Arabian Desert Research Articles

Stress-driven metabolites of desert soil fungi

ABSTRACT Microorganisms produce secondary metabolites to survive under stressful conditions. The effect of drought and heat stress on fungi isolated from Arabian desert soil during the hot (ca 40°C) and cool (ca 10°C) seasons was studied using the genome mining approach. The presence of three stress-related genes (calmodulin, polyketide synthase and beta tubulin) was analyzed molecularly using specific primers. The presence of the genes in desert fungi was compared to their antimicrobial (ten bacterial or fungal pathogens) and anticancer (liver, cervical and breast) properties and the production of thermostable enzymes (phytase and xylanase). The genes appeared to be present in the fungal sequence obtained during the summer, while none of the genes were present during winter. Appreciable differences were observed in enzyme activities, with summer activities high and winter low. The antagonistic activities of A. niger were relatively stable and varying, while those of P. chrysogenum were consistently higher in summer than in winter. The presence of the three genes seemed to correlate with the highly antagonistic activities of P. chrysogenum, while A. niger had relatively active winter isolates without any of the genes. The hot season in deserts yields fungal isolates with biological activities useful in biotechnological solutions.

MEDEA randomised intervention study protocol in Cyprus, Greece and Israel for mitigation of desert dust health effects in adults with atrial fibrillation

IntroductionMediterranean countries experience frequent desert dust storm (DDS) events originating from neighbouring Sahara and Arabian deserts, which are associated with significant increase in mortality and hospital admissions, mostly from cardiovascular...

Source apportionment and potential source regions of size-resolved particulate matter at a heavily polluted industrial city in the Indo-Gangetic Plain

This study presents results from size-resolved particulate matter (PM) source apportionment in Ghaziabad, an industrial city adjoining New Delhi in the Indo Gangetic Plain (IGP). A full-year of measurement of PM2.5 and PM10 along with their chemical constituents was performed at two locations in the city. The annual average PM2.5 and PM10 concentrations were ∼150±85 μgm−3 and ∼270±140 μgm−3, respectively, with a ratio of 0.55, indicating the considerable influence of dust. USEPA PMF5 was applied to a combination of ions, elements, and carbon fractions of both PM2.5 and PM10. The model resolved eight factors, including combustion aerosol, secondary aerosol, vehicular emissions, resuspended dust I, resuspended dust II, brick manufacturing, copper smelter, and mixed metal processing. These factors were common to both sites and PM fractions, but with different contributions. Annually, the major contributors to PM2.5 were vehicular emissions (∼21–23%), secondary aerosol (20%), and combustion aerosol (∼17–19%) and to PM10, they were dust (∼44–54%) and combustion aerosol (∼23%). When daily average PM2.5dailyavg>90 μgm−3, brick processing, vehicular emissions, and secondary aerosols were found to be contributing to ∼60% of the PM2.5 loading. However, when PM10dailyavg>250 μgm−3, combustion aerosol, and resuspended dust (I and II) were found to be contributing to ∼70% of the PM10 loading. The likely PM source locations were local as well as regional, with the brick kilns and biomass combustion in the region and states in the upper IGP, namely Punjab, Haryana, and Delhi, being important source regions. Also, specifically for PM10, local construction activity and long-range transport of aged dust from the Arabian desert through western India were found to be the source regions. The results of this study suggested that lowering the contribution of combustion sources, including vehicles, industry, and brick kilns can significantly lower the PM2.5 loading by lowering primary particle loading and secondary particle generation. Controlling local dust re-suspension can lower PM10 mass loading, enhancing local air quality.

Экологические ловушки» и «кормовые оазисы» на зимовках и миграциях молодых больших подорликов

The present study is based on data on the spatial distribution, habitats used and limiting factors during wintering, migration, and summer movements for 9 young Greater Spotted Eagles (Aquila [Clanga] clanga, GSE) obtained via GPS-GSM tracking. In 2019, four individuals (Oduvanchik, Boets, Zadira, Klyazma) were tagged in the center of European Russia and one (Prosha) in the Republic of Tatarstan; in 2022 – three individuals in the center of European Russia (Leto, Dina, Tisha) and one (Kirya) in the Chuvash Republic. Scant published data based on telemetry indicate that young GSEs migrate to wintering sites independently, using different route than their parents (Meyburg et al., 2005). Apparently, the first autumn migration of young individuals does not yet have a strict direction and is largely a matter of chance (Maciorowski et al., 2014). We confirmed this by tracking our GSEs: some of them accidentally found “feeding oases” on migration routes and in wintering areas, while others fell into “ecological traps”. Having memorized the location of the “feeding oases” discovered on the migration in the first autumn, birds can change the wintering grounds in subsequent years, settling for the winter in these territories. So, in October 2019, Oduvanchik made an 18-day stopover in the area of Slavyansk-on-Kuban in the Krasnodar Territory. The next three winters he spent on Prikubanskaya Plain, without further migration to the delta of the Nile River, where he spent the first winter. Another eagle named Prosha during the first winter stayed for a month (from 25/10 to 24/11/2019) on Salyan Plain of Azerbaijan, mainly in swampy areas not used in agriculture. Then he flew along the western coast of the Caspian Sea to the south and settled in Gilan province of Iran. During the two subsequent winterings, Prosha did not stay in Azerbaijan. Favorable combination of habitats in the winter territory of Prosha in northwest Iran and the rice fields with easily accessible prey for Oduvanchik on Prikubanskaya Plain (see the theses of Mischenko and Sukhanova in this book) results in the minimum wintering areas and the smallest average daily movements of these two birds. Unlike them, Dina and Zadira ended up wintering in “ecological traps” – deserts. Dina died in Saudi Arabia 18 days later. Zadira, who also wintered in the Arabian Peninsula and the coastal pains of the Persian Gulf, was able to survive, but was forced to make the greatest daily movements in search of food. The places of the longest stopovers of Oduvanchik and Boets during summer vagrancies were the territories with extensive farmlands in Bezhetsk district of Tver region (60 days in 2020 and 102 days in 2021) and Orsha district of Belarus (67 days in 2020), in which the terms of harvesting and haymaking are greatly extended. Harvesting kills and displaces many birds and small mammals turning such areas into a “fodder oasis” for raptors, thus they can stay here for long making very short daily movements. We found that GSEs stop at large landfills, with concentration of Corvidae and gulls, and the abundance of rodents. Oduvanchik spent 9 days, from (28/06 to 06/07/2020) on landfill near the city of Tver. Boets for a week (from 05 to 12/06/2021) stayed on landfill near the city of Rzhev. Here, on 22/06/2023, we visually recorded a GSE that was not tagged with a tracker. GSE named Leto discovered an unusual “fodder oasis”: an industrial estate with flooded quarries within the city of Kostroma, where an outbreak of avian flu was registered on 18/05/2023. Leto flew to this place on 02/06 and stayed there until 07/07/2023. The abundance of dead and dying birds did not last long, and later the GSE probably began to prey on gull chicks in colonies. Easy access to prey, reduced disturbance (quarantine in the 500 m zone), and the presence of trees convenient for roosting results in minimal movements withing the industrial zone – no more than 1.1 km. We have identified very high mortality rate of young GSEs as a result of anthropogenic factors: only two of the nine birds remained alive by 2023. Prosha died in a fox-trap with a bait in the Samara region at the 4th year of life. Tisha was killed by a poacher in Abkhazia during the first autumn migration. Poles of power lines in arid zone possess deadliest risk for raptors. Zadira and Kirya perished on them in Iran at the 1st year of life. Dina died in the Arabian desert, probably from lack of food. The reasons for the death of Klyazma in Libya, also at the 1st year of life, and the Boets in Israel at the 3rd year of life are unknown.

Wind Tunnel Experiments and Field Observations of Aeolian Sand Encroachment around Vernacular Settlements in the Saharan and Arabian Deserts

One of the key repercussions of the desertification process in the Sahara and the Arabian desert is increased aeolian sand drift and sand deposition. Despite its isolated location and severe desert climate—particularly in terms of solar radiation, sand drift, and sand deposition—the region of El-Oued Souf in the Grand Erg Oriental in the Algerian Sahara has been a key cultural and trade center for many centuries. To resist the extreme weather conditions, the architecture of the vernacular settlements in the region of El-Oued Souf has unique design traits. Newly constructed buildings, on the other hand, frequently employ technologies based on models imported or imposed from climates that bear little resemblance to the desert. As a result, the inhabitants of these structures live more ‘in the desert’ than ‘with the desert’. This study investigates the impact and the effectiveness of vernacular desert architecture to resist aeolian sand encroachment problems in sandy desert areas. The sand accumulation patterns around vernacular buildings were identified and quantified using wind tunnel experiments. The size and shape of the buildings, as well as their geometric configuration within the settlement, were investigated in relation to the shape and dimension of sand accumulation formations. Field observations in north Algeria and the United Arab Emirates confirmed the accumulation patterns produced by the wind tunnel experiments. The study proposes possible design indicators for building forms to minimize the impact of sand deposition on such forms.

Martha Sharp Joukowsky, 1936–2022

Martha Sharp Joukowsky, 1936–2022

Ecological study on native plant diversity in Kuwait desert ecosystem

The scarcity and irregularity of rainfall and the prevalence of strong northwesterly winds in Kuwait have a significant influence on the stability of the fragile ecosystem. The Aeolian landforms constitute most of the landscapes in Kuwait. Naturally grown native shrubs and trees can provide potential shelter to the soil surface in desert areas. To identify the characteristics of dominant perennial plant species, sediments of desert and saline (sabkhas) nabkha formed around different types of desert and halophytes plants are studied. Haloxylon salicornicum, Nitraria retusa, Cyperus conglomerates, Panicum turgidum, Rhanterium epapposum, Calligonum polygonoides, Stipagrostis plumosa Lycium shawii, Astragalus spinosus, Convolvolus oxyphyllus, Tamarix aucheriana, Halocnemum strobilaceum, and Citrullus colocynthis are landmarks characterizing the Arabian deserts and coastal salt marshes. The analyses of soil samples around the native plants showed that each native plants has its characteristics. The sediments of desert nabkhas differ from coastal nabkhas (Nitraria sp., Halocnemum sp., and Tamarix sp.). The sediments of coastal nabkha were characterized by lower pH, higher moisture content, total dissolved salts, and conductivity levels than desert nabkhas. Maximum mobile sediments were trapped by N. retusa, T. aucheriana, H. salicornicum, C. colocynthis, and L. shawii because of their ability to develop wider and longer nabkhas than other native plants. The vegetated dunes can trap maximum mobile sediments from 0.5 to 10.5 tons thus cost-saving per plant is estimated to be from 0.3 to 7.3 USD.

Antimicrobial efficacy of extracts of Saudi Arabian desert Terfezia claveryi truffles

BackgroundTerfezia claveryi truffles are known for their nutritional value and have been considered among traditional treatments for ophthalmic infections and ailments. ObjectivesWe sought to investigate the in vitro antimicrobial efficacy of several T. claveryi extracts from Saudi Arabia. Certain pathogenic fungi and gram-negative and gram-positive bacteria were included. MethodsDry extracts were prepared using methanol, ethyl acetate, and distilled water, while the latter was used for preparing fresh extracts. The extracts were microbiologically evaluated through the disc-diffusion agar method; the zones of inhibition of microbial growth were measured post-incubation. The minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) were determined in Müller-Hinton Broth through the microdilution susceptibility method. anti-biofilm activity was assessed for potent extracts. ResultsDry extracts showed potent activity (>16-mm inhibition zones) against gram-positive (Bacillus subtilis IFO3007 and Staphylococcus aureus IFO3060) and gram-negative (Pseudomonas aeruginosa IFO3448 and Escherichia coli IFO3301) bacteria. The activity against fungi was moderate (12–16-mm inhibition zones) for both Aspergillus oryzae IFO4177 and Candida albicans IFO0583; there was no activity against Aspergillus niger IFO4414 growth. Methanolic extract had the lowest MIC and MBC, exhibiting remarkable activity against B. subtilis growth. Fresh extract showed moderate activity against bacterial growth and inactivity against fungal growth. Methanolic extract showed potent anti-biofilm activity (IC50, 2.0 ± 0.18 mg/mL) against S. aureus. ConclusionsT. claveryi extracts showed antibacterial effects potentially suitable for clinical application, which warrants further in-depth analysis of their individual isolated compounds.

Effect of Salinity and Temperature on the Seed Germination and Seedling Growth of Desert Forage Grass Lasiurus scindicus Henr.

Lasiurus scindicus Henr. is one of the most important forage grass species of the Arabian deserts. Temperature and soil salinity are well known to influence the germination and seedling development of various forage species. Therefore, in the current study, the effect of temperature and salinity and their interaction on the germination parameters, seedling growth, and physiological parameters of L. scindicus were evaluated. For this reason, L. scindicus seeds were treated with five salinity concentrations (i.e., 0, 50, 100, 150, and 200 mM NaCl) and incubated at two temperature levels (T1 = 25/20 °C, D/N and T2 = 35/30 °C, D/N). The results indicated that the salinity and temperature significantly affected the germination indices, seedling growth parameters, chlorophyll, and proline content. The highest germination percentage (GP; 90%) was recorded in the non-saline-treated seeds incubated at T1. The seeds at T2 under the non-saline treatment exhibited an increased germination rate (GR = 17.5%). The interactive effect of salinity and temperature on germination and growth parameters was significant, indicating that the germination response to salinity depends on temperature. The germination of seeds treated with 200 mM NaCl was completely inhibited at both temperatures T1 and T2. However, the ungerminated seeds at both T1 (85%) and T2 (78%) restored their germination abilities after they were transferred to distilled water. Also, the seed vigor index (SVI) constantly showed a decline with the increasing salinity levels especially at T2, which was lowest when seeds were treated with 150 mM salinity. Growth parameters (i.e., aRL, aSL, RDW, SDW, SB, and SLA) and the chlorophyll content showed a similar pattern as that of germination. However, the proline content (shoot proline and root proline) showed a progressive increase with increasing salinity and temperature. All of these characteristics indicate that L. scindicus seeds were not able to germinate under extreme salinity and temperature conditions but remained viable in a state of enforced dormancy. This is most likely an important adaptive strategy of this species for survival in the high-saline changing habitats of the arid region of Saudi Arabia, and thus, it can be an excellent choice for restoring degraded rangelands and salinity-inflicted abundant farmlands for forage agriculture.

Big Data Analytics Model for Preventing the Spread of COVID-19 During Hajj using the Proposed Smart Hajj Application

Unlike the Pool of Bethesda, Makkah is a moment of sacrifice, a space of unified worship in the lives of Muslim worshipers. The Makkah experience symbolizes the “farewell pilgrimage” of the Prophet Muhammad through the Arabian desert in 632 A.D. (Aljazeera, 2021). The annual Hajj expedition to the Saudi holy city is the fifth of the five Muslim Pillars of Islam. Hajj occurs during Dhu’al-Hijjah, the last month of the year according to the Islamic calendar. Millions of people from across the world assemble to pray in the direction of Ka’bah, the holiest Islamic shrine constructed by Abraham and Ishmael. The 2012 Hajj attracted more than 3 million pilgrims journeyed to Hajj. However, the 2019 SARS-CoV-2 outbreak has since forced decision-makers for the Kingdom of Saudi Arabia to take further preventive measures in the interests of public health that affect the outcomes of the traditional prayer and worship. Saudi Arabian government officials significantly downsized capacity and instituted protocols for attendance to the 2020 and 2021 Hajj events due to the Covid-19 pandemic. In addition to Muslim pilgrimages, several nations have implemented mHealth apps designed for Covid-19 contact tracing, quarantine enforcement, symptom monitoring, and information provision for mass crowding events. Independently, the apps do not provide a holistic approach to Covid-19 transmission control in mass gatherings. A more universal, less intrusive technological approaches to managing and protecting the Hajj pilgrimage populations using credible, real-time data is needful. This study proposes an information-generating SMART app based on the success of prior apps, the implementation of a Smart Hajj application, which allows authorities to track Hajj pilgrim movement, and collect data as a part of efforts to prevent Covid-19 from disrupting centuries-old tradition Muslim pilgrimages to worship in sacred places.

Antecedent Soil Moisture Conditions Influenced Vertical Dust Flux: A Case Study in Iran Using WRF-Chem Model

Soil moisture is one of the most important parameters affecting dust emission flux. This study was conducted to investigate the effects of soil moisture on vertical dust flux in the central plateau region of Iran. In this study, the WRF-Chem (Weather Research and Forecast with Chemistry) model, with the GOCART (Global Ozone Chemistry Aerosol Radiation and Transport) scheme, was used to estimate the dust emission flux during a major storm from 19 to 21 July 2015, and to discriminate between dust sources. The results showed that the Kyrgyz deserts in Turkmenistan, the Arabian deserts in Saudi Arabia, the deserts of Iraq, and the Helmand region in Afghanistan are sources of foreign dust. Additionally, the central desert plain was identified as an internal dust source, where the dust level reached 7000 µg m−2 s−1. The results of WRF-Chem simulation were verified with reanalysis data from MERRA2 and AERONET data from Natanz station, which showed good agreement with the simulation. Based on the GLDAS reanalysis, soil moisture content varied between 2.6% and 34%. Linear and nonlinear regression of vertical dust flux values and soil moisture showed nonlinear behavior following the exponential function, with a correlation coefficient of 0.8 and a strong negative association between soil moisture and vertical dust flux.

Antimicrobial Activity of Green Silver Nanoparticles Synthesized by Different Extracts from the Leaves of Saudi Palm Tree (Phoenix Dactylifera L.).

The Arabian desert is rich in different species of medicinal plants, which approved variable antimicrobial activities. Phoenix dactylifera L. is one of the medical trees rich in phenolic acids and flavonoids. The current study aimed to assess the antibacterial and antifungal properties of the silver nanoparticles (AgNPs) green-synthesized by two preparations (ethanolic and water extracts) from palm leaves. The characteristics of the produced AgNPs were tested by UV-visible spectroscopy and Transmitted Electron Microscopy (TEM). The antifungal activity of Phoenix dactylifera L. was tested against different species of Candida. Moreover, its antibacterial activity was evaluated against two Gram-positive and two Gram-negative strains. The results showed that AgNPs had a spherical larger shape than the crude extracts. AgNPs, from both preparations, had significant antimicrobial effects. The water extract had slightly higher antimicrobial activity than the ethanolic extract, as it induced more inhibitory effects against all species. That suggests the possible use of palm leaf extracts against different pathogenic bacteria and fungi instead of chemical compounds, which had economic and health benefits.

Riding East—Western Myths, Nostalgia, and the Crossing of Generic Boundaries in Hidalgo (2004)

<i>Riding East</i>—Western Myths, Nostalgia, and the Crossing of Generic Boundaries in <i>Hidalgo</i> (2004)

Geochemistry and granulometry as indicators of paleoclimate, weathering, and provenance of sediments for the past 1,00,000 years in the eastern Arabian Sea

• Climate during MIS1, 3, 5a & 5c was hot and humid with intense SWM than YD, LGM, MIS2, 4, 5b. • Source area has experienced moderate to intense chemical weathering. • Provenance of sediments was felsic rocks during warm periods and mafic rocks and dust during cold periods. • Sources of sediments are ∼50% basalt , 40–80% gneiss and 10–20% dust. • Climate of lower and higher latitudes suggests inter-regional teleconnections . Geochemical and granulometric investigation of a 408 cm long sediment core raised from the Eastern Arabian Sea was carried out to decipher the climate, weathering, dust flux and provenance of sediments during the past 100 ka. The diagnostic ratio of Cr/Ni (0.99 to 1.77), Rb/Al (6.01 to 17.14), Ti/Al (0.02 to 0.03), Fe/Al (0.94 to 1.61), Mg/Al (0.31 to 0.59) and silt% (38.68 to 66.37) indicate hot and humid climate with the intensification of south-west monsoon during marine isotope stage (MIS) 1, 3, 5a and 5c and cold and dry climate with the intensification of the northeast monsoon and high dust flux during Younger Dryas cooling, last glacial maximum, MIS 2, 4 and 5b. The clay% (20.42 to 53.92), Silica–Titanium Index (71.88 to 86.28), Ruxton Ratio (2.89 to 7.22), and Th/U ratio (0.98 to 4.11) indicate moderate to intense chemical weathering in the source area during warmer climate. Th(ppm) versus Sc(ppm), La/Th versus Th/Yb, Al 2 O 3 % versus Fe 2 O 3 %, Th/Sc versus Sc(ppm), La/Sc versus Sc/Th ratios and La-Th-Sc plot indicate intermediate/mixed sources for sediment provenance. Sand% (2.82 to 25.3), Si/Al (2.74 to 7.43), ΣLREE/ΣHREE (7.65 to 10.40), La/Sc (2.24 to 3.55) indicate felsic sources from Peninsular India during warm climates and ΣREE (103.98–201.17), Rb/Ga (1.36–4.33), Ni (70.42–137.3 ppm), Rb (55.39–138.90 ppm) indicate mafic sources from Deccan Traps and Arabian desert during cold climates. The synchronous relationship between the climate of lower and higher latitudes was observed, suggesting the global teleconnections of climate during the Late Quaternary.

Об особенностях пространственно-временной изменчивости характеристик волн тепла последних трех десятилетий (Араратская долина, Армения)

The aim of this work to study, identify the repeatability and duration of heat waves of the study area. For it were suggested and decided the following tasks: Findings. The study of regularities of variability of the spatial-temporal distribution of characteristics of heat wave in conditions of regional and global changes of climate is current task of modern geographical science. Extremely high temperatures and heat waves of study area excessively conditioned by the influence of secondary thermal depressions from the Arabian Peninsula, a number of cases that last for 2-3 decades are significantly increased. Tropical thermal depression, forming of extreme hot summers and heat waves, have cycles of activation and weakening, periodicity of which is estimated at 20-22 years. Starting from July (sometimes from the second half of June) to the last ten days of August (sometimes to first half of September), weather conditions of Ararat valley are formed under influence of thermal depression. The invasion of southern and south-eastern tropical warm and dry air currents from the Arabian deserts is increasing. As a result in some years the air temperature in Ararat valley is increased to 40-43 °C, and relative humidity is low than 30%. Heat waves are dangerous weather phenomena, is threat for live and activity, are characterized with some negative consequences. They can be accompanied by droughts and dry winds, forest fires, desertification, disruption of the natural ecosystem, economic damage, decreased working capacity, psychological and sociological consequences, even deaths. Temporal tendencies in course of values of the characteristics of heat wave for last 2-3 decades have positive unambiguous character, more frequent heat waves and extremely warm summers. Heat waves of low and medium intensity have a particularly high frequency. The probability of strong waves is less. The study area is distinguished a characteristic regime and an almost uniform spatial distribution of summer extreme high temperatures. They range from 41,5 to 42,6 °C. The entire study area is vulnerable to heat waves. Heat waves can cause dangerous meteorological phenomena such as droughts or dry winds, which cause great damage to various sectors of the economy, especially agriculture. Therefore the results of the work can be used in the field of agriculture, mitigating and reducing the consequences of possible damage caused. They can also be used in agrometeorological forecasts. In the study area, summer conditions become warmer and drier, which should be taken into account when developing strategic programs for the future development of this area.

Moisture transport and water vapour budget over the Sahara Desert

AbstractPrevious studies documented that near‐surface temperatures over the Sahara and Arabian deserts have been amplified in a warming climate, which is termed desert amplification (DA). DA has been linked possibly to the large‐scale greenhouse effects associated with increasing water vapour. With very limited moisture availability over the driest desert, two key questions unanswered are the desert moisture sources and the relative contributions of thermodynamic and dynamic processes to the changes in moisture transport. In this study, the atmospheric water vapour budget over the Sahara Desert from 1981–2020 is analysed to address these two questions. Results indicate that the water vapour content over the Sahara Desert has increased significantly since 1981, primarily during the boreal summer and in the lower to middle troposphere. The water vapour budget analysis indicates that in the boreal summer, most of the added moisture is transported into the Sahara Desert through the intensifying northerly inflow across the northern boundary of the desert, while the other boundaries are all export channels. The northerly inward moisture transport is associated with the ridge in the lower troposphere and the Saharan high above the lower troposphere. Further analysis indicates that both dynamic and thermodynamic factors contribute to the increase of the inward moisture flux at the northern boundary, while the associated interannual variability is dominated by the dynamic component related to the circulation pattern changes. The changes of the circulation pattern in the lower troposphere are manifested as the westward extension of the low over the Arabian Peninsula and as the strengthening of the Saharan high above the lower troposphere, both contributing to the increase of the northerly inward moisture transport.

Wet Scavenging in Removing Chemical Compositions and Aerosols: A Case Study Over the Lake Urmia

AbstractLake 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.

A statistical approach for identification of dust-AOD hotspots climatology and clustering of dust regimes over Southwest Asia and the Arabian Sea

Daily atmospheric composition and meteorological data from MACC and ERA-5 reanalysis, were combined to analyse the spatiotemporal variability of dust-aerosol optical depth (DAOD) and to identify the prevailing dust regimes using Empirical Orthogonal Functions (EOFs) and Principal Component Analysis (PCA), respectively, over southwest Asia and the Arabian Sea from 2003 to 2012. The analysis reveals four DAOD regimes influenced by the relative positions of the monsoon low, persistent high-pressure systems and thermal lows and the associated wind regimes. The Southeast (SE) Arabia regime, is detected over the eastern Rub-Al Khali and Oman Deserts and is associated with cyclonic flows and low-pressure systems over the southeast Arabian Peninsula, while the highest DAOD are observed over the convergence zone of Shamal and monsoon winds. The Arabian Sea regime is associated with high dust presence over the marine environment originated from arid/desert lands in Saudi Arabia, Iran and Pakistan, and the concurrent action of monsoon, Shamal and Levar winds. The Thar regime is characterized by a deep thermal low over Pakistan and strong monsoon winds acting as density currents over the desert area, resulting in highest DAOD over NW India. The Aden Gulf regime, is characterized by a ridge stretched through Sudan to Bab al-Mandab Strait and a surface high-pressure system prevailed over the eastern Mediterranean and west Arabian Peninsula, resulting in anticyclonic pathway of dust plumes from the Arabian deserts and westerly dust flows from sources in Eritrea and Sudan that accumulate dust over the Gulf of Aden.

Effect of seed coat mucilage, temperature, and photoperiod on germination of four Arabian desert species

In this study, we assessed the effects of mucilage presence, thermoperiod, and photoperiod on seed germination percentage and germination velocity (mean germination time) of four Arabian desert species. We hypothesized that mucilage presence, thermoperiod, and photoperiod and their interaction would influence seed germination. Seeds with and without mucilage were germinated under different alternating temperature regimes of 15/25, 20/30, and 25/35 °C night/day temperatures with a 12/0 h light/dark photoperiod. Results showed that the incubation temperature affected the germination of all the studied species. The photoperiod significantly affected the germination of Boerhavia elegans Choisy, Salvia aegyptiaca L., and Sporobolus ioclados (Trin.) Nees, while the mucilage presence influenced the germination of S. ioclados only. The interaction between mucilage presence, temperature, and photoperiod significantly influenced the germination percentage of B. elegans and S. aegyptiaca. Neither removal of the mucilage nor light conditions affected the germination percentages of Sporobolus spicatus (Vahl) Kunth. However, the temperature affected the germination of S. spicatus. The germination of all the studied species was faster for demucilaged seeds. Ecologically, the mucilaginous seed coat is considered an important adaptation for dispersal as it anchors seeds on the ground and holds water around the seed during the germination stage in the stressful arid desert habitats.

Expansion of eastern Mediterranean Middle Paleolithic into the desert region in early marine isotopic stage 5

Marine Isotopic Stage 5 is associated with wetter climatic conditions in the Saharo-Arabian deserts. This stage also corresponds to the establishment of Middle Paleolithic hominins and their associated material culture in two geographical provinces in southwest Asia—the Eastern Mediterranean woodland and the Arabian Peninsula desert. The lithic industry of the Eastern Mediterranean is characterized by the centripetal Levallois method, whereas the Nubian Levallois method characterizes the populations of the Arabian desert. The Negev Desert, situated between these regions is a key area to comprehend population movement in correlation to climatic zones. This investigation addresses the nature of the Middle Paleolithic settlement in the Negev Desert during MIS 5 by studying the site of Nahal Aqev. High resolution chronological results based on luminescence dating and cryptotephra show the site was occupied from MIS 5e to MIS 5d. The lithic industries at Nahal Aqev are dominated by centripetal Levallois core method. These data demonstrate that Nahal Aqev is much closer in its cultural attributes to the Eastern Mediterranean Middle Paleolithic than to the Arabian Desert entity. We conclude that Nahal Aqev represents an expansion of Middle Paleolithic groups from the Mediterranean woodland into the desert, triggered by better climatic conditions. These groups possibly interacted with hominin groups bearing the Nubian core tradition from the vast region of Arabia.