Search Results (367)

The depletion of water resources caused by climate change and human activities is a pressing global issue. Lake Ereen is one of the ten natural landmarks of the Gobi-Altai of western Mongolia is included in the list of “important areas for birds” recognized by the international organization Birdlife. However, the construction of the Taishir Hydroelectric Power Station, aimed at supplying electricity to the western provinces of Mongolia, had a detrimental effect on the flow of the Zavkhan River, resulting in a drying-up and pollution of Lake Ereen, which relies on the river as its water source. This study assesses the pollution levels in Ereen Lake and determines the feasibility of its rehabilitation by redirecting the flow of the Zavkhan River. Field studies included the analysis of water quality, sediment contamination, and the composition of flora. The results show that the concentrations of ammonium, chlorine, fluorine, and sulfate in the lake water exceed the permissible levels set by the Mongolian standard. Analyses of elements from sediments revealed elevated levels of arsenic, chromium, and copper, exceeding international sediment quality guidelines and posing risks to biological organisms. Furthermore, several species of diatoms indicative of polluted water were discovered. Lake Ereen is currently in a eutrophic state and, based on a water quality index (WQI) of 49.4, also in a “polluted” state. Mass balance calculations and box model analysis determined the period of pollutant replacement for two restoration options: drying-up and complete removal of contaminated sediments and plants vs. dilution-flushing without direct interventions in the lake. We recommend the latter being the most efficient, eco-friendly, and cost-effective approach to rehabilitate Lake Ereen. Full article

Lake Chinchaycocha, Peru’s second-largest high-altitude lake and a Ramsar-designated wetland of international importance, is increasingly threatened by anthropogenic pollution and hydroclimatic shifts. This study integrates Sentinel-2 multispectral imagery with in situ water quality data from Peru’s National Water Observatory to assess spatiotemporal dynamics in 31 physicochemical parameters between 2018 and 2024. We evaluated 40 empirical algorithms developed globally for Sentinel-2 and tested their transferability to this ultraoligotrophic Andean system. The results revealed limited predictive accuracy, underscoring the need for localized calibration. Subsequently, we developed and validated site-specific models for ammoniacal nitrogen, electrical conductivity, major ions, and trace metals, achieving high predictive performance during the rainy season (R² up to 0.95). Notably, the study identifies consistent seasonal correlations—such as between total copper and ammoniacal nitrogen—and strong spectral responses in Band 1, linked to runoff dynamics. These findings highlight the potential of combining public monitoring data with remote sensing to enable scalable, cost-effective assessment of water quality in optically complex, high-Andean lakes. The study provides a replicable framework for integrating national datasets into operational monitoring and environmental policy. Full article

In a large deep lake, the generation of internal Kelvin waves and internal Poincaré waves due to wind stress on the lake surface is a significant phenomenon. These internal waves play a crucial role in material transport within the lake and have profound effects on its ecosystem and environment. Our study, which investigated the modes of internal waves in Lake Biwa using the vertical temperature distribution from field observations, has yielded important findings. We have demonstrated the applicability of the frequency equation solutions, considering the Coriolis force. The period of the internal Poincaré waves, as observed in the field, was found to match the solutions of the frequency equation. For example, observational data collected in late October revealed excellent agreement with the theoretical solutions derived from the frequency equation, showing periods of 14.7 h, 11.8 h, 8.2 h, and 6.3 h compared to the theoretical values of 14.4 h, 11.7 h, 8.5 h, and 6.1 h, respectively. However, the periods of the internal Kelvin waves in the field observation results were longer than those of the theoretical solutions. The Modified Mathew function uses a series expansion around $q_i=0$, making it difficult to estimate the periods of internal Kelvin waves under conditions where $\left|q_i\right|>1.0$. Furthermore, in lakes with an elliptical shape, such as Lake Biwa, the elliptical cylinder showed better reproducibility than the circular cylinder. These findings have significant implications for the rapid estimation of internal wave periods using the frequency equation. Full article

Jacking-pipe construction has the advantages of high mechanization, low environmental impact and fast construction speed. It is widely used in the project of underground pipeline under river. However, jacking-pipe grouting under shallow burial conditions is prone to cause surface bubbling problems. Based on the jacking-pipe project of Meichong Lake in Changfeng County, Hefei, this paper discussed the mechanism of grouting surface leakage, and defined the relationship between the critical pressure of jacking-pipe grouting and the ultimate pressure of shear damage of mud jacket. Mechanical model of surface leakage from shallow buried jacking-pipe grouting was established. A general mathematical expression for the grouting critical pressure was derived and a sensitivity analysis was performed. A numerical model was established based on the background engineering, and multiple sets of grouting pressure conditions for simulation and analysis were set up. The results showed that the cohesive force $c$, the angle of internal friction $\phi$, and the overburden thickness $h_s$ were all approximately linearly and positively correlated with the critical pressure of grouting. When the grouting pressure was less than 197.54 kPa the surface settlement increased. When this value was exceeded the surface displacement changed from settlement to uplift and the risk of slurry bubbling increased significantly. The theoretical calculation matched the value of grouting critical pressure from numerical simulation. The actual grouting pressure in the project was lower than the theoretical grouting critical pressure value and no slurry bubbling occurred during construction, which had verified the reliability of the theoretical model. This study can provide theoretical basis and investigation ideas for the setting of reasonable grouting pressure in similar projects. Full article

Ice wedges, which are ubiquitous in permafrost areas, play a significant role in the evolution of permafrost landscapes, influencing the topography and hydrology of these regions. In this paper, we combine a detailed multi-generational, interdisciplinary, and international literature review along with our own field experiences to explore the development of low-centered ice-wedge polygons and their orthogonal networks. Low-centered polygons, a type of ice-wedge polygonal ground characterized by elevated rims and lowered wet central basins, are critical indicators of permafrost conditions. The formation of these features has been subject to numerous inconsistencies and debates since their initial description in the 1800s. The development of elevated rims is attributed to different processes, such as soil bulging due to ice-wedge growth, differential frost heave, and the accumulation of vegetation and peat. The transition of low-centered polygons to flat-centered, driven by processes like peat accumulation, aggradational ice formation, and frost heave in polygon centers, has been generally overlooked. Low-centered polygons occur in deltas, on floodplains, and in drained-lake basins. There, they are often arranged in orthogonal networks that comprise a complex system. The prevailing explanation of their formation does not match with several field studies that practically remain unnoticed or ignored. By analyzing controversial subjects, such as the degradational or aggradational nature of low-centered polygons and the formation of orthogonal ice-wedge networks, this paper aims to clarify misconceptions and present a cohesive overview of lowland terrain ice-wedge dynamics. The findings emphasize the critical role of ice wedges in shaping Arctic permafrost landscapes and their vulnerability to ongoing climatic and landscape changes. Full article

Lake Winona, a 129 ha eutrophic urban lake comprised of two interconnected basins, exceeds state water quality standards for total phosphorus. Historical lake nutrient data and traditional watershed modeling for the lake’s two basins highlighted multiple major pathways (e.g., municipal stormwater discharges, watershed runoff, internal loading, and wetland discharges) for total phosphorus (P) loading, with >900 kg P/year estimated entering the water columns of each basin. Updated data sources and newer watershed modeling resulted in significantly different (both higher and lower) P loading estimates for the various P sources, especially watershed runoff and internal loading. Overall, basin-specific loading estimates using the updated model were significantly lower (28–40%) than previous estimates: 680 and 546 kg P/year mobilized in the western and eastern basins, respectively. To achieve state water quality standards (<60 ppm P for the western basin, <40 ppm for the eastern basin), watershed and internal P loading each would need to be reduced by approximately 120 kg P/year across the two basins. Reductions could be achieved by a combination of alum treatments to reduce internal loading, removal of common carp (Cyprinus carpio) to prevent interference with alum treatments and nutrient releases via excretion and defecation, and six engineered structures to intercept P before it enters the lake. The different P reduction projects would cost USD 119 to 7920/kg P removed, totaling USD 5.2 million, or USD 40,310/hectare of lake surface area. Full article

Lake eutrophication, often driving harmful algal blooms (HABs) and ecosystem degradation, involves complex biogeochemical shifts within sediments. Changes in the sedimentary dissolved organic matter (DOM) composition during transitions from macrophyte to algal dominance are thought to critically regulate internal phosphorus (P) loading, yet the underlying mechanisms, especially in vulnerable plateau lakes like Qilu Lake, require further elucidation. This study investigated the coupled cycling of carbon (C) and P in response to historical ecosystem succession and anthropogenic activities using a 0–24 cm sediment core from Qilu Lake. We analyzed the total organic carbon (TOC), total phosphorus (TP), sequential P fractions, and DOM fluorescence characteristics (EEM-PARAFAC), integrated with chronological series data. The results revealed an asynchronous vertical distribution of TOC and TP, reflecting the shift from a submerged macrophyte-dominated, oligotrophic state (pre-1980s; high TOC, low TP, stable Ca-P dominance) to an algae-dominated, eutrophic state. The eutrophication period (~1980s–2010s) showed high TP accumulation (Ca-P and NaOH85 °C-P enrichment), despite a relatively low TOC (due to rapid mineralization), while recent surface sediments (post-2010s) exhibited a high TOC, but a lower TP following input controls. Concurrently, the DOM composition shifted from microbial humic-like dominance (C1) in deeper sediments to protein-like dominance (C3) near the surface. This study demonstrates that the ecosystem shift significantly regulates P speciation and mobility by altering sedimentary DOM abundance and chemical characteristics (e.g., protein-like DOM correlating negatively with Ca-P), reinforcing a positive feedback mechanism that sustains internal P loading and potentially exacerbates HABs. DOM molecular characteristics emerged as a key factor controlling the internal P cycle in Qilu Lake, providing critical insights for managing eutrophication in plateau lakes. Full article

Conventional diagnostic methods (CDMs) for lower respiratory infections (LRIs) have limitations in detecting causative pathogens. This study evaluates the utility of shotgun metagenomic sequencing (SMS) as a complementary diagnostic tool using bronchoalveolar lavage (BAL) fluid. Sixteen BAL fluid samples from pneumonia patients with positive CDM results—including bacterial/fungal cultures; PCR for Mycobacterium tuberculosis or cytomegalovirus; and the BioFire^® FilmArray^® Pneumonia Panel (BioFire Diagnostics LLC, Salt Lake City, UT, USA)—underwent 10 Gb SMS on the Illumina NovaSeq 6000 platform (Illumina, San Diego, CA, USA). Reads were aligned to the NCBI RefSeq database; with fungal identification further supported by internal transcribed spacer (ITS) analysis. Antibiotic resistance genes (ARGs) were annotated using the Comprehensive Antibiotic Resistance Database. Microbial reads accounted for 0.00002–0.04971% per sample. SMS detected corresponding bacteria in 63% of cases, increasing to 69% when subdominant taxa were included. Fungal reads were low; however, Candida species were identified in four samples via ITS. No viral reads were detected. ARGs meeting perfect match criteria were found in two cases. This is the first real-world study comparing SMS with CDMs, including semiquantitative PCR, in BAL fluid for LRI. SMS shows promise as a supplementary diagnostic method, with further research needed to optimize its performance and cost-effectiveness. Full article

Phosphorus plays a key role in water eutrophication. The release of endogenous phosphorus from sediments maintains eutrophication in Dianchi Lake. This study aimed to summarize and analyze the research trends, occurrence characteristics, adsorption and release characteristics, influencing factors, and prospects of internal phosphorus pollution control in Dianchi Lake based on a literature search and data integration. The results revealed that sediment phosphorus in Dianchi Lake has been widely studied. From previous studies, the total phosphorus (TP) content and various forms of phosphorus in the Dianchi Lake sediments have decreased since 2010. The TP contents measured in Dianchi Lake in previous research were considerably different owing to the influence of sampling depth and dredging projects. The TP content in the sediments of Dianchi Lake was higher but its release risk was lower than those in other lakes in China. The risk of release was higher in Caohai and North Waihai than that in Central Waihai and South Waihai. In addition to environmental factors at the sediment–water interface, sediment characteristics, and ecosystem degradation are important factors that affect phosphorus migration and transformation. Over the past 30 years, sediment dredging has been the primary measure for reducing the internal pollution load in Dianchi Lake. However, more accurate sediment dredging and systematic vegetation–algae–sediment co-management measures are needed for water ecosystem restoration in Dianchi Lake. This study provides new insights into the study of internal phosphorus pollution. Full article

Establishing a resilient bird habitat network (BHN) and identifying ecological strategic areas for protection are critical for conserving biodiversity and maintaining ecosystem stability in wetland cities. However, existing ecological network studies often overlook dynamic resilience that incorporates explicit species information, and their scenario-based assessments lack systematic evaluation metrics. This study, using Wuhan—an international wetland city—as a case study, integrates Maximum Entropy (MaxEnt), remote sensing ecological index (RSEI) and circuit theory to identify a high-quality BHN. A comprehensive resilience assessment and optimization framework is developed, grounded in structure–function–quality indicators and informed by resilience and complex network theory. Key findings include: (1) The network comprises 147 habitat patches and 284 ecological corridors, demonstrating marked spatial heterogeneity. Habitats are predominantly located in the southern and southwestern regions of Wuhan, concentrated in contiguous green spaces. In contrast, habitats in the urban core are fragmented and small. Corridors are mainly distributed in the southwestern and central metropolitan areas. (2) Under deliberate attack, considering resilience centrality, the network’s resilience declined more slowly than in scenarios based on traditional centrality measures. Across combined node and corridor attack simulations, two critical resilience thresholds were identified at 30% and 50%. (3) The ecological strategic space is primarily composed of key habitat patches (58, 108, 117, and 27) and corridors (119–128, 9–12, 122–147, 128–138, 76–85, and 20–29), mainly located in the southern region of Wuhan, particularly around Liangzi Lake and Anshan National Wetland Park. This study advances a dynamic framework for BHN resilience assessment, planning, and restoration, providing scientific guidance for enhancing ecological security and biodiversity conservation in urban wetland environments. Full article

This paper provides a novel approach to airport sustainability with a comparative analysis of frameworks presented by Airports Council International (ACI) and the World Economic Forum (WEF), a case study on environmental social governance (ESG) reporting for large US airports, a historical perspective and discussion regarding legal considerations, and sustainability metrics. Airport sustainability reporting provides numerous advantages, including enhanced transparency and accountability, and it also supports risk management, regulatory compliance, operational efficiency, risk management, community engagement, and investor relations. There are 30 large hub airports in the US, and each one of these publishes information on sustainability, which may consist of a sustainability report, reports on sustainability related topics, or website information. Eight of these large US airports publish an ESG report. ESG reports are of increasing interest due to their use internationally and due to the role of ESG reports in investment decisions. This paper presents an analysis of the information contained in ESG reports published by US airports and compares the frame of reference used by airports that utilize UN Sustainable Development Goals (SDGs) in their reporting. Case studies of ESG reports for Salt Lake City and Dallas Fort Worth Airports are presented to illustrate ESG reports, and the use of the SDG identified in these reports is compared the framework identified by Airports Council International (ACI) and the World Economic Forum (WEF). The discussion of airport ESG reporting provides a thorough and contextual review of the topic and examines how this framework may evolve to address the increasing interest in ESG reporting for US airports. The information provided may be used by airports to improve their sustainability reporting. Full article

In recent decades, wetlands have played a significant role in the global carbon cycle, making it essential to quantify their greenhouse gas (GHG) emissions at regional, national, and international levels. This study examines three dammed water bodies (Dalpatsagar, Gangamunda, and Dudhawa lake–wetland complexes) in Chhattisgarh, India, to estimate their GHG emission potentials. Methane (CH₄) showed the highest emission rate, peaking at 167.24 mg m⁻² h⁻¹ at 29.4 °C in Dalpatsagar during the standard meteorological week of 21–27 May. As temperatures rose from 17 °C to 18 °C, CH₄ emissions ranged from 125–130 mg m⁻² h⁻¹. Despite slightly higher temperatures, Dudhawa showed lower emissions, likely due to its larger surface area and shallower depth. Carbon dioxide (CO₂) emissions from Gangamunda increased sharply from 124.25 to 144.84 mg m⁻² h⁻¹ as temperatures rose from 12 °C to 25 °C, while Dudhawa recorded a peak CO₂ emission of 113.72 mg m⁻² h⁻¹ in April. Nitrous oxide (N₂O) emissions peaked at 29.11 mg m⁻² h⁻¹ during the 8th meteorological week, with an average of approximately 10.0 mg m⁻² h⁻¹. These findings indicate that climate-induced changes in water quality may increase health risks. This study offers critical insights to inform policies and conservation strategies aimed at mitigating emissions and enhancing the carbon sequestration potential of wetlands. Full article

Using ArcGIS software to conduct spatial autocorrelation analysis, it was found that the price distribution of rural homestays in Suzhou is not random but shows apparent spatial clustering. Among the 81 rural homestays were 9 high-high clusters, 25 low-low clusters, 1 high-low outlier, and 5 low-high outliers. The hedonic price model is an economic model that breaks down goods or services into multiple attributes to estimate their prices. Based on this model, this paper further investigates the differentiated impacts and interactions between internal accommodation characteristics and external environmental attributes in the pricing mechanism of rural homestays in Suzhou. The results show that (1) the high-priced rural homestays in Suzhou are concentrated in the lake island resort with good natural environment and perfect infrastructure; (2) the location, facility quality, and network score of rural homestays have a positive impact on housing prices; (3) the parking lot of rural homestays hurts housing prices; (4) the quality of rural residential buildings and facilities has the most significant positive impact on housing prices. By comparing the hedonic price model of rural homestay and the heterogeneous preferences of consumers, this study provides rural homestay operators with effective room pricing strategies and marketing implications, provides policymakers with reference factors to promote the development of rural homestay industry, and has specific guiding significance for the sustainable development of the homestay industry. Full article

The internal nutrient load of natural and artificial lakes is a worldwide problem. To minimize its potential risks, the dredging of the highly eutrophic shallow first reservoir of Kis-Balaton (Lake Hídvégi) is planned in the near future. Our study aimed to evaluate the potential effects of dredging and desiccation on water and sediment quality. Experimental dredging was carried out in the northernmost part of Lake Hídvégi (2023). The physical and chemical characteristics of the sediment and nutrient loss during desiccation were examined in a column experiment. The relationships between the properties of leachate and sediment were identified using principal component analysis (SPSS). Spatial variations in sediment particle size distribution, nutrient content, and other chemical parameters (e.g., organic matter) suggest that deeper core sampling than the depth of preliminary dredging is necessary for a more comprehensive assessment of potential impacts. We found that spatiotemporally varying the dominance of chemical and biological processes affects the amount of and changes in phosphorus fractions under lake-/sediment-specific conditions. The readily available calcium- and iron-bound phosphorus, texture, and organic matter content of the sediment play an important role in phosphorus fixation/release. Based on our results, dredging and desiccation are feasible within the intended operating parameters. The sediment’s composition does not preclude potential agricultural disposal. Full article

Lake Maggiore is a deep subalpine lake that has been well studied since the last century thanks to a monitoring program funded by the International Commission for the Protection of Italian–Swiss Waters. The monitoring program comprises both abiotic and biotic parameters, including zooplankton pelagic organisms. In this study, we present a dataset of 15,563 records of population densities and standing stock biomass for zooplankton pelagic taxa recorded over 43 years (1981–2023). The long-term dataset is valuable for tracing changes in trophic conditions experienced by the lake during the last century (eutrophication and its reversal) and the impact of global warming. Zooplankton samples (Crustacea and Rotifera Monogononta) were collected within 0–50 m depth by vertical hauls with an 80 µm light plankton sampler. The sampling frequency was monthly, with the exception of the 2009–2012 period, which employed seasonal frequency. The estimation of zooplankton taxon abundance and of its standing stock biomass is crucial in order to quantify the flux of matter, energy, and pollutants up to the upper trophic levels of the food web. The dataset provided is also suitable for food web analysis because the zooplankton taxa have been classified according to their ecological roles (microphagous organisms; primary and secondary consumers). Full article