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A radiogenic isotope tracer study of transatlantic dust transport from Africa to the Caribbean

Atmospheric Environment

By:
, , , , ,
DOI: 10.1016/j.atmosenv.2013.10.021

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Abstract

Many studies have suggested that long-range transport of African desert dusts across the Atlantic Ocean occurs, delivering key nutrients and contributing to fertilization of the Amazon rainforest. Here we utilize radiogenic isotope tracers – Sr, Nd and Pb – to derive the provenance, local or remote, and pathways of dust transport from Africa to the Caribbean. Atmospheric total suspended particulate (TSP) matter was collected in 2008 on quartz fibre filters, from both sides of the Atlantic Ocean at three different locations: in Mali (12.6°N, 8.0°W; 555 m a.s.l.), Tobago (11.3°N, 60.5°W; 329 m a.s.l.) and the U.S. Virgin Islands (17.7°N, 64.6°W; 27 m a.s.l.). Both the labile phase, representative of the anthropogenic signal, and the refractory detrital silicate fraction were analysed. Dust deposits and soils from around the sampling sites were measured as well to assess the potential contribution from local sources to the mineral dust collected. The contribution from anthropogenic sources of Pb was predominant in the labile, leachate phase. The overall similarity in Pb isotope signatures found in the leachates is attributed to a common African source of anthropogenic Pb, with minor inputs from other sources, such as from Central and South America. The Pb, Sr and Nd isotopic compositions in the silicate fraction were found to be systematically more radiogenic than those in the corresponding labile phases. In contrast, Nd and Sr isotopic compositions from Mali, Tobago, and the Virgin Islands are virtually identical in both leachates and residues. Comparison with existing literature data on Saharan and Sahelian sources constrains the origin of summer dust transported to the Caribbean to mainly originate from the Sahel region, with some contribution from northern Saharan sources. The source regions derived from the isotope data are consistent with 7-day back-trajectory analyses, demonstrating the usefulness of radiogenic isotopes in tracing dust provenance and atmospheric transport.

Geospatial Extents

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
A radiogenic isotope tracer study of transatlantic dust transport from Africa to the Caribbean
Series title:
Atmospheric Environment
DOI:
10.1016/j.atmosenv.2013.10.021
Volume
82
Year Published:
2014
Language:
English
Publisher:
Elsevier
Contributing office(s):
Southeast Ecological Science Center
Description:
14 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
130
Last page:
143
Number of Pages:
14
Country:
Mali;Tobago;U.S. Virgin Islands
Other Geospatial:
Africa;Atlantic Ocean;Caribbean;Sahara;Sahel