Downward particle fluxes of biogenic matter and Saharan dust across the equatorial North Atlantic

Laura F. Korte, Geert Jan A. Brummer, Michèlle Van Der Does, Catarina V. Guerreiro, Rick Hennekam, Johannes A. Van Hateren, DIrk Jong, Chris I. Munday, Stefan Schouten, Jan Berend W. Stuut

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Massive amounts of Saharan dust are blown from the coast of northern Africa across the Atlantic Ocean towards the Americas each year. This dust has, depending on its chemistry, direct and indirect effects on global climate which include reflection and absorption of solar radiation as well as transport and deposition of nutrients and metals fertilizing both ocean and land. To determine the temporal and spatial variability of Saharan dust transport and deposition and their marine environmental effects across the equatorial North Atlantic Ocean, we have set up a monitoring experiment using deep-ocean sediment traps as well as land-based dust collectors. The sediment traps were deployed at five ocean sites along a transatlantic transect between north-west Africa and the Caribbean along 12° N, in a downwind extension of the land-based dust collectors placed at 19° N on the Mauritanian coast in Iouîk. In this paper, we lay out the setup of the monitoring experiment and present the particle fluxes from sediment trap sampling over 24 continuous and synchronized intervals from October 2012 through to November 2013. We establish the temporal distribution of the particle fluxes deposited in the Atlantic and compare chemical compositions with the land-based dust collectors propagating to the downwind sediment trap sites, and with satellite observations of Saharan dust outbreaks. First-year results show that the total mass fluxes in the ocean are highest at the sampling sites in the east and west, closest to the African continent and the Caribbean, respectively. Element ratios reveal that the lithogenic particles deposited nearest to Africa are most similar in composition to the Saharan dust collected in Iouîk. Downwind increasing Al, Fe and K contents suggest a downwind change in the mineralogical composition of Saharan dust and indicate an increasing contribution of clay minerals towards the west. In the westernmost Atlantic Ocean, admixture of re-suspended clay-sized sediments advected towards the deep sediment trap cannot be excluded. Seasonality is most prominent near both continents but generally weak, with mass fluxes dominated by calcium carbonate and clear seasonal maxima of biogenic silica towards the west. The monitoring experiment is now extended, with autonomous dust sampling buoys for better quantification of Saharan dust transport and deposition from source to sink and their impact on fertilization and carbon export to the deep ocean.

LanguageEnglish
Pages6023-6040
Number of pages18
JournalAtmospheric Chemistry and Physics
Volume17
Issue number9
DOIs
StatePublished - 16 May 2017

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dust
sediment trap
ocean
sampling
particle
monitoring
experiment
coast
calcium carbonate
environmental effect
temporal distribution
seasonality
clay mineral
global climate
solar radiation
transect
silica
chemical composition
clay
land

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Korte, Laura F. ; Brummer, Geert Jan A. ; Van Der Does, Michèlle ; Guerreiro, Catarina V. ; Hennekam, Rick ; Van Hateren, Johannes A. ; Jong, DIrk ; Munday, Chris I. ; Schouten, Stefan ; Stuut, Jan Berend W./ Downward particle fluxes of biogenic matter and Saharan dust across the equatorial North Atlantic. In: Atmospheric Chemistry and Physics. 2017 ; Vol. 17, No. 9. pp. 6023-6040
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Downward particle fluxes of biogenic matter and Saharan dust across the equatorial North Atlantic. / Korte, Laura F.; Brummer, Geert Jan A.; Van Der Does, Michèlle; Guerreiro, Catarina V.; Hennekam, Rick; Van Hateren, Johannes A.; Jong, DIrk; Munday, Chris I.; Schouten, Stefan; Stuut, Jan Berend W.

In: Atmospheric Chemistry and Physics, Vol. 17, No. 9, 16.05.2017, p. 6023-6040.

Research output: Contribution to JournalArticleAcademicpeer-review

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AU - Korte,Laura F.

AU - Brummer,Geert Jan A.

AU - Van Der Does,Michèlle

AU - Guerreiro,Catarina V.

AU - Hennekam,Rick

AU - Van Hateren,Johannes A.

AU - Jong,DIrk

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AU - Schouten,Stefan

AU - Stuut,Jan Berend W.

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