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Variability in sediment particle size, mineralogy, and Fe mode of occurrence across dust-source inland drainage basins: the case of the lower Drâa Valley, Morocco

González-Romero, Adolfo ; González-Flórez, Cristina ; Panta, Agnesh ; Yus-Díez, Jesús ; Reche, Cristina ; Córdoba, Patricia ; Moreno, Natalia ; Alastuey, Andres ; Kandler, Konrad ; Klose, Martina ; Baldo, Clarissa ; Clark, Roger N. ; Shi, Zongbo ; Querol, Xavier ; Pérez García-Pando, Carlos (2024)
Variability in sediment particle size, mineralogy, and Fe mode of occurrence across dust-source inland drainage basins: the case of the lower Drâa Valley, Morocco.
In: Atmospheric Chemistry and Physics, 2023, 23 (24)
doi: 10.26083/tuprints-00027295
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Item Type: Article
Type of entry: Secondary publication
Title: Variability in sediment particle size, mineralogy, and Fe mode of occurrence across dust-source inland drainage basins: the case of the lower Drâa Valley, Morocco
Language: English
Date: 7 May 2024
Place of Publication: Darmstadt
Year of primary publication: 22 December 2023
Place of primary publication: Göttingen
Publisher: Copernicus Publications
Journal or Publication Title: Atmospheric Chemistry and Physics
Volume of the journal: 23
Issue Number: 24
DOI: 10.26083/tuprints-00027295
Corresponding Links:
Origin: Secondary publication DeepGreen
Abstract:

The effects of desert dust upon climate and ecosystems depend strongly on its particle size and size-resolved mineralogical composition. However, there is very limited quantitative knowledge on the particle size and composition of the parent sediments along with their variability within dust-source regions, particularly in dust emission hotspots. The lower Drâa Valley, an inland drainage basin and dust hotspot region located in the Moroccan Sahara, was chosen for a comprehensive analysis of sediment particle size and mineralogy. Different sediment type samples (n= 42) were collected, including paleo-sediments, paved surfaces, crusts, and dunes, and analysed for particle-size distribution (minimally and fully dispersed samples) and mineralogy. Furthermore, Fe sequential wet extraction was carried out to characterise the modes of occurrence of Fe, including Fe in Fe (oxyhydr)oxides, mainly from goethite and hematite, which are key to dust radiative effects; the poorly crystalline pool of Fe (readily exchangeable ionic Fe and Fe in nano-Fe oxides), relevant to dust impacts upon ocean biogeochemistry; and structural Fe. Results yield a conceptual model where both particle size and mineralogy are segregated by transport and deposition of sediments during runoff of water across the basin and by the precipitation of salts, which causes a sedimentary fractionation. The proportion of coarser particles enriched in quartz is higher in the highlands, while that of finer particles rich in clay, carbonates, and Fe oxides is higher in the lowland dust emission hotspots. There, when water ponds and evaporates, secondary carbonates and salts precipitate, and the clays are enriched in readily exchangeable ionic Fe, due to sorption of dissolved Fe by illite. The results differ from currently available mineralogical atlases and highlight the need for observationally constrained global high-resolution mineralogical data for mineral-speciated dust modelling. The dataset obtained represents an important resource for future evaluation of surface mineralogy retrievals from spaceborne spectroscopy.

Status: Publisher's Version
URN: urn:nbn:de:tuda-tuprints-272954
Classification DDC: 500 Science and mathematics > 550 Earth sciences and geology
Divisions: 11 Department of Materials and Earth Sciences > Earth Science > Atmospheric Aerosol
Date Deposited: 07 May 2024 09:51
Last Modified: 12 Sep 2024 09:24
SWORD Depositor: Deep Green
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/27295
PPN: 521334292
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