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Nowadays, dried lake beds constitute the largest source of saline dust storms, with serious environmental and health issues in the surrounding areas. In this study, we examined the spatial–temporal distribution of monthly and annual dust events of varying intensity (dust in suspension, blowing dust, dust storms) in the vicinity of the desiccated Urmia Lake in northwestern (NW) Iran, based on horizontal visibility data during 2009–2022. Dust in suspension, blowing dust and dust storm events exhibited different monthly patterns, with higher frequencies between March and October, especially in the southern and eastern parts of the Urmia Basin. Furthermore, the intra-annual variations in aerosol optical depth at 500 nm (AOD550) and Ångström exponent at 412/470 nm (AE) were investigated using Terra/Aqua MODIS (Moderate Resolution Imaging Spectroradiometer) data over the Urmia Lake Basin (36–39°N, 44–47°E). Monthly distributions of potential coarse aerosol (AE < 1) sources affecting the lower troposphere over the Urmia Basin were reconstructed, synergizing Terra/Aqua MODIS AOD550 for AE < 1 values and HYSPLIT_4 backward trajectories. The reconstructed monthly patterns of the potential sources were compared with the monthly spatial distribution of Terra MODIS AOD550 in the Middle East and Central Asia (20–70°E, 20–50°N). The results showed that deserts in the Middle East and the Aral–Caspian arid region (ACAR) mostly contribute to dust aerosol load over the Urmia Lake region, exhibiting higher frequency in spring and early summer. Local dust sources from dried lake beds further contribute to the dust AOD, especially in the western part of the Urmia Basin during March and April. The modeling (DREAM8-NMME-MACC) results revealed high concentrations of near-surface dust concentrations, which may have health effects on the local population, while distant sources from the Middle East are the main controlling factors to aerosol loading over the Urmia Basin. [ABSTRACT FROM AUTHOR]

Introduction The formation and occurrence of any climatic phenomenon require conditions that, when the sum of these atmospheric and environmental conditions occur simultaneously, make it possible for the phenomenon to form and occur. Depending on the type of phenomenon, some of these atmospheric or environmental factors are formed in the atmosphere alone, while others are formed in the physical environment under it. A phenomenon like a dust storm is a combined atmospheric-environmental phenomenon. The existence of dry and highly fragmented soils provides favorable conditions for the rise of dust. For this reason, dry deserts, bare plains with soft and granular soils are always prone to this phenomenon as sources of dust production. Therefore, physical substrates with this feature should always be studied and investigated as potential places for dust phenomenon to occur. What is related to atmospheric conditions, severe instabilities without moisture or with little moisture are the basis of dust storms. This weather pattern is more likely to appear in arid and semi-arid climates. It is not possible to control or change the structure of atmospheric phenomena with current human technology. Therefore, the best way to reduce the effects of destructive phenomena such as dust storms in a geographical area is to first identify the source and path of dust storms . Materials and Methods The selected study area for this research is the southwest of Iran, an area that has experienced an increasing trend in the frequency and intensity of dust storms in recent decades. The study area includes the three provinces of Kohgiluyeh, Boyer Ahmad, Chaharmahal and Bakhtiari. In the first step of the research, all synoptic stations with complete statistics for 33 years (1986-2019) in the study area were identified and extracted. In the second step, using the data (number of reports of dust phenomenon (nhz), number of reports with dust phenomenon (ndu), number of reports with sand and dust storm phenomenon (nbdu), wind speed and horizontal visibility less than 1000 meters and codes (06.07, 08.09, 30.31, 32.33, 34.35, 98) days with dust were extracted from the data of Meteorological Organization. In the next step, using the website [https://www.ready.noaa.gov/HYSPLIT, ...] (https://www.ready.noaa.gov/HYSPLIT,) the origin of dust storms in the southwest of Iran was plotted using the backward method from the GDAS data system with a resolution of 0.5 degrees. This data is available from 2007. Therefore, for all the dust reports with the above characteristics from each of the sample stations, the origin of the storm has been determined. Results and Discussion Statistical analysis of dust storm reports from selected stations showed that 3027 cases of dust storm have been reported during the 33-year statistical period from a total of selected stations. In terms of monthly distribution, the months of January, February and December respectively have reported the highest number of dust storms. In terms of seasonal distribution, the highest number of pollen reports were from winter (1153 cases, 38.1%) and spring (711 cases, 23.5%) respectively. The highest number of dust storms was reported from the two dry years of 2008 (225 cases) and 2009 (243 cases). In terms of stations, the highest number of dust storms was reported from Ahvaz and Abadan stations. Based on the routing performed in this study, the input dust storms came from six areas: Iraq (from four parts), eastern Mediterranean countries, Saudi Arabia, central and northeast Africa, distant sources in eastern Europe, and local sources within the study area.The origin of 93.25% of the input dust storms to the study area was from sources in central Iraq, and about 20% of the dust storms originated from eastern Mediterranean countries, while 16% of the dust storms were from local sources in Khuzestan province. The origin of dust storms in high-altitude stations in the eastern part of the study area, such as Shahr-e Kord, Yasuj, and Kuhrang, was from distant sources in Syria and Jordan or northeastern Africa. Conclusion Given that, 84% of the dust storms entering the region originate from outside the border. Considering that the two sources of the west and the center of Iraq are the source of 35% of the storms entering the region. Diplomatic efforts for the cooperation of the country of Iraq to stabilize the soil in these resources are very necessary. [ABSTRACT FROM AUTHOR]

Introduction: Recent climate changes and droughts have exacerbated the impact of dust sources globally, necessitating a thorough understanding of their influence on air quality. In Tehran, the interaction between internal dust sources from Iran and external sources from neighboring countries significantly affects air quality. Materials and methods: This study spans a 20-year period (2003-2022), utilizing satellite data and advanced algorithms to analyze dust event trends and patterns. The material and methods section outlines the use of Aqua satellite MODIS sensor data alongside two algorithms to identify dust sources, focusing on Aerosol Optical Depth (AOD) data during peak dust event seasons. Statistical analysis of dust events in 2022 supplements the investigation. Results: The analysis reveals distinct patterns in dust particle origin and transport, highlighting the predominant contribution of internal dust sources from Iran's southern Semnan province and significant input from external sources in Iraq and northern Saudi Arabia. Examining meteorological conditions during severe dust events highlights the role of synoptic conditions, particularly the presence of a tropospheric trough, in facilitating dust transport. Increased convective motions and downburst occurrences in specific regions further exacerbate the spread of dust particles, particularly those originating from external countries and provinces. Conclusion: The conclusion emphasizes the complex interplay between internal and external dust sources and the necessity of understanding dust emission dynamics for effective mitigation strategies. It calls for proactive measures involving local and regional cooperation to mitigate dust pollution's adverse effects on air quality in Tehran and similar urban centers.

Understanding the effect of dust upon climate and ecosystems needs comprehensive analyses of the physiochemical properties of dust-emitting sediments in arid regions. Here, we analyse a diverse set of crusts and aeolian ripples (n=55) from various dust-hotspots within the Mojave Desert, California, USA, with focus on their particle size distribution (PSD), mineralogy, aggregation/cohesion state and iron mode of occurrence characterization. Our results showed differences in fully and minimally dispersed PSDs, with crusts average median diameters (92 and 37 µm, respectively) compared to aeolian ripples (226 and 213 µm, respectively). Mineralogical analyses unveiled variations between crusts and ripples, with crusts enriched in phyllosilicates (24 vs 7.8 %), carbonates (6.6 vs 1.1 %), Na salts (7.3 vs 1.1 %) and zeolites (1.2 and 0.12 %), while ripples enriched in feldspars (48 vs 37 %), quartz (32 vs 16 %), and gypsum (4.7 vs 3.1 %). Bulk Fe content analyses indicate higher concentrations in crusts (3.0±1.3 wt %) compared to ripples (1.9±1.1 wt %), with similar Fe speciation proportions; nano Fe-oxides/readily exchangeable Fe represent ~1.6 %, hematite/goethite ~15 %, magnetite/maghemite ~2.0 % and structural Fe in silicates ~80 % of the total Fe. We identified segregation patterns in PSD and mineralogy differences within the Mojave basins, influenced by sediment transportation dynamics and precipitates due to groundwater table fluctuations. Mojave Desert crusts show similarities with previously sampled crusts in the Moroccan Sahara for PSD and readily exchangeable Fe, yet exhibit differences in mineralogical composition, which could influence the emitted dust particles characteristics. [ABSTRACT FROM AUTHOR]

Dust storms are one of the major causes of the destruction of natural ecosystems and human infrastructure worldwide. Therefore, the identification and mapping of susceptible regions to dust storm formation (SRDSFs) is of great importance. Determining SRDSFs by considering the concept of risk in the decision-making process and the kind of manager's attitude and planning can be very valuable in dedicating financial resources and time to identifying and controlling the negative impacts of SRDSFs. The purpose of this study was to present a new risk-based method in decision making to create SRDSF maps of pessimistic and optimistic scenarios. To achieve the purpose of this research, effective criteria obtained from various sources were used, including simulated surface data, satellite products, and soil data of Saudi Arabia. These effective criteria included vegetation cover, soil moisture, soil erodibility, wind speed, precipitation, and absolute air humidity. For this purpose, the ordered weighted averaging (OWA) model was employed to generate existing SRDSF maps in different scenarios. The results showed that the wind speed and precipitation criteria had the highest and lowest impact in identifying dust centers, respectively. The areas identified as SRDSFs in very pessimistic, pessimistic, neutral, optimistic, and very optimistic scenarios were 85,950, 168,275, 255,225, 410,000, and 596,500 km2, respectively. The overall accuracy of very pessimistic, pessimistic, neutral, optimistic, and very optimistic scenarios were 84.1, 83.3, 81.6, 78.2, and 73.2%, respectively. The very pessimistic scenario can identify the SRDSFs in the study area with higher accuracy. The overall accuracy of the results of these scenarios compared to the dust sources obtained from the previous studies were 92.7, 94.2, 95.1, 88.4, and 79.7% respectively. The dust sources identified in the previous studies have a higher agreement with the results of the neutral scenario. The proposed method has high flexibility in producing a wide range of SRDSF maps in very pessimistic to very optimistic scenarios. The results of the pessimistic scenarios are suitable for risk-averse managers with limited financial resources and time, and the results of the optimistic scenarios are suitable for risk-taking managers with sufficient financial resources and time. [ABSTRACT FROM AUTHOR]

Dust storm is one of the destructive weather phenomena that strongly affects regions with arid and semiarid climates like Yazd province. This phenomenon leads to many losses, including environmental, socio-economic, human health, climate and microclimate problems. Accurate spatial and temporal monitoring of dust can help identify the trajectories and sources of this atmospheric hazard and play a vital role in management and reduction of possible damages of storm. In the present study, three examples of dust storms that occurred in 2022 in Yazd province were analyzed. When the visibility is less than 3.5 km and one of the codes 06 to 09 or 30 to 35 is reported, it is considered as an effective dust storm. The lagrangian HYSPLIT model was used to identify the trajectories of dust transfer to Yazd province. The results of this model indicate that dust masses travel three main pathways to reach Yazd province: southwest, west-northwest, and northeast. In order to investigate the spatial distribution of dust and also to identify dust sources more accurately, the aerosol optical depth data based on remote sensing, the MOD04/MYD04_L2 product and also the MOD08_D3 product, were used. These images showed that the external sources of dust are the large deserts of Iraq, Syria, the Arabian Peninsula, and the desert of Turkmenistan, and the internal source of dust is the desert areas located in the provinces of Semnan, Isfahan in the northeast of Yazd province. In addition, the Gavkhoni wetland in the northwest of the study area acts as an intensifier of the dust transferred from the western borders of the country. Also, the results obtained from the satellite data and the HYSPLIT model are consistent with each other. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are major environmental concerns due to their high carcinogenic properties and resistance to decomposition. These substances accumulate in the soil and reach living organisms through agriculture/leaching or dust sources. Zero-valent iron nanoparticles (ZVI NPs) have high regenerative power to remove environmental pollutants (such as PAHs) due to their extremely small size, specific surface area, and high reactivity. This study was conducted to investigate the effect of ZVI NPs on the removal of PAHs. The refinery effluent sample, control soil, and two soil samples in the effluent path were collected, followed by measuring the type and percentage of aromatic hydrocarbons and comparing the amount of pollution and its effect on the soil. PAH health risk assessment showed that the risk of carcinogenesis is higher through skin contact. The incremental lifetime cancer risk (ILCR) was possible in terms of carcinogenic risk (10−5–10−6). Next, two samples of the soil contaminated with iron NPs at three concentrations of 2.5, 5, and 10 g of NPs per 100 g of the soil were mixed. Then, each treatment was tested at 24, 48, and 72 h, and the amount of PAHs was obtained using a chromatogram. The results showed that the refinery effluent caused soil pollution in the route, and the concentration of 10% nanomaterials more than other concentrations led to a decrease in PAHs. In addition, the longer the iron NPs are in contact with the soil, the lower the amount of PAHs, and in some cases, it has reached zero. [ABSTRACT FROM AUTHOR]

IntroductionAtmospheric mineral dust particles play a key role in the radiation budget of the atmosphere and the hydrological cycle, and have an important effect on public health by disrupting climate systems and air pollution. Due to Iran’s location in the arid and semi-arid belt of the world, Iran is constantly exposed to local and regional dust systems. Considering the importance of the negative effects of dust storms and their increasing trend in some dust sources, the study of these changes in the last two decades show the importance of the dust storms in recent years. Moreover, spatial-temporal identification and analysis of the properties of these dust particles is very important in order to manage this crisis and prevent the harmful effects of dust particles. In Iran, due to desert conditions, the presence of dust hotspots has always caused air pollution and reduced the quality of life of people. In recent years, some dust hotspots have been ambiguous about increasing the intensity of dust emission. In this study, using the AOD product of MODIS, which compute the dust intensity, and based on the annual frequency and averages of dusty days, the location of dust hotspots were identified and then the trend of dust intensity in each hotspots were examine. The results showed that despite the relatively similar climate, the trend of changes in these dust hotspots does not follow the same pattern and complex human activities and natural changes.Data and Method In this study AOD product from MODIS with the resolution of 10 km was used to extract dust information then the frequencies of days with AOD greater than 0.6 per year were extracted. In addition to correctly calculating the average of AODs, calculating the number of days without data is also important in the results. The spatial and temporal distribution of the study period, were identified in three periods, 2000-2006, 2007-2012 and 2013-2018. The percentage of changes in each of the dust sources compared in different periods. The standard deviation was extracted to identify the areas most vulnerable to dust storms. Finally, to detect the quantitative distribution, the trend of AOD changes in the extracted dust hotspots was used to investigate the changes in the dust intensity trends.Results and DiscussionThe map of dust hotspots in the first period shows the main dust sources are in the north of Sistan and Baluchestan (Zabol) and south of Sistan and Baluchestan (Chahbahar), in the southeast of Semnan (Dasht Kavir), Damghan, Garmsar, Jazmourian, southwest of Hormozgan, (Bandar Lengeh area), south and southwest of Khuzestan, southwest of Yazd (Nayer), as well as parts of Qom, Ilam (Mehran), Isfahan, and south of Fars provinces. In the second period of study, many dust centers have become more intense and extensive. According to the map of dust centers in the third period of studies, compared to the first and second periods, the area of dust centers has decreased.According to the results, about half of the areas without emission has been turned into areas with dust with different frequencies in second period, and also about half of the area of ​​very high-frequency hotspots has been turned into other dust sources with less intensity in the third period. Also, the most fluctuations in dust intensity have occurred in Sistan, Jazmorian, southeast of Semnan, East Azerbaijan, Zanjan and Khuzestan provinces. The results of trend analysis of dust intensity in different dust hotspots show that despite the relatively uniform climate, the dust sources trends in different dust sources do not follow the same pattern.ConclusionDue to the geographical location of Iran and the existence of vast deserts, the wethear has always affected by dust sources of inside and outside of the country. In this study, using satellite data with appropriate resolution, the location of dust sources in three time periods were extracted. The changes of each dust intensity class in the second and third periods were compared with the first period so that regardless of location, changes in dust intensity can be evaluated in general. Then, using the standard deviation method, the dust hotspots with the highest percentage of changes were identified. Finally, the trend of changes was calculated by examining the trends of changes in 24 main dust centers. According to the results of the present study, many changes have been observed in some dust sources and the intensity of dust in many dust sources has decreased. While some sources such as Isfahan, and Khuzestan province due to the role of human factors such as agricultural activities as well as the reduction of surface and ground water and as a result of drought and changes in soil texture have an increasing in trend of dust intensity. Since a decreasing trend is observed in most of dust sources, eastern and southern parts of Iran, the results of this study indicate the key role of climatic factors in changes and fluctuations in dust emission in Iran. Because climatic factor can be the only factor which has a relatively uniform effect on the dust emission on a large scale of Iran.

Icelandic topsoil sediments, as confirmed by numerous scientific studies, represent the largest and the most important European source of mineral dust. Strong winds, connected with the intensive cyclonic circulation in the North Atlantic, induce intense emissions of mineral dust from local sources all year and carry away these fine aerosol particles for thousands of kilometers. Various impacts of airborne mineral dust particles on local air quality, human health, transportation, climate and marine ecosystems motivated us to design a fully dynamic coupled atmosphere–dust numerical modelling system in order to simulate, predict and quantify the Icelandic mineral dust process including: local measurements and source specification over Iceland. In this study, we used the Dust Regional Atmospheric Model (DREAM) with improved Icelandic high resolution dust source specification and implemented spatially variable particle size distribution, variable snow cover and soil wetness. Three case studies of intense short- and long-range transport were selected to evaluate the model performance. Results demonstrated the model's capability to forecast major transport features, such as timing, and horizontal and vertical distribution of the processes. This modelling system can be used as an operational forecasting system, but also as a reliable tool for assessing climate and environmental Icelandic dust impacts. [ABSTRACT FROM AUTHOR]

Land cover change has become one of the main challenges as a result of synergistic interaction between negative effects of climate change and human activities. In this study, land cover changes in the Hendijan Basin with a focus on the impact on dust sources located in Khuzestan province were investigated. Areas of forests, rangelands, woodlands, water, agricultural lands, residential and barren lands were extracted during 30 years at 1987 and 2017 using Landsat image processing. Dust sources located in Khuzestan have been monitored from past to present and their land cover changes have been evaluated. The results showed that the trend of land cover changes inside and outside Khuzestan province is different from each other. In fact, the highest rate of change compared to beginning of study was occurred in mountainous part of the Hindijan Basin due to increasing areas of dam lakes (9.7 times) and in the downstream plains due to the expansion of residential lands and also increasing cultivated area (8 and 4.9 times). Also, 936.31 square kilometers, has been added to barren lands, at the same time, the area of rangelands and forests has decreased 367.60 and 2633.40 square kilometers, respectively. Detection of changes in Khuzestan dust sources showed that the east and southeast area of Ahvaz, which was covered with vegetation and water (seasonal floods and flood plains) in winter of 1366, has become barren land in 1396. Monitoring land cover changes and reporting results to decision makers enables more informed decisions regarding future changes. [ABSTRACT FROM AUTHOR]

Recurrent dust storms represent a significant concern in Australia because of their related hazards and damages since particulate matter (PM) has harmful impacts on the environmental, health and economic sectors. The particulate matter may be released from natural sources and human activities. The major part of natural particulate matter is emitted into the air by wind erosion processes from desert and semi-desert areas at the world scale. A huge dust storm crossed over several areas of New South Wales (NSW), Australia, including the Sydney region on 21–22 November 2018 and decreased the horizontal visibility to less than 1 km for 22 h. This study examined the synoptic weather conditions, and assessed the air quality and identified the source and transport trajectory of the dust storm over Sydney using ground and satellite remote sensing data. PM10 (< 10 μm) concentrations were obtained from selected air quality monitoring sites operated by the Environmental Protection Agency in NSW. The highest hourly concentration of PM10 (578.7 μg/m3) was recorded at Singleton in the Hunter Valley, while concentrations in Sydney ranged from 480 to 385 μg/m3, well above the standard air quality level in Australia (50 μg/m3 per 24 h). The HYSPLIT back trajectories of air parcels suggest that the potential sources of the dust episode originated from the Lake Eyre Basin and northeast South Australia, the Mundi Mundi plains west of Broken Hill, Cobar and the grazing lands and the red sandplains in northwestern NSW. It then travelled towards the east coast. These long-range airflows transported suspended dust particles, raising air quality to hazardous levels (elevated PM10 levels) over most areas of NSW. The results from the HYSPLIT model for dust movement are confirmed by MODIS satellite images. Many areas of NSW experienced this intense dust storm due to northwest wind generated by the low-pressure systems and cold fronts over South Australia and many parts of western NSW as it moved eastward. [ABSTRACT FROM AUTHOR]

In this study, using remote sensing and calculating the physical parameters related to dust emission, the soil erodibility as a criterion of dust sources has been re-calculated and added to the WRF/Chem model, to replace the default dust sources (based on topography) in WRF/Chem, over West Asia. SEVIRI Dust RGB products, as the remote sensing data, and ECMWF-ERA5 meteorological data have been extensively used in the geographical identification of dust sources and calculation of their activity. Over 1100 dust sources have been identified by the aim of dust RGB images, and converted to dust frequency map, which at the next step, converted to the weighted frequency map, by applying the turbulence (friction and convection velocity), and 10m wind speed. One of the key innovations in this study is the combination of dust event frequencies (weighted frequencies) with the meteorological factors, including friction velocity, convection velocity, and 10m wind speed. The results show that the weighted dust frequencies are effective in improving the simulation of dust concentration. The spatial distributions of the new dust sources are similar to the default dust sources (based on Ginoux function), and different in many other regions. New redefined dust sources include regions in Iraq, Syria, eastern Iran, northern coasts of Oman Sea, and the Aral Sea. There are considerable regions in the new dust source map, including eastern coasts of Caspian Sea and southern coast of Persian Gulf, which in comparison to the default dust sources are not identified as active dust sources. The distribution and magnitude of the dust concentrations and the results of the WRF/Chem simulations of dust concentrations for two major dust episodes with the new dust sources and comparing them with the simulations with default dust sources show significant improvements. The new erodibility maps as the new West Asia dust sources, developed in this study, result in a relative improvement in the simulated dust concentration. It cannot be expected that all WRF/Chem dust simulations with the new dust sources in any region of the study area produce more accurate results. One of the most important purposes of this study was to provide a new dust source map that makes the WRF/Chem results of dust concentration more reliable; therefore, it can be used in operational and warning advisory systems for sand and dust storms. It is shown that for some cases the simulated dust concentrations are not different, using the weighted dust frequencies or only the dust frequencies. But in some other cases (especially eastern Iran), there are major differences between the simulated dust concentration and station data, in a way that confirms the significant role of weighted frequencies in reaching better erodibility factors (dust sources) in comparison to the dust frequencies alone. The capability of the WRF model is a key factor in correcting the dust sources. Good accuracy of WRF in wind simulation makes it a capable model in predicting the temporal and spatial variability of the dust storms. However, the stochastic variables, including the turbulence, can affect the accuracy of model. [ABSTRACT FROM AUTHOR]

This study explores the characteristics of crucial dust sources and changes in their emissions over the Arabian Peninsula (AP) over the 2000–2022 period using high-resolution dust aerosol optical depth data from the Moderate Resolution Imagining Spectroradiometer (MODIS) aerosol measurements onboard Terra and Aqua platforms. The MODIS dust retrievals successfully unravel the hitherto-unexplored key dust source regions and spatial heterogeneity in dust emissions. Critically, MODIS-defined dust sources display a robust geomorphological signature. In Iraq, the Tigris and Euphrates River basins contain extensive dust sources; the Euphrates dust sources are stronger and more widespread. Localized dust sources are noticed over Syria. In the Kingdom of Saudi Arabia (KSA), the eastern province particularly facilitates extensive dust activity. Oman is the prominent dust source in the southern AP due to the presence of intruding sand dunes. Dust emissions in the Iraq and KSA regions exhibit a significant negative correlation with the Standardized Precipitation-Evapotranspiration Index, a drought index, establishing that the local droughts enhance the dust emissions in these regions. The recent sustained droughts from 2008 to 2013 caused a remarkable escalation in the dust emissions in these regions through the modification of land surface conditions.

Anthropogenic dust (AD), as a crucial component of particulate matter, is defined as dust emitted through modifying or disturbing soil particles directly or indirectly associated with human activities in urban areas, croplands, pasturelands and dry lakes. The sources, characteristics, and impacts of AD remain poorly studied, in contrast to the large body of research on natural dust (ND). This review summarizes scientific findings published since the 1990s regarding the emissions, physical-chemical characteristics, and spatio-temporal distributions of AD from the micro to the global scale. AD accounts for 5%–60% of the global dust loading, with notable spread in existing estimates. Compared with ND, AD has more complex and variable compositions and physical-chemical properties. Influenced by human disturbances, AD exhibits small particle sizes, easily accessible critical friction velocity, and large emissions. Further research should improve the observations and simulations to investigate the complex interactions among AD, climate change, and human health.

Mineral dust deposition characteristics are poorly constrained, even in the Northeastern Tropical Atlantic Ocean, which is immediately downwind of the Saharan desert and the largest marine repository of aeolian dust in the world. Here, we report on a 2‐year (March 2013–February 2015) time series of deposited dust on the Senegalese margin. This record enables us to document the chemical variability (major elements) of the settling Saharan dust (<30 µm silicate fraction, i.e., carbonate‐free) at a resolution varying from one week to one day, along with the deposition flux. This continuous time series reveals a greater geochemical diversity than previously reported, particularly during the dry winter‐spring season when continental trade winds sweep across vast regions of West Africa at low atmospheric levels before reaching the sampling site. By contrast, during major deposition events, which make up for most of the yearly flux, our record shows that Saharan dust chemical composition displays much narrower ranges. Trajectory analyses indicate that these relatively well‐defined chemical signatures are due to the limited number of provenance sectors involved during major deposition occurrences. The chemical characterization of the dust deposited during these events, hence, allows identifying the major element fingerprint of the related source regions, the most important one being a sizable area at the border of Algeria and Mali including the Tanezrouft desert north of the Taoudeni basin. Also, since these major events are associated with major Saharan outbreaks, they provide estimations of the prevailing elemental signatures for Saharan dust impacting the Northeastern Tropical Atlantic Ocean. Plain Language Summary: Several hundred million tons of Saharan dust are transported yearly in the atmosphere across the tropical Atlantic Ocean, with implications for the sunlight budget, for marine and terrestrial ecosystems, as well as for air quality. Although the temporal and spatial variability of this transport is relatively well documented by satellite observations, there is incomplete knowledge of the characteristics of Saharan dust deposited on ocean and continental surfaces due to the dearth of dust sampling on the path of its main atmospheric routes. Here, for the first time, we provide an assessment of the chemical composition variability (major elements) of Saharan dust deposited on the eastern side of the tropical Atlantic over a 2‐year period. We find a greater than expected geochemical diversity, including marked seasonal shifts. By contrast, large dust deposition events display much narrower compositional ranges. These well‐defined chemical signatures can be explained by the fact that only two main regions are chiefly involved during these events. Our time series thus enables us to determine indirectly the chemical fingerprint of these two regions, inaccessible for sampling otherwise. The chemical mapping of major Saharan dust sources will be useful to track Saharan dust and its impacts in the northern hemisphere. Key Points: Saharan dust deposited on the West African margin shows greater than expected geochemical diversity, including marked seasonal shiftsBut large deposition events display much less variability, revealing the signature of the major Saharan outbreaks impacting the AtlanticAir mass back‐trajectories show that two main regions are chiefly involved, whose chemical fingerprint could therefore be identified [ABSTRACT FROM AUTHOR]

In recent decades, land use changes have been one of the most important environmental issues worldwide. This study was carried out to investigate and analyse land use changes in dust sources of south and south-east Ahwaz and surrounding lands using remote sensing technique. Firstly, based on the standard precipitation index (SPI), the years 1986, 2002 and 2016 were selected as years with near normal situation. In the next step, land use maps of the study area were extracted using a Landsat satellite images and supervised classification methods. MNDWI index was used to increase the accuracy of image classification. In order to evaluate the efficiency of each method, the overall accuracy and kappa coefficient were used. Finally, to investigate land use change a post-classification comparison method was employed. According to research findings, in the first period (1986-2002), the area of vegetation, wet land with vegetation and water bodies have increased by 419%, 219% and 40.7%, respectively, in contrast, the area of barren and poor range has reduced by 36.6%. One of the major causes of these changes is human factors such as population growth and climate variables such as proper amounts of precipitation. In the second period (2002-2016), the area of wet land with vegetation, water bodies and vegetation has been decreased by 94%, 49.3% and 46.7%, respectively; in contrast, barren and poor range land has been increased by 45.4%. Recent droughts increase the temperature and incorrect and non-principled management of water resources has been effective in reducing green cover and water bodies and increasing in bare land. The results show that, during the three decades, built-up land has been increased by 157%, while River bed has decreased by 28.8%. These results indicate a total degradation in the region due to climate change and human activities.

At present, the Russian coal industry is demonstrating an increase in coal production against the background of increased mineral exports. Coal mining in the Russian Federation is carried out by opencast and underground mining methods; currently 59 underground mines and 108 open-pit coal mines are operating. High concentration and intensification of all technological processes related to mining and processing of minig raw materials is the specifics of the present-day stage of mining development at coal strip mines. This all is accompanied by complication of the process of ventilation of mined-out space of the strip mine, deterioration of working conditions with dust and gas factors, and negative effect on the human health and environment. At dust release exceeding 58 kg/ha per month, the effect of vital activity suppression of the majority of flora and fauna in the given area is observed. The inhaled dust causes acute upper respiratory tract illnesses. The accumulation of dust from explosive and combustible materials in the air poses a risk of explosion or fire. Increased dust levels produce a negative impact on machinery. In addition to purely mechanical wear caused by abrasive particles entering the moving parts, machine control systems can also malfunction, as more dust enters the electronic control units. The lifespan of an engine functioning in the dusty conditions is reduced by 2-3 times. Exposure to dust increases the intensity of the corrosion process, while machinery maintenance and repair becomes more complicated and time-consuming. Therefore, dust suppression is an extremely important measure to be applied in many industries. Dust suppression is a very broad concept. This Article studies only one aspect of the issue: a complex of methods and means. Various methods and equipment are used to combat dust: from complex stationary exhaust ventilation systems, cyclone separators and electrostatic dust collectors to sprinkler installations, hydraulic mining giants and fog cannons spraying water, chemicals and foam. This Article analyses the specifics of mining in subzero conditions, dust sources, dust effect on human health and dust suppression methods used at open pits in general, and also examines the problem of dust suppression at open pits in the Extreme North. This is a pressing issue, as of today, as many coal-mining enterprises in Russia operate in low temperature conditions.

In recent years, dust storms with huge adverse impacts on the environment have become more frequent and intense in the southwest of Iran. The first step to control or influence the dust storm process is source identification. The objective of this study is to detect the major sources of dust storms in Bushehr Province of Iran using the analytic network processes (ANP) and the weather research and forecasting (WRF) models. Five synoptic stations for this purpose were examined over 17 years from 2001 to 2017. The spatial data includes land use, NDVI, slope, aspect-slope, elevation, and soil used as the major layers. The layers were weighted by applying the paired comparison and analytic hierarchy process methods. Also, local scale pressure systems were identified using the WRF numerical model. Results revealed that pressure systems at the local scale in different seasons are located exactly over areas prone to dust storm generation within the study area. Furthermore, the WRF model correctly showed the atmospheric pressure and wind field locations at a local scale. Based on ANP output, more than 25% of Bushehr Province has been active as dust-prone regions at a local scale. The ANP model identified the zones of erosion-prone areas, and the WRF model determined the location of permanent or semi-permanent pressure systems. Results demonstrated that applying the WRF and ANP models provided a useful tool to identify and validate the local dust sources with high accuracy in the study sites. [ABSTRACT FROM AUTHOR]

Geo- and palaeoecological studies focusing on the late Pleistocene require a detailed knowledge of the spatial distribution of aeolian sediments. In Germany, existing maps are either on large scales, have a regional focus or show significant inaccuracies such as artificial boundaries within different geological units. To obtain a more detailed, seamless map of the distribution of aeolian sediments and their potential source areas, we combined and reanalysed available geodata, using a Geographical Information System. The resultant maps (scale: approx. 1:2,600,000) show the link between source areas and the late Quaternary aeolian deposits in Germany and can provide one context for further work on, e.g. palaeogeographical studies. This work was compared with other already published datasets and the problems of sediment mapping at a small scale were discussed.

Supraregional (palaeo)geoecological studies require detailed knowledge of the distribution of aeolian sediments and their sources. Such spatial data can be visualised and shared in maps, but often these are constrained in their resolution or extent. This is the case for the Carpathian Basin, where cross-border maps are not detailed enough to answer many research questions. Problems occur especially along political borders due to different geological mapping standards and varying lithological definitions. Using a Geographic Information System (GIS), we compiled a map showing the distribution of loess and related Quaternary sediments in the Carpathian Basin, with unprecedented detail. We vectorised and analysed existing data (mainly from geological maps) and combined and transferred these into a common (loess) sediment classification system. This cross-border map shows the distribution of aeolian sediments in the Carpathian Basin at a scale of 1:1,500,000. For the northwestern and the southern Carpathian Basin, we added maps that clarify the extent of late Pleistocene and Holocene terrace and floodplain deposits, which were merged in the Main Map to highlight the predominant dust source areas for this region.

The provenance of voluminous eolian dust on the Chinese Loess Plateau (CLP) is still highly debated. Here we apply machine learning methods of support vector machine and convolutional neural network to train models using element compositions of surface sediments from eight potential source regions, accordingly, to determine the dust sources and contributions by classifying the last glacial loess and present interglacial sediments on the CLP. The trained models succeed in differentiating major secondary sources and quantitatively estimating the contributions of both primary and secondary sources at least during the last glacial‐interglacial cycle. The understanding that a constant dust source despite changing climate conditions agrees with those derived from Sr‐Nd isotopes and U‐Pb age spectra. Our observations demonstrate that big geochemical data sets coupled with machine learning technology are fully capable of tracing sources. Plain Language Summary: Central northern China is occupied by a unique landscape called the Loess Plateau which is formed by accumulation of extensive eolian dust (640,000 km2 in area and 105 km3 in volume). To understand this majestic Earth surface process, it is of great significance to study the dust sources. In the present study, we use a big geochemical data set and machine learning algorithms to decipher the mystery of where the dust on the Loess Plateau originates. The advantage of the new methods is that they can fully exploit the used big data set. Our results indicate that the contributions of major secondary sources are dominated (approximately 50%) by the recycled Yellow River sediments from the Hetao Graben, followed by materials from inland basins in the northwest of China (>15% for eastern Tibetan Plateau, approximately 15% for Qaidam Basin, and >5% for Tarim Basin, Junggar Basin, and Alxa Plateau). Two primary sources, that is, northern Tibetan Plateau and Central Asian Orogenic Belt, thus contribute about 80% and 20%, respectively, to the dust deposition. An unchanged dust source structure during the last glacial‐present interglacial cycle structure is also recognized. These findings strengthen our understanding of the formation of the Loess Plateau. Key Points: We use chemical compositions of 81 elements in surface sediments from potential dust sources to train machine learning modelsThe trained models clearly differentiate major secondary dust sources and predict their sedimentary budgets on the Chinese Loess PlateauA constant dust source structure defined by element compositions agrees with those derived from Sr‐Nd isotopes and U‐Pb age spectra [ABSTRACT FROM AUTHOR]

In recent decades, land use changes have been one of the most important environmental issues worldwide. This study was carried out to investigate and analyse land use changes in dust sources of south and south-east Ahwaz and surrounding lands using remote sensing technique. Firstly, based on the standard precipitation index (SPI), the years 1986, 2002 and 2016 were selected as years with near normal situation. In the next step, land use maps of the study area were extracted using a Landsat satellite images and supervised classification methods. MNDWI index was used to increase the accuracy of image classification. In order to evaluate the efficiency of each method, the overall accuracy and kappa coefficient were used. Finally, to investigate land use change a post-classification comparison method was employed. According to research findings, in the first period (1986-2002), the area of vegetation, wet land with vegetation and water bodies have increased by 419%, 219% and 40.7%, respectively, in contrast, the area of barren and poor range has reduced by 36.6%. One of the major causes of these changes is human factors such as population growth and climate variables such as proper amounts of precipitation. In the second period (2002-2016), the area of wet land with vegetation, water bodies and vegetation has been decreased by 94%, 49.3% and 46.7%, respectively; in contrast, barren and poor range land has been increased by 45.4%. Recent droughts increase the temperature and incorrect and non-principled management of water resources has been effective in reducing green cover and water bodies and increasing in bare land. The results show that, during the three decades, built-up land has been increased by 157%, while River bed has decreased by 28.8%. These results indicate a total degradation in the region due to climate change and human activities. [ABSTRACT FROM AUTHOR]

Air‐borne dust affects all aspects of human life. The sources of dust have high spatial variation and a better quantification of dust emission helps to identify remediation measures. Orographic and statistical source functions allow a better estimation of dust emission fluxes in coarse‐scale modeling, but a high‐resolution source function is necessary to represent the highly heterogeneous nature of dust sources at the finer scale. Here we use a newly developed high‐resolution (~500 m) source function in Weather Research and Forecasting model, coupled with chemistry (WRF‐Chem) to simulate dust emission over the Middle East and North Africa and evaluate our simulated results against observations. Using a 4‐km grid spacing, we also simulate the emission and transport of dust originating from the Tigris‐Euphrates basin, one of the most important regional dust sources, and quantify the effects of this source on the air quality of the entire Arabian Peninsula. Results show that the use of new source function effectively represents the key dust sources and provides reasonable estimates of dust optical depth and concentrations. We find that the atmospheric dust originating from the Tigris‐Euphrates basin alone exceeds the particulate matter 10 air quality standards in several downwind cities. Our results have broader environmental implications and indicate that the mobilization of depleted uranium deposited in Kuwait and Southern Iraq during the Gulf War (1991) could potentially affect the urban centers over the peninsula, albeit in low concentrations. Our results suggest that an integrated and coordinated management of the Tigris‐Euphrates basin is necessary to maintain good air quality across the Arabian Peninsula. Key Points: A new high‐resolution dust source function is used in WRF‐Chem to simulate dust emissions over Middle East and North Africa (MENA)Contribution of Tigris‐Euphrates dust sources on total dust distribution over the Arabian Peninsula is quantifiedDust originating from Tigris‐Euphrates region alone causes exceedances of air quality standards in several cities of the Arabian Peninsula [ABSTRACT FROM AUTHOR]

Modeled estimates of eolian dust emission can vary by an order of magnitude due to the spatiotemporal heterogeneity of emissions. To better constrain location and magnitude of emissions, a surface erodibility factor is typically employed in models. Several landscape‐scale schemes representing surface dust emission potential for use in models have recently been proposed, but validation of such schemes has only been attempted indirectly with medium‐resolution remote sensing of mineral aerosol loadings and high‐resolution land surface mapping. In this study, we used dust emission source points identified in Namibia with Landsat imagery together with field‐based dust emission measurements using a Portable In‐situ Wind Erosion Laboratory wind tunnel to assess the performance of schemes aiming to represent erodibility in global dust cycle modeling. From analyses of the surface and samples taken at the time of wind tunnel testing, a Boosted Regression Tree analysis identified the significant factors controlling erodibility based on Portable In‐situ Wind Erosion Laboratory dust flux measurements and various surface characteristics, such as soil moisture, particle size, crusting degree, and mineralogy. Despite recent attention to improving the characterization of surface dust emission potential, our assessment indicates a high level of variability in the measured fluxes within similar geomorphologic classes. This variability poses challenges to dust modeling attempts based on geomorphology and/or spectral‐defined classes. Our approach using high‐resolution identification of dust sources to guide ground‐based testing of emissivity offers a valuable means to help constrain and validate dust emission schemes. Detailed determination of the relative strength of factors controlling emission can provide further improvement to regional and global dust cycle modeling. Plain Language Summary: Atmospheric mineral dust plays an important role in Earth system processes, influencing climate, providing nutrients to ecosystems, and affecting human health. The effect that atmospheric dust has on the climate and environment requires accurate modeling of emission at source, transport through the atmosphere, and deposition. To enable regional to global modeling of the dust cycle, therefore, requires realistic representation of where and when dust emission takes place. However, the highly variable nature of dust emission has resulted in modeling attempts producing disparate results. This research used Landsat remote sensing data in Namibia to identify sources of dust emission at high resolution, followed by ground‐based testing using a portable wind tunnel to assess surface classification schemes intended to represent the surface in dust emission models. Despite the proposed schemes offering valuable approaches for characterization of the land surface for modeling, globally applicable representation of dust emission is still hampered by the variability of small‐scale emissions. At the sublandform level of our analysis, the heterogeneous nature of dust emission results from the highly variable nature of the surfaces. Our analysis identified several factors controlling the potential for surfaces to emit dust that can be used as inputs to improve dust modeling. Key Points: The combination of remote sensing and ground‐based measurement is potent for studying dust emission potential across spatial scalesResults demonstrate substantial variability of emission at each scale of analysis (individual erosional surface, landform, and landscape)A Boosted Regression Tree model determines the relative influence of specific variables controlling surface erodibility [ABSTRACT FROM AUTHOR]

With the rapid development of the social economy in China, numerous Chinese cities are facing high levels of particulate matter (PM) pollution problems. In this study, high-resolution ZY-3 images and GIS techniques were used to establish the emission inventory of total suspended particle (TSP), particulate matter 10 (PM10) and particulate matter 2.5 (PM2.5) from fugitive dust sources in May 2016, and a spatial grid of 3 km × 3 km resolution was established to demonstrate the spatial distribution of PM emission. Results showed that the total emissions of TSP, PM10 and PM2.5 in Zhengzhou city were 237.5 kt·a−1, 103.7 kt·a−1 and 22.4 kt·a−1, respectively. Construction dust source was the main fugitive dust emission source in Zhengzhou city—the TSP, PM10 and PM2.5 emission of which account for 76.42%, 89.68% and 88.39%, respectively, of the total emission, followed by road dust source and soil dust source. PM emission was higher in Zhongyuan, Huiji, Jinshui and Zhengdong New District, while Zhongmou, Xingyang, Dengfeng and other remote areas had low PM emissions. Compared to other Chinese cities or regions, the PM emission from the construction dust source was at a high level in Zhengzhou city, while the PM emissions from the soil dust source and road dust source were at moderate levels.

Natural mineral particulate matter deposited from aerosols and trapped in glaciers—herein defined as “cryodust”—may be an excellent indicator of atmospheric circulation, if terrestrial sources of dust can be identified. In this study, we analyzed the composition of cryodust in shallow ice cores taken from five glaciers in Southern Spitsbergen (Svalbard Archipelago, Northern Norway). The chemical composition, magnetic properties and radiogenic ages of individual grains were measured, where possible, to provide indicators of source areas. To identify mineral and rock fragments, solid particulates were examined by Scanning Electron Microscope fitted with a backscattered electron and Energy Dispersive Spectroscopic detectors. An Electron MicroProbe was employed for the U-Th-Pb chemical dating of monazite grains. Magnetic measurements comprised analyses of magnetic susceptibility (κ) vs. temperature (T) variations and determination of magnetic hysteresis parameters. Monazite ages span 445–423 Ma, consistent with mineral growth during the Caledonian orogeny. Caledonian rocks are exposed in the Nordaustlandet area of North-Eastern Svalbard, and this is the most probable source for monazite grains. Magnetic analyses show a predominance of ferrous (FeII) over ferric (FeIII) phases, consistent with a lack of input from subtropical sources. The results from both methods are consistent with local sources of dust from exposures in the Svalbard archipelago.

This Special Issue on soil erosion invites novel and original articles based on physical and chemical theories, field and laboratory experimental, soil analyses, and/or statistical and mathematical modeling that advance our knowledge on dust control and sand stabilization.

This Special Issue on soil erosion invites novel and original articles based on physical and chemical theories, field and laboratory experimental, soil analyses, and/or statistical and mathematical modeling that advance our knowledge on dust control and sand stabilization. [ABSTRACT FROM AUTHOR]

Supraregional (palaeo)geoecological studies require detailed knowledge of the distribution of aeolian sediments and their sources. Such spatial data can be visualised and shared in maps, but often these are constrained in their resolution or extent. This is the case for the Carpathian Basin, where cross-border maps are not detailed enough to answer many research questions. Problems occur especially along political borders due to different geological mapping standards and varying lithological definitions. Using a Geographic Information System (GIS), we compiled a map showing the distribution of loess and related Quaternary sediments in the Carpathian Basin, with unprecedented detail. We vectorised and analysed existing data (mainly from geological maps) and combined and transferred these into a common (loess) sediment classification system. This cross-border map shows the distribution of aeolian sediments in the Carpathian Basin at a scale of 1:1,500,000. For the northwestern and the southern Carpathian Basin, we added maps that clarify the extent of late Pleistocene and Holocene terrace and floodplain deposits, which were merged in the Main Map to highlight the predominant dust source areas for this region. [ABSTRACT FROM AUTHOR]

Geo- and palaeoecological studies focusing on the late Pleistocene require a detailed knowledge of the spatial distribution of aeolian sediments. In Germany, existing maps are either on large scales, have a regional focus or show significant inaccuracies such as artificial boundaries within different geological units. To obtain a more detailed, seamless map of the distribution of aeolian sediments and their potential source areas, we combined and reanalysed available geodata, using a Geographical Information System. The resultant maps (scale: approx. 1:2,600,000) show the link between source areas and the late Quaternary aeolian deposits in Germany and can provide one context for further work on, e.g. palaeogeographical studies. This work was compared with other already published datasets and the problems of sediment mapping at a small scale were discussed. [ABSTRACT FROM AUTHOR]

The Sr and Nd isotopic compositions of siliciclastic sediments and the Nd isotopic compositions of planktonic foraminifera are investigated in sediment trap samples collected in 2015 at water depths of 500 and 2,800 m to (1) track the seasonal changes in the sources and transport patterns of siliciclastic sediments to Benham Rise, (2) constrain the Nd isotopic compositions of the planktonic foraminifera throughout the water column, and (3) assess the influences of lithogenic inputs on the Nd isotopic compositions of the water masses. We demonstrate that volcanic matter and eolian dust are derived primarily from Luzon Island and the Ordos Desert, respectively. In addition, we show that reduced precipitation over Luzon Island and the weakened East Asian winter monsoon intensity result in mass fluxes from Luzon Island and the eastern Asian deserts to the sea, respectively, that are weaker in the winter than in the spring. Furthermore, the εNd values of the foraminifera collected at a water depth of 500 m change slightly in 2015, suggesting negligible impacts of lithogenic Nd inputs characterized by significant seasonal flux variations. In contrast, the εNd values of the planktonic foraminifera collected at a water depth of 2,800 m are systematically more radiogenic and appear to display seasonal variability. Such results suggest the rapid modification of εNd values during the settling of planktonic foraminifera by the precipitation of Mn coatings derived from water masses at deposition depths, with greater contributions of colder water masses originating from the volcanic Luzon Island margin during the winter. Plain Language Summary: Based on the first report of Sr‐Nd isotopic compositions of siliciclastic sediments and Nd isotopic compositions of planktonic foraminifera in sediment trap samples collected from the western Philippine Sea in 2015 at water depths of 500 and 2,800 m together with the relevant current information, we try to recover the potential linkages between the East Asian winter monsoon strength, the East Asian summer monsoon (precipitation) intensity, and the siliciclastic sediment source‐to‐sink processes as well as the influences of lithogenic inputs on the Nd isotopic compositions of the water masses at the northern margin of the western Pacific Warm Pool in different seasons of 2015. On the one hand, we quantitatively estimate the eolian dust sources to the study area. On the other hand, we find the rapid changes in planktonic foraminiferal εNd values during settling in the western Philippine Sea. Such results are critical for effectively interpreting the siliciclastic sediment source‐to‐sink processes and marine circulation as well as the behind controlling mechanisms at low latitudes during the geological past. Key Points: The eolian dust sources to the western Philippine Sea are determined and quantifiedThe impacts of the East Asian monsoon on the siliciclastic fluxes to the Benham Rise are characterizedRapid changes in planktonic foraminiferal εNd values occur during settling in the ocean [ABSTRACT FROM AUTHOR]

There is an urgent need for zoning the dust sources, as the first step to control dust storms. Hence, this study aimed to identify the exact interior sources of dust in Khuzestan Province (Iran), using a hybrid method of remote sensing, GIS and sedimentology. To this end, the spatial data of pedology, landuse, climate, slope and sedimentology were used as the constraint layers and vegetation, land surface temperature and soil moisture were used as the major layers. The major layers were extracted by performing the necessary computational process on the image of the Landsat 8 satellite. Constraint layers were used to eliminate the regions without dust production potential. In the next step, the major layers were weighted applying the paired comparison and fuzzy analytic hierarchy process methods. Then, the final integration of the layers took place by multiplying each major layer in the respective weight, and the map of the dust sources in the region was prepared. To validate the results, field trips were done for 180 points of the sources which indicate the high accuracy of the identified regions. The results revealed that 9% of the area in Khuzestan Plain equal to 350,000 ha is regarded as the source of dust production. Moreover, according to the results, it can be said that satellite images, especially those with efficient resolutions such as Landsat 8 products, are suitable basis data for extracting indicators (temperature, humidity and vegetation) of the dust sources. [ABSTRACT FROM AUTHOR]

The central and southwest Asia is usually suffered by dust events of various intensity due to extended arid/desert regions and, therefore, the statistical evaluation of the dust activity over the region has received an increasing interest. This study analyses the characteristics of the dust events (according to their intensity) over the central and southwest Asia during the dusty months May to September from 2010 to 2016, based on visibility observations at 12 meteorological stations in Turkmenistan, Iran, Afghanistan and Pakistan. The dust events are classified based on visibility thresholds such as suspended dust (vis <10 km), blowing dust (visibility between 1 and 5 km) and dust storm for visibility below 1 km. The inter-annual evolution of the frequency of the dust events is examined on monthly basis for both hourly and daily data series (dust hours and dust days, respectively). Depending on intensity, the dust frequency shows remarkable inter-annual and intra-seasonal variability between the stations attributed to differences in topographic and soil characteristics, vicinity to major dust sources, prevailing meteorology and dust-plumes pathways. In general, June and July are the months with the highest dust activity, while the dust events seem to be more frequent during the morning hours, but with large differences between the stations. The highest frequency of the dust storms is observed in the Sistan Basin and around the deserts of southern Afghanistan, while the dust-plume pathways have a distinct north-to-south pattern from the Caspian Sea to the Arabian Sea. [ABSTRACT FROM AUTHOR]

Aerosols and their radiative effects are of primary interest in climate research because of their vital influence on climate change. Dust aerosols are an important aerosol type in the North China Plain (NCP), mainly as a result of long-range transport, showing substantial spatiotemporal variations. By using measurements from the Aerosol Robotic Network (AERONET) between September 2004 and May 2017, and the space-borne Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) aerosol products, we investigated the properties of dust aerosols and their radiative effects at Xianghe (XH)—a suburban site in the NCP. Dust events occurred most frequently during spring (a total of 105 days) relative to the other three seasons (a total of 41 days) during the periods concerned. The dust aerosol optical depth (AOD) at 675 nm was at a maximum in spring (0.60 ± 0.44), followed (in decreasing order) by those in autumn (0.58 ± 0.39), summer (0.54 ± 0.15), and winter (0.53 ± 0.23). Cooling effects of dust aerosol radiative forcing (RF) at the bottom and top of the atmosphere tended to be strongest in spring (−96.72 ± 45.69 and −41.87 ± 19.66 Wm−2) compared to that in summer (−57.08 ± 18.54 and −25.54 ± 4.45 Wm−2), autumn (−72.01 ± 27.27 and −32.54 ± 15.18 Wm−2), and winter (−79.57 ± 32.96 and −37.05 ± 17.06 Wm−2). The back-trajectory analysis indicated that dust air mass at 500 m that arrived at XH generally originated from the Gobi and other deserts of northern China and Mongolia (59.8%), and followed by northwest China and Kazakhstan (37.2%); few dust cases came from northeast China (3.0%). A single-peaked structure with the maximum occurring at ~2 km was illustrated by all dust events and those sorted by their sources in three directions. Three typical dust events were specifically discussed to better reveal how long-range transport impacted the dust properties and radiative effects over the NCP. The results presented here are expected to improve our understanding of the physical properties of dust aerosols over the NCP and their major transport path and significant impacts on the regional solar radiation budget.

Research into global hot spots of dust emission has focused on exposed fine-grained sediments in palaeo- or ephemeral dryland lake basins including Etosha (Namibia) and Makgadikgadi (Botswana) in southern Africa. Namibia's western ephemeral river valleys are also known to produce dust but have remained largely overlooked as a regionally significant source. Nutrient enrichment of valley sediments and proximity to the South Atlantic suggests aeolian dust could play an important role in ocean fertilization. The fertility of valley dust is dependent on fluvial sediments originating in the upper catchments on the Southern African Central Plateau. In this study we investigate climate, geology, vegetation and land use variability and how these may influence the nitrogen, phosphorus and iron availability in the catchments.We intensely sampled the Huab, Kuiseb and Tsauchab river systems to map the spatial distribution of nutrients from upper catchments to river termini. Samples were analysed for the bioavailable fractions of iron, nitrogen and phosphorus as well as total nitrogen and phosphorus. Results show that the lower valley reaches are sources of aeolian dust enriched in nutrients. Nitrogen levels correlate with precipitation and vegetation levels and phosphorus levels with geology. However, differences in upper catchment sediment nutrient levels were not representative of downstream nutrient differences between valleys. Rather, it is the hydrological and geomorphological processes of the ephemeral river systems that are key for producing the enriched sediments in the lower reaches. We demonstrate that the ephemeral river valleys of western Namibia are an extensive and enriched source of mineral dust that could play a critical role in marine productivity of the southern Atlantic. [ABSTRACT FROM AUTHOR]

The sediments deposited at the depocenter of the Dead Sea comprise high-resolution archive of hydrological changes in the lake's watershed and record the desert dust transport to the region. This paper reconstructs the dust transport to the region during the termination of glacial Marine Isotope Stage 6 (MIS 6; ∼135–129 ka) and the last interglacial peak period (MIS5e, ∼129–116 ka). We use chemical and Nd and Sr isotope compositions of fine detritus material recovered from sediment core drilled at the deepest floor of the Dead Sea. The data is integrated with data achieved from cores drilled at the floor of the Red Sea, thus, forming a Red Sea-Dead Sea transect extending from the desert belt to the Mediterranean climate zone. The Dead Sea accumulated flood sediments derived from three regional surface cover types: settled desert dust, mountain loess-soils and loess-soils filling valleys in the Dead Sea watershed termed here “Valley Loess”. The Valley Loess shows a distinct 87 Sr/ 86 Sr ratio of 0.7081 ± 1, inherited from dissolved detrital calcites that originate from dried waterbodies in the Sahara and are transported with the dust to the entire transect. Our hydro-climate and synoptic conditions reconstruction illustrates the following history: During glacial period MIS6, Mediterranean cyclones governed the transport of Saharan dust and rains to the Dead Sea watershed, driving the development of both mountain soils and Valley Loess. Then, at Heinrich event 11, dry western winds blew Saharan dust over the entire Red Sea - Dead Sea transect marking latitudinal expansion of the desert belt. Later, when global sea-level rose, the Dead Sea watershed went through extreme aridity, the lake retreated, depositing salt and accumulating fine detritus of the Valley Loess. During peak interglacial MIS 5e, enhanced flooding activity flushed the mountain soils and fine detritus from all around the Dead Sea and Red Sea, marking a significant “contraction” of the desert belt. At the end of MIS 5e the effect of the regional precipitation diminished and the Dead Sea and Red Sea areas re-entered sever arid conditions with extensive salt deposition at the Dead Sea. [ABSTRACT FROM AUTHOR]

The 1930s Dust Bowl Drought on the US Great Plains was an environmental crisis with failure of agricultural systems, landscape denudation, and elevated atmospheric dust loads. Poor agricultural practices were implicated for triggering widespread eolian erosion and heightened dust emissions, but this assumption is called into question. This study classified land surface changes in southwest Kansas from aerial images taken in 1936 and 1939 to infer surficial processes, dust sources, and associated emissivity. In total, seven distinctive surface classes were identified from an ArcGIS analysis of spectral reflectance values connected to surface vegetation cover and eolian activity, demonstrating a strikingly heterogeneous landscape response to the drought. Stratigraphic studies indicate accumulation of up to 4 m of eolian sand in places with erosion of a subjacent silty pre-1930s soil surface. Potential dust emissivity estimates for particulate matter were derived from the distribution of classified land surfaces and from empirical relations on analogous dust-emissive surfaces in the western US. Over 60% of total suspended particles in 1939 were inferred to be derived from uncultivated sandy surfaces and eolian landforms within the study area, with the remainder from human-modified surfaces. The PM2.5 and PM10 emissivity estimates for a single dust event with winds over 6 m s−1 in the study area were 510–4514 and 4700–41,607 µg m−3 d−1, respectively, similar in magnitude to current dust storm events from North Africa and East Asia. Drought frequency is forecast to increase in late 21st century, potentially with greater severity than the Dust Bowl and may be associated with magnitude increase in atmospheric dust loads. [ABSTRACT FROM AUTHOR]

To determine dust sources in the northwestern China, the spatial distribution of dust geochemical elements in the Hexi Corridor Desert, a total of 40 samples were collected at a height of 1.5 m over sandy and gravel surfaces at six field sites. In this work, 21 trace elements and seven major oxides were analyzed. Land surface characteristics influenced the dust emission, and the percentages of transported silt, clay, silt/sand, and clay/sand at a height of 1.5 m were related to gravel cover and the percentage of 0.063-mm-sized grains at the surface. The SiO 2 content was the highest (mean 61.20 ± 9.17%), whereas the K 2 O content was the lowest (mean 1.9 ± 0.3%) in all field sites. For the six sites, the Ti content was the highest (mean 3247.5 ± 502.5 μg/g) and the Nb content was the lowest (mean 9.6 ± 1.9 μg/g). At all sites, Co, As, and Nd were enriched, whereas Mn, Ti, Sr, Ce, Ni, Rb, Y, P, V, Ga, and Ba were depleted. P, Ti, V, Ni, Rb, Sr, Y, Ba, and La originated from crustal sources, and Cl, Cr, Cu, and Zn were sensitive to anthropogenic activity. The main transported trace elements were Ti, Mn, Ba, P, Cl, Sr, and Zr, which accounted for > 90% of the total trace elements. PCA analysis indicated that two principal components with eigenvalues > 1 could be extracted from the data. The relationship between Rb/Sr and Ba/Sr and between Fe/Al, Mg/Al, and Ca/Al was used to identify dust sources. Two dust sources were identified in northwestern China: one source comprised the Badain Jaran Desert, Tengger Desert, Hexi Corridor Desert, and part of the Inner Mongolian Gobi Desert, and the other source comprised the desert adjacent to Dunhuang Gobi Desert, and part of the Inner Mongolian Gobi Desert. [ABSTRACT FROM AUTHOR]

• The natural and anthropogenic dust sources of the QTP were identified. • The contribution of natural and anthropogenic dust sources to the total dust emission over the QTP were determined. • The effects of climatic fluctuations and land use changes on the dust emission of the QTP were estimated. • Transformation of anthropogenic disturbances to ecosystems were discussed. Human activity in modulating dust emissions is one of the major causes of large uncertainties in the global dust budget. However, the division of natural and anthropogenic dust sources remains controversial, and the natural and anthropogenic effects on the variations in dust emissions were hardly distinguished. To bridge these gaps, a model was employed to simulate the dust emission processes over the Qinghai-Tibetan Plateau (QTP) whose dust yield remains uncertain. Integrating the Human Activity Intensity (HAI) dataset, the natural and anthropogenic dust sources were identified. By combining the different scenarios of land use and climate, the dust emission processes under 15 scenarios from 1982 to 2020 were simulated, and the effects of climatic fluctuations (CF) and land use changes (LUC), which were roughly recognized as the natural and anthropogenic effects, respectively, on the variations in dust emissions were distinguished. The results showed that the annual dust emission quantities ranged from 41.12 to 240.68 Tg/a during the period. The natural dust sources (NDSs) and anthropogenic dust sources (ADSs) occupied an average of 13.30% and 59.77% of the total area of the QTP, respectively, and their contributions to the total dust emissions of the QTP were 8.11% and 91.89%, respectively. During these decades, the CF had an obvious trend of restraining dust emissions, while the effects of LUC promoted dust emissions, and after 2000, the promoted effect slowed down. Overall, the effects of LUC on dust emissions were slightly larger than those of CF. From the perspective of dust emission variations, we discussed the anthropogenic disturbance on the ecosystems of the QTP. We believe the study method can provide valuable references for identifying natural and anthropogenic sources and quantifying the effects of natural and anthropogenic factors on dust emission variations, and the results can reduce the uncertainty of the global dust budget. [ABSTRACT FROM AUTHOR]

In this study, we investigate the diurnal evolution of the summer Shamal wind (a quasi-permanent low-level northwesterly wind feature) and its role in dust emission and transport over Iraq, using ground-based and space-borne observations together with a numerical simulation performed with the mesoscale model meso-NH. A 6-year dataset from the synoptic stations over Iraq allows establishing the prominence of the link between strong near surface winds and reduced visibility in the summer. The detailed processes at play during Shamal events are explored on the basis of a meso-NH simulation for a given, representative case study (25 June–3 July 2010). The Shamal exhibits an out-of-phase relationship between the surface wind and winds in the lower troposphere (typically 500 m above ground level), the maximum surface wind speeds being observed during the day while in altitude the maximum wind speeds are observed at night. The daytime near surface winds, at the origin of dust emission, are associated with the downward transfer of momentum from the nocturnal low-level jet to the surface due to turbulent mixing after solar heating commences each day. For the first time, an estimate of the dust load associated with summer Shamal events over Iraq has been made using aerosol optical depths derived from the Spinning Enhanced Visible and Infrared Imager, the Moderate Resolution Imaging Spectroradiometer, and the simulation. The dust load exhibits a large diurnal variability, with a daily minimum value of 1 Tg around 0600 UTC and a daily peak of 2.5 Tg or more around 1500 UTC, and is driven by the diurnal cycle of the near surface wind speed. The daily dust load peak associated with the summer Shamal over Iraq is in the same order of magnitude as those derived from simulations downstream of the Bodélé depression in Chad, known to be the world’s largest dust source. [ABSTRACT FROM AUTHOR]

Human-driven dynamics of land cover types in the Tarim Basin are able to affect potential dust source regions and provide particles for dust storms. Analyses about dynamics of potential dust source regions are useful for understanding the effects of human activities on the fragile ecosystem in the extremely arid zone and also provide scientific evidence for the rational land development in the future. This paper therefore selected the Tarim Basin, NW China, as a representative study area to reveal spatiotemporal dynamics of land cover and their impacts on potential dust source regions. The results showed that farmland, desert and forest increased by 28.63, 0.64 and 29.27%, while grassland decreased by 10.29% during 1990-2010. The largest reclamation, grassland loss and desertification were 639.17 × 10, 2350.42 × 10 and 1605.86 × 10 ha during 1995-2000. The relationship between reclamation and grassland loss was a positive correlation, while a highly positive correlation was 0.993 between the desertification and grassland loss at different stages. The most serious dust source region was the desertification during 1990-2010 (1614.58 thousand ha), and the serious region was stable desert (40,631.21 thousand ha). The area of the medium and low dust source region was 499.08 × 10 and 2667.27 × 10 ha. Dramatic reclamation resulted in the desertification by destroying natural vegetation and breaking the balance of water allocation in various regions. [ABSTRACT FROM AUTHOR]

For the very first time, the mesoscale circulation patterns and synoptic-dynamic structure of the atmospheric systems that led to the dust emission to the south coast region of Caspian Sea (SCRCS) were identified and classified using the region synoptic stations' observations of 2005-2013. Satellite measurements and images, NCEP/NCAR reanalysis data, and Weather Research and Forecasting (WRF) model coupled with Chemistry (WRF-CHEM) model products were also used in this study. Results showed that in 49 % of cases, cyclonic circulations over the Middle East deserts were the main transporter of dust particles into the atmosphere where then transferred to the SCRCS by southerly winds over the Alborz mountains in the lower troposphere and by westerly waves in the middle and upper troposphere. During the warm seasons, the surface heating lead to the development of mesoscale thermal low pressures over the hot deserts on the eastern regions of the Caspian Sea, like Turkmenistan and Qura Qum. Those heat lows were responsible for the 38 % of the occurred events. Turbulence and instabilities in the lower troposphere were identified as the second important dust emitter to the atmosphere where those dust particles transported to the SCRCS with the strong northeasterly wind. The third pattern by 13 % of cases was belonging to the mesoscale thermal low pressure that was developed over the arid regions of Iran like Dasht-é-Kavir. Because of the nature of the turbulence in the lower troposphere and heat lows, the ascent of dust particles by these two mechanisms was limited to a shallow layer in the troposphere. The results of simulation with the WRF-CHEM model, analysis of moderate resolution imaging spectroradiometer (MODIS) images, and spatial zoning of atmospheric optical depth (AOD) confirmed the results of the synoptic study. [ABSTRACT FROM AUTHOR]

This paper promotes an understanding of the mineralogical, chemical, and physical interrelationships of re-suspended mineral dusts collected as grab samples from global dust sources. Surface soils were collected from arid regions, including the southwestern USA, Mali, Chad, Morocco, Canary Islands, Cape Verde, Djibouti, Afghanistan, Iraq, Kuwait, Qatar, UAE, Serbia, China, Namibia, Botswana, Australia, and Chile. The < 38 µm sieved fraction of each sample was re-suspended in a chamber, from which the airborne mineral dust could be extracted, sampled, and analyzed. Instruments integrated into the entrainment facility included two PM10 and two PM2.5 filter samplers, a beta attenuation gauge for the continuous measurement of PM10 and PM2.5 particulate mass fractions, an aerodynamic particle size (APS) analyzer, and a three wavelength (405, 532, 781 nm) photoacoustic instrument with integrating reciprocal nephelometer for monitoring absorption and scattering coefficients during the dust re-suspension process. Filter sampling media included Teflon® membrane and quartz fiber filters for chemical analysis, and Nuclepore® filters for individual particle analysis by Scanning Electron Microscopy (SEM). The < 38 µm sieved fractions were also analyzed by X-ray diffraction for their mineral content while the > 75 µm, < 125 µm soil fractions were mineralogically assessed by optical microscopy. Presented here are results of the optical measurements, showing the interdependencies of single scattering albedos (SSA) at three different wavelengths and chemical as well as mineralogical content of the entrained dust samples. Relationships between the SSA of airborne dusts, and iron (Fe) in hematite, goethite, and clay minerals (montmorillonite, illite, palygorskite) are demonstrated. Differences in clay mineralogy between samples from Mali and those from other localities are highlighted. Results from this study can be integrated into a database of mineral dust properties, for applications in climate modeling, remote sensing, visibility, health (medical geology), ocean fertilization, and impact on equipment. [ABSTRACT FROM AUTHOR]