Iron oxides, as the main carriers of soluble iron in dust, play an important role in supplying nutrients to terrestrial and marine ecosystems and in the global carbon cycle. Although deserts are important source regions, the generation and release processes of iron-oxide-rich dust remain poorly documented. Grain-size fractionation can effectively reveal these processes. Therefore, for the first time in the Kumtagh Desert, this study conducted grain-size-fractionated magnetic susceptibility and mineralogical analyses. The results show that: (1) Magnetic susceptibility shows pronounced grain-size dependence, reflecting the combined effects of grain-size sorting and variations in the abundance and magnetic behavior of Fe-bearing mineral phases; even within a limited grain-size interval of Δ ≤ 0.5 Φ, significant differences in magnetic susceptibility can be observed. (2) Nano-scale Fe-rich particles observed in the fine fractions are inferred to be associated with desert-varnish coatings and Fe-bearing detrital materials. Their production is consistent with abrasion and fragmentation during aeolian transport. (3) The sorting of sand-sized detrital minerals in the desert leads to the enrichment of iron oxides with decreasing grain size, thereby causing spatial variations in magnetic susceptibility. This study demonstrates the necessity of grain-size-fractionated analysis of desert sediments and provides a new perspective for understanding the mechanisms of iron oxide emission to the atmosphere in desert regions.
Although heavy metal concentrations in urban areas are influenced by anthropogenic activities, they may also be affected by dust load. Heavy metals have been investigated in urban dust and soil but have been rarely assessed in non-urban environments. This study aimed to assess dust metals in urban environments (Zabol and Zahak) and non-urban environments (Adimi, Aliakbar and Ghorghori) of Sistan, Iran, and to explore the influence of dust load on metal concentration. Analysis of 15 dust and 15 soil samples using ICP-MS revealed that dust samples were polluted with nickel (Ni) (41 ± 1.6) and arsenic (As) (26.4 ± 2.8), while soil samples showed contamination from Ni (46.9 ± 12.4), As (27.4 ± 7.7), and chromium (Cr) (128 ± 29). The values of enrichment factor, geo-accumulation index, and pollution load index were similar between the urban and non-urban sites. The highest EF and Igeo values were for As and S. Aliakbar and Ghorghori were identified as the most serious heavy metal-hazardous sites due to highest recorded dust flux (32.1 and 49.8 g cm2) and metal content (e.g., P (15,697.4 and 25,189.3 μg cm2) and As (849.0 and 1484.4 μg cm2)). Although spatial variability in the metal concentration (per gram of dust) was slight, and differences in the metal concentrations in dust samples were insignificant between urban and non-urban environments (P > 0.05), the metal content (per dust sample) was higher in non-urban environments than in urban environments and differences in the metal content in the dust samples were significant between urban and non-urban environments (P < 0.001) due to the influence of dust load.
Drift Potential (DP) is essential for understanding wind-energy environments and aeolian geomorphic processes. However, limited observations from the sand sea have constrained mechanistic insights into sand sea interior dynamics. To address this gap, we use meteorological observations (2010–2024) from stations within and around the sand sea to examine the spatiotemporal variability of wind speed and DP. DP was calculated using the Fryberger method and analyzed through trend analysis, seasonal comparison, correlation analysis, and SHAP-based analysis to evaluate associated factors. Results show a significant decline in DP across most stations and seasons, primarily associated with weakening above-threshold winds rather than changes in mean wind speed. Stations in the sand sea interior exhibit substantially lower wind speeds and DP than those at the margins. DP variability increases from the interior toward the margins, indicating greater stochasticity in wind-energy environments at the margins and implying that margin station data may overestimate wind-energy conditions in the interior. Clear within sand sea heterogeneity is evident: with dune-crest sites experience stronger wind energy than stations near interdune lakes. Temporally, DP peaks earlier at the margins (April) but is delayed to May–June within the interior, a pattern consistent with local topographic and thermodynamic modulation. These findings reveal a long-term attenuation of the Badain Jaran Sand Sea wind-energy regime, associated with weakening above-threshold winds, and indicate the role of local environmental conditions in shaping aeolian dynamics in arid regions.
Coastal dunes are important features of sandy coasts due to their multifunctionality. In recent decades, dune management has shifted from stabilization towards remobilization to enhance coastal resilience and biodiversity. This study investigates a remobilized dune system in Zuid-Kennemerland, along the Dutch west coast, where multiple artificial foredune notches and reactivated parabolic dunes (RPD's) were created in 2013. Over more than a decade, 15 sand traps monitored suspended aeolian sand transport, with samples correlated to meteorological data and geomorphological changes. Up to 89% of annual suspended sand load occurs during storm events (with average hourly wind speeds >20.8 m/s) with sand deposition reaching 1200 m inland of the foredune. Sand traps downwind of notches indicate declining suspended loads over time because flow acceleration and sedimentation declines as notches become wider. In contrast, traps downwind of RPD's indicate increasing suspended sand transport, related to the landward migration of depositional lobes. In unnotched areas, continuous suspended load trends align with the general linear growth of Dutch foredunes. Volumetric analyses indicate that notches and blowouts have created a transport corridor connecting the beach and hinterland. These findings emphasize the significance of suspended aeolian sand transport in accounting for spatial variation in reactivated dune systems. The results also contribute to improved morphodynamic coastal models since the importance of suspended transport has to date been underrecognized. Future research should quantify depositional patterns and sediment characteristics to clarify their roles in dune evolution, soil formation, and ecosystem development.
African dust deposition is a major driver of atmospheric inputs to Mediterranean and southwestern European ecosystems, yet high-resolution source apportionment able to discriminate sub-regional North African origins across contrasting environments remains limited. Here we provide a comprehensive assessment of African dust deposition in southwestern Europe using 114 bulk-deposition samples collected at 15 monitoring sites spanning urban, remote, agricultural, and industrial settings across the Iberian Peninsula and the Balearic Islands. Total bulk aerosol deposition fluxes ranged from 10 to 55 g m(-2) year(-1), and African dust accounted for up to 75% of the insoluble fraction at hotspots such as the southern Pyrenees and the southern Iberian coast. To capture meteorological controls and spatial heterogeneity, we analyzed four case studies representative of distinct synoptic scenarios along a seasonal gradient. Seasonal shifts in deposition fluxes and geochemical composition were observed, and elemental ratios (Fe/Ti, Ca/Al, Fe/Al, and (Ca + Mg)/Fe) enabled discrimination of three North African source regions (Western Sahara-Morocco, southern Algeria-northern Mali, and northern AlgeriaTunisia), addressing previous challenges in attributing deposition to sub-regional origins. Positive Matrix Factorization (PMF v5.0) yielded a ten-factor solution including three African dust factors alongside regional resuspension, marine input, traffic, regional pollution, combustion-related sources, and two industrial profiles; the African dust factors were separated by distinct chemical signatures, with the northern Algeria-Tunisia source enriched in carbonates. Source contributions varied markedly in space and time across the case studies, underscoring the need for event and region-specific source information to improve impact assessment and deposition modelling in southwestern Europe.
Ephemeral lake beds (playas) are major global sources of atmospheric mineral dust, yet controls governing sediment availability and emission potential at fine spatial scales remain poorly constrained. This study presents the first in situ measurements of surface erodibility and potential PM10 emission fluxes from Etosha Pan, Namibia. Threshold shear velocities and PM10 emission fluxes were quantified using a Portable In-Situ Wind ERosion Laboratory (PI-SWERL) across five surface types spanning highly emissive hotspots to non-emissive consolidated salt crusts. Threshold shear velocities ranged from 0.38 m s(-1) on deflated clay-rich surfaces to >1.14 m s(-1) on recently inundated or cemented salt crusts, and PM10 fluxes at u(*) = 0.56 m s(-1) varied by more than three orders of magnitude. Emissions were highest where degraded efflorescent crusts exposed fine sediment, whereas halite-rich crusts exhibited greater mechanical strength and resisted wind erosion despite low surface moisture. X-ray diffraction analyses confirmed spatial variability in evaporite and silicate mineral assemblages, with halite abundance inversely related to dust emission potential. Antecedent hydrological conditions regulated sediment availability. Moderate wetting-drying cycles promoted weak, emissive crusts, whilst persistently wet or dry conditions were associated with continuous, resistant crusts and reduced emissions. Distinct emission regimes arose from differences in crust failure and saltation feedbacks, highlighting sub-landform-scale variability in dust sources. Crust dynamism, driven by spatial variability in surface conditions and antecedent hydrological regime, is identified as a key, under-represented control on dust emission. The relationships quantified here provide new empirical constraints for improving the representation of sediment availability in global dust modelling.
Understanding dune patterning on a landscape scale provides key insights into the controls shaping dune fields and requires robust methods that capture morphological patterns in a geomorphologically meaningful manner. This study presents a data-driven approach for the creation of dune pattern classification schemes and their mapping. We apply dimensionality reduction and clustering to 198 randomly distributed dune crest tiles to derive morphometric-based classification schemes for the planimetric dune patterns across the south-western Kalahari dune field. A convolutional neural network is trained on two newly generated and a foundational classification scheme to map pattern distribution across the study area. Maps based on the new schemes presented here reproduced some broad spatial trends from previous work, like the shift from straight, parallel ridges in the north to dendritic patterns in the south. We further characterise the defining morphometrics and morphometric signature of classification schemes and pattern types, finding that orientation range is the dominant discriminating morphometric. Based on model uncertainty, we locate transitional zones between patterns in the study area. We argue that these are the most geomorphologically meaningful product of the classification: their recurrence across schemes suggests that they may reflect changes in boundary conditions that have shaped dune morphology.
The lower Mesopotamia and Kuwait exposed to human pressures and environmental changes and described as one of the main natural sources of dust worldwide, influencing nearby cities. The challenges of undertaking field studies in the region, due to access difficulty and source location uncertainty, have hindered identification of the specific geomorphic units that act as significant dust sources. The capability of high-resolution satellite data to pinpoint small-scale dust-emitting units now enables precise surface identification, which is crucial for understanding the spatial variability and controls on dust emissions. Launching Sentinel 2 A-B in 2015 and 2017 and Landsat 7-9 in 1999, 2013 and 2021 means the possibility of systematic high-resolution monitoring every 3-4 days at 10-15 m2 (pixel size), is now possible. This paper aims to identify dust-emitting units in lower Mesopotamia and Kuwait (2013-2023) within a regional context, based on a systematic analysis of I) MODIS\VIIRS data associated with wind data to identify the regional dust sources and dynamics, II) Sentinel-2\Landsat 7-9 data to pinpoint the exact dust sources and their geomorphic units, and III) MODIS Aerosol Optical Depth (AOD) to identify the relative magnitude of dust emission from each identified unit. The dominant dust-emitting geomorphic units, primarily located in southern Mesopotamia and along the northern coastline of Kuwait, include inland sabkhas and barchan sand dunes in Al-Batha, generating 62% (number of events = 446) of dust events, the intertidal zone of Subiya (11%, n = 76), coastal sabkhas and muddy flats in Bubiyan Island (10%, n = 68), the estuarine environment of Al-Faw (9%, n = 61). These units, many with crusted or moisture-affected surfaces, were previously generalized or overlooked in regional assessments. Seasonal trends indicate that dust emissions peak in June and July, driven by prevailing wind speeds exceeding 6.5 m/s and AOD values reaching up to 0.6. Collectively, these units cover approximately 2.5% (2743 km2) of the total research region (111,042 Km2) and amounted to about 651 dust events over 11 years, offering a more refined and spatially explicit understanding of dust sources at high spatio-temporal resolution.
Wind erosion is a major contributor to land degradation, and its accurate assessment relies critically on the erodibility factor. Yet, the erodibility factor widely used in dust models is quite uncertain. In this study, we developed an improved erodibility factor and incorporated it into the Integrated Wind Erosion Model System (IWEMS) and the Dust Entrainment and Deposition (DEAD) model to simulate wind erosion and dust emissions across China from 2000 to 2023. Validation against field measurements of sand and dust flux showed that the improved erodibility factor substantially enhanced model performance. Specifically, the Root Mean Square Error (RMSE) of sand flux decreased from 4.33 kg/m/d to 0.92 kg/m/d, and the Relative error (Re) decreased from 74.56% to 1.54%, while lowering the RMSE of dust flux from 1.04 g/m2/d to 0.75 g/m2/d and its Re from 18.03% to 1.67%. Long-term results reveal pronounced spatial heterogeneity and seasonal differences. Sand and dust emissions peak in spring and are lowest in summer. Spatially, the highest emissions consistently occur in major deserts, gobi regions, and sandy lands, with additional high-emission zones on the Qinghai-Tibetan Plateau. Scenario comparisons further illustrate that land-use changes since 2000 have reduced potential erodible surfaces and consequently lowered dust emissions in Northern China. Overall, this study provides a refined erodibility framework for long-term wind erosion assessment and offers quantitative evidence on how land-surface characteristics influence sediment availability at regional scales. The improved erodibility factor can serve as a fundamental dataset for future soil erosion modeling and land-degradation evaluations.
Accurate identification of dune crestlines on Mars is crucial for understanding morphodynamic processes and environmental conditions. Although reliable crestline extraction has been achieved in morphologically simple dune fields with limited external disturbances, and three mainstream approaches—Digital Image Processing (DIP)-based methods, Digital Terrain Analysis (DTA)-based methods, and Deep Learning (DL)-based methods—have been established, comparative studies of these methods under consistent Martian conditions are still lacking. Moreover, uneven illumination, background interference, and diverse dune types are common on Mars, making automated crestline extraction particularly challenging. In this study, we select dune fields under three types of common complex conditions and conduct a systematic evaluation of the applicability of the three methods using high-resolution imagery and corresponding digital terrain models (DTMs). Results show that the DIP-based method accurately captures crestline position and shape, but its vulnerability to external interferences and intrinsic dune characteristics, resulting in frequent false detections. The DTA-based method is unaffected by illumination, effectively preserves crestline continuity and completeness, and demonstrates strong stability and generalization capability, but is prone to misidentifying terrain features resembling crestlines, and has limited positional accuracy. The DL-based method performs well in distinguishing crestlines from non-target features and generally produces high-quality outputs, but suffers from omissions and local discontinuities, and shows limited generalization capability. This study provides a comprehensive methodological reference for automated dune crestline extraction on Mars and offers valuable insights for aeolian geomorphological investigations on other planetary bodies.
Each year, huge quantities of silt-sized (<63 & micro;m) sediments are emitted from the Sahara and transported all over the world. Reconstruction of air circulation and identification of source area(s) are the key issues in aeolian research. Here, we propose a microtextural analysis of dust-forming silt grains as an effective tool for reconstructing the source(s) of airborne sediments and the formative processes of silt grains. We analyzed more than 1,000 grains collected in different locations in the Iberian Peninsula during the extreme dust storm that occurred between March 14 and 18, 2022. The examination using a scanning electron microscope included determination of the grain size, recognition of the general appearance of grains (microtextures), their shape and degree of encrustation. HYSPLIT and MONARCH models were used to track the air circulation of the studied event. The studied samples show different microtextural composition, i.e. various proportions of grains with fresh, etched, encrusted and/or cracked surfaces. The results suggest that the majority of the sediments carried in the studied dust storm originated from the alluvial and paleolakes deposits. Considering the distribution of such deposits in the Northern Sahara, we conclude that dust emissions from areas located south of the Northern Sahara must have actively contributed to the studied event. These are, in particular, areas located in the Sahel Zone, mainly in its northern part-Chad, Niger, Mali, and Mauretania. Dust emitted from the Sahel zone mixed at higher altitudes with dust emitted from the Northern Sahara, and traveled as a heterogenous dust plume.
Predicting aeolian sand transport in the atmospheric surface layer (ASL) is difficult because turbulence-driven intermittency produces hysteresis and burst-like saltation. This study develops an interpretable machine learning framework for aeolian transport event detection using high-frequency wind and saltation flux measurements. The analysis compares raw velocity components, first-order statistics, fluctuation velocities, and second-moment derivatives including friction velocity (u*) and turbulence intensity (TI). Model performance was benchmarked across averaging windows and heights and interpreted using SHapley Additive exPlanations (SHAP) to quantify the contribution of individual features to model predictions. Streamwise velocity emerged as the strongest predictor, with importance peaking near the surface and reemerging aloft where reduced dissipation provided cleaner signals. Rolling-window aggregates of first-order statistics achieved superior accuracy to raw inputs and the Time Frequency Equivalence Method, with optimal performance at a 30 s window that matched the velocity decorrelation timescale. Fluctuation velocities alone yielded poor results but enhanced predictive skill when combined with first-order statistics, with sweeps and outward interactions dominating saltation initiation. Models based on u* and TI achieved comparable accuracy but required longer windows (300 s), and SHAP analysis indicated that features derived from near-surface winds, including u* and TI as well as fluctuation components, ranked highest in importance. Overall, the framework improves predictive accuracy beyond traditional methods, preserves physical interpretability, and offers valuable insights for feature selection, measurement strategies, and atmospheric monitoring of aeolian processes.
Relative height is a key landform indicator of dunes, and topographic barriers exert a significant effect on it; however, the quantitative assessment of the topographic barrier effect remains to be improved. Three discrete deserts were selected as the study areas. Landform indicators, including relative dune height, transverse distance, longitudinal distance, and mountain ridge height, were calculated using digital terrain data. Results show that: (1)Topographic barriers control the maximum relative dune height; (2)Mountain ridge height and maximum relative dune height exhibit a linear relationship, with a slope of approximately 0.93 in the Matartag area. There exists an effective range of mountain ridge height that influences dune development. The relationship between transverse distance and maximum relative dune height conforms to the form of a normal distribution density function. When dunes are fully developed, the relationship between longitudinal distance and maximum relative dune height follows a negative exponential function; when dunes are underdeveloped, their relationship conforms to a Burr distribution. The influences of various factors on relative dune height can be summarized as the mountain height effect, transverse distance effect, and longitudinal distance effect; (3)The impact area of topographic barriers on dune height can be delineated using relative dune height as a threshold (>37 m in the Matartag area), and the impact boundary is a function of transverse distance and mountain ridge height. This study enable the quantitative assessment of the magnitude and extent of the topographic barrier effect, and can also be applied to the quantitative attribution of dunes with complex origins.
In this paper, laboratory experiments of sand grains lifted by an electric field at different relative humidities were carried out. The electric field threshold, Eth, which is the lowest electric field that can lift sand grains in a relative humidity range of 10% to 80%, was experimentally obtained. The experimental results show that Eth decreases with increasing relative humidity for the given grain size, while it remains a constant when the relative humidity exceeds 60%. Based on the kinematics, it can be concluded that the inter-grain bonding forces exhibit the same trend in the relative humidity. An empirical formula of Eth is proposed, which is a function of the sand size and the relative humidity. By the trajectory image processing method, the charges of the lifted sand grains induced by the electric field were measured. It was found that the charges carried by an individual sand grain are independent of the relative humidity, and an empirical formula for the charges carried by an individual sand grain lifted by electrostatic force was obtained. The experimental method used in this paper is reproducible, and can be applied to investigate the dependence of charging characteristics and inter-grain bonding forces of other grains on relative humidity.
