Seasonal, spatial, and compositional variability of aeolian dust deposition across the northeastern Red Sea

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Dust deposition in the Al Wajh carbonate platform lagoon (northeastern Red Sea) plays a key role in marine productivity. This study investigates the spatial and seasonal patterns of dust storms, their composition, sources, and transport pathways, and the meteorological controls of the hyperarid deserts surrounding the lagoon. From April 2021 to May 2022, nine islands were instrumented monthly with frisbee-type dust gauges, yielding 93 dust samples over the entire period. Grain size distributions were measured via laser diffraction, mineralogy was determined via X-ray diffraction, and textures were characterized via scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy; dust mass accumulation rates were determined gravimetrically. Meteorological data, remote sensing, and satellite imagery were integrated to trace dust sources and pathways. The siliciclastic dust mass accumulation rates ranged from 1.0 to 6.0 g month −1 m −2 (annual mean: 2.6 g month −1 m −2 ), peaking in spring and summer (April–August). The dust was dominated by feldspars (41.5%), quartz (32%), and clays (18.3%); the iron-bearing minerals constituted up to 17%, potentially enhancing productivity in the lagoon. The grain size decreased offshore, over a distance of 23 km, from average 30 μm mode nearshore to 15 μm offshore (R 2 = 0.89). Observations revealed four transport pathways; however, only three pathways dominated the dust budget by observing satellite images: from coastal Arabia via easterlies, from the Sinai–northern Red Sea via prevailing northwesterlies, and from the Sahara via westerlies. Dust storms occurred at wind gust speeds as low as 10 m s −1 . Intense but infrequent late autumn and winter (November to February) rainfall replenished fine particles in the floodplain, thereby linking chemical weathering and subsequent aeolian transport. This study provides the first field-based, high-resolution (monthly) characterization of dust deposition in a Red Sea lagoon, reaching a distance of more than 20 km offshore, offering new insights into the mineral composition, delivery mechanisms, and potential fertilization effects on coastal marine ecosystems.

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