Date of Award

Fall 12-2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean & Earth Sciences

Program/Concentration

Ocean and Earth Sciences

Committee Director

Peter Sedwick

Committee Member

Gregory Cutter

Committee Member

Joesph Resing

Abstract

Aluminum (Al), a major component of mineral aerosol (dust), partially dissolves in seawater and is widely used as a tracer for estimating time‐averaged dust fluxes to the ocean. Such estimates rely on dissolved Al (DAl) inventories in the surface mixed layer (SML), an assumed SML residence time of DAl (TDAl), the fractional solubility of Al in dust (AlS), and the mass fraction of Al in dust. In this study, dust flux estimated from seasonal, water-column DAl data from the Bermuda Atlantic Time-series Study (BATS) region are compared with direct dust flux estimated from contemporaneous measurements of Al in aerosols and rain collected at Tudor Hill, Bermuda, over a 318-day period. The DAl-based flux estimates, using a 200 m deep SML, range from 5.3–11.2 g m⁻² yr⁻¹, which is substantially higher than the flux estimate of 1.2 g m⁻² yr⁻¹ based on Al in aerosols and rain. This discrepancy likely results from an underestimate of ʈDAI, as well as the influence of lateral transport over the longer timescale of the true τDAl value. A seasonally constrained DAl-based flux estimate, limited to the stratified summer months (April–August), yielded fluxes of 1.5–6.3 g m⁻² yr⁻¹, which are more consistent with the directly measured summer-period deposition of 1.31 g m⁻² yr⁻¹. These results highlight the importance of seasonal dynamics, temporal context and physical transport in tracer-based estimates of dust deposition in the open ocean.

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DOI

10.25777/4te4-hd31

ISBN

9798276042169

ORCID

0000-0001-6694-7334

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