Search Results (1,151)

Root exudates represent a critical belowground carbon flux; however, direct field-based quantification of these rates on intact mangrove roots remains limited due to methodological challenges. Here, we present, to our knowledge, the first in situ evaluation of root exudation rates in a subtropical Bruguiera gymnorhiza forest in Japan, employing a modified cuvette method specifically designed for field measurements on intact root systems. The net root exudation rates measured in artificial seawater at depths of 0–60 cm ranged from 0.01 to 0.97 mg C g⁻¹ h⁻¹, with a mean of 0.22 mg C g⁻¹ h⁻¹. Although this mean rate was comparable to values reported for tropical terrestrial forests, the spatiotemporal variation exhibited variable site-specific patterns. At the midstream site, exudation rates were closely coupled with fine root biomass under nitrogen-limited conditions and peaked during summer. In contrast, the upstream site exhibited unusually high exudation rates during winter, even in deep soil layers. Furthermore, contrary to patterns typically observed in terrestrial forests, exudation rates showed positive correlations with root C:N ratios and proton efflux. These findings suggest that root exudation in mangroves is regulated by complex interactions among site-specific hydrological regimes and stress-adaptation mechanisms, particularly salinity tolerance and nutrient acquisition, rather than by simple growth trade-offs. When integrated over a depth of 0–60 cm, the estimated annual root exudate carbon flux was approximately 0.4 kg C m⁻² yr⁻¹. This likely represents a conservative lower-bound estimate because fine root systems extend well below this depth in mangrove forests. Our results strongly suggest that root exudates constitute an important, previously under-recognized component of the “missing carbon” in mangrove ecosystems and underscore the need to explicitly incorporate this flux into blue carbon models to more accurately evaluate mangrove carbon sequestration capacity. Full article

As an effective technology for enhancing oil recovery, low-salinity water flooding requires further investigation into its microscopic displacement mechanisms and the regulatory roles of key ions. Based on microscopic visualization displacement experiments, this study systematically investigated the effects of injected water salinity, key ion types (Na⁺, K⁺, Ca²⁺, Mg²⁺, HCO₃⁻, CO₃²⁻, SO₄²⁻, and OH⁻), and their concentrations on crude oil displacement behavior in both high- and low-permeability zones. Experimental results indicate that no significant correlation exists between displacement efficiency and injected water salinity in high-permeability zones. In low-permeability zones, displacement efficiency increases with decreasing salinity, peaking at 26.5% when injected water salinity reaches 5000 mg/L. The cation displacement efficiency in the formation, from highest to lowest, is Ca²⁺ > K⁺ > Mg²⁺ > Na⁺. The anion displacement efficiency, from highest to lowest, is OH⁻ > SO₄²⁻ > CO₃²⁻ > HCO₃⁻. When the CaCl₂ concentration decreased from 100 wt% to 50 wt%, the displacement effect in the low-permeability zone improved further, indicating that a higher concentration of the divalent cation Ca²⁺ is not necessarily better. In medium-to-high salinity formation water reservoirs, and under conditions where the influence of clay minerals is disregarded, ion type and reservoir permeability are the most significant factors affecting oil recovery efficiency. These findings provide theoretical support for elucidating the micro-dynamic mechanisms of low-salinity water flooding in low-permeability zones and optimizing injection water formulations. Full article

Sustainable groundwater management is critical in semi-arid coastal regions, where municipal landfills pose a severe threat to aquifer integrity and long-term water security. However, there is still a lack of seasonally resolved hydrogeochemical monitoring around newly established landfills, particularly in rapidly urbanizing Mediterranean settings. This study assesses the hydrogeochemical impact of the newly operational Tangier Landfill and Recovery Center on local groundwater resources to inform sustainable remediation strategies. A combined approach was applied to samples collected in dry and wet seasons, using Piper and Stiff diagrams to trace facies evolution together with a dual-index assessment based on the Canadian (CCME-WQI) and Weighted Arithmetic (WAWQI) Water Quality Indices. Results show that upgradient waters remain of Good–Excellent quality and are dominated by Ca–HCO₃ facies, whereas downgradient wells display extreme mineralization, with EC up to 15,480 µS/cm and Cl⁻ and SO₄²⁻ exceeding 1834 and 2114 mg/L, respectively. At hotspot sites P4 and P8, As reaches 0.065 mg/L and Cd 0.006 mg/L, far above the WHO drinking-water guidelines. While the CCME-WQI captures the general salinity-driven degradation pattern, the WAWQI pinpoints these acute toxicity zones as Very poor–Unsuitable. The study demonstrates that rainfall intensifies toxicity through a seasonal “Piston Effect” that mobilizes stored contaminants rather than diluting them, underscoring the need for seasonally adaptive monitoring to ensure the environmental sustainability of landfill-adjacent aquifers. Full article

This study investigates the effects of saline reclaimed water recharge on soil salt accumulation and water migration in Xinjiang, China, aiming to provide scientific guidance for the sustainable utilization of reclaimed water in arid regions. Indoor vertical infiltration simulation experiments were conducted using reclaimed water with varying salinity levels (0, 1, 2, 3, and 4 g L⁻¹) to evaluate their impacts on soil water–salt distribution and infiltration dynamics. Results showed that irrigation with saline reclaimed water increased soil pH and significantly enhanced both the infiltration rate and wetting front migration velocity, while causing only minor changes in the moisture content of the wetted zone. When the salinity was 2 g L⁻¹, the observed improvement effect was the most significant. Specifically, the cumulative infiltration increased by 22.73% after 180 min, and the time required for the wetting peak to reach the specified depth was shortened by 21.74%. At this salinity level, the soil’s effective water storage capacity reached 168.19 mm, with an average moisture content increase of just 6.20%. Soil salinity increased with the salinity of the irrigation water, and salts accumulated at the wetting front as water moved downward, resulting in a characteristic distribution pattern of desalination in the upper layer and salt accumulation in the lower layer. Notably, reclaimed water recharge reduced soil salinity in the 0–30 cm layer, with salinity in the 0–25 cm layer decreasing below the crop salt tolerance threshold. When the salinity of the reclaimed water was ≤2 g L⁻¹, the salt storage in the 0–30 cm layer was less than 7 kg ha⁻¹, achieving a desalination rate exceeding 60%. Reclaimed water with a salinity of 2 g L⁻¹ enhanced infiltration (wetting front depth increased by 27.78%) and desalination efficiency (>60%). These findings suggest it is well suited for urban greening and represents an optimal choice for the moderate reclamation of saline-alkali soils in arid environments. Overall, this study provide a reference for the water quality threshold and parameters of reclaimed water for urban greening, farmland irrigation, and saline land improvement. Full article

The imbalance between water supply and demand in the arid and semi-arid regions of northwest China has become increasingly severe, highlighting the urgent need to develop and utilize unconventional water resources. Return flow, originating from canal leakage and field drainage, is widely distributed in these regions. However, as it contains a certain amount of salts, long-term use of return flow can lead to soil salinization and degradation of soil structure. Therefore, the scientific utilization of return flow has become a key issue for achieving sustainable agricultural development and efficient water use in arid areas. This study was conducted in the Yinbei Irrigation District, Ningxia, northwest China. Water samples were collected from the main and branch drainage ditches and analyzed to evaluate the feasibility of using return flow irrigation in the area. In addition, based on two years of continuous field monitoring and HYDRUS model simulations, the long-term dynamics of soil salinity under moderate return flow irrigation over the next 20 years were predicted. The results show that the total salinity of the main return ditches consistently remained below the agricultural irrigation water quality standard of 2000 mg/L, with Na⁺ and SO₄²⁻ as the predominant ions. Seasonal variations in return flow salinity were notable, with higher levels observed in spring compared to summer. Simulation results based on field trial data indicated that soil salinity displayed regular seasonal fluctuations. During the rice-growing season, strong leaching kept the salinity in the plough layer (0–40 cm) low. However, after irrigation ceased, evaporation in autumn and winter led to an increase in surface soil salinity, creating annual peaks. Long-term simulations showed that soil salinity throughout the entire profile (0–100 cm) followed a pattern of “slight increase—gradual decrease—dynamic stability.” Specifically, winter salinity peaks slightly increased during the first two years but then gradually declined, stabilizing after approximately 15 years. This indicates that long-term return-flow irrigation does not result in the accumulation of soil salinity in the plough layer. Full article

Groundwater is the main water source for irrigated agriculture, accounting for an increasing share of the domestic supply in the hyper-arid district of La Yarada Los Palos (Tacna, Peru); however, at the sector scale, concerns about arsenic, boron and salinity remain poorly quantified. Arsenic and boron were selected as target contaminants because of their naturally elevated concentrations associated with coastal and volcanic hydrogeological settings, and their well-documented implications for human health and irrigation suitability. This study reports a 12-month monitoring program (September 2024–August 2025) in three irrigated sectors, in which wells were sampled monthly and analyzed by inductively coupled plasma–mass spectrometry (ICP-MS) for total arsenic, boron, lithium and sodium, along with electrical conductivity, pH, temperature and total dissolved solids. The sector–month total arsenic means ranged from 0.0089 to 0.0143 mg L⁻¹, with 33 of 36 exceeding the 0.010 mg L⁻¹ drinking water benchmark recommended by the World Health Organization (WHO). Total boron ranged from 1.11 to 2.76 mg L⁻¹, meaning that all observations were above the 0.5 mg L⁻¹ irrigation guideline for agricultural use proposed by the United Nations Food and Agriculture Organization (FAO). A marked salinity gradient was observed from the inland Sector 1-BH (median Na ≈ 77 mg L⁻¹; EC ≈ 1.2 mS cm⁻¹) to the coastal Sector 3-LC (median Na ≈ 251 mg L⁻¹; EC ≈ 3.3 mS cm⁻¹), with Sector 2-FS showing intermediate salinity but the highest median boron and lithium levels. Spearman rank correlations indicate that sodium, electrical conductivity and total dissolved solids define the main salinity axis, whereas arsenic is only moderately associated with boron and lithium and is not a simple function of bulk salinity. Taken together, these results show that groundwater from the monitored wells is not safe for drinking without treatment and is subject to at least moderate boron-related irrigation restrictions. The sector-resolved dataset provides a quantitative baseline for La Yarada Los Palos and a foundation for future work integrating expanded monitoring, health-risk metrics and management scenarios for arsenic, boron and salinity in hyper-arid coastal aquifers. Full article

Availability of irrigation water during growing seasons in the Republic of South Africa (RSA) remains a significant concern. Persistent droughts and unpredictable rainfall patterns attributed to climate change, coupled with an increasing population, have exacerbated irrigation water scarcity. Globally, treated wastewater has been utilised as an irrigation water source; however, despite global advances in the usage of treated wastewater, its suitability for irrigation in RSA remains a contentious issue. Considering this uncertainty, this review article aims to unravel the South African scenario on the suitability of treated wastewater for irrigation purposes and highlights the potential environmental impacts and public health risks. The review synthesised literature in the last two decades (2000–present) using Web of Science, ScienceDirect, ResearchGate, and Google Scholar databases. Findings reveal that treated wastewater can serve as a viable irrigation source in the country, enhancing various soil parameters, including nutritional pool, organic carbon, and fertility status. However, elevated levels of salts, heavy metals, and microplastics in treated wastewater resulting from insufficient treatment of wastewater processes may present significant challenges. These contaminants might induce saline conditions and increase heavy metals and microplastics in soil systems and water bodies, thereby posing a threat to public health and potentially causing ecological risks. Based on the reviewed literature, irrigation with treated wastewater should be implemented on a localised and pilot basis. This review aims to influence policy-making decisions regarding wastewater treatment plant structure and management. Stricter monitoring and compliance policies, revision of irrigation water standards to include emerging contaminants such as microplastics, and intensive investment in wastewater treatment plants in the country are recommended. With improved policies, management, and treatment efficiency, treated wastewater can be a dependable, sustainable, and practical irrigation water source in the country with minimal public health risks. Full article

Graphene oxide (GO) is a carbon-based nanomaterial explored for agricultural and forestry uses, but plant responses are strongly subject to both the dose and the route of exposure. We summarized recent studies with defined graphene oxide (GO) exposures by seed priming, foliar delivery, and root or soil exposure, while comparing annual crops with woody forest plants. Mechanistic progress points to a shared physicochemical basis: surface oxygen groups and sheet geometry reshape water and ion microenvironments at the soil–seed and soil–rhizosphere interfaces, and many reported shifts in antioxidant enzymes and hormone pathways likely represent downstream stress responses. In crops, low-to-moderate doses most consistently improve germination, root architecture, and tolerance to salinity or drought stress, whereas high doses or prolonged root exposure can cause root surface coating, oxidative injury, and photosynthetic inhibition. In forest plants, evidence remains limited and often relies on seedlings or tissue culture. For forest plants with long life cycles, processes such as soil persistence, aging, and multi-seasonal carry-over become key factors, especially in nurseries and restoration substrates. The available data indicate predominant root retention with generally limited root-to-shoot translocation, so residues in edible and medicinal organs remain insufficiently quantified under realistic-use patterns. This review provides a scenario-based framework for crop- and forestry-specific safe-dose windows and proposes standardized endpoints for long-term fate and ecological risk assessment. Full article

Protein-based materials such as human serum albumin (HSA) have demonstrated significant potential for the development of novel wound management materials. For the first time, the formation of HSA-based hydrogels was proposed using a combination of thermal- and ethanol-induced approaches. The combination of phosphate-buffered saline (PBS) and limited (up to 20% v/v) ethanol content offers a promising strategy for fabricating human serum albumin-based hydrogels with tunable properties. The hydrogel formation was studied using in situ dynamic light scattering (DLS) for qualitative and semi-quantitative analysis of the patterns of protein hydrogel formation through thermally induced gelation. The rheological properties of human serum albumin-based hydrogels were investigated. Hydrogels synthesized via thermally induced gelation using a denaturing agent exhibit a dynamic viscosity ranging from 100 to 10,000 mPa·s. The biocompatibility, biodegradability, and structural stability of human serum albumin-based hydrogels were comprehensively evaluated in physiologically relevant media. These human serum albumin-based hydrogels represent a promising platform for developing topical therapeutic agents for wound management and tissue engineering applications. This study investigated the kinetics of tetracycline release from human serum albumin-based hydrogels in PBS and fetal bovine serum (FBS). All tested formulations of HSA-based hydrogels loaded with tetracycline (1 mg/mL) demonstrated antibacterial activity against Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus haemolyticus, and Corynebacterium striatum strains. Full article

This study investigates the Lower Cretaceous Madongshan Formation in the Liupanshan Basin, a classic saline lacustrine succession, to elucidate the key mechanisms for high-quality source rock development. An integrated approach combining organic geochemistry (Rock-Eval, Gas Chromatography–Mass Spectrometry [GC-MS], δ¹³C) and inorganic elemental geochemistry (X-ray Fluorescence [XRF]) was applied to a well-characterized outcrop section. The results reveal that the Madongshan Formation contains mature, oil-prone source rocks dominated by Type II₁ and II₂ kerogen. Geochemical proxies consistently indicate deposition within an arid to semi-arid climate, which drove the formation of a stratified, saline-to-hypersaline water column with persistent bottom-water anoxia (Pristane/Phytane [Pr/Ph] < 0.5). Isotopic and biomarker data confirm a mixed source input, with an average contribution of approximately 55% from aquatic organisms supplemented by a significant terrestrial influx. Based on these findings, we propose a “Salinity-Driven Preservation” model. This model posits that climate-induced salinity played a critical role in establishing a persistent halocline, leading to an intensely anoxic “preservation factory” at the lake bottom. Current evidence suggests that this exceptional preservation efficiency was a pivotal factor compensating for moderate productivity to control organic matter enrichment. This study provides a robust framework for predicting source rock quality in the Liupanshan Basin and serves as a valuable analogue for other saline lacustrine systems. Full article

In arid regions, irrigation is essential for sustaining crop production, but irrigation water often contains high levels of salts that may reduce yields. This study aimed to evaluate crop responses to irrigation water with salinity levels exceeding 4 g/L (≈6.25 dS/m). A large-scale field survey was conducted across several Tunisian governorates, covering a wide range of crops and production systems. Irrigation water salinity and corresponding crop yields were recorded and analyzed to determine tolerance patterns under real farming conditions. Results indicate that, even under high salinity conditions, several cropssuch as carrot (Daucus carota), barley (Hordeum vulgare), and tomato (Solanum lycpersicum), can maintain high yields, highlighting their potential for saline irrigation in arid regions. These findings provide valuable insights for irrigation management, crop selection, and the development of sustainable agricultural practices in arid environments. Full article

Salt permeation erosion is a key factor leading to the deterioration of service performance and shortening the lifespan of asphalt pavement in salt-rich areas. In this environment, the combined action of water and salt accelerates the decline in the asphalt–aggregate interface, leading to distress, such as raveling and loosening, which severely limit pavement durability. The authors systematically reviewed the research progress on asphalt–aggregate adhesion in a saline corrosion environment and discussed the complex mechanisms of adhesion degradation driven by intrinsic factors, including aggregate chemical properties, surface morphology, asphalt components, and polarity, as well as environmental factors, such as moisture, salt, and temperature. We also summarized multi-scale evaluation methods, including conventional macroscopic tests and molecular dynamics simulations, and revealed the damage evolution patterns caused by the coupled effects of water, salt, heat, and mechanical forces. Based on this, the effectiveness of technical approaches, such as asphalt modification and aggregate modification, is explored. Addressing the current insufficiency in research on asphalt adhesion under complex conditions in salt-rich areas, this study highlights the necessity for further research on mechanisms of multi-environment interactions, composite salt erosion simulation, development of novel anti-salt erosion materials, and intelligent monitoring and early warning, aiming to provide a theoretical basis and technical support for the weather-resistant design and long-term service of asphalt pavement in salt-rich regions. Full article

Issues related to malnutrition are addressed primarily through the consumption of fish meat, as it is both affordable and accessible to economically weaker sections of the population. Therefore, challenges observed in the aquaculture and fishery sectors, such as the detection of environmental changes, disease outbreaks, hindered growth, and poor fish health management, need to be addressed to increase production. The employment of modern technologies, such as (bio)sensors, helps to enhance production in artisanal and large aquaculture systems, because these can timely detect challenges, including climate change factors, sea-level-rise-induced salinity load, changes in inland temperatures, ocean acidification, changes in precipitation patterns, ammonia toxicity, infectious diseases, and stress factors in aquatic systems. As a result, appropriate and timely measures can be taken at various stages of fish culture to address common problems. Using major scientific electronic databases, we comprehensively reviewed the topic of emerging needs, expanding applications, and recent technological advances in biosensors, with a particular focus on pisciculture. We highlight the biosensor technology used in the fisheries industry, which represents a pivotal step towards addressing its various aspects. Full article

Alfalfa cultivation is an effective way to achieve soil improvement while utilizing saline soils. Irrigation and drainage, as physical measures to leach salts, can effectively reduce the soil salt content, while application of organic fertilizer fermented with an effective microorganism (EM) may further enhance the improvement effect of saline–alkaline soil by improving soil fertility and microbial community structure. However, there is still a lack of systematic assessment on the effects of applying these three measures on the saline soil–plant system. In this study, we used alfalfa as the plant material and set three water depths of 8 mm (IR1), 16 mm (IR2), and 24 mm (IR3) under the condition of irrigating every 10 days with remote-controlled timed and quantitative irrigation, which is the most acceptable to farmers in the era of smart agriculture. EM organic fertilizer dosage was designed as 0 kg/ha (CK), 1500 kg/ha (OF1), 3000 kg/ha (OF2), 4500 kg/ha (OF3), and 6000 kg/ha (OF4). The multiple-crop alfalfa yield, quality (crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF)), and soil electrical conductivity (EC) were observed. The results showed that after the application of EM organic fertilizer, the soil’s EC value of fertilized treatments was higher than that of CK, but this difference became smaller with the prolongation of alfalfa’s growing period, implying that EM organic fertilizer could absorb more soil salts by promoting alfalfa’s growth; the water depth was obviously negatively correlated with the soil’s EC value, demonstrating that the increase in the water depth had a stronger ability to reduce the soil salts. By the end of the experiment, the soil’s EC values were reduced by 21.4–43.7% for the treatments. The alfalfa yield was significantly increased by EM organic fertilizer application, and the three alfalfa yields were increased by 63.3–69.1%, 65.4–83.6%, and 52.6–56.2%, respectively, when fertilizer application was elevated from CK to OF4. The highest alfalfa yields were all found at IR2OF4, reaching 1164.7, 2637.3 and 2519.7 t/ha, corresponding to the first, second, and third alfalfa crops, respectively. The analysis of alfalfa quality indexes revealed that higher CP values were found in the IR2 treatments, and increasing fertilizer application from OF1–OF4 resulted in an increase in CP values by 2.4–9.1%, 1.5–7.4%, and 0.8–6.7% for the three alfalfa crops. Relatively low NDF and ADF values were observed for alfalfa under IR2 conditions; however, the application of EM organic fertilizer reduced the NDF and ADF values within a certain range. According to the results of the entropy weight evaluation model, IR3OF4, IR3OF2, and IR3OF3 were the top three treatments with the best overall benefits, respectively, with relative closeness values of 0.71, 0.70, and 0.68, in that order, which suggests that the appropriate water depth is 24 mm, while the appropriate EM organic fertilizer dosage is in the range of 3000–6000 kg/ha. There was a pattern observed in our study, in which the treatments with better overall benefits were better distributed at high water depths, which emphasizes the critical role of the irrigation volume in ameliorating saline soils. The conclusions of the study are intended to provide a practical basis for the comprehensive utilization and sustainable development of saline soils. Full article

The Eocene fourth member of the Shahejie formation (Es4x) in the Bonan Depression, Bohai Bay Basin, records syn-rift sedimentation under alternating arid and humid climates. It provides insight into how orbital-scale climatic fluctuations influenced tectonics, facies patterns, and reservoir distribution. This study integrates 406 m of core data, 92 thin sections, 450 km² of 3D seismic data, and multiple geochemical proxies, leading to the recognition of five facies associations (LFA): (1) alluvial fans, (2) braided rivers, (3) floodplain mudstones, (4) fan deltas, and (5) saline lacustrine evaporites. Three major depositional cycles are defined within the Es4x. Seismic reflections, well-log patterns, and thickness trends suggest that these cycles represent fourth-order lake-level fluctuations (0.8–1.1 Myr) rather than short 21-kyr precession rhythms. This implies long-term climate and tectonic modulation, likely linked to eccentricity-scale monsoon variability. Hyperarid phases are marked by Sr/Ba > 4, δ¹⁸O > +4‰, and thick evaporite accumulations. In contrast, Sr/Ba < 1 and δ¹⁸O < −8‰ reflect humid conditions with larger lakes and enhanced fluvial input. During wet periods, rivers produced sand bodies nearly 40 times thicker than in dry intervals. Reservoir quality is highest in braided-river sandstones (LFA 2) with 12%–19% porosity, preserved by chlorite coatings that limit quartz cement. Fan-delta sands (LFA 4) have <8% porosity due to calcite cementation, though fractures (10–50 mm) improve permeability. Floodplain mudstones (LFA 3) and evaporites (LFA 5) act as seals. This work presents a predictive depositional and reservoir model for arid–humid rift systems and highlights braided-river targets as promising exploration zones in climate-sensitive basins worldwide. Full article