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One of the most significant environmental catastrophes throughout the Middle East and Caucasus region has been the desiccation of Lake Urmia, the world second-largest hypersaline lake. This lake has lost approximately two-thirds of its water volume since 1999, resulting in increased exposure of lacustrine deposits that are considered as a new aerosol source. This in situ study investigates for the first time the spatial distribution of water-soluble ion concentrations (Cl–, Br–, NO2 –, NO3 –, SO4 2–, methanesulfonate (MSA), pyruvate, oxalate, adipate, Na+, K+, Ca2+, Mg2+, and NH4 +) in wet deposition samples collected around the Lake Urmia region to characterize relationships between rainwater composition and location relative to the lake. Rainwater collection was performed for 21 rain events from September 2017 to September 2018 across 13 sampling stations, providing representative coverage of the region surrounding Lake Urmia. The most dominant ions are as follows: Ca2+ > Cl– > SO4 2– > Na+ > NO3 –. Organic acids and MSA contribute negligibly to the total ion concentrations. Principal component analysis (PCA) and correlation coefficient (CC) analyses show that the majority of ions throughout the region are associated with salt and crustal particles comprised of Cl–, Br–, SO4 2–, Na+, Ca2+, and Mg2+, with the minority of ions (e.g., NH4 + and NO3 –) stemming from anthropogenic emissions. Concentrations of salt and crustal tracer species (i.e., Na+, Cl–, Br–, Mg2+, and SO4 2–) were inversely related to the distance from the Lake Urmia shoreline, suggestive of potential subcloud scavenging (washout) of freshly emitted aerosols. Backward trajectory analysis (HYSPLIT) shows that most of the rain events were linked to air masses originating in areas far upwind of Lake Urmia. Results of this study emphasize that wet deposition data provide support for effective scavenging of salt and crustal emissions as a function of distance from a desiccated lakebed.

Lake Urmia, NW Iran, and S Caucasus region, has lost approximately three‐fourth of its water volume resulting in increased exposure of lacustrine deposits. Therefore, the role of Lake Urmia desiccated saline lands on local aerosols and rainwater compositions is still vague. This study investigates the temporal and seasonal patterns of rainwater chemistry from January 2018 to June 2018 (six months) in 13 stations throughout the Lake Urmia basin. The samples collected were analyzed using triple quadrupole inductively coupled plasma mass spectrometry (ICP‐QQQ) and ion chromatography (IC) to measure elemental and ionic concentrations. Then, the Hybrid Single‐Particle Lagrangian Integrated Trajectory model (HYSPLIT) was applied to identify the pathway and contribution of emissions. The results depict that the concentration of elemental and ionic components over different parts of the Lake Urmia basin are significantly different. West and north directions have the highest concentrations of marine ions associated with fewer toxic elements. In contrast, the east and south directions show a high concentration of heavy metal elements and ions. The high level of heavy and toxic elements at the east and south directions indicates that local anthropogenic sources are more influential. The seasonal and monthly variabilities of chemical compositions depict that the highest concentration of Na+, Mg2+, Ca2+, K+, Cl−, Br−, NO3−, Al, Cr, Mn, Fe, and Co were in the spring season and SO42−, NH4+ and NO2− were highest in winter. Seasonal variation for MSA, organic acids (i.e., Pyruvate, Adipate, and Oxalate), Ni, Cu, Zn, V, and Ti were not apparent. Cluster‐mean HYSPLIT backward trajectories results show the most dominant air mass sectors are from W (a: Iraq, Syria, and Arabian deserts; b: Mediterranean Sea; and c: KSA) and NE (the Caspian Sea and its vicinity), contributed to almost 65% and 22%, respectively. These air masses bring a significant quantity of crustal and marine aerosols, respectively. It is inferred that the Lake Urmia dried‐up lakebeds have less impact on the contribution of emissions across the region.

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<p>To enhance the understanding of aeolian landforms and their processes, the assessment of origin, migration and evolution of newly-born sand dunes is vital. In this regard, Lake Urmia, in NW Iran, was considered as a representative case study, given that it has lost approximately two-thirds of its water volume in the past two decades and, consequently, the newly-born sand ridges and sand dunes on its western shores were formed. The emerging sand dunes are located close to the villages, adjacent to the agricultural and farmlands, international transit road, and industrial zone, encompassing the whole area. The present study aims to assess the sand dunes’ origin and their migration both in speed and direction in the past decade.</p><p>To understand the questions above, remote sensing techniques and in-field studies were coupled. Therefore, wind data from the closest meteorological station were employed to calculate the wind rose, drift potential (DP), the resultant drift potential (RDP), and the resultant drift direction (RDD) across the region. Change detection techniques using high-resolution satellite images were chosen to detect the migration rate and morpho-dynamic changes of Lake Urmia sand dunes. To classify the geomorphological features and land uses in the region, a hybrid supervised classification approach including a customised decision tree classifier was used to distinguish sand dune units from other signatures. Using the minimum bounding geometry method, feature classes were created. These feature classes represent the length, width, and orientation of sand dunes, retrieved after the image classification process. Also, fieldwork surveying was carried out on the sixteen sand dunes in different periods to measure the morphological and evolutionary changes.</p><p> As the wind results show, the trend of DP parameters between the years 2006-2009 and the years 2015-2020, the percentage of wind speeds above the threshold velocity (V>Vt%) to DP has significant gaps, suggestive of weaker winds in those periods. However, between the years 2009-2015, the V>Vt% and DP values are corresponding and coequal. This indicates that the most erosive and shifting winds are between 2009-2015, with the weakest wind power in tails. Moreover, the annual variability of DPt is well correlated with Lake Urmia water level changes; but there is no correlation between the DPt and precipitation amount. The evaluation of image processing results depicted that after 2003, the area of sand dunes had dramatically increased. On average, the smallest area belongs to 2010 (287.3 m2), and the largest area is for years 2019 (775.96 m2), 2018 (739.08 m2), and 2017 (739.74 m2). In addition, between the years 2010 and 2014, a significant increase in area of the sand dunes from 287.25 to 662.8 m2 was observed. The migration rate is the highest between 2010 and 2015, with the lowest values before 2010 and after 2015.</p><p>The results of this study have broad implications in the context of sustainable development and climate-related challenges, ecosystem management and policy-making for regions with sand dune challenges, hence crucial insights can be gained by coupling remote sensing techniques and in-situ studies.</p>