Search Results (26,317)

The sustainable development of arid regions is significantly constrained by the availability of water resources, which play a crucial role in this context. It is necessary to deeply investigate and analyze the hydrochemical characteristics and major ion sources. This study, which was based on data from 183 water samples collected from the Jinghe River Basin, provided a comprehensive analysis of the river water hydrochemistry. The results show that the average TDSs (total dissolved solids) was measured at 49.8 mg·L⁻¹. HCO₃⁻ (82.4%) and Ca²⁺ (77.1%) were the ions present in the highest abundances. The river water was classified as the HCO₃⁻-Ca²⁺ hydrochemical type. The Gibbs diagrams indicated that the ion composition was primarily influenced by rock weathering. Additionally, the Na-normalized molar ratio diagrams suggested that the chemical composition was primarily governed by the weathering and dissolution of silicate rocks, while the carbonate rock dissolution played a lesser role. This study demonstrates a critical aspect of water resources quality evaluation, which is of great significance for the sustainable development, utilization and environmental protection of regional water resources. Full article

The Fen River Basin (FRB), an ecologically fragile region in China, exemplifies the intricate interplay between vegetation dynamics and both climatic and human-driven factors. This study leverages a 40-year (1982–2022) dataset, utilizing the kernel-based normalized difference vegetation index (kNDVI) alongside key climatic variables—rainfall (PRE), temperature (TMP), and solar radiation (SRAD)—to investigate vegetation variations and their drivers in the FRB, particularly in relation to the Grain for Green Program (GGP). Our analysis highlights significant greening across the FRB, with the kNDVI slope increasing by 0.0028 yr⁻¹ and green-covered areas expanding by 92.8% over the study period. The GGP facilitated the greening process, resulting in a notable increase in the kNDVI slope from 0.0005 yr⁻¹ to 0.0052 yr⁻¹ and a marked expansion in the area of significant greening from 24.6% to 95.8%. Regional climate shifts, characterized by increased warming, heightened humidity, and a slight rise in SRAD, have further driven vegetation growth, contributing 75%, 58.7%, and 23.6% to vegetation dynamics, respectively. Notably, the GGP has amplified vegetation’s sensitivity to climatic variables, with areas significantly impacted by multiple climate factors expanding from 4.8% to 37.5%. Specially, PRE is the primary climatic influence, impacting 71.3% of the pertinent regions, followed by TMP (60.1%) and SRAD (30%). The integrated effects of climatic and anthropogenic factors, accounting for 47.8% and 52.2% of kNDVI variations, respectively, collectively influence 96% of the region’s vegetation dynamics. These findings underscore the critical role of climate change and human interventions in shaping vegetation patterns and provide a robust foundation for refining ecological conservation strategies, particularly in the context of global warming and land-use policies. Full article

The rapid pace of urbanization and global climate change necessitates a thorough assessment of urban ecological resilience to cultivate sustainable regional ecosystem development. Cities along the Yangtze River face an intensifying conflict between ecological preservation and socio-economic growth. Analyzing the ecological resilience of these urban centers is essential for achieving equilibrium in regional urban ecosystems. This study proposes a “system process space” attribute analysis framework, taking into account urban development processes, ecosystem structure, and resilience evolution stages. Utilizing data from 45 Yangtze River cities, we establish a “Driver, Pressure, State, Impact, and Response” (DPSIR) evaluation index system to evaluate changes in ecological resilience levels and evolution trends from 2011 to 2022. Our findings indicate that: (1) The ecological resilience index of Yangtze River cities increased from 0.177 to 0.307 between 2011 and 2022, progressing through three phases: ecological resilience construction, rapid development, and stable development. (2) At the city level, ecological resilience along the Yangtze River exhibits uneven development characteristics. Upstream cities display a significant “stepped” pattern, midstream cities exhibit a significant “Matthew effect”, and downstream cities present a pyramid-shaped pattern. While regional differences in ecological resilience persist, overall polarization is gradually decreasing, intercity connections are strengthening, and there is a growing focus on coordinated regional development. (3) The spatial distribution of ecological resilience in Yangtze River cities demonstrates both continuity and evolution, generally forming a “core-edge” clustered pattern. Based on these findings, we recommend enhancing inter-city cooperation and connectivity, addressing imbalances in urban ecological resilience, and promoting high-quality ecological resilience development along the Yangtze River through tailored development strategies for each city. Full article

The exogenous application of oxalic acid is a potential approach to amplifying phytoremediation performance on Cd-contaminated soils. However, few studies explore the optimal oxalic acid application regime from a perspective of coupling different concentrations and timings to maximize Cd removal rate. Given this, a pot experiment was conducted using oil sunflower (Helianthus annuus L.) as the test plant. Oxalic acid was added to the pots at concentrations of 1, 2, 3, 4, 5, and 6 mmol/kg at 20, 30, 40, and 50 days after emergence. A control (CK) without exogenous oxalic acid was also included. We examined the discrepancies in various soil Cd forms, sunflower height, plant non-protein thiol (NPT) levels, and soil Cd remediation efficiency under different oxalic acid application regimes. The results showed that applying oxalic acid at a concentration of 4 mmol/kg reduced the proportion of Fe-Mn oxide Cd and organic Cd compared to the control (CK), while increased the proportion of available Cd. The optimal application time is 30 or 40 days after emergence. The addition of exogenous oxalic acid promoted the growth of sunflowers, with the greatest increase in plant height observed when 4 mmol/kg oxalic acid was applied at 30 days after emergence. Exogenous oxalic acid enhanced the absorption of Cd by sunflower roots, with the total Cd accumulation in roots, stems, and leaves being higher than in the control (CK). When 4 mmol/kg oxalic acid was applied at 30 days after emergence, the total Cd accumulation in roots, stems, and leaves was highest. Under different application times and concentration levels of oxalic acid, Cd accumulation was highest in roots, followed by leaves, with stems showing the lowest accumulation. The NPT content in each part is as follows: root > stem > leaf. Applying 5 mmol/kg oxalic acid after 30 days of sunflower emergence resulted in relatively higher total NPT content in roots, stems, and leaves compared to the control (CK). The TOPSIS model was used for comprehensive evaluation, which showed that 4 mmol/kg oxalic acid application at 30 days after emergence could be used as the optimal oxalic acid application regime for phytoremediation. These findings indicate that the addition of oxalic acid effectively promoted the absorption of Cd by sunflower and increased the efficiency of Cd removal from the rhizosphere soil, with the optimal removal of soil Cd achieved by applying oxalic acid at a concentration of 4 mmol/kg 30 days after the emergence of oilseed sunflower seedlings. Full article

This study explored the characteristics of benthic animal communities in different water functional areas and the driving factors affecting changes in the community structure of four water functional zones of the Jiangsu section of the Yangtze River: the protection, buffer, reserve, and development and utilization zones. The results showed that the alpha diversity of the benthic animal communities in the protected and reserved zones was significantly higher than that of the buffer and development and utilization zones, and the benthic animal community structure differed significantly across different water functional zones. These zones indirectly affected the community of benthic fauna due to their environmental heterogeneity. Furthermore, the average degree, map density, and average clustering coefficient of the molecular ecological network were highest in the protected zone. The average path length was shorter, and there were more types and numbers of key species in the benthic animal community in the protected zone, indicating high levels of connectivity and efficiency in transferring substances, energy, and information between benthic animals. These results will provide a scientific basis for studying the characteristics and driving factors of benthic animal communities in the Yangtze River and have important significance for assessing and restoring aquatic ecology in the Yangtze River Basin. Full article

Abstract: Understanding groundwater–surface water interaction is essential for water resource management and watershed ecological protection. However, the existing studies often emphasize the tracer role of hydrogeochemical methods (including hydrochemistry and isotopes) while underestimating the importance of analyzing watershed hydraulic characteristics, thus neglecting the indications of the driving mechanisms (hydraulic head difference) for the water exchange. Taking the Songhua River in the Sanjiang Plain as an example, this study combines hydraulic, hydrochemical, and isotopic methods to clarify the groundwater–surface water interactions from both a driving mechanism perspective and a hydrogeochemical characterization perspective within the water cycle. The results indicate that human exploitation has caused river water to infiltrate into groundwater, converting the section into a losing river, where surface water consistently exhibits a hydraulic tendency to recharge the aquifer. The influence zone of the river extends up to 3.5 km from the riverbank, with an average recharge rate from the river reaching 78.04% within this area. This recharge mixes and dilutes the adjacent groundwater, impacting its hydrogeochemical characteristics. This study enhances the understanding of combined methods for groundwater–surface water interaction and provides a scientific basis for water resource management and pollution control strategies in the local agricultural regions. Full article

This study evaluates two reanalysis precipitation products (CRA40 and ERA5) over the Ganjiang River Basin with precipitation data from 37 ground rainfall gauges and surface-observed stream flow data from January 1998 to December 2008. Direct comparison with rain gauge observations shows that both CRA40 and ERA5 can capture the spatial and temporal characteristics of precipitation at the basin scale of the Ganjiang River and reflect most of the precipitation events, but there are pronounced differences in the quality of precipitation between them. ERA5 performs better on the daily scale, capturing precipitation changes more accurately over short periods of time, while CRA40 performs better on the monthly scale, providing more stable and long-term precipitation trends. The results of stream flow simulations using two reanalysis precipitation products driving the VIC hydrological model show that (1) CRA40 outperforms ERA5 with a better Nash–Sutcliffe Efficiency (NSE, 0.65 and 0.6) and higher CC (0.96 and 0.91) in daily and monthly scale stream flow simulations, and ERA5 has a good CC (0.86 and 0.93, respectively), but its NSE is poor (0.29 and 0.30, respectively); (2) both CRA40 and ERA5 generally overestimate basin stream flows, especially during the flood season (April–September), with ERA5’s overestimation being more pronounced. This study is expected to provide a basis for the selection of reliable reanalysis products for Ganjiang River Basin precipitation and hydrological simulation. Full article

One trend in the development of building materials is the partial or complete replacement of traditional materials that have a high carbon footprint with eco-friendly ecological raw materials and ingredients. In the present work, the influence of replacing cement with 10 wt% thermally activated natural zeolite on the structural and physical-mechanical characteristics of cured mortars based on white Portland cement and river sand was investigated. The phase compositions were determined by wavelength dispersive X-ray fluorescence (WD-XRF) analysis, X-ray powder diffraction (PXRD), diffuse reflectance infrared Fourier transformed spectroscopy (DRIFTS), and scanning electron microscopy (SEM), as well as thermogravimetric analysis simultaneously with differential scanning calorimetry (TG/DTG-DSC). The results show that the incorporation of zeolite increases the amount of pores accessible with mercury intrusion porosimetry by about 40%, but the measured strengths are also higher by over 13%. When these samples were aged in an aqueous environment from day 28 to day 120, the amount of pores decreased by about 10% and the compressive strength increased by nearly 15%, respectively. The microstructural analysis carried out proves that these results are due to hydration with a low content of crystal water and the realization of pozzolanic reactions that last over time. Replacing some of the white cement with thermally activated natural zeolite results in the formation of a greater variety of crystals, including new crystalline CSH and CSAH phases that allow better intergrowth and interlocking. The results of the investigations allow us to present a plausible reaction mechanism of pozzolanic reactions and of the formation of new crystal hydrate phases. This gives grounds to claim that the replacement of part of the cement with zeolite improves the corrosion resistance of the investigated building solutions against aggressive weathering. Full article

Recent studies have revealed that the frequency and magnitude of floods tend to increase due to climate change. Hence, excessive scouring due to flood events puts river bridges at greater risk of failure. This paper presents the initial findings of an experimental study to improve the understanding of the main characteristics of bridge pier scour under pressurized flow encountered during flooding. The experiments were carried out in four main groups according to two deck alignments with circular and oblong pier shapes. For each group of experiments, thirty-six tests were conducted under partially and fully pressurized flow conditions using four approach flow depths and three discharge values. The validity of the structured design approach for pier scour estimation implemented in the guidelines was investigated. The results showed that the bridge pier scour depths were up to 29.4% and 49.4% greater than the sum of the vertical contraction and local scour depths for 100 L/s for partially and fully pressurized flow conditions, respectively. However, as the discharge increased to 120 L/s, the bridge pier scour depth became 38.3% and 17.8% smaller than the sum of the vertical contraction and local scour depths for partially and fully pressurized flow, respectively. So, the structured design approach was determined to be safe for high discharge values. Furthermore, it was found that tests with a circular pier resulted in higher bridge pier scour depths than the sum of the vertical contraction and local scour depths up to 19.3% even for 120 L/s. Conversely, smaller bridge pier scour depths than the sum of the vertical contraction and local scour depths were observed up to 17.8% for tests with oblong piers. Thus, it can be concluded that the pier shape has a profound effect on scour holes and oblong piers cause smaller scour depths than circular piers in pressurized flow conditions. This study showed that the flow–pier–deck interaction significantly affects the depth and width of the scour hole, especially for small discharges and fully pressurized flow conditions. Full article

For a given aquatic ecosystem that will be used as a water source, it is necessary to establish the quality of the water from a microbiological point of view by identifying the pathogens present in the water. The aim of this study was to determine and analyze the antimicrobial activity of some biocides derived from garlic (garlic–methanol extract) and lavender (lavender–water extract). Their efficiency was evaluated at different concentrations and contact times. Initially, through specific laboratory analyses, the microbiological characteristics of the river were determined. Biomimetic studies on the antimicrobial activity of biocides based on garlic and lavender in surface waters involved detailed exploration of how the natural antimicrobial properties of these plants can be effectively utilized to treat water contaminated with harmful microorganisms. Both the contact time and the amount of biocide used have a significant effect on the microorganisms of interest. Thus, to describe the degradation rate of coliform bacteria, a pseudo-first-order and zero-order kinetic model was used, $\mathrm{r}=-(\mathrm{d}\mathrm{N}/\mathrm{d}\mathrm{t})=k_{\mathrm{o}\mathrm{b}\mathrm{s}}·t$ şi $r_0=k_{obs}·N_0=k_0$, where r is the rate of degradation of microorganisms (CFU/min), N₀ is the initial number of microorganisms in the aqueous solution (colony-forming unit, CFU), N is the final number of microorganisms after a contact time t (CFU), k_obs is the pseudo-first-order rate constant (min⁻¹), t is the contact time (min), r₀ is the initial rate of degradation of microorganisms (CFU/min), and k₀ is the pseudo-rate constant zero order (min⁻¹). Following 60 min of treatment with 1 mL of lavender-water biocide, the inhibition rate of pathogenic microorganisms in the water reached 59.09%, whereas, under the same conditions, the garlic–methanol biocide achieved an inhibition rate of 40.86%. This study confirms the antimicrobial activity of both lavender and garlic biocides, highlighting their potential in mitigating water pollution caused by pathogens. Full article

Abstract: The accurate characterization of soil structure is fundamental to groundwater science, environmental ecology, and Earth systems science. To address the challenge of quantifying the high spatial variability of large-scale soil structures, this study used a laser particle size analyzer to measure the distribution of soil particle size in 207 samples from ten profiles across the Daqing and Ziya River basins in the North China Plain. The quantified soil structure, expressed as soil fractal dimension D, was derived using monofractal theory. Various spatial analysis techniques, including Moran’s I index, correlation analysis heat maps, the Kolmogorov–Smirnov one-sample test, and geostatistical semivariogram function, were jointly applied to investigate the spatial variability of soil structural fractals across different depths in the piedmont plain–coastal areas of the two river basins. The results indicate the following: (1) Quantitative analysis confirms that under the influence of piedmont alluvial and fluvial dynamics, soil D values homogenize from the piedmont to the coastal areas, with decreasing particle size differences closer to the coast. However, the spatial variability of the soil structural fractals in the Ziya River Basin was greater than that in the Daqing River Basin. (2) The combined effects of climate change, regional differences, and human activity led to greater spatial variability in the soil structural fractals in the Ziya River Basin than in the Daqing River Basin. The correlation between D values and burial depth was strongest in the Xianxian profile (−0.78), whereas the spatial correlation was strongest in the Hengshui and Dacheng profiles (−0.47). (3) The greatest spatial variability in soil D values occurred at depths of 1–2 m, with a coefficient of variation of 23.595%, which was significantly higher than those at depths of 0–1 (14.569%) and 2–3 m (16.284%). Full article

Recurrent wildfires can negatively affect soil quality, and post-fire soil quality recovery is critical for maintaining sustainable ecosystem development. The objective of this study was to evaluate the changes and recovery of soil properties and soil quality in the forests of dry/warm river valleys in southwest China after disturbance by high-severity fires. In this study, the impact of fire on soil properties and soil quality was investigated for three years post-fire. Unburned forest land with a similar natural environment compared to the fire area was used as a control. Soil samples were collected from three different depths of 0–10 cm, 10–20 cm, and 20–30 cm, respectively. Principal component analysis (PCA) combined with the Norm value was used to select the minimum data set (MDS), thus calculating the soil quality index (SQI). The results showed that the soil properties changed significantly after high-severity fires. On average, soil bulk density (0.91 g/cm³, p = 0.001), total nitrogen (0.12 g/kg, p = 0.000), total phosphorus (0.10 g/kg, p = 0.000), and total potassium (5.55 g/kg, p = 0.000) were significantly lower in the burned areas than in the unburned areas at the first sampling. These indicators increased in the following three years but still did not recover to unburned levels. Compared with the above indicators, soil porosity and organic matter increased post-fire, but gradually decreased over time. Soil clay, geometric mean diameter, and total potassium were included in the MDS. The SQI was ranked as unburned > 3 years > 2 years > 1 year > 6 months. The SQI was significantly (p = 0.001) reduced six months post-fire by an average of 36%, and, after three years of recovery, the soil quality of the post-fire areas could be restored to 81% of soil in unburned areas. Apparently, high-severity fires caused changes in soil properties, thereby significantly decreasing soil quality. Soil quality gradually improved with increasing restoration time. However, the complete recovery of soil quality post-fire in forest land in the dry/warm river valley will take a longer time. Full article

Water resources, energy, and food are essential for the development of society, and they are strongly interdependent. The coupling and coordination relationships of the water–energy–food (WEF) system are important for regional resource security and high-quality development. The Yellow River Irrigation Area in Shandong Province, China, is a grain production base and has a substantial impact on national food security. To examine the water, energy, and food subsystem dynamics in this area, an evaluation system for the WEF system was established. A comprehensive weighting method based on game theory was employed to determine index weights. TOPSIS was used to assess the development level of the WEF system. A coupling coordination degree model was used to analyze the evolution of the coupling coordination degree of the WEF system from 2000 to 2020, and a GWR model was constructed to explore the spatial heterogeneity of its driving factors. The findings indicated that the development level of the WEF system in the study area was moderate, with a gradual upward trend. The coupling coordination degree fluctuated between 0.62 and 0.739. The GWR model revealed that temperature had an overall negative effect on the coupling coordination degree, with the greatest impact on the central irrigation area; the slope and NDVI had a negative effect, with increasing intensity from the southwest to the northeast; and rainfall had an overall positive effect, with the greatest impact on the irrigation area near the estuary in the northeast. Overall, the building area ratio had a negative effect on the coupling coordination degree, with exceptions in some areas. These research outcomes provide theoretical support for sustainable agricultural development in the Yellow River irrigation areas of Shandong Province and methodological reference data for studying collaborative resource utilization in irrigation regions. Full article

Infectious spleen and kidney necrosis virus (ISKNV) has brought huge economic loss to the aquaculture industry. Through interfering with the viral replication and proliferation process that depends on host cells, its pathogenicity can be effectively reduced. In this study, we investigated the role of asparagine metabolites in ISKNV proliferation. The results showed that ISKNV infection up-regulated the expression of some key enzymes of the asparagine metabolic pathway in Chinese perch brain (CPB) cells. These key enzymes, including glutamic oxaloacetic transaminase 1/2 (GOT1/2) and malate dehydrogenase1/2 (MDH1/2) associated with the malate-aspartate shuttle (MAS) pathway and asparagine synthetase (ASNS) involved in the asparagine biosynthesis pathway, were up-regulated during ISKNV replication and release stages. In addition, results showed that the production of ISKNV was significantly reduced by inhibiting the MAS pathway or reducing the expression of ASNS by 1.3-fold and 0.6-fold, respectively, indicating that asparagine was a critical limiting metabolite for ISKNV protein synthesis. Furthermore, when asparagine was added to the medium without glutamine, ISKNV copy number was restored to 92% of that in the complete medium, indicating that ISKNV could be fully rescued from the absence of glutamine by supplementing asparagine. The above results indicated that asparagine was a critical factor in limiting the effective replication of ISKNV, which provided a new idea for the treatment of aquatic viral diseases. Full article

Leaves are the most significant parts of forage crops such as alfalfa. Senescence is the terminal stage of leaf development and is controlled by an integrated myriad of endogenous signals and environmental stimuli. WRKY transcription factors (TFs) play essential roles in regulating leaf senescence; however, only a few studies on the analysis and identification of the WRKY TF family in Medicago Sativa have been reported. In this study, we identified 198 WRKY family members from the alfalfa (M. sativa L.) cultivar ’XinjiangDaye’ using phylogenetic analysis and categorized them into three subfamilies, Groups I, II, and III, based on their structural characteristics. Group II members were further divided into five subclasses. In addition, several hormone- and stress-related cis-acting elements were identified in the promoter regions of MsWRKYs. Furthermore, 14 aging-related MsWRKYs genes from a previous transcriptome in our laboratory were selected for RT-qPCR validation of their expression patterns, and subsequently cloned for overexpression examination. Finally, MsWRKY5, MsWRKY66, MsWRKY92, and MsWRKY141 were confirmed to cause leaf yellowing in Nicotiana benthaminana using a transient expression system. Our findings lay a groundwork for further studies on the mechanism of M. sativa leaf aging and for the creation of new germplasm resources. Full article