Aeolian Sand Research Articles

The role of abrasion and resident fines in dust production from aeolian sands as measured by the Portable in situ Wind Erosion Laboratory (PI-SWERL)

Aeolian deposits are important sources of atmospheric dust, particularly from extensive dune fields, interdune areas and vast sand sheet deposits across the globe. This study quantified the total suspended particle flux (TSP), particulate matter <10 μm (PM10) and PM2.5 emissions with the Portable in situ Wind Erosion Laboratory (PI-SWERL) for eighteen different types of sand to determine the role of aeolian abrasion in dust production. Aeolian abrasion results in grain coating removal, chipping, and spalling of sand grains during saltation transport, producing dust-sized particles. The studied sands were poorly- to well-sorted, round to angular, coarse to fine sand composed of quartz-rich to gypsum-rich particles. Some sand samples contained up to 14 % silt and clay, referred to as resident fines. Experiments on sand with diverse characteristics elucidated dust production processes. Samples composed of 100 % sand produced dust by aeolian abrasion with fluxes of 0.2–2.5 mg m−2 s−1 indicating aeolian abrasion as a potentially important process contributing to dust storms and desert loess deposits. Sand containing resident fines produced up to 42 mg m−2 s−1, an order of magnitude more dust than clean sand samples, with >60 % of the dust produced by the release of silt and clay and up to 40 % from aeolian abrasion. These high fluxes rival dust storms emanating from playas like Owens Lake in California. Climate change and anthropogenic disturbance of stabilized aeolian sand deposits in arid lands will likely result in increased dust emissions in the future which should be parameterized in climate models.

Investigation of Small Strain Dynamics in Modified Aeolian Sand under Vibration Triaxial Conditions

By utilizing vibration triaxial tests, this study analyzed the effects of various factors, such as confining pressure, consolidation ratio, and silt content on the elastic modulus and damping ratio of silt-modified aeolian sand under conditions of minor deformation. The results indicate that with increasing confining pressure and consolidation ratio, the dynamic elastic modulus of improved aeolian sand gradually increases, while the damping ratio decreases progressively. The dynamic elastic modulus growth rate of untreated aeolian sand demonstrates a positive correlation with confining pressure, while the corresponding rate for the modified aeolian sand by adding cement and silt exhibits an inverse correlation with confining pressure. As dynamic strain increases, the dynamic elastic modulus decreases and approaches a stable value. The damping ratio rises at a diminishing rate and eventually stabilizes as dynamic strain continues to increase. The dynamic stress-strain backbone curve of the modified aeolian sand follows a theoretical hyperbolic model, while the small strain dynamic behavior is consistent with the Hardin-Drnevich model.

Record of aeolian processes in Pleistocene deposits in the foreland of the European sand belt

Abstract This article presents the degree of aeolization of Pleistocene deposits in the foreground of the European sand belt in southern Poland. Ten of the 13 sites were established in the Oświęcim Basin and three in the south part of the Silesian Upland. Attention was focused on four types of deposits formed during three glaciations (Sanian, Odranian, Vistulian): boulder clay, fluvioglacial sands and gravels, end moraine deposits, and aeolian sands. Quartz grain abrasion (for the 0.8–1.0 mm fraction) was examined by mechanical graniformametry and the morphoscopic method. The record of aeolian processes in analyzed deposits is the presence of quartz grains RM (very well-rounded and mat) and EM/RM (moderately rounded and mat). They were found in deposits of various origins and ages but in variable proportions. Considering only the average percentage of grains RM, it should be regarded that abrasion of deposits is low in the case of fluvioglacial deposits, moderate in the case of glacial deposits, and good in the case of aeolian deposits. However, the key factor in determining the degree of abrasion is the share of EM/RM grains, which in the abovementioned deposits are seven, three, and twice as many as RM grains. Therefore, the most noteworthy research result is the very high total share of grains with aeolian abrasion (RM + EM/RM), amounting on average to 84.1% for Odranian fluvioglacial deposits, 86.7% for Sanian glacial deposits and 92.6% for Late Glacial aeolian deposits. It means that in the study area, glacial and fluvioglacial transport included deposits with good aeolian abrasion obtained in the periglacial environment before the transgression of the ice sheets. Probably due to the longer persistence of periglacial conditions in southern Poland, compared to its central and northern parts, the degree of aeolization of fluvioglacial and glacial deposits is better. At the same time, there is a significant differentiation in the aeolization of fluvioglacial deposits within the outwash plain in the foreland of the maximum extent of the Odranian ice sheet. In its proximal part, near the front of the ice sheet, fluvioglacial deposits are characterized by much worse abrasion of quartz grains than in the distal part.

Long‐Term Landscape Evolution in Response to Climate Change, Ecosystem Dynamics, and Fire in a Basaltic Catchment on the Colorado Plateau

AbstractPredicting responses of semi‐arid to montane landscapes in southwestern North America to ongoing anthropogenic changes requires understanding of past interplay among geomorphic, ecologic, and climatic factors. This study utilizes modern weathering and sediment transport processes to inform the interpretation of a 250‐kyr lacustrine sediment record of paleoecology, hydrology, and erosion from a small, closed basin, basaltic catchment on the southwestern edge of the Colorado Plateau. Geochemical and mineralogical analyses of bedrock, colluvium, and lake sediments indicate that clastic sediments in the basin are a mixture of local physical weathering products (albite and ilmenite) and eolian dust (quartz, illite, and zircon). Dust fractions increase during glacial periods coincident with lower overall sedimentation rates, suggesting this pattern results from decreased local erosion rates and not increased dust deposition. Titanium counts from X‐ray fluorescence core scanning, a proxy for ilmenite content, traces past local erosion rates. The highest erosion rates, inferred from the highest Ti counts, follow climatic transitions toward interglacial conditions (Marine Isotope Stage 5e, 3a, and the Holocene), periods characterized by vegetation changeover (observed in the core's palynology), higher temperatures (piñon‐juniper‐oak pollen abundance), lower effective precipitation (shallow lake facies), and increased wildfire activity (microscopic charcoal particle counts and sizes). While brief inferred episodes of erosion occur following abrupt transitions to cooler and wetter conditions, indicated by the abundance of subalpine tree (spruce and fir) pollen and deeper lake facies, landscapes appear more stable during glacial periods. This long‐term perspective suggests that aridification and resulting vegetation succession and increased wildfires will increase erosion rates in similar settings regionwide.

An Auto-Detection and classification algorithm for identification of sand dunes based on remote sensing images

Dunes are among the most abundant aeolian landforms found on Earth and other planets. The automatic mapping of dunes over large-scale areas is crucial for predicting, monitoring, and managing lands threatened by sand encroachment. However, the spectral similarity between dune and inter-dune areas, as well as the diverse presentations of dunes of the same type, have made it challenging to automatically classify and map dunes. In this study, we propose a two-step 'detect-then-classify' framework that enables the automatic identification of heterogeneous dune types. The first step involves dune detection. We introduce a newly developed convolutional neural network called SandUnet, which is adapted from Attention U-Net. This network is designed to preserve uncompressed input signals ensuring that minor differences in the color and texture of the dunes are retained. The second step focuses on dune-type classification. To classify dunes, a fine-tuned MobileNet was constructed to integrate the wealth of knowledge ingrained in MobileNet's pre-trained layers with the adaptations tailored specifically for the sand dune images. Subsequently, each dune image is automatically classified into six different types using this framework. By applying this framework to all the bare sand areas of the Taklamakan (or Taklimakan) Desert using Landsat-8 imagery, the final classification of dune types of the desert was achieved. Testing on randomly selected 10% image patches of whole desert, the overall accuracy of the dune-type classification is 70%. This study presents an automatic and economical solution for identifying dunes in large-scale areas.

Weathering Saharan dust beyond the Spanish Mediterranean Basin: An interdisciplinary dialogue

This interdisciplinary dialogue draws on climatology and cultural studies to explore the phenomenon of “Saharan dust” that passes through and beyond the Spanish Mediterranean Basin. The dialogic process seeks to unearth the power relations within which weather stories and the authors are always already entangled, with a view to re-imagining weather writing and climatic storytelling in decolonial terms. Our parallel inquiries trace how origin stories, material mobilities, atmospheres, and environmental regulation work to codify the aeolian dust as an intrusion across borders. Drawing on critical theory, we argue that this weather “from” the Sahara Desert is othered in Eurocentric weather narratives, mapping onto geopolitical logic of “Fortress Europe”. Our research is instructed by postcolonial thought, political ecology, and the speculative feminist position of weathering. Through critical engagement with science in context, we dwell lastly on African air quality and experiences of weathering atmospheric dust further upwind. Our concluding comments speculatively drift with Mediterranean winds to animate a positionality of middleness.

Aeolian Sediment Transport Responses to Vegetation Cover Change: Effects of Sampling Error on Model Uncertainty

AbstractAlthough it is widely known that observations of aeolian sediment transport are susceptible to large sampling errors, sample designs are frequently used that do not sufficiently reduce the measurement uncertainties inherent in the study of aeolian processes. Here, we examine the influence of sample size (n) and sampling location on uncertainty in models of aeolian sediment transport responses to vegetation cover change. We compare measurements from a stratified random array of 27 horizontal sediment mass flux samplers to vegetative cover data collected at a 1 ha site over a period of nearly 6 years. To assess the sensitivity of modeled relationships between aeolian transport and vegetative cover to sample design, we analyze statistical regressions for all possible combinations of sample size and sampler locations. We show that at least 17 randomly located samplers are needed to consistently capture the sediment mass flux response to vegetative cover change. We found that multiple statistically significant models can describe the sediment flux‐vegetative cover relationship when using smaller sample sizes, demonstrating the risks of inferring sediment transport response from an underpowered sample design. Across vegetative functional groups, we found that woody cover generally influenced aeolian sediment transport rates more than herbaceous cover, while model uncertainty at large sample sizes (n &gt; 17) showed the limitation of using vegetative cover as an indicator of aeolian sediment transport. Our results suggest an evaluation of sampling practices in aeolian sediment transport studies may be needed to avoid inferential errors that are likely pervasive in this field of study.

Dust deposition in agricultural landscapes: Temporal and spatial dynamics along a transect into a natural forest patch

This work presents the results of the deposition rate of aeolian sediments within a forest patch of semiarid Argentina. The goal of this study was to evaluate the spatial and temporal dynamic of the dust deposition rate (Dr), mainly of the mineral fraction. Passive collectors were installed along transects in a forest patch at 5, 15, 25, 50, 100 and 300 m downwind from the border of an agricultural plot. The average Dr during 30 months was 38.3 ± 26.8 g m−2 yr−1. Dr was statistically similar between spring-summer (47.5 ± 30.1 g m−2 yr−1) and the autumn–winter period (29.2 ± 21.7 g m−2 yr−1). The mean diameter of sediment particles was higher in spring-summer (70 µm) than in autumn–winter (50 µm), probably due to the greater contribution of coarser sediments from wind erosion of surrounding agricultural soils (local source) during spring-summer. During both periods silt-sized particles (40 %) and very fine sand (20 %) were the most abundant, while clay content was 3.5 %. Clay and silt contents were higher in autumn–winter, while fine sand content was higher in spring-summer. Dr within the forest patch was highly variable, therefore statistically homogeneous, despite the fact that 300 m inside the forest the average Dr was ≈35 % lower than at 5 m from the agricultural plot. Sediment deposited at the forest border showed higher aggregation than the sediment collected inside the forest. Forest patches are capable of retaining particles that are key for the soil fertility of semiarid areas, highlighting the importance of aeolian source-sink processes and of forest patches for long-term management decisions in agricultural landscapes.

Study on the deterioration characteristics of aeolian sand concrete under the coupling effect of multiple factors in harsh environments.

This study takes the aeolian sand concrete as a research object, uses the relative dynamic elastic modulus to study its macro characteristics, and combines nuclear magnetic resonance、scanning electron microscope to study its pore characteristics and micro morphology under the action of prestress, freeze-thaw and salt intrusion. The results show that with the increase of the amount of aeolian sand, the dynamic elastic modulus of aeolian sand concrete shows a pattern of first decreasing, then increasing, and then decreasing; when no prestress is applied, the porosity of aeolian sand concrete first increases, then decreases, and then continues to increase. Among them, the porosity of aeolian sand concrete with a 40% content of aeolian sand decreases by 0.06% compared to that with a 0% content of aeolian sand, and decreases by 0.003% compared to that with a 60% content of aeolian sand; with the increase of prestress, the porosity of aeolian sand concrete with the same amount of aeolian sand increases gradually with the increase of damage degree. The porosity of concrete with 40% aeolian sand content increases by 0.33% when the damage degree is 0.0 compared to 0.3, with a 6.31% increase in the number of multi damage pores; under the coupling effect of multiple factors, when the amount of aeolian sand is 40%, the damage degree of the four groups of aeolian sand concrete before and after the coupling effect is 0.0, 0.1, 0.2, and 0.3, respectively, increases by 25.8%, 32.2%, 73.8%, and 85.8%, respectively; under the coupling effect of multiple factors, the content of aeolian sand is 60%, the damage degree is 0.2 and 0.3 groups, and the content of aeolian sand is 20%, the damage degree is 0.3 groups, which does not meet the standard requirements; under the coupling action of stress, freeze-thaw, salt intrusion and the amount of aeolian sand, the filling effect of aeolian sand on the internal pores of aeolian sand concrete decreases first, then increases, and then decreases with the increase of the amount of aeolian sand. The filling effect is further weakened after the action of stress. After the superposition of freeze-thaw and salt intrusion, the coupling effect of water and salt solution in frost heaving medium makes the variation law and range of physical and chemical characteristics of aeolian sand concrete show a great difference.

The Cretaceous palaeodesert of the Sanfranciscana Basin (SE Brazil): A key record to track dissolved evaporites in the West Gondwana

Extensive palaeodeserts are known from the intracontinental basins of South American Platform, simultaneously to volcanic activity and thick salt beds developed during the rifting phase of Brazilian coastal basins. Based on palaeoenvironmental conditions and modern analogues, it would be expected that Cretaceous evaporites were frequently described in the intracontinental basins of West Gondwana, however, such deposits are rarely mentioned. This work evaluated the recognition and role of evaporitic-related features as palaeoclimatic/palaeoenvironmental proxies, through outcrop-based facies, X-ray diffraction and petrographic analyses of the Areado Group (Lower Cretaceous), Sanfranciscana Basin, southeastern Brazil. The Areado Group stands out as a remarkable record of evaporitic-siliciclastic interactions, consisting of alluvial, lacustrine and aeolian deposits. The stacking pattern reflects the progressive drying-up of the Sanfranciscana Basin during Cretaceous times. Regardless salt dissolution, the Areado Group comprises pseudomorphs after evaporites, evaporitic moulds, sand patch-fabric, and replication of the microtopography of efflorescent crusts. Preservation of evaporitic features in the Areado Group was controlled by the unique geological context of the Sanfranciscana Basin, which was submitted to syndepositional/eodiagenetic cementation and pseudomorphism, along with rapid burial caused by the progradation of aeolian dunes. Equivalent sedimentary structures and morphological aspects also occur in other Cretaceous palaeodeserts of intracontinental basins throughout Brazil. Timing of salt dissolution and isovolumetric/non-isolumetric replacement are important controlling factors on the geological record of evaporitic-siliciclastic systems that undergo post-depositional modifications. The database provided here indicates that playa lake deposits are commonest than traditionally represented in the non-marine Cretaceous record of the West Gondwana and other similar settings worldwide.

Aeolian–lacustrine margins: implications for carbon capture and storage within the Rotliegend Group, Southern North Sea

The Southern North Sea Basins of the United Kingdom were renowned for their hydrocarbon resources and exploited extensively from the 1960s to the 1990s. The Permian Leman Sandstone in particular formed an excellent reservoir due to its extensive clean aeolian sediments and was subsequently explored for decades, resulting in a wealth of subsurface data that are now widely accessible. The strata of the Leman Sandstone comprises mixed continental deposits from aeolian, fluvial and lacustrine environments which interfinger with the saline lake deposits of the Silverpit Formation. With the potential reassessment of depleted gas reservoirs in the North Sea for use as sequestration targets for captured carbon dioxide, there is significant renewed interest in the reservoir geology of the Leman Sandstone. A regional study of the sedimentology and petrophysical properties of the Leman Sandstone and Silverpit formations within quadrants 43, 44, 48 and 49 of the Southern North Sea has been conducted. Multiple interactions between the depositional environments are observed, resulting in a complex interplay between aeolian and lacustrine transgressive/regressive events, and migration and expansion/contraction of the fluvial system. In wireline petrophysical data, each depositional environment, along with their transitional environments, form relatively distinct clusters that can be used as a predictive tool for reservoir interpretation in the absence of core, despite extensive sediment recycling between environments.

Modern periglacial eolian deposits and landforms in the Søndre Strømfjord area, West Greenland and their palaeoenvironmental implications

Modern fluvio glacial sediments in two east-west oriented valleys between Søndre Strømfjord Air Base and the Inland Ice (West Greenland) are partly redeposited by eolian activity. Topographic barriers have induced an areal distinction between sandy and silty eolian sediments. Morphological and sedimentological investigations enable a facies analysis of these rare, active cold-climate eolian deposits and a comparison with the extensive Pleistocene sand sheets and loess deposits of Europe.&#x0D; Eolian processes are active throughout the year in a dry cold-climate environment. Accumulation of eolian material on the eolian sand sheets and silt covers mainly takes place in summer, whereas deflation and redeposition is dominant in winter. Meteorological conditions (especially thickness of snow cover) may prevent eolian activity.&#x0D; The vegetation on the sand sheets adapts itself to the intensity of the eolian activity. Vegetation is scarce in the low areas near the active flood plains where deflation is intensive, whereas the downwind depositional areas are more densely vegetated. Only a few species play an active role in the formation of small phytogenic dunes, which are characterized by a low preservation potential. Similar conditions are envisaged for the extensive Pleistocene sand seas of northwestern Europe.&#x0D; A characteristic sedimentary sequence occurs in downwind, upslope direction. Fluvio-eolian deposits on and near the active flood plain are characterized by horizontally bedded eolian sand interbedded with fluvial deposits. The latter are partly winnowed by eolian activity leading to inversely graded lamination. Horizontal bedding of fine-medium grained sand interbedded with thin coarse-grained strata is the proximal facies of cold-climate eolian sand sheets. Within-bed structures are dominated by plane bed lamination. A more homogeneous (fine-medium grained) horizontally bedded sediment, comparable to that dominating in the extensive Pleistocene sand sheets, represents the distal facies of these sand sheets.&#x0D; The uplands are covered by eolian silt deposits. These are coarser than 'typical' loess and lack other loess characteristics. This is explained by the local source area and the short transport distance. These 'proximal loess' deposits are mainly deposited on the windward side of the valley walls due to blocking of dust-laden airflows by these topographic barriers. The primary micro-lamination in these deposits may also have been present in the Pleistocene loess deposits.

Tracing provenance of eolian sands in the northern Ulan Buh Desert, China: Evidence from the REE geochemical characteristics

Desertification is a primary threat to crop farming, the livestock industry, and the eco-environment in northwestern China. Through field research and satellite imagery, it has been discovered that there are 4–5 sand belts in the shape of handclasps connecting major deserts in the Alxa Plateau region of northern China. These sand belts have been expanding for several decades. However, eolian sand transport between major deserts through these expanding sand belts is still underestimated. Identifying the source areas of eolian sands in deserts provide essential knowledge to prevent desertification. In this study, we collected samples from the northern Ulan Buh Desert (UBD), the Yamalik Desert (YD), and the Langshan Mountains and analyzed their REE contents in the <125 μm fraction. We compared REE geochemical characteristics of fine-grained sands in the UBD with other recently published REE data for potential source areas. Our findings indicate that the primary origins of fine-grained sands in the northern UBD are from the Qilian Mountains (QM) and Badain Jaran Desert (BJD), which are transported through the YD. Contributions from the Gobi-Altay Mountains to the north are relatively minor. The Langshan Mountains and Hawula Mountains are not considered as the primary sources of fine-grained sands in the UBD. In contrast, surface sediments in the southern UBD have a local mixture of the paleo-lacustrine deposits, the Gobi sediments, and minor external inputs from the BJD and QM. Our findings demonstrate that sand belts connecting these deserts play a crucial role in the eolian transport of fine-grained sands. Therefore, both the Chinese government and scientists should pay close attention to them in future efforts to combat desertification.

Comparative study on cavernous weathering features formed by coastal processes and acidic alteration: Implications for rounded pits on Martian rocks

Surface images taken by rovers and landers show the existence of rounded pits with diameter of centimeters on Martian rock surfaces. These pits seem to be similar to terrestrial cavernous weathering features, generated by salt weathering (e.g., alveoli), or by stream flow erosion (e.g., potholes), found near coastal areas. Alternatively, if the weathered rocks contained carbonate minerals, the pits might have been formed by acidic weathering. Here, we compare geomorphology of cavernous weathering features formed by coastal processes on Earth and by laboratory experiments simulating acidic weathering of carbonate. Our field observations for coastal areas of the Japanese islands show that a high cavity number density and small cavities characterize cavernous features formed by salt weathering as compared with those formed by stream flow. Our experimental results show that acidic weathering can generate cavernous features, with high number densities and small diameters. Based on principal component analysis, cavernous weathering features formed by salt weathering, stream flow, and acidic alteration can be distinguished mainly by the number density and diameter. By applying our approach to Martian rocks, we find that the morphological characteristics of rounded pits on Jezero Crater rocks are different from the above cavernous weathering features, and that the Martian pits are categorized as being intermediate between cavernous features formed by salt weathering and acidic weathering. If the pits on Jezero Crater rocks were formed by salt weathering, salt weathering on Mars could have been less effective (possibly, due to a difference in water salinity or salt composition) than those found in coastal areas of Earth. Alternatively, these Martian pits might be formed by other processes (e.g., vesicles in volcanic breccia, eolian processes, or freeze-thaw cycles of porewater).

Impermeability and Durability of Self-Compacting Concrete Prepared with Aeolian Sand and Recycled Coarse Aggregate

Impermeability and Durability of Self-Compacting Concrete Prepared with Aeolian Sand and Recycled Coarse Aggregate

Study on the Attenuation of Long-Term Skid Resistance of Asphalt Mixtures under Aeolian Sand Conditions

In this work, the long-term skid resistance attenuation law of asphalt mixtures in the presence of aeolian sand was studied. Four types of asphalt mixtures underwent skid resistance abrasion tests using an accelerated loading tester. The pendulum value (BPN) and structure depth (MTD) of these four mixtures were determined under various conditions of sand density and abrasion times. The correlation between the BPN and density and the number of times of abrasion were investigated, respectively, to analyze the skid resistance attenuation law at the microscopic and macroscopic levels. Our results indicate that the skid resistance of the four types of asphalt mixtures initially decreased and subsequently reached a stable state. Sand density primarily influences skid resistance during the initial stage, while the number of abrasions becomes the dominant factor affecting skid resistance in the later stages.

Wind erosion after steppe conversion in Kazakhstan

Semi-arid regions of Central Asia suffer from wind erosion due to expanding steppe conversion and unsustainable farming practices. Empirical data from field observations are needed to support the implementation of adapted management. In this study, a mobile wind tunnel was used for the first time in Kazakhstan to assess the soil's erodibility under real conditions. Field experiments were conducted on loamy sands with different initial conditions that are typical for the most erosive time of the year: a bare surface with a cloddy structure after recent steppe conversion, a weak crust on a plot with barley (Hordeum vulgare L.), and a plot with loose material in the rows of maize plants (Zea mays L.). Subsequently, different levels of mechanical stress (low, moderate, high) were considered to analyze the effect of disruptive forces soils experience during field cultivation (light cultivator, disc harrow, tractor tires) on possible soil losses. The results of wind tunnel experiments showed already great differences under initial conditions. The cloddy structure of the recent steppe conservation had the lowest susceptibility against wind erosion due to a good aggregation and a large roughness, resulting in soil loss of 12 g m−2. The plot grown with barley was less affected by wind erosion due to the weak crust, smaller distances between plants, and leaves close to the ground (soil loss of 34 g m−2). Maize was also the most problematic crop in the study area because wind can blow below the plant canopy without considerable resistance during the early growth stages. Additionally, existing deposits in the maize rows from previous erosion events led to the highest soil loss of 1609 g m−2. Mechanical stress by seedbed preparation generally increased the erodible fraction, resulting in higher soil losses (light cultivator: 198 ± 129 g m−2, disc harrow: 388 ± 258 g m−2). The most severe disruption of soil structure occurred on tractor tire tracks, causing a loss of 2767 ± 1810 g m−2. Consequently, the pulverizing effect of tractor tires on dry soil must be considered a serious emission source. Comparing the soil organic carbon content of topsoil and eroded material showed that organic carbon was enriched only in the aeolian sediments of the recently converted plot (+69%). We conclude that soils after steppe conversion need to be treated with particular care from the very beginning so that severe events from the past are not repeated.

Aeolian dust movement and deposition under local atmospheric circulation in a desert-oasis transition zone of the northeastern Taklimakan desert

Taklimakan Desert, in the northwest China, is one of the main sources of dust storms in the world. Frequent dust storms have seriously affected the ecological environment of surrounding oases. Quantification of dust deposition on the different underlying surface is vital to understand the local atmospheric cycling and its effect on movement of the dust particles in desert fringe areas. To examine the contribution of airflow from different direction to the dust deposition rate, the desert–oasis transition zone between the Korla oasis and the northeast edge of the Taklimakan desert is selected as the study area. 36 h backward trajectories of air masses arriving at the study site from 1st March to 31st May 2023, were determined by using the HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model) model. The trajectories were categorized by k-means clustering into 3 clusters, which show distinct features in terms of the trajectory origins and the entry direction to the site. Dust collection tank were placed on five underlying surfaces from south to north: shifting sand desert, semi-shifting sand desert, desert vegetation, shelter forestland and croplands at the height of 0.2 m, 0.5 m, and 1.5 m. At the each of height, four dust collection tanks were arranged to collect the dust from 4 directions. Results show that, air masses from the south with highest frequency (46 days) and highest dust storm occurrence (91.3 %) is the main contributor of dust particles to the study area. Dust deposition rate on different underlying surfaces showed a significant decreasing trend from the desert to oasis, and the dust deposition on all underlying surfaces decreased with the height. Dust deposition corresponding to the southward wind direction is the highest, and the amount of fine dust particles are increased with the height of the dust collection tank. The results of this study could be helpful to forecast the potential occurrence and mowing pathway of dust storms, which can provide the basis for mitigation of the negative effects on the environment.

Aeolian dust and hydro-biological characteristics: Decoding dust storm impacts on phytoplankton in the northern Arabian Gulf

Aeolian dust is an essential source of growth-limiting nutrients for marine phytoplankton. Despite being at the core of the Global Dust Belt, the response of the Arabian Gulf ecosystem to such atmospheric forcing is rarely documented. Here, the hydro-biological effect of mineral dust was studied in the northern Arabian Gulf (NAG) off Kuwait through monthly water sampling (December 2020 to December 2021), dust-storm follow-up sampling, and mineral dust and nutrient addition in-situ experiments. The multivariate analysis of oceanographic data revealed pronounced hydro-biological seasonality. The mineral dust deposition during two severe dust storm events in March and June 2021 showed a spatially varying effect of dust on coastal waters. The dust storms elevated the surface dissolved iron levels by several magnitudes, increased the dissolved inorganic nitrogen and phosphorous levels, changed their stoichiometry, and offset the hydrobiological seasonality. In the microcosms, dust input temporarily reduced phytoplankton phosphorous limitation in a dose-dependent manner when mesozooplankton (copepods) grazing was minimal. The microphytoplankton response to mineral dust inputs was comparable to that with nitrogen and phosphorous treatment. While Both treatments increased diatom size structure and biomass, the abundance of single-celled diatoms was comparatively higher in dust treatment. Multivariate analysis indicated that dust deposition alters the hydrographical properties of the surface ocean during dust storm events. The effects, though transient, were traceable for 3–16 days post-storm in coastal waters. The response of the summer phytoplankton to these changes, if delayed or muted, should be interpreted with caution given the summer water column stratification, the high nitrogen: phosphorous ratio and the low phosphorous solubility of aerosol dust, and the complex pelagic microbial food web interactions in the NAG. This study thus underlines the importance of a multivariate approach in documenting the ecological implications of Aeolian dust storms on marine environments closer to the dust source regions.

Westerly aridity in the western Tarim Basin driven by global cooling since the mid-Pleistocene transition

To explore the relationship between the global cooling, westerlies, and central Asian aridity, we report ∼1.1 Ma local sedimentary environment changes according to physical-chemical parameters from an 800-m core (KT11) from the Kashgar region in the western Tarim Basin, China. Grain size end-member (EM) modelling is employed to quantify the processes of sediment transport and deposition. Four end members with modal values of 272 μm, 144 μm, 45.6 μm and 12.7 μm were extracted and explained 97.9% of the variance in the grain size data, corresponding aeolian dynamics, river energies, delta development and pedogenesis/long-term suspension components transported by wind or water, respectively. Four dominant sedimentation types, including lacustrine facies, delta facies, fluvial facies, and aeolian dunes, were identified through lithology and grain size frequency curves. The 1.1 Ma sedimentary successions experienced delta deposits interbedded with fluvial and aeolian deposits and lacustrines (1.1–0.6 Ma), alternating fluvial and aeolian facies with the occurrence of deltas and lacustrines (0.6–0.15 Ma), and aeolian facies interbedded with deltas and fluvial facies (0.15 Ma-present). Stepwise drying sedimentary conditions and enhanced desertification indicated by increasing rubidium/strontium ratios and proportion of aeolian sands, and decreasing total organic carbon since the past 1.1 Ma, implied intensified westerlies, likely resulted from ice volume expansion and ongoing global cooling according to geological record comparison and simulations during the Last Glacial Maximum compared to preindustrial conditions, which may have controlled the expansion of the permanent deserts in inland Asia. These persistent drying trends and intensified westerly circulation in arid regions during glacial periods after the mid-Pleistocene Transition indicated by larger amplitudes of aeolian sand proportion than prior to 0.6 Ma are similar to those in the interior monsoonal Asia, where the larger-amplitude of median grain size indicated enhanced Asian winter monsoon intensity and drier glacials.