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Search Results (169)

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Keywords = hyper-arid

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17 pages, 3875 KiB  
Article
Phytogeographic Transition Areas Hide Floristic Diversity in Hyper-Arid Environments (Sharaan Natural Reserve, NW-Saudi Arabia)
by Mohamed Djamel Miara, Sami Youssef, Yassine Fendane, Louise Marris, Robin Sallio, Hassan Boukcim, Sami D. Almalki, Shauna K. Rees, Benjamin P. Y.-H. Lee, Abdalsamad Aldabaa and Ahmed H. Mohamed
Diversity 2025, 17(1), 30; https://doi.org/10.3390/d17010030 - 31 Dec 2024
Viewed by 619
Abstract
Phytogeographic transition zones are often considered areas rich in biodiversity due to their ecological and landscape diversity. This study constitutes the first floristic investigation of the Sharaan Natural Reserve (SNR) located in the northwest of the KSA, which is supposed to be a [...] Read more.
Phytogeographic transition zones are often considered areas rich in biodiversity due to their ecological and landscape diversity. This study constitutes the first floristic investigation of the Sharaan Natural Reserve (SNR) located in the northwest of the KSA, which is supposed to be a phytogeographic transition zone due to its location between the central zone of the country dominated by Saharo-Arabic flora and the northern zone characterized by a Mediterranean and Irano-Turanian floristic affinities. The floristic studies carried out in the vegetation season from 2022 to 2024 led to the identification of 166 plant taxa belonging to 38 botanical families. The flora of the SNR is dominated by Therophytes, while the Saharo-Arabian element dominates the chorology of the taxa. The comparative phytogeographic analysis of SNR flora compared to the available literature on published floristic inventories in different phytogeographic regions of the country has confirmed the floristic affinities of the flora of the reserve, especially with the northern and Nefud regions. Among the identified plants, 13 taxa were not mentioned in the 44 consulted references and seem more or less exclusive to the reserve/phytogeographic region. Also, 12 taxa are considered of Least Concern according to the IUCN red list while the presence of Calligonum comosum L’Hér. allows the classification of its natural habitat (dunes) as a Critical Habitat according to the PS6 criteria. This study reports that SNR constitutes a phytogeographic and floristic transitional area by the presence of a significant number of Irano-Turanian (43) and Mediterranean (21) taxa mixed with the dominant Saharo-Arabic species. The SNR region contains a rich and diverse flora due to the biogeographical situation as a transitional zone and the protection due to the closure. This conservation should be strengthened and extended to other neighboring areas with the same biological wealth. Full article
(This article belongs to the Special Issue Ecology and Diversity of Plants in Arid and Semi-Arid Ecosystems)
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19 pages, 2606 KiB  
Article
Recovery of Perennial Plant Communities in Disturbed Hyper-Arid Environments (Sharaan Nature Reserve, Saudi Arabia)
by Sami Youssef, Mohamed Djamel Miara, Stéphane Boivin, Robin Sallio, Jérôme Nespoulous, Hassan Boukcim, Sami D. Almalki, Shauna K. Rees, Benjamin P. Y.-H. Lee and Ahmed H. Mohamed
Land 2024, 13(12), 2033; https://doi.org/10.3390/land13122033 - 28 Nov 2024
Viewed by 880
Abstract
Background: Human activities such as agriculture are known to markedly affect natural ecosystems, including plant communities and soil properties. Biological activities are reduced in hot, hyper-arid ecosystems compared to temperate and tropical climatic conditions. Anthropogenic disturbances therefore have greater impacts on the ecosystem’s [...] Read more.
Background: Human activities such as agriculture are known to markedly affect natural ecosystems, including plant communities and soil properties. Biological activities are reduced in hot, hyper-arid ecosystems compared to temperate and tropical climatic conditions. Anthropogenic disturbances therefore have greater impacts on the ecosystem’s recovery potential. This study aimed to assess the diversity and recovery of post-agriculture plant communities in the Sharaan Nature Reserve (SNR), located in northern Saudi Arabia. Methods: Three types of habitats representative of different disturbance situations were identified in the reserve and sampled through 103 floristic and pedological surveys. The floristic composition was recognized and relative quantification of soil atomic elements was performed. The obtained data were processed using different statistical treatments such as the Shannon index and Bray–Curtis dissimilarities, non-metric multidimensional scaling (NMDS), Kruskal–Wallis tests and Redundant analysis (RDA). Results: Investigations led to the identification of 48 plant species belonging to 24 genera and 22 botanical families. Specific plant community structures were correlated with each habitat, and bioindicator plant species were identified. Polycarpaea repens and Stipagrostis plumosa were linked with natural habitats, while Atriplex leucoclada was specific to disturbed habitats. In contrast, Asteriscus graveolens and Haloxylon salicornicum were found to be ubiquitous species. Conclusions: The presence of bioindicator species was closely associated with the different soil properties measured in each habitat. Restoration strategies related to the overall dynamic plant community succession pattern observed in the Sharaan Nature Reserve are discussed. Active ecological restoration strategies based on targeted active ecological restoration interventions should facilitate the recovery and restoration of disturbed plant communities in hyper-arid areas. Full article
(This article belongs to the Special Issue 2nd Edition: Land Use Change and Its Environmental Effects)
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13 pages, 2054 KiB  
Article
Analysis of the Chemical Composition, Antimicrobial, and Antioxidant Qualities of Microwave and Supercritical CO2-Extracted Lavender Essential Oils Cultivated in a Hyperarid Region of Türkiye
by Ayça Gedikoğlu, Hale İnci Öztürk and Afranur Özçoban
Molecules 2024, 29(23), 5605; https://doi.org/10.3390/molecules29235605 - 27 Nov 2024
Viewed by 944
Abstract
This study compares the chemical composition, antioxidant capacity, and antibacterial properties of lavender essential oils extracted using microwave-assisted extraction (MAE) and supercritical CO2 extraction (SCDE). Gas chromatography–mass spectrometry analysis revealed that the MAE oil contained higher levels of linalyl acetate (36.19%) and [...] Read more.
This study compares the chemical composition, antioxidant capacity, and antibacterial properties of lavender essential oils extracted using microwave-assisted extraction (MAE) and supercritical CO2 extraction (SCDE). Gas chromatography–mass spectrometry analysis revealed that the MAE oil contained higher levels of linalyl acetate (36.19%) and linalool (28.29%) compared with the SCDE oil, which had values of 28.72% and 27.48%, respectively. The MAE oil also showed superior antioxidant activity, with DPPH IC50 values of 72.99 mg/mL and FRAP values of 1.31 mM Fe2+/g, compared with 80.84 mg/mL and 1.14 mM Fe2+/g for the SCDE oil. Antibacterial tests indicated that the MAE oil exhibited lower MIC values, demonstrating twice the antibacterial activity against Bacillus cereus NRRL B3711, Bacillus subtilis PY79, and Enterococcus faecalis ATCC 29212 compared with the SCDE oil. These results highlight the superior bioactivity of MAE-extracted lavender oil, making MAE a preferred method for high-quality oil extraction from drought-affected lavender plants. Full article
(This article belongs to the Special Issue Chemical Composition and Bioactivities of Essential Oils, 2nd Edition)
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19 pages, 3410 KiB  
Article
Effects of Drought and Fire Severity Interaction on Short-Term Post-Fire Recovery of the Mediterranean Forest of South America
by Ana Hernández-Duarte, Freddy Saavedra, Erick González, Alejandro Miranda, Jean-Pierre Francois, Marcelo Somos-Valenzuela and Jason Sibold
Fire 2024, 7(12), 428; https://doi.org/10.3390/fire7120428 - 22 Nov 2024
Cited by 1 | Viewed by 1071
Abstract
Wildfires and drought stressors can significantly limit forest recovery in Mediterranean-type ecosystems. Since 2010, the region of central Chile has experienced a prolonged Mega Drought, which intensified into a Hyper Drought in 2019, characterized by record-low precipitation and high temperatures, further constraining forest [...] Read more.
Wildfires and drought stressors can significantly limit forest recovery in Mediterranean-type ecosystems. Since 2010, the region of central Chile has experienced a prolonged Mega Drought, which intensified into a Hyper Drought in 2019, characterized by record-low precipitation and high temperatures, further constraining forest recovery. This study evaluates short-term (5-year) post-fire vegetation recovery across drought gradients in two types of evergreen sclerophyllous forests and a thorny forest and shrubland, analyzing Landsat time series (1987–2022) from 42 wildfires. Using the LandTrendr algorithm, we assessed post-fire forest recovery based on NDVI changes between pre-fire values and subsequent years. The results reveal significant differences in recovery across drought gradients during the Hyper Drought period, among the three forest types studied. The xeric forest, dominated by Quillaja saponaria and Lithrea caustica, showed significant interaction effects between levels of drought and fire severity, while the thorny forest and shrubland displayed no significant interaction effects. The mesic forest, dominated by Cryptocarya alba and Peumus boldus, exhibited additional significant differences in recovery between the Hyper Drought and Mega Drought periods, along with significant interaction effects. These findings underscore the critical role of prolonged, severe drought in shaping forest recovery dynamics and highlight the need to understand these patterns to improve future forest resilience under increasingly arid conditions. Full article
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15 pages, 9201 KiB  
Article
Decoupling and Insensitivity of Greenness and Gross Primary Productivity Across Aridity Gradients in China
by Yuzhen Li, Xiuliang Yuan, Lei Zheng, Wenqiang Zhang and Yue Zhang
Remote Sens. 2024, 16(22), 4234; https://doi.org/10.3390/rs16224234 - 14 Nov 2024
Viewed by 656
Abstract
The ecosystem’s gross primary productivity (GPP) and greenness, as indicated by the normalized difference vegetation index (NDVI), are both essential ecological indicators used to evaluate how ecosystems responded to climate variability. However, the relationships between NDVI and GPP under the influence of drying [...] Read more.
The ecosystem’s gross primary productivity (GPP) and greenness, as indicated by the normalized difference vegetation index (NDVI), are both essential ecological indicators used to evaluate how ecosystems responded to climate variability. However, the relationships between NDVI and GPP under the influence of drying and wetting and its characteristics along aridity (AI) gradients were not yet fully understood. In this study, we investigated the relationships of the NDVI-GPP (i.e., the strength of the coupling and the sensitivity, as quantified by the coefficient of determination (R2) and slope of the linear regression, respectively) along the aridity gradients during the growing season from 1982 to 2018 in China. The results show that the coupling between NDVI and GPP was stronger (i.e., high R2) in semi-arid regions (0.24) compared to humid and hyper-humid regions (R2 values were 0.11). For different plant functional types (PFTs), decoupling occurred in ENF with a determination coefficient value (R2) of 0.04, whereas GRA shows a higher coupling with an R2 of 0.20. The coupling trend experienced a shift in semi-arid regions, characterized by an aridity index (AI) ranging from 0.20 to 0.50. Additionally, the sensitivity of GPP to NDVI also decreased with increasing aridity. The slope values were 0.19, 0.21, 0.24, 0.20, 0.11, and 0.11 in hyper-arid, arid, semi-arid, dry sub-humid, humid, and hyper-humid, respectively. What is more, asynchronous changes in vegetation productivity and greenness can be detected by capturing the inter-annual variability (IAV) of NDVI and GPP. The IAV of GPP steadily decreased with the aridity gradients, while the IAV of NDVI present fluctuated, suggesting that NDVI was more variable than GPP under the influence of drying and wetting conditions. Our study suggests that there may be a stronger trade-off between ecosystem greenness and photosynthesis in more humid areas. Full article
(This article belongs to the Section Ecological Remote Sensing)
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10 pages, 3664 KiB  
Article
High Performance of Mn2O3 Electrodes for Hydrogen Evolution Using Natural Bischofite Salt from Atacama Desert: A Novel Application for Solar Saline Water Splitting
by Felipe M. Galleguillos-Madrid, Sebastian Salazar-Avalos, Edward Fuentealba, Susana Leiva-Guajardo, Luis Cáceres, Carlos Portillo, Felipe Sepúlveda, Iván Brito, José Ángel Cobos-Murcia, Omar F. Rojas-Moreno, Víctor Jimenez-Arevalo, Eduardo Schott and Alvaro Soliz
Materials 2024, 17(20), 5129; https://doi.org/10.3390/ma17205129 - 21 Oct 2024
Viewed by 764
Abstract
Solar saline water splitting is a promising approach to sustainable hydrogen production, harnessing abundant solar energy and the availability of brine resources, especially in the Atacama Desert. Bischofite salt (MgCl2·6H2O) has garnered significant attention due to its wide range [...] Read more.
Solar saline water splitting is a promising approach to sustainable hydrogen production, harnessing abundant solar energy and the availability of brine resources, especially in the Atacama Desert. Bischofite salt (MgCl2·6H2O) has garnered significant attention due to its wide range of industrial applications. Efficient hydrogen production in arid or hyper arid locations using bischofite solutions is a novel and revolutionary idea. This work studied the electrochemical performance of Mn2O3 electrodes using a superposition model based on mixed potential theory and evaluated the superficial performance of this electrode in contact with a 0.5 M bischofite salt solution focusing on the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) that occur during saline water splitting. The application of the non-linear superposition model provides valuable electrochemical kinetic parameters that complement the understanding of Mn2O3, this being one of the novelties of this work. Full article
(This article belongs to the Special Issue Advances in Sustainable Energy Materials and Devices)
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16 pages, 1699 KiB  
Article
Soil Bacteria from the Namib Desert: Insights into Plant Growth Promotion and Osmotolerance in a Hyper-Arid Environment
by Tiago Lopes, Jacinta Santos, Diana Matos, Carina Sá, Diogo Pina, Ricardo Pinto, Paulo Cardoso and Etelvina Figueira
Land 2024, 13(10), 1678; https://doi.org/10.3390/land13101678 - 15 Oct 2024
Viewed by 1317
Abstract
The Namib Desert is characterized by a number of abiotic stresses, including high temperature, high salinity, osmotic pressure, alkaline pH, and limited water availability. In such environments, dry soils typically exhibit a low water potential, scarce nutrients, and high concentrations of dissolved ions, [...] Read more.
The Namib Desert is characterized by a number of abiotic stresses, including high temperature, high salinity, osmotic pressure, alkaline pH, and limited water availability. In such environments, dry soils typically exhibit a low water potential, scarce nutrients, and high concentrations of dissolved ions, collectively creating a challenging habitat for microbial life. In this study, 89 bacterial isolates belonging to 20 genera were identified. Bacteria demonstrated significant osmotolerance, with some strains thriving at polyethylene glycol (PEG) concentrations exceeding 20%. Furthermore, these bacteria demonstrated halotolerance, high pH tolerance, and capacity to produce plant growth-promoting (PGP) traits under conditions of osmotic stress. Osmotolerant bacteria exhibited higher proficiency in siderophore production, potassium solubilization, and phosphorus solubilization, all of which are critical for supporting plant growth in nutrient-scarce and stressful environments, such as deserts. However, alginate production was higher in isolates that were less osmotolerant, indicating the potential for a compensatory mechanism in strains that were more sensitive. These findings highlight the complex strategies employed by desert bacteria to survive and support host plants in extreme environments. The present study not only enhances our understanding of microbial adaptations in arid ecosystems, but also provides important information for the development of potential applications for these bacteria in the reclamation of arid land and agricultural practices aimed at improving crop resilience to abiotic stress. Full article
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30 pages, 11211 KiB  
Article
Hydro-Geochemistry and Water Quality Index Assessment in the Dakhla Oasis, Egypt
by Mahmoud H. Darwish, Hanaa A. Megahed, Asmaa G. Sayed, Osman Abdalla, Antonio Scopa and Sedky H. A. Hassan
Hydrology 2024, 11(10), 160; https://doi.org/10.3390/hydrology11100160 - 30 Sep 2024
Cited by 1 | Viewed by 1195
Abstract
Water quality is crucial to the environmental system and thus its chemistry is important, and can be directly related to the water’s source, the climate, and the geology of the region. This study focuses on analyzing the hydrochemistry of specific locations within the [...] Read more.
Water quality is crucial to the environmental system and thus its chemistry is important, and can be directly related to the water’s source, the climate, and the geology of the region. This study focuses on analyzing the hydrochemistry of specific locations within the Dakhla Oasis in Egypt. A total of thirty-nine groundwater samples representing the Nubian Sandstone Aquifer (NSSA) and seven surface water samples from wastewater lakes and canals were collected for analysis. Key parameters such as pH, electrical conductivity (EC), and total dissolved solids (TDS) were measured on-site, while major ions and trace elements (Fe+2 and Mn+2) were analyzed in the laboratory. The water quality index (WQI) method was employed to assess the overall water quality. Hydro-chemical facies were investigated using Piper’s, Scholler’s, and Stiff diagrams, revealing sodium as the dominant cation and chloride, followed by bicarbonate as the dominant anion. The hydro-chemical composition indicates that Na–Cl constitutes the primary water type in this study. This points to the dissolution of evaporates and salt enrichment due to intense evaporation resulting from the region’s hyper-aridity. In groundwater samples, the order of hydro-chemical facies is HCO3 > Cl > SO4−2 > Na+ > Ca+2 > K+ > Mg+2, while in wastewater samples, it is Cl > Na+ > SO4−2 > HCO3 > Ca+2 > Mg+2 > K+. When considering iron and manganese parameters, the water quality index (WQI) values suggest that most groundwater samples exhibit excellent to good quality but become poor or very poor when these elements are included. This study could prove valuable for water resource management in the Dakhla Oasis. Full article
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27 pages, 25123 KiB  
Article
Evaluation of Reanalysis and Satellite Products against Ground-Based Observations in a Desert Environment
by Narendra Nelli, Diana Francis, Abdulrahman Alkatheeri and Ricardo Fonseca
Remote Sens. 2024, 16(19), 3593; https://doi.org/10.3390/rs16193593 - 26 Sep 2024
Cited by 4 | Viewed by 1294
Abstract
The Arabian Peninsula (AP) is notable for its unique meteorological and climatic patterns and plays a pivotal role in understanding regional climate dynamics and dust emissions. The scarcity of ground-based observations makes atmospheric data essential, rendering reanalysis and satellite products invaluable for understanding [...] Read more.
The Arabian Peninsula (AP) is notable for its unique meteorological and climatic patterns and plays a pivotal role in understanding regional climate dynamics and dust emissions. The scarcity of ground-based observations makes atmospheric data essential, rendering reanalysis and satellite products invaluable for understanding weather patterns and climate variability. However, the accuracy of these products in the AP’s desert environment has not been extensively evaluated. This study undertakes the first comprehensive validation of reanalysis products—the European Centre for Medium-Range Weather Forecasts’ European Reanalysis version 5 (ERA5) and ERA5 Land (ERA5L), along with Clouds and Earth’s Radiant Energy System (CERES) radiation fluxes—against measurements from the Liwa desert in the UAE. The data, collected during the Wind-blown Sand Experiment (WISE)–UAE field experiment from July 2022 to December 2023, includes air temperature and relative humidity at 2 m, 10 m wind speed, surface pressure, skin temperature, and net radiation fluxes. Our analysis reveals a strong agreement between ERA5/ERA5L and the observed diurnal T2m cycle, despite a warm night bias and cold day bias with a magnitude within 2 K. The wind speed analysis uncovered a bimodal distribution attributed to sea-breeze circulation and the nocturnal low-level jet, with the reanalysis overestimating the nighttime wind speeds by 2 m s−1. This is linked to biases in nighttime temperatures arising from an inaccurate representation of nocturnal boundary layer processes. The daytime cold bias contrasts with the excessive net radiation flux at the surface by about 50–100 W m−2, underscoring the challenges in the physical representation of land–atmosphere interactions. Full article
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21 pages, 7689 KiB  
Article
Assessment of Potential Aquifer Recharge Zones in the Locumba Basin, Arid Region of the Atacama Desert Using Integration of Two MCDM Methods: Fuzzy AHP and TOPSIS
by Víctor Pocco, Arleth Mendoza, Samuel Chucuya, Pablo Franco-León, Germán Huayna, Eusebio Ingol-Blanco and Edwin Pino-Vargas
Water 2024, 16(18), 2643; https://doi.org/10.3390/w16182643 - 18 Sep 2024
Viewed by 1240
Abstract
Natural aquifers used for human consumption are among the most important resources in the world. The Locumba basin faces significant challenges due to its limited water availability for the local population. In this way, the search for possible aquifer recharge zones is crucial [...] Read more.
Natural aquifers used for human consumption are among the most important resources in the world. The Locumba basin faces significant challenges due to its limited water availability for the local population. In this way, the search for possible aquifer recharge zones is crucial work for urban development in areas that have water scarcity. To evaluate this problem, this research proposes the use of the hybrid Fuzzy AHP methodology in conjunction with the TOPSIS algorithm to obtain a potential aquifer recharge map. Ten factors that influence productivity and capacity in an aquifer were implemented, which were subjected to Fuzzy AHP to obtain their weighting. Using the TOPSIS algorithm, the delineation of the most favorable areas with high recharge potential was established. The result shows that the most influential factors for recharge are precipitation, permeability, and slopes, which obtained the highest weights of 0.22, 0.19, and 0.17, respectively. In parallel, the TOPSIS result highlights the potential recharge zones distributed in the Locumba basin, which were classified into five categories: very high (13%), high (28%), moderate (15%), low (28%), and very low (16%). The adapted methodology in this research seeks to be the first step toward effective water resource management in the study area. Full article
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21 pages, 12105 KiB  
Article
Assessment of Total Mercury Levels Emitted from ASGM into Soil and Groundwater in Chami Town, Mauritania
by Mohamed Mamoune Maha, Akito Matsuyama, Takahiko Arima and Atsushi Sainoki
Sustainability 2024, 16(18), 7992; https://doi.org/10.3390/su16187992 - 12 Sep 2024
Viewed by 990
Abstract
Artisanal and small-scale gold mining (ASGM) is a serious growing concern in Sub-Saharan Africa. In Mauritania, recent gold discoveries in the north and northwest have led to an increase in ASGM centers, reflecting trends across the region and posing considerable risks of mercury [...] Read more.
Artisanal and small-scale gold mining (ASGM) is a serious growing concern in Sub-Saharan Africa. In Mauritania, recent gold discoveries in the north and northwest have led to an increase in ASGM centers, reflecting trends across the region and posing considerable risks of mercury (Hg) contamination. Notwithstanding this fact, the extent of mercury contamination in the region remains unclear due to insufficient knowledge on the mechanisms of Hg dispersion in hyper-arid regions. In light of this, the present study aimed to acquire fundamental knowledge to elucidate the dispersion mechanism of mercury through conducting soil and groundwater sampling in and around Chami town, Mauritania, where ASGM activities have intensified. We analyzed 180 soil samples and 5 groundwater samples for total mercury (total Hg) using cold vapor atomic absorption spectrometry (CVAAS) and atomic fluorescence spectrometry (AFS) methods. The total Hg levels in soil samples ranged from 0.002 to 9.3 ppm, with the highest concentrations found at ASGM sites. Groundwater samples exhibited low total Hg levels (0.25–1.25 ng/L). The total Hg content in soil and groundwater samples was below Japanese standards, yet soil samples from hotspot points exceeded other international standards. Our study emphasizes the Hg dispersion patterns around Chami town, suggesting a gradual decrease in total Hg with increasing distance from ASGM sites and a potential influence of wind dynamics. The knowledge accumulated in this study provides essential insights into the Hg dispersion mechanisms in Chami town, laying the foundation for establishing a predictive model of Hg contamination in hyper-arid regions. Full article
(This article belongs to the Special Issue Sustainable Environmental Analysis of Soil and Water)
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17 pages, 2380 KiB  
Review
Unlocking the Potential: Epstein-Barr Virus (EBV) in Gastric Cancer and Future Treatment Prospects, a Literature Review
by Salvatore Corallo, Angioletta Lasagna, Beatrice Filippi, Domiziana Alaimo, Anna Tortorella, Francesco Serra, Alessandro Vanoli and Paolo Pedrazzoli
Pathogens 2024, 13(9), 728; https://doi.org/10.3390/pathogens13090728 - 28 Aug 2024
Viewed by 2264
Abstract
Gastric cancer (GC) is a complex disease with various etiologies. While Helicobacter pylori infection is still one of the leading risk factors for GC, increasing evidence suggests a link between GC and other infective agents such as Epstein Bar Virus (EBV). EBV-associated gastric [...] Read more.
Gastric cancer (GC) is a complex disease with various etiologies. While Helicobacter pylori infection is still one of the leading risk factors for GC, increasing evidence suggests a link between GC and other infective agents such as Epstein Bar Virus (EBV). EBV-associated gastric cancer (EBVaGC) is now recognized as a distinct subgroup of GC, and the complex interactions between the virus and gastric mucosa may influence its development. A recent integrative analysis of the genome and proteome of GC tissues by The Cancer Genome Atlas project has identified EBVaGC as a specific subtype characterized by PIK3CA and ARID1A mutations, extensive DNA hyper-methylation, and activation of immune signaling pathways. These molecular characteristics are markers of the unique molecular profile of this subset of GC and are potential targets for therapy. This review aims to provide an overview of the current knowledge on EBVaGC. It will focus on the epidemiology, clinic-pathological features, and genetic characteristics of EBVaGC. Additionally, it will discuss recent data indicating the potential use of EBV infection as a predictive biomarker of response to chemotherapy and immune checkpoint inhibitors. The review also delves into potential therapeutic approaches for EBVaGC, including targeted therapies and adoptive immunotherapy, highlighting the promising potential of EBV as a therapeutic target. Full article
(This article belongs to the Special Issue Oncogenic Viruses)
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29 pages, 4045 KiB  
Article
Produced Water from the Oil and Gas Industry as a Resource—South Kuwait as a Case Study
by Feras Alsalem and Thies Thiemann
Resources 2024, 13(9), 118; https://doi.org/10.3390/resources13090118 - 27 Aug 2024
Viewed by 4308
Abstract
Produced Water (PW) represents the largest waste stream in the oil and gas industry. As a water resource and as a source of valuable minerals such as alkali salts, it is has been highly under-valued, especially in hyper-arid regions. The beneficial use of [...] Read more.
Produced Water (PW) represents the largest waste stream in the oil and gas industry. As a water resource and as a source of valuable minerals such as alkali salts, it is has been highly under-valued, especially in hyper-arid regions. The beneficial use of PW ranges from water reinjection to elevated oil recovery from reservoirs with almost instantaneous returns, to the extraction of minerals from PW, which involves a number of different processes and setups. The economic value of PW-derived end products offers alternative revenue sources, with market fluctuations and conditions different from those of the hydrocarbon market. The end products of water and industrial salt support local industries such as agriculture, reflecting positively on the gross domestic product (GDP). Furthermore, resource extraction from PW of the oil and gas industry helps countries augment their circular economy. In this regard, the economic feasibility of three scenarios—the use of PW for oil recovery, the use of PW as an alternate source of water and industrial salt, and a hybrid process of both—is explored. The results show that there is great potential for water reuse in Enhanced Oil Recovery operations, as well as in the reduction in freshwater consumption for oil- and gas-extraction operations in the state of Kuwait by up to 4.8 percent when PW generated by SK oilfields is considered, and by 42 percent if PW from all oilfields in Kuwait is reused in the same manner. Full article
(This article belongs to the Special Issue Editorial Board Members' Collection Series: Water Resources)
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23 pages, 29093 KiB  
Article
Utilizing the Google Earth Engine for Agricultural Drought Conditions and Hazard Assessment Using Drought Indices in the Najd Region, Sultanate of Oman
by Mohammed S. Al Nadabi, Paola D’Antonio, Costanza Fiorentino, Antonio Scopa, Eltaher M. Shams and Mohamed E. Fadl
Remote Sens. 2024, 16(16), 2960; https://doi.org/10.3390/rs16162960 - 12 Aug 2024
Cited by 2 | Viewed by 2988
Abstract
Accurately evaluating drought and its effects on the natural environment is difficult in regions with limited climate monitoring stations, particularly in the hyper-arid region of the Sultanate of Oman. Rising global temperatures and increasing incidences of insufficient precipitation have turned drought into a [...] Read more.
Accurately evaluating drought and its effects on the natural environment is difficult in regions with limited climate monitoring stations, particularly in the hyper-arid region of the Sultanate of Oman. Rising global temperatures and increasing incidences of insufficient precipitation have turned drought into a major natural disaster worldwide. In Oman, drought constitutes a major threat to food security. In this study, drought indices (DIs), such as temperature condition index (TCI), vegetation condition index (VCI), and vegetation health index (VHI), which integrate data on drought streamflow, were applied using moderate resolution imaging spectroradiometer (MODIS) data and the Google Earth Engine (GEE) platform to monitor agricultural drought and assess the drought risks using the drought hazard index (DHI) during the period of 2001–2023. This approach allowed us to explore the spatial and temporal complexities of drought patterns in the Najd region. As a result, the detailed analysis of the TCI values exhibited temporal variations over the study period, with notable minimum values observed in specific years (2001, 2005, 2009, 2010, 2014, 2015, 2016, 2017, 2019, 2020, and 2021), and there was a discernible trend of increasing temperatures from 2014 to 2023 compared to earlier years. According to the VCI index, several years, including 2001, 2003, 2006, 2008, 2009, 2013, 2015, 2016, 2017, 2018, 2020, 2021, 2022, and 2023, were characterized by mild drought conditions. Except for 2005 and 2007, all studied years were classified as moderate drought years based on the VHI index. The Pearson correlation coefficient analysis (PCA) was utilized to observe the correlation between DIs, and a high positive correlation between VHI and VCI (0.829, p < 0.01) was found. Based on DHI index spatial analysis, the northern regions of the study area faced the most severe drought hazards, with severity gradually diminishing towards the south and east, and approximately 44% of the total area fell under moderate drought risk, while the remaining 56% was classified as facing very severe drought risk. This study emphasizes the importance of continued monitoring, proactive measures, and effective adaptation strategies to address the heightened risk of drought and its impacts on local ecosystems and communities. Full article
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31 pages, 3112 KiB  
Article
Fusing Multispectral and LiDAR Data for CNN-Based Semantic Segmentation in Semi-Arid Mediterranean Environments: Land Cover Classification and Analysis
by Athanasia Chroni, Christos Vasilakos, Marianna Christaki and Nikolaos Soulakellis
Remote Sens. 2024, 16(15), 2729; https://doi.org/10.3390/rs16152729 - 25 Jul 2024
Cited by 2 | Viewed by 1119
Abstract
Spectral confusion among land cover classes is quite common, let alone in a complex and heterogenous system like the semi-arid Mediterranean environment; thus, employing new developments in remote sensing, such as multispectral imagery (MSI) captured by unmanned aerial vehicles (UAVs) and airborne light [...] Read more.
Spectral confusion among land cover classes is quite common, let alone in a complex and heterogenous system like the semi-arid Mediterranean environment; thus, employing new developments in remote sensing, such as multispectral imagery (MSI) captured by unmanned aerial vehicles (UAVs) and airborne light detection and ranging (LiDAR) techniques, with deep learning (DL) algorithms for land cover classification can help to address this problem. Therefore, we propose an image-based land cover classification methodology based on fusing multispectral and airborne LiDAR data by adopting CNN-based semantic segmentation in a semi-arid Mediterranean area of northeastern Aegean, Greece. The methodology consists of three stages: (i) data pre-processing, (ii) semantic segmentation, and (iii) accuracy assessment. The multispectral bands were stacked with the calculated Normalized Difference Vegetation Index (NDVI) and the LiDAR-based attributes height, intensity, and number of returns converted into two-dimensional (2D) images. Then, a hyper-parameter analysis was performed to investigate the impact on the classification accuracy and training time of the U-Net architecture by varying the input tile size and the patch size for prediction, including the learning rate and algorithm optimizer. Finally, comparative experiments were conducted by altering the input data type to test our hypothesis, and the CNN model performance was analyzed by using accuracy assessment metrics and visually comparing the segmentation maps. The findings of this investigation showed that fusing multispectral and LiDAR data improves the classification accuracy of the U-Net, as it yielded the highest overall accuracy of 79.34% and a kappa coefficient of 0.6966, compared to using multispectral (OA: 76.03%; K: 0.6538) or LiDAR (OA: 37.79%; K: 0.0840) data separately. Although some confusion still exists among the seven land cover classes observed, the U-Net delivered a detailed and quite accurate segmentation map. Full article
(This article belongs to the Special Issue Remote Sensing in Environmental Modelling)
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