Search Results (246)

This article documents the widespread absence of sessile species in bedrock intertidal habitats at the head of the St. Lawrence Estuary, a large macrotidal estuary located in eastern Canada. Extensive observations revealed that no seaweeds or sessile invertebrates occurred anywhere (including cracks and crevices) on substrate areas that become exposed to the air during low tides. Only one sessile species, a green filamentous alga, was found submerged in tidepools. The lack of truly marine sessile species is likely explained by the very low water salinity of this coast, while the absence of sessile freshwater species on intertidal substrates outside of tidepools likely responds to a combination of oligohaline conditions during high tides and daily exposures to the air during low tides, which freshwater species are typically not adapted to. Influences of winter ice scour and coastal suspended sediments are likely secondary. Experimental research could unravel the interactive effects of these abiotic stressors. Overall, this “intertidal desert” could be a useful model system to further explore the boundaries of life on our planet. Full article

The Inner Mongolia Plateau (IMP), situated in the arid and semi-arid ecological transition zone of northern China, is particularly vulnerable to both climate change and human activities. Understanding the spatiotemporal vegetation dynamics and their driving forces is essential for regional ecological management. This study employs Sen’s slope estimation, BFAST analysis, residual trend method and Geodetector to analyze the spatial patterns of Normalized Difference Vegetation Index (NDVI) variability and distinguish between climatic and anthropogenic influences. Key findings include the following: (1) From 1982 to 2022, vegetation cover across the IMP exhibited a significant greening trend. Zonal analysis showed that this spatial heterogeneity was strongly regulated by regional hydrothermal conditions, with varied responses across land cover types and pronounced recovery observed in high-altitude areas. (2) In the western arid regions, vegetation trends were unstable, often marked by interruptions and reversals, contrasting with the sustained greening observed in the eastern zones. (3) Vegetation growth was primarily temperature-driven in the eastern forested areas, precipitation-driven in the central grasslands, and severely limited in the western deserts due to warming-induced drought. (4) Human activities exerted dual effects: significant positive residual trends were observed in the Hetao Plain and southern Horqin Sandy Land, while widespread negative residuals emerged across the southern deserts and central grasslands. (5) Vegetation change was driven by climate and human factors, with recovery mainly due to climate improvement and degradation linked to their combined impact. These findings highlight the interactive mechanisms of climate change and human disturbance in regulating terrestrial vegetation dynamics, offering insights for sustainable development and ecosystem education in climate-sensitive systems. Full article

The article provides a comprehensive analysis of the Magal Gebreel granitic suites (MGGs) using petrological (fieldwork, petrography, mineral chemistry, and bulk rock analysis) aspects to infer their petrogenesis and emplacement setting. Our understanding of the development of the northern portion of the Arabian Nubian Shield is significantly improved by the Neoproterozoic granitic rocks of the seldom studied MGGs in Egypt’s south Eastern Desert. According to detailed field, mineralogical, and geochemical assessments, they comprise syn-collision (granodiorites) and post-collision (monzogranites, syenogranites, and alkali feldspar rocks). Granodiorite has strong positive Pb, notable negative P, Ti, and Nb anomalies, and is magnesian in composition. They have high content of LREEs (light rare-earth elements) compared to HREEs (heavy rare-earth elements) and clear elevation of LFSEs (low-field strength elements; K Rb, and Ba) compared to HFSEs (high-field strength elements; Zr and Nb), which are in accord with the contents of I-type granites from the Eastern Desert. In this context, the granodiorites are indicative of an early magmatic phase that probably resulted from the partial melting of high K-mafic sources in the subduction zone. Conversely, the post-collision rocks have low contents of Mg#, CaO, P₂O₅, MgO, Fe₂O₃, Sr, and Ti, and high SiO₂, Fe₂O₃/MgO, Nb, Ce, and Ga/Al, suggesting A-type features with ferroan affinity. Their P, Nb, Sr, Ba, and Ti negative anomalies are in accord with the findings for Eastern Desert granites of the A2-type. Furthermore, they exhibit a prominent negative anomaly in Eu and a small elevation of LREEs in relation to HREEs. The oxygen fugacity (fO₂) for the rocks under investigation can be calculated using the biotite chemistry. The narrow Fe/(Fe + Mg) ratio range (0.6–0.75) indicates that they crystallized under moderately oxidizing conditions between ~QFM +0.1 and QFM +1. The A-type rocks were formed by the partial melting of a tonalite source (underplating rocks) in a post-collisional environment during the late period of extension via slab delamination. The lithosphere became somewhat impregnated with particular elements as a result of the interaction between the deeper crust and the upwelling mantle. Full article

The El Bola mafic–ultramafic intrusion (EBMU) in Egypt’s Northern Eastern Desert represents an example of Neoproterozoic post-collisional layered mafic–ultramafic magmatism in the Arabian–Nubian Shield (ANS). The intrusion is composed of pyroxenite, olivine gabbro, pyroxene gabbro, pyroxene–hornblende gabbro, and hornblende-gabbro, exhibiting adcumulate to heter-adcumulate textures. Mineralogical and geochemical analyses reveal a coherent trend of fractional crystallization. Compositions of whole rock and minerals indicate a parental magma of ferropicritic affinity, derived from partial melting of a hydrous, metasomatized spinel-bearing mantle source, likely modified by subduction-related fluids. Geothermobarometric calculations yield crystallization temperatures from ~1120 °C to ~800 °C and pressures from ~5.2 to ~3.1 kbar, while oxygen fugacity estimates suggest progressive oxidation (log fO₂ from −17.3 to −15.7) during differentiation. The EBMU displays Light Rare Earth element (LREE) enrichment, trace element patterns marked by Large Ion Lithophile Element (LILE) enrichment, Nb-Ta depletion and high LILE/HFSE (High Field Strength Elements) ratios, suggesting a mantle-derived source that remained largely unaffected by crustal contribution and was metasomatized by slab-derived fluids. Tectonic discrimination modeling suggests that EBMU magmatism was triggered by asthenospheric upwelling and slab break-off. Considering these findings alongside regional geologic features, we propose that the mafic–ultramafic intrusion from the ANS originated in a tectonic transition between subduction and collision (slab break-off) following the assembly of Gondwana. Full article

Mangrove ecosystems are crucial coastal habitats that support life and regulate the Earth’s atmosphere. However, these ecosystems face prominent threats due to anthropogenic activities and environmental constraints. For instance, the Saudi Arabian coast is particularly vulnerable to species extinction and biodiversity loss due to the fragility of the ecosystem; this highlights the need to understand the spatial and temporal dynamics of mangrove forests in desert environments. Hence, this is the first national study to quantify mangrove forests and analyze at-risk zone-based land use along Saudi Arabian coasts over 40 years. Thus, the primary contents of this research were (1) to produce a new long-term dataset covering the entire Saudi coastline, (2) to identify the patterns, analyze the trends, and quantify the change of mangrove areas, and (3) to determine vulnerability zoning of mangrove area-based land use and transportation networks. This study used Landsat satellite imagery via Google Earth Engine for national-scale mangrove mapping of Saudi Arabia between 1985 and 2024. Visible and infrared bands and seven spectral indices were employed as input features for the random forest classifier. The two classes used were mangrove and non-mangrove; the latter class included non-mangrove land-use and land-cover areas. Then, the study employed the output mangrove mapping to delineate vulnerable mangrove forest-based land use. The overall results showed a substantial increase in mangrove areas, ranging from 27.74 to 59.31 km² in the Red Sea and from 1.05 to 8.65 km² in the Arabian Gulf between 1985 and 2024, respectively. However, within this decadal trend, there were noticeable periods of decline. The spatial coverage of mangroves was larger on Saudi Arabia’s western coasts, especially the southwestern coasts, than on its eastern coasts. The overall accuracy, conducted annually, ranged between 91.00% and 98.50%. The results also show that expanding land uses and transportation networks within at-risk zones of mangrove forests may have a high potential effect. This study aimed to benefit the government, conservation agencies, coastal planners, and policymakers concerned with the preservation of mangrove habitats. Full article

Methane (CH₄) is a potent greenhouse gas with a significant impact on short- and medium-term climate forcing, and its atmospheric concentration has been increasing rapidly in recent decades. This study aims to analyze spatio-temporal patterns of atmospheric methane concentrations between 2019 and 2025, focusing on comparisons between regions characterized by high and low emission intensities. Level-3 XCH₄ data from the TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor satellite were used, which were aggregated into seasonal and annual composites. High-emission regions, such as the Mekong Delta, Nile Delta, Eastern Uttar Pradesh and Bihar, Central Thailand, Lake Victoria Basin, and Eastern Arkansas, were contrasted with low-emission areas including Patagonia, the Mongolian Steppe, Northern Scandinavia, the Australian Outback, the Sahara Desert, and the Canadian Shield. The results show that high-emission regions exhibit substantially higher seasonal amplitude in XCH₄ concentrations, with an average seasonal variation of approximately 30.00 ppb, compared to 17.39 ppb in low-emission regions. Methane concentrations generally peaked at the end of the year (Q4) and reached their lowest levels during the first half of the year (Q1 or Q2), particularly in agriculturally dominated regions. Principal component and cluster analyses further confirmed a strong spatial differentiation between high- and low-emission regions based on both temporal trends and seasonal behavior. These findings demonstrate the potential of satellite remote sensing to monitor regional methane dynamics and highlight the need for targeted mitigation strategies in major agricultural and wetland zones. Full article

The granitic rocks and the Dokhan Volcanics at the transect between Safaga and Qena, the Egyptian Northern Eastern Desert represent the northern termination of the Arabian–Nubian Shield (ANS), which, in turn, represents the northern part of the East African Orogeny (EAO). The geochronological development of the magmatic activities that constructed the ANS is critical in understanding these orogenies. The ANS was constructed through pre-collisional, syn-collisional, and post-collisional magmatic phases. The transition between these magmatic phases marks tectonic shifting from subduction to compressional and extensional tectonic settings, respectively. The chronological constraints of these tectonic–magmatic phases are still questionable. Our study aims to refine these chronological constraints through the dating of four calc-alkaline granitic rocks (722 ± 5 Ma–561 ± 4 Ma), five alkaline granitic rocks (758 ± 5 Ma–555 ± 4 Ma), and three Dokhan Volcanic rocks (618 ± 5 Ma–606 ± 5 Ma). Our results suggest the absence of any pre-collisional rocks. The syn-collisional magmatism extended here from 758 ± 5 Ma to 653 ± 7 Ma, demonstrating the chronological domination of the syn-orogenic compressional regime in the NED. The Dokhan Volcanic activity marked the shifting of the tectonic setting from a compressional to an extensional regime at 618 ± 5 Ma. Post-collisional plutonism dominated between 583 ± 5 Ma and 555 ± 4 Ma in the studied region, suggesting that ANS magmatic activity was extended to the Phanerozoic edge. These findings refute the classical interpretations of older magmatism as calc-alkaline granitoids and younger magmatism as alkaline granitoids. Pre-Neoproterozoic (pre-ANS) xenocrysts with ages of 1879 ± 22, 1401 ± 25, 1385 ± 12, 1232 ± 27, 1210 ± 18, and 1130 ± 15 Ma were yielded, which might support a local reworked ancient magmatic source. Full article

The current work records for the first time the rare-metal pegmatites with mixed NYF-LCT located at Wadi Sikait, south Eastern Desert of the Egyptian Nubian Shield. Most of the Sikait pegmatites are associated with sheared granite and are surrounded by an alteration zone cross-cutting through greisen bodies. Sikait pegmatites show zoned and complex types, where the outer wall zones are highly mineralized (Nb, Ta, Y, Th, Hf, REE, U) than the barren cores. They consist essentially of K-feldspar, quartz, micas (muscovite, lepidolite, and zinnwaldite), and less albite. They contain a wide range of accessory minerals, including garnet, columbite, fergusonite-(Y), cassiterite, allanite, monazite, bastnaesite (Y, Ce, Nd), thorite, zircon, beryl, topaz, apatite, and Fe-Ti oxides. In the present work, the discovery of Li-bearing minerals for the first time in the Wadi Sikait pegmatite is highly significant. Sikait pegmatites are highly mineralized and yield higher maximum concentrations of several metals than the associated sheared granite. They are strongly enriched in Li (900–1791 ppm), Nb (1181–1771 ppm), Ta (138–191 ppm), Y (626–998 ppm), Hf (201–303 ppm), Th (413–685 ppm), Zr (2592–4429 ppm), U (224–699 ppm), and ∑REE (830–1711 ppm). The pegmatites and associated sheared granite represent highly differentiated peraluminous rocks that are typical of post-collisional rare-metal bearing granites. They show parallel chondrite-normalized REE patterns, enriched in HREE relative to LREE [(La/Lu)_n = 0.04–0.12] and strongly negative Eu anomalies [(Eu/Eu*) = 0.03–0.10]. The REE patterns show an M-type tetrad effect, usually observed in granites that are strongly differentiated and ascribed to hydrothermal fluid exchange. The pegmatite has mineralogical and geochemical characteristics of the mixed NYF-LCT family and shows non-CHARAC behavior due to a hydrothermal effect. Late-stage metasomatism processes caused redistribution, concentrated on the primary rare metals, and drove the development of greisen and quartz veins along the fracture systems. The genetic relationship between the Sikait pegmatite and the surrounding sheared granite was demonstrated by the similarities in their geochemical properties. The source magmas were mostly derived from the juvenile continental crust of the Nubian Shield through partial melting and subsequently subjected to a high fractional crystallization degree. During the late hydrothermal stage, the exsolution of F-rich fluids transported some elements and locally increased their concentrations to the economic grades. The investigated pegmatite and sheared granite should be considered as a potential resource to warrant exploration for REEs and other rare metals. Full article

Iraq faces significant challenges in sustainable water resource management, due to intensive agriculture and climate change. Modern irrigation leads to depleted natural springs and abandoned traditional canal systems, creating a nexus between climate, water availability, agriculture, and cultural heritage. This work unveils this nexus holistically, from the regional to the local scale, and by considering all the components of the nexus. This is achieved by combining five decades (1974–2024) of satellite data—including declassified HEXAGON KH-9, Copernicus Sentinel-1/2/3, COSMO-SkyMed radar, and PlanetScope’s Dove optical imagery—and on-the-ground observations (photographic and drone surveying). The observed landscape changes are categorised as “proxies” to infer the presence of the given land processes that they correlate to. The whole of southern Iraq is afflicted by dust storms and intense evapotranspiration; new areas are desertifying and thus becoming local sources of dust in the southwest of the Euphrates floodplain and close to the boundary with the western desert. The most severe transformations happened around springs between Najaf Sea and Hammar Lake, where centre-pivot and herringbone irrigation systems fed by pumped groundwater have densified. While several instances of run-off and discharge highlight the loss of water in the western side of the study area, ~5 km² wide clusters of crops in the eastern side suffer from water scarcity and are abandoned. Here, new industrial activities and modern infrastructure have already damaged tens of archaeological sites. Future monitoring based on the identified proxies could help to assess improvements or deterioration, in light of mitigation measures. Full article

The relationship between global warming and heatwaves contributes to environmental risks. We investigate lake heatwaves (LHWs) in the Eastern Mediterranean, where dust intrusions are frequently observed. The dust intrusions are characterized by the arrival of warm air masses containing dust pollution from the desert. In saline lakes, LHWs caused by dust intrusions have not been investigated in previous studies. In our study we focus on this point. It was found for the first time that, in the hypersaline Dead Sea, a severe dust intrusion (aerosol optical depth of over 3) caused the formation of LHWs, as appeared in September 2015. At the water surface, the LHWs were represented by abnormally high daily maximal and minimal surface water temperature (SWT) in comparison with their seasonally varied 90th percentile thresholds for 10 consecutive days (7–17 September). The surface LHWs’ intensity was up to 3 °C. Satellite (MODIS-Terra and METEOSAT) SWT did not detect the LHWs. Surface LHWs were accompanied by subsurface LHWs down to a depth of 20 m. The subsurface LHWs lasted longer (16 days) than the surface LHWs (10 days). There was a 4-day delay between the first date of the surface LHWs (7 September) and the start date of the subsurface LHWs (11 September). The maximal intensity of the subsurface LHWs decreased with depth from 1 m (0.6 °C) down to 5 m (0.3 °C), followed by an increase (up to 0.6 °C) at the deeper layers (from 10 m to 20 m). Taking into account that, over the Eastern Mediterranean, desert dust has increased during the past several decades, one can expect frequent occurrence of dust-related intense persistent heatwaves in the Dead Sea in the coming years. This will contribute to additional water heating and further drying up of the Dead Sea. Full article

The Sierra Madre Occidental (SMO) is a biogeographic province of Mexico that serves as a corridor for the northward expansion of subtropical species, while also acting as a barrier for the movement of species between western and eastern Mexico. The SMO houses 57 species of amphibians and 160 species of reptiles, representing 19.4% of the total number of amphibian and reptile species found in Mexico. Ten amphibian and thirteen reptile species are endemic to the SMO, and >50% of amphibian and reptile species found in the SMO are endemic to Mexico. Five amphibian species and three reptile species are listed in a category of conservation concern in the IUCN Red List. Specific threats include habitat loss, logging, mining, pollution, and climate change. The SMO shares a significant percentage of its species with neighboring provinces. In the cluster analysis for amphibians, a group comprising the SMO, the Pacific Lowlands, and the Chihuahuan Desert is linked to the Transvolcanic Belt. For reptiles, two distinct groups emerge: one including the SMO and the Chihuahuan Desert and one including the Transvolcanic Belt and the Pacific Lowlands. In conclusion, the rich biodiversity of the SMO, along with its role as both a corridor and barrier for species distribution, highlights the importance of targeted conservation efforts to mitigate the various threats facing this biogeographically significant province. Full article

The paper presents data on the phylogeny, anatomy of vegetative organs, phytocenosis composition, and ploidy of two populations of endemic Allium lehmannianum Merckl. ex-Bunge. in the flora of northeastern Betpakdala. Some discrepancies in nomenclature and sectional affiliation are discussed and corrected. Allium lehmannianum belongs to the section Multicaulea F. O. Khass. and & Yenglal. subgenus Allium, the main range covering the eastern Old Mediterranean region. The ploidy of Allium lehmannianum was studied for the first time using flow cytometry techniques. The sequencing of nrITS was used to construct a phylogenetic tree, including sequences from the NCBI database. The phylogenetic tree of A. lehmannianum was compiled by taking into account previously published data. During the fieldwork in the northeastern part of Betpakdala, the species was found to grow in a rubbly, stony, weakly undulating plain in two different communities. In this work, we applied molecular genetic, cytometric, and anatomical studies on the collected samples of two populations from the northeastern part of the Betpakdala desert to determine the taxonomic composition of a relict and endemic species of Kazakhstan. Full article

Punjab, the most populous province in Pakistan, is currently facing substantial electricity shortages that are adversely affecting both residential and industrial sectors. To address this issue, the Cholistan Desert presents a promising solution due to its high solar irradiance, making it an ideal location for solar energy production. This study aims to identify the most suitable area for solar photovoltaic (PV) power plants in the Cholistan Desert using Geographic Information System (GIS) and machine learning techniques. The analysis included field survey data encompassing 14 conditioning factors such as geophysical, socio-economic, and resource conditions. Three machine learning models were utilized: Random Forest, XGBoost, and Multilayer Perceptron (MLP). The Random Forest model demonstrated superior performance with an AUC of 0.92, and feature importance was measured through SHAP. The resulting suitability map indicates that Bahawalnagar in the eastern region and Bahawalpur in the central region have 10.50% and 11.06% of their areas classified as having a “high” and “very high” probability for solar PV installation, respectively. For stakeholders in the wind industry, these regions also present potential for wind farm feasibility due to favorable wind conditions and flat terrain. The methodology can be adapted to prioritize wind energy sites by incorporating factors such as land availability, wind direction, and other related factors. Co-locating solar and wind farms in these regions could optimize land use, enhance grid stability, and support Pakistan’s renewable energy targets. Future research integrating real-time solar and wind data could further refine site selection and support multi-source renewable energy planning, providing actionable insights for policymakers and investors. Full article

Flash floods are highly destructive natural disasters, particularly in arid and semi-arid regions like Egypt, where data scarcity poses significant challenges for analysis. This study focuses on the Wadi Al-Barud basin in Egypt’s Central Eastern Desert (CED), where a severe flash flood occurred on 26–27 October 2016. This flash flood event, characterized by moderate rainfall (16.4 mm/day) and a total volume of 8.85 × 10⁶ m³, caused minor infrastructure damage, with 78.4% of the rainfall occurring within 6 h. A significant portion of floodwaters was stored in dam reservoirs, reducing downstream impacts. Multi-source data, including Landsat 8 OLI imagery, ALOS-PALSAR radar data, Global Precipitation Measurements—Integrated Multi-satellite Retrievals for Final Run (GPM-FR) precipitation data, geologic maps, field measurements, and Triangulated Irregular Networks (TINs), were integrated to analyze the flash flood event. The Soil Conservation Service Curve Number (SCS-CN) method integrated with several hydrologic models, including the Hydrologic Modelling System (HEC-HMS), Soil and Water Assessment Tool (SWAT), and European Hydrological System Model (MIKE-SHE), was applied to evaluate flood forecasting, watershed management, and runoff estimation, with results cross-validated using TIN-derived DEMs, field measurements, and Landsat 8 imagery. The SCS-CN method proved effective, with percentage differences of 5.4% and 11.7% for reservoirs 1 and 3, respectively. High-resolution GPM-FR rainfall data and ALOS-derived soil texture mapping were particularly valuable for flash flood analysis in data-scarce regions. The study concluded that the existing protection plan is sufficient for 25- and 50-year return periods but inadequate for 100-year events, especially under climate change. Recommendations include constructing additional reservoirs (0.25 × 10⁶ m³ and 1 × 10⁶ m³) along Wadi Kahlah and Al-Barud Delta, reinforcing the Safaga–Qena highway, and building protective barriers to divert floodwaters. The methodology is applicable to similar flash flood events globally, and advancements in geomatics and datasets will enhance future flood prediction and management. Full article

This study integrates morphometric analysis, remote sensing, and GIS with the analytical hierarchical process (AHP) to identify high potential groundwater recharge areas in Wadi Abadi, Egyptian Eastern Desert, supporting sustainable water resource management. Groundwater recharge primarily comes from rainfall and Nile River water, particularly for Quaternary aquifers. The analysis focused on the Quaternary and Nubian Sandstone aquifers, evaluating 16 influencing parameters, including elevation, slope, rainfall, lithology, soil type, and land use/land cover (LULC). The drainage network was derived from a 30 m-resolution Digital Elevation Model (DEM). ArcGIS 10.8 was used to classify the basin into 13 sub-basins, with layers reclassified and weighted using a raster calculator. The groundwater potential map revealed that 24.95% and 29.87% of the area fall into very low and moderate potential categories, respectively, while low, high, and very high potential zones account for 18.62%, 17.65%, and 8.91%. Data from 41 observation wells were used to verify the potential groundwater resources. In this study, the ROC curve was applied to assess the accuracy of the GWPZ models generated through different methods. The validation results indicated that approximately 87% of the wells corresponded accurately with the designated zones on the GWPZ map, confirming its reliability. Over-pumping in the southwest has significantly lowered water levels in the Quaternary aquifer. This study provides a systematic approach for identifying groundwater recharge zones, offering insights that can support resource allocation, well placement, and aquifer sustainability in arid regions. This study also underscores the importance of recharge assessment for shallow aquifers, even in hyper-arid environments. Full article