,6]. Atmospheric Fe deposition in oligotrophic waters such as the GBR may promote nitrogen fixation and, alter the carbon cycle [17,18,19,20]

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