Salinity Levels Research Articles

Determining the effects of large dams and urbanization on soil salinity and surface temperature using satellite images in a Middle Eastern country

Land use and land cover (LULC) changes affect natural ecosystems, and surface temperatures have become a major concern for environmentalists and land use planners. Understanding the extent of these changes at the ground level is crucial. Numerous dam constructions in Khuzestan province have significantly influenced LULC, normal difference salinity index (NSDI), and land surface temperature (LST). This study aims to explore these changes and the broader effects of big dam construction on soil salinity and surface temperature. We used satellite images from Landsat 5 and 8 for 1987, 1998, and 2022 to achieve this. The results showed that shrublands, irrigated agriculture, residential areas, and salty and dune lands expanded, with shrublands increasing by 4%. A closer look at the big dams revealed that the Karkheh Dam and its surroundings experienced the most significant temperature change, with a 15 °C difference before and after its construction. Urban areas, however, showed a 6 °C rise in temperature over the past 30 years due to climate change, industrial growth, increased vehicle use, and fossil fuel consumption, contributing to urban heat islands. Also, the NDSI maps indicate increased soil salinity downstream of Gotvand Dam and a significant and increasing trend in EC, indicating a marked rise in soil and water salinity levels. These findings highlight the significant impact of human activities, such as big dam construction and urban expansion, on land cover and surface temperatures. Understanding these changes is essential for developing sustainable land use strategies that mitigate environmental degradation and help manage climate-related challenges.

Effectiveness of Grafting in Enhancing Salinity Tolerance of Tomato (Solanum lycopersicum L.) Using Novel and Commercial Rootstocks in Soilless Systems

The scarcity of high-quality water in arid regions like Saudi Arabia necessitates saline water use in irrigation. Sustainable techniques, such as grafting and soilless cultivation, enhance crop resilience and optimize resource use, ensuring long-term agricultural and water sustainability to meet rising food demand. So, this study evaluated grafting’s effectiveness in enhancing the salt tolerance of tomato (Solanum lycopersicum L.) under soilless culture. The experiment tested two salinity levels, two growing media (volcanic rock and sand), and six grafting treatments: the scion ‘Tone Guitar F1’ was cultivated through non-grafting (G1), self-grafted onto itself (G2), and grafted onto the commercial rootstock ‘Maxifort F1’ (G3), which was grafted onto three newly developed rootstocks, namely X-218 (G4), X-238 (G5), and Alawamiya365 (G6). The results indicated that plants performed better at 2 dS m−1, while higher salinity (4 dS m−1) negatively impacted growth. However, grafting under saline stress improved most of the measured traits, excluding fruit quality (vitamin C, titratable acidity, and total soluble sugars). Grafted plants (G2–G6), particularly those grown in volcanic rock at 2 dS m−1, exhibited superior fruit characteristics, yield, water productivity, and leaf calcium (Ca2+) and potassium (K+) content compared to the non-grafted controls (G1). The sand medium generally produced lower values for all the traits, regardless of salinity or grafting. Moreover, grafting under 2 and 4 dS m−1 reduced leaf sodium (Na+) and chloride (Cl−). The best overall performance was provided by the rootstocks X-218 and X-238. Grafting onto salt-tolerant rootstocks is a promising strategy for improving tomato yield and water productivity under saline irrigation in arid and semi-arid regions.

Effects of water-saving irrigation on microbial community structures, assembly, and metabolic activities in alfalfa rhizosphere soils.

In agricultural areas of arid Xinjiang, China, selecting appropriate irrigation strategies for farmland is essential. Increasing attention is being paid to the ecological effects of different irrigation methods on the soil environment. As a crucial component of soil quality, the microbial community is a key indicator of the impacts of irrigation on the soil environment. To investigate the effects of irrigation treatments on the properties of rhizosphere soil and the underlying microbial community characteristics, this study conducted an alfalfa field experiment applying three water-saving treatments (3750, 4500, and 5250 m3hm-2) and regular irrigation (6750 m3hm-2, CK). The results showed that the water-saving treatments increased the soil pH, salinity, available nitrogen, and phosphorus levels. The water-saving treatments decreased the richness and diversity of the bacterial community in the rhizosphere but increased those of the fungal community. The influence of stochastic processes on fungal and bacterial communities assembly under water-saving treatments was more noticeable than that under CK. Compared with CK, water-saving treatments reduced the complexity of microbial network and increased the potential negative interaction between bacteria and fungi. Functional prediction analysis showed that species specificity among treatments may result from a specific selection of rhizosphere functional requirements. This study reveals the effect of controlling irrigation quantity on protecting soil microbial diversity and function and improves the understanding of rhizosphere soil community response affected by different irrigation strategies. The results facilitate the development of effective and beneficial agricultural measures.

Salinity affects root growth of container grown saltgrass

AbstractThe need for salinity tolerant turfgrasses is increasing because of the growing use of effluent or other low‐quality waters for turfgrass irrigation. Salinity can affect soils and plants in all climates but is particularly common in arid environments and has numerous causes. Salinity impacts the growth of most plants, albeit with variations among species. The objective of this experiment was to quantify the effects of salinity on root growth of an experimental line of saltgrass (Distichlis spicata L. Greene) (SG) and NuGlade Kentucky bluegrass (Poa pratensis L.) (KBG), two grasses with contrasting salinity tolerance. In this experiment, SG and KBG were grown in containers within separate growth chambers, each maintained at their optimal growing temperatures. Salinity was imposed on the plants by irrigating with saline waters of ∼0, 8, and 16 dS/m for SG and ∼0, 4, and 8 dS/m for KBG. Root growth was monitored using minirhizotron and in‐growth root cores. The data from in‐growth root cores revealed contrasting effects of salinity on root and rhizome growth trends between SG and KBG. Root growth of SG increased by 22% under 8 and 16 dS/m salinity treatments. Conversely, salinity treatment of 8 dS/m decreased KBG root growth by 33% compared to the control. Saltgrass rhizome growth increased by 130% with the rise in salinity from the control to 16 dS/m treatment, whereas KBG rhizome growth decreased by 57% as salinity increased from the control to 8 dS/m. Minirhizotron observation indicated that SG showed increased flushes of fine roots in the moderate levels of salinity (8 dS/m) compared to the control about 3 weeks after salt treatments began. Increased fine root production greatly increased the root surface area for absorption, an adaptive response of SG to salinity. Turf quality did not deteriorate by even the highest level of salinity tested in saltgrass, suggesting it is a good candidate for turf growing under saline conditions.

Modeling the Salinity Distribution Suitable for the Survival of Asian Clam (Corbicula fluminea) and Examining Measures for Environmental Flow Supply in the Estuary of the Seomjin River, Korea

The Seomjin River estuary is a key habitat for the Asian clam (Corbicula fluminea), contributing significantly to the local economy and aquatic biodiversity in South Korea. However, long-term reductions in upstream discharge, geomorphological alterations, land reclamation, and climate change have intensified saltwater intrusion, gradually displacing clam habitats upstream. This study employed the Environmental Fluid Dynamics Code (EFDC) model to simulate salinity distribution and evaluate optimal environmental flow strategies for clam conservation. Simulation results indicated that maintaining a minimum upstream flow of 23 m3/s was essential to prevent salinity levels from exceeding the critical threshold of 20 psu at Seomjin Bridge, a key habitat site. During neap tides, reduced tidal flushing led to prolonged saltwater retention, elevating salinity levels and increasing the risk of mass clam mortality. A historical event in May 2017, when salinity exceeded 20 psu for over four consecutive days, resulted in a major die-off. This study successfully reproduced that event and evaluated mitigation strategies. A combined approach involving increased dam releases and temporary reductions in intake withdrawal was assessed. Notably, a pulse release strategy supplying an additional 9.9–10.37 m3/s (total 30.4 m3/s) over three days during neap tide effectively limited critical salinity durations to fewer than four days. The preservation of Asian clams in the Seomjin River estuary is a sustainability measure not only from an ecological perspective but also from a cultural one.

Attenuation of salinity-induced stress and improvement of brackish water aquaculture of Labeo rohita through dietary interventions of multi-species probiotics

The present investigation was targeted to determine the attenuating role of multi-species probiotics (MSP) of Bacillus subtilis (1.9 × 1010 CFU/g), Bacillus licheniformis (2 × 1010 CFU/g), and Clostridium butyricum (2.2 × 108 CFU/g), against salinity-induced stress and dietary influence on physiological indices of aquaria reared Labeo rohita fingerlings. Three hundred and twenty-four fish (weighed = 60 ± 2.35 g initially) were divided into nine equal groups, each with three replicates for a duration of 60 days. These experimental groups were represented as follows: (S0/NS) salinity-free group fed with basal diet, (S6/NS) 6.00 ppt salinity stress group fed with basal diet, (S12/NS) 12.00 ppt salinity stress group fed with basal diet, (S0/MSP1) salinity-free group fed with 1% MSP, (S6/MSP1) 6.00 ppt salinity stress group fed with 1% MSP, (S12/MSP1) 12.00 ppt salinity stress group fed with 1% MSP, (S0/MSP2) salinity-free group fed with 2% MSP, (S6/MSP2) 6.00 ppt salinity stress group fed with 2% MSP, and (S12/MSP2) 12.00 ppt salinity stress group fed with 2% MSP. Probiotics supplemented fish exhibited positively improved growth, digestive enzymes, nutrient utilization, hematobiochemical traits, and antioxidant capacity under different levels of salinity compared to non-supplemented fish (p < 0.05). Stress indices in terms of oxidative stress, cortisol and glucose and osmoregulatory responses under salinity stress improved significantly in fish nurtured on probiotic added diet over time compared to non-probiotic diet groups (p < 0.05). The histomorphology of hepato-renal, intestine and gills structures was observed with improved histoarchitecture in terms of cellular integrity and functionality in MSP diet groups compared to non-probiotics ones. Studies of erythrocytes structures and intestinal histometric indices revealed significant improvement across MSP feeding in salinity test groups, compared to non-probiotic salinity groups (p < 0.05). Consequently, we find that dietary administration of these multi-species probiotics enhanced stress coping capacity and yielding improvements in physiology of reared Labeo rohita under salinity stress conditions, resulting in a significant enhancement in brackish fish culture production.

Comparative Analysis of Morphological Responses in Rice Genotypes under Salinity Stress at the Seedling Stage

Aims: To evaluate the morphological responses of contrasting rice genotypes under varying EC levels and identify the EC concentration at which the genotypes exhibit minimal adverse effects. Methodology: FL478 (salt-tolerant) and BPT5204 (salt-susceptible) genotypes were evaluated under a completely randomized design (CRD) with three replications. Seedlings were exposed to salinity levels ranging from 0 to 12 dS/m for 7 days at the seedling stage. Morpho-physiological traits including shoot length (SL), root length (RL), shoot-to-root ratio (SLR), fresh weight (FW), dry weight (DW), water content (WC), total shoot length (TSL), and dry matter content (DMC) were measured. Significant differences from the control were assessed using Dunnett’s test. Results: A significant reduction was observed in shoot length (SL), shoot-to-root length ratio (SLR), fresh weight (FW), total shoot length (TSL), and water content percentage (WC), along with fluctuations in root length (RL) and dry weight (DW). However, dry matter content (DMC) increased with increasing salinity levels. Among the two genotypes, the susceptible BPT5204 exhibited a greater percentage of reduction in trait values compared to the tolerant FL478. Conclusion: Salinity levels of 2-4 dS/m caused only minor physiological changes, with no significant differences from the control in most traits, indicating their potential as effective priming treatments. From 5 dS/m onwards, significant growth impairments were observed. Notably, a hormetic response was evident at 11 dS/m, where both BPT5204 and FL478 showed greater growth inhibition than at higher salinity levels, suggesting a complex, non-linear relationship between salinity and plant performance. Correlation analysis further revealed strong negative associations between salinity and key morpho-physiological traits, underscoring the inhibitory impact of elevated electrical conductivity (EC) on plant growth.

Exploring the Potential of Desmodesmus sp. KNUA231 for Bioenergy and Biofertilizer Applications and Its Adaptability to Environmental Stress

As global energy demand continues to rise, microalgae have gained attention as a promising feedstock for biofuel production due to their environmental adaptability and renewable nature. This study investigated the growth performance and stress tolerance of Desmodesmus sp. KNUA231 under varying pH and salinity conditions to evaluate its potential as a biofuel candidate. The strain was cultivated under controlled laboratory conditions and exhibited stable growth across a broad pH range (4–10) and moderate salinity levels (up to 5 g L−1 NaCl), indicating its resilience to diverse environmental conditions. Fatty acid methyl ester (FAME) analysis revealed that the biodiesel properties of Desmodesmus sp. KNUA231 comply with ASTM and EN standards in specific parameters, reinforcing its feasibility as a renewable biofuel feedstock. Additionally, its high calorific value (CV) suggests its potential as an energy-dense biomass source. The results of inductively coupled plasma mass spectrometry (ICP) analysis show that the soil is supplied with essential nutrients while minimizing heavy metal contamination, suggesting the possibility of biofertilizers. Although Desmodesmus sp. KNUA231 demonstrated promising characteristics for biofuel applications, further research is required to optimize large-scale cultivation and improve productivity for industrial applications. These findings highlight the potential of Desmodesmus sp. KNUA231 as a biofuel resource, particularly in non-optimal environmental conditions where pH and salinity fluctuations are common, contributing to the ongoing search for sustainable bioenergy solutions.

Salinity-induced virulence alteration of Aeromonas hydrophila isolated from Scatophagus argus: insights from transcriptomic profiling and phenotypic characterization

BackgroundThe emerging foodborne pathogen, Aeromonas hydrophila, co-infects humans and animals, especially fish, threatening aquacultural production and public health. Previously, we found that Scatophagus argus, a widely cultivated fish species with high economic value, exhibited enhanced growth but increased susceptibility to A. hydrophila infection under freshwater conditions compared to seawater conditions. However, the exact mechanisms involved remain unclear.ResultsOur study demonstrated that the enhanced virulence of A. hydrophila 201416, isolated from S. argus, in response to increasing salinity was associated with altered quorum sensing-related gene expression and regulated behaviors. Results from virulence assays incorporating phenotypic characterization indicated that elevated salinity levels (from 0 to 35‰) significantly hindered Ah201416 infection of S. argus. This trend correlated with increased biofilm mass and swimming motility, yet was inversely related to bacterial growth. RNA-sequencing and quantitative reverse transcriptional PCR analysis confirmed significant upregulation of genes related to flagellar assembly (flgB, flgH, flgC, flgI, flhA, and fliA), bacterial secretion (HlyD and Ahh1), and quorum sensing (AhyR, LuxO, and LuxE) of Ah201416 in response to elevated salinity. These findings suggested that increased salinity not only enhanced the virulence of Ah201416 but also bolstered the resistance of S. argus, thereby mitigating its susceptibility.ConclusionsThis study provides deeper insights into the microbial risks associated with A. hydrophila in aquacultural production, which is critical to developing effective prevention and control strategies and ensuring a safe seafood supply.Clinical trial numberNot applicable.

Improved productivity of seawater desalination systems through humidification–dehumidification process integrated with renewable and fogging technologies in a lowest cost

Water desalination using renewable energy with a cooling system integrated with a fogging technique has recently made significant advancements. This study investigates the influence of the fogging technique on improving the process of HDH water desalination integrated with a cooling system. An experimental study investigated how operational factors like the mass flow rate ratio, feed water temperature, feed water salinity, cooling water temperature, and nozzle orifice diameter affected the salinity of the produced water, freshwater productivity, and GOR. The fogging system achieves maximum productivity of 25.08 L/h and 25.39 L/h when employing nozzles with orifice sizes of 0.3 mm for feed water salinity levels of 34,000 ppm and 12,000 ppm, respectively. The greatest GOR was achieved by utilizing a nozzle orifice of 0.3 mm, resulting in GOR values of 8.79 and 8.84 for concentrations of 34,000 ppm and 12,000 ppm, respectively. The salinity of the produced water reaches 1500 ppm and 500 ppm when the fog is created at a temperature of 80 °C, with feed water salinity levels of 34,000 ppm and 12,000 ppm, respectively. The fogging nozzle’s size directly affects the generated water’s salinity. When the size of the fogging nozzle reduces from 0.3 to 0.1 mm, the salinity decreases by about 34.8% and 33.3% for 34,000 ppm and 12,000 ppm, respectively. This pattern indicates that the water’s salinity decreases as the nozzle’s diameter decreases. Nevertheless, under identical circumstances, water productivity declined by 56% and 55% at 34,000 ppm and 12,000 ppm, respectively. The water production cost was 0.0268–0.0088 ($/liter). The study concludes that the salinity of the generated water reduces as the feed water temperature increases and the nozzle size decreases. In contrast, water productivity, GOR, and lower cost are enhanced using a larger nozzle.

Evaluating the global sea snake diversity and distribution under climate change scenario.

Evaluating the global sea snake diversity and distribution under climate change scenario.

Exiguobacterium aurantiacum SA100 induces antioxidant enzymes and salinity tolerance gene expression in wheat.

This study evaluated the effects of Exiguobacterium aurantiacum SA100 on wheat (Triticum aestivum) growth under varying levels of salinity stress. Results indicated that SA100 significantly enhanced seed germination, root and shoot length, and fresh and dry biomass across salinity levels, particularly at 50 and 100 mM NaCl. Inoculation improved antioxidant enzyme activities (CAT, APX, POD, PPO), increased total phenolic content, and reduced oxidative damage by lowering MDA and H2O2 levels under 150 mM salinity. Ionic balance was maintained, with significant increases in K+, Mg++, and Ca++ and a reduction in Na+ accumulation. Gene expression analysis revealed upregulation of salt-tolerance genes (NAC7, NHX1, SOS1) and downregulation of stress-responsive genes (GS1, DREB2, DHN13, WRKY32). Principal component analysis confirmed that SA100 promotes salinity tolerance by modulating both biochemical and molecular responses. These findings suggest E. aurantiacum SA100 as a promising bioinoculant for enhancing wheat resilience under salinity stress.

Proximate Composition and Nutritional Indices of Fenugreek Under Salinity Stress: The Role of Biocyclic Vegan and Other Organic Fertilization Systems in Forage Quality

Fenugreek (Trigonella foenum-graecum L.) is an emerging forage crop known for its high nutritional value and adaptability to diverse environmental conditions, making it a promising alternative in sustainable livestock feeding systems in the Mediterranean region. A field experiment was established at the Agricultural University of Athens during the growing season 2020–2021 in a split-plot design with five fertilization treatments (Biocyclic-Vegan Humus Soil; BHS, Farmyard Manure; FMA, Organic Compost; OCP, Inorganic Fertilizer; IFZ, and No Treatment Control; CTRL, and two main salinity treatments (High Salinity Level; HSL, and Normal Salinity Level; NSL). The Forage Quality Index (FQI) was the highest under BHS at NSL (45) and lowest under CTRL at HSL (32), emphasizing the positive impact of organic fertilization. Crude ash (CA) was higher under NSL (9.7%), with OCP and IFZ performing best, while salinity reduced CA under CTRL. Crude fiber (CF) increased under salinity, particularly with OCP and IFZ, whereas BHS and FMA at NSL showed the lowest CF (15.8%), enhancing digestibility. Total fat (TF) was the highest under BHS and FMA at NSL (5.8%) and lowest under IFZ and CTRL at HSL (4.0%), underscoring the importance of balanced fertilization in maintaining fat content. These results highlight the potential of organic amendments to improve nutrient availability, digestibility, and overall feed value.

Biochar application improved soil properties, growth performances, essential oil, and rosmarinic acid content of Thymus vulgaris L. under salt stress.

Biochar application improved soil properties, growth performances, essential oil, and rosmarinic acid content of Thymus vulgaris L. under salt stress.

Weak salinization alleviates the harmful impact of cyanobacteria on water fleas.

Weak salinization alleviates the harmful impact of cyanobacteria on water fleas.

Comparative analyses of transient batch operations of hollow-fiber DCMD and WGMD desalination systems at high salinity levels

Comparative analyses of transient batch operations of hollow-fiber DCMD and WGMD desalination systems at high salinity levels

Effect of pH and salinity on the release of polystyrene microplastics derived dissolved organic matter as revealed by experimental studies and molecular dynamic simulations.

Effect of pH and salinity on the release of polystyrene microplastics derived dissolved organic matter as revealed by experimental studies and molecular dynamic simulations.

Comparative studies on biochemical, antioxidants and yield characters on salt-resistant and salt-sensitive pea genotypes

Salinity is a vibrant environmental dynamic that has a detrimental impact on crop productivity. This experiment was initiated to compare the biochemical, antioxidant, and yield attributes of salt-resistant and sensitive pea (Pisum sativum L.) genotypes under saline environments. Four pea genotypes were cultivated in a two-factorial pot experiment based on completely randomized design and exposed to four distinct levels of salinity; control, 2.5, 5.0, 7.0, and 10 dS m-1 NaCl, MgSO4, CaCl2, and Na2SO4 in order to study the salt sensitivity of pea. The findings demonstrated that under salt stress, pea production and growth decreased. With applied salt stress, both genotypes displayed notable genetic variation. In terms of biochemical, antioxidant, and yield attributes, the salt-tolerant genotype of pea namely samrena zard unmistakably demonstrated the best results in comparison to the rest of the tested genotypes. The following enzymatic, biochemical, and yield-related traits of the tested pea genotypes showed a substantial difference: two genotypes were found and exposed to salt stress: one was salt-sensitive (ambasidar) and the other was salt-tolerant (samrena zard).

Density and distribution of holothuria leucospilota along the coast of dedap island, pulau abang waters

The black rubber sea cucumber (Holothuria leucospilota) is prevalent along the coast of Dedap Island in Batam, unlike other sea cucumber species that face significant fishing pressure. This study examines the population and distribution of Holothuria leucospilota near Dedap Island in Abang Island, Batam. Surveys were conducted at three sites, where we carefully counted and mapped the sea cucumbers. A total of 236 individuals were recorded, with the highest density in Transect 1 (0.97/m²) and the lowest in Transect 2 (0.66/m²). Our results indicate notable variability in sea cucumber density across the surveyed areas, with some locations showing high abundance and others fewer individuals. The distribution pattern, assessed using the Morisita Index, suggested a clustering tendency, especially in Transect 1. We also examined substrate types to better understand these distribution trends. Additionally, water quality assessments showed that conditions across the transects were favourable for sea cucumber survival, with suitable levels of salinity, pH, and dissolved oxygen. These findings are vital for the management and conservation of sea cucumbers in the area.

Assessment of Soil Salinity Situation in Agricultural Land Areas in Coastal and Lagoon Regions of Hue City, Vietnam using the Normalized Difference Vegetation Index

This study utilized remote sensing technologies to assess soil salinity levels in agricultural lands in the coastal and lagoon regions in Hue City, Vietnam using the Normalized Difference Vegetation Index (NDVI). The result indicated that with a Coefficient of Determination of 0.65, there are 1,016.08 hectares fall into the slightly saline soil category, while the remaining area is classified as saline soil. The soil saline levels vary significantly across different land use types, with double-crop rice cultivation areas has lower soil salinity, whereas coastal forests be in the strongly saline class. Application of NDVI is simple method and suitable way which can be done by local officer to evaluate soil salinity situation in order contribute to the sustainable land use.