Search Results (244)

The aim of this study is to determine the characteristics of the chemical and mineral composition of sediment layers in a technogenic settling pond. This pond is located on urban land in Berezniki (Perm Krai, Russia), outside the territory of operating industrial facilities, and contains alkaline saline industrial wastes. The origin of this waste was related to sludge from the Solvay soda production process, which had been deposited in this pond over a long period of time. However, along with the soda waste, the pond also received wastewater from other industries. As a result, the accumulated sediment is characterized by variation in morphological properties both in depth and laterally. Five undisturbed columns were taken to study the composition of the accumulated sediment. The obtained samples were analyzed by X-ray diffraction (XRD), synchronous thermal analysis (STA), and X-ray fluorescence (XRF) analysis. The results showed that the mineral composition of bottom sediments in each layer of all studied columns is characterized by the predominance of calcite precipitated from wastewater. Along with calcite, due to the presence of magnesium and sodium in the solution, other carbonates precipitated—dolomite and soda (natron), as well as complex transitional carbonate phases (northupite and trona). Together with carbonate minerals, the chloride salts halite and sylvin, sulfate minerals gypsum and bassanite, and pyrite and nugget sulfur were established. The group of terrigenous mineral components is represented by quartz, feldspars, and aluminosilicates. The chemical composition of sediments in the upper part of the section generally corresponds to the mineral composition. In the lower sediment layers, the role of amorphous phase and non-mineral compounds increased, which was determined by the results of thermal analysis. The content of heavy metals and metalloids also increases in the middle and lower sediment layers. When categorized according to the Igeo value, an excessive degree of contamination (class 6) was observed in all investigated columns for copper content (Igeo 5.2–6.1). Chromium content corresponds to class 5 (Igeo 4.1–4.6), antimony to class 4 (Igeo 3.0–4.0), and lead, arsenic, and vanadium to classes 2 and 3 (moderately polluted and highly polluted). The data obtained on variations in the mineral and chemical composition of sediments represent the initial information for the selection of methods of accumulated waste management. Full article

Mangrove forests, vital coastal ecosystems that provide critical biodiversity habitats and carbon sequestration services, face increasing heavy metal pollution that threatens their ecological functions through bioaccumulation and toxicity to marine organisms. However, existing studies lack dynamic insights into temporal and spatial variations of heavy metals in mangrove sediments. This study systematically analyzed two mangrove reserves in Hainan Island, China (Hainan Dongzhaigang National Nature Reserve [DZG] and Hainan Qinglan Provincial Nature Reserve [QL]), by collecting sediment samples in 2014 and 2022, analyzing metals (Cr, Cu, Zn, As, Cd, and Pb) via ICP-MS, and applying the geo-accumulation index, potential ecological risk index, Markov transition matrix, and statistical analyses. Results showed that DZG exhibited rising Cu and Zn levels but declining Cr, As, Cd, and Pb, with Cd showing the most significant decrease (66.83%). In contrast, QL saw only a 42.7% reduction in Cd, while other heavy metals increased. Spatial heterogeneity linked higher concentrations to anthropogenic hotspots, DZG’s southeast (industrial/aquaculture inputs), and QL’s northwest (urban/industrial discharges). Although ecological risks were generally low, Cd in QL reached a moderate risk level (E_Cd = 46.44, 40 ≤ E_i < 80). The large-scale pond-to-mangrove conversion significantly increased vegetation cover, which enhanced sedimentation rates and exerted a “dilution effect” on sediment heavy metals. These findings underscore anthropogenic activities as the dominant driver of heavy metal contamination. We recommend (1) stringent wastewater control near QL, (2) enhanced shipping regulation, and (3) the establishment of mangrove buffers in heavy metal accumulation zones to improve ecological status. Full article

With the rapid development of urbanization in rural areas of China, various environmental issues have become increasingly prominent, particularly the water pollution problems in small rural watersheds, which have garnered considerable attention. Comprehensive management of small watersheds requires an initial analysis of the sources and characteristics of water pollution. This study focuses on small rural watersheds in the Pearl River Delta. Based on the characteristics of the watersheds, 35 water quality monitoring stations were set up to collect water quality data. Cluster analysis was used to study the spatial distribution characteristics of water quality indicators at each monitoring point. Further, factor analysis methods (PCA/FA) and Absolute Principal Component Scores-Multiple Linear Regression (APCS-MLR) models were employed to identify water quality influencing factors and quantify pollution source contributions. Finally, the comprehensive index method for eutrophication assessment was used to evaluate and analyze the potential eutrophication pollution risk in the watersheds. The results indicate significant pollution in the water quality of rural small watersheds in the study area, with varying degrees of pollution over time and space. During the wet season, water quality is mainly influenced by agricultural nutrients, followed by biochemical factors. In the normal and dry seasons, water quality is primarily affected by oxygen-consuming organic pollutants, followed by eutrophication factors. The comprehensive eutrophication evaluation shows that the overall water quality in the watershed is better during the wet season, with a lower risk of eutrophication; during the normal season, the overall water quality is poorer, with the highest eutrophication risk in the midstream; during the dry season, the upstream and midstream water quality is better, while the downstream water quality is poorer. In contrast, the pond water exhibits a higher risk of eutrophication during the wet season compared to the normal and dry seasons. This is mainly due to the peak of fish farming during the wet season, which results in a heavier load on the water body. This study provides effective data support for the water environment management of rapidly developing rural small watersheds. Full article

Continuous use of agricultural chemicals and fertilizers, sporadic sewer overflow events, and an increase in urbanization have led to significant nutrient/pollutant loadings into the semi-arid Arroyo Colorado River basin, which is located in South Texas, U.S. Priority nutrients that require reduction include phosphorus and nitrogen and to mitigate issues of low dissolved oxygen, in some of its river segments. Consequently, the river’s potential to support aquatic life has been significantly reduced, thus highlighting the need for restoration. To achieve this restoration, a watershed protection plan was developed, comprising several preventive mitigation measures, including installing green infrastructure (GI) practices. However, for effective reduction of excessive nutrient loadings, there is a need to study the effects of different combinations of GI practices under current and future land use scenarios to guide decisions in implementing the cost-effective infrastructure while considering factors such as the existing drainage system, topography, land use, and streamflow. Therefore, this study coupled the Soil and Water Assessment Tool (SWAT) model with the System for Urban Stormwater Treatment and Analysis Integration (SUSTAIN) model to determine the effects of different combinations of GI practices on the reduction of nitrogen and phosphorus under changing land use conditions in three selected Arroyo Colorado subwatersheds. Two land use maps from the U.S. Geological Survey (USGS) Forecasting Scenarios of land use (FORE-SCE) model for 2050, namely, A1B and B1, were implemented in the coupled SWAT-SUSTAIN model in this study, where the urban area is projected to increase by 6% and 4%, respectively, with respect to the 2018 land use scenario. As expected, runoff, phosphorus, and nitrogen slightly increased with imperviousness. The modeling results showed that implementing either vegetated swales or wet ponds reduces flow and nutrients to meet the Total Maximum Daily Loads (TMDLs) targets, which cost about USD 1.5 million under current land use (2018). Under the 2050 future projected land use changes (A1B scenario), the cost-effective GI practice was implemented in vegetated swales at USD 1.5 million. In contrast, bioretention cells occupied the least land area to achieve the TMDL targets at USD 2 million. Under the B1 scenario of 2050 projected land use, porous pavements were most cost effective at USD 1.5 million to meet the TMDL requirements. This research emphasizes the need for collaboration between stakeholders at the watershed and farm levels to achieve TMDL targets. This study informs decision-makers, city planners, watershed managers, and other stakeholders involved in restoration efforts in the Arroyo Colorado basin. Full article

Facing the problems in determining the distribution range of karst areas and detecting karst caves under the restrictions of complex building and human exploration environments on the urban surface, taking the karst detection of Tianmeixin village and its southern pond in the north extension section of Guanghua Intercity Railway Line 18 as the application research object, based on the formation mechanism of karst and the existing geophysical detection methods, the electrical resistivity tomography method with a large detection range and the cross-well seismic computed tomography method with a high detection accuracy are used to carry out application research on concealed karst cave detection, which are two geophysical technical detection methods with strong adaptability and anti-interference ability. The results show that the optimized combination of geophysical exploration techniques can effectively overcome the limitations of the environment, draw the main karst development areas, reveal the interface between rock and soil, and accurately characterize the size and shape of karst caves. The electrical resistivity tomography method was used to find a number of potential water conduction channels in the middle zone between Tianmeixin village and the south river. The overall distribution characteristics of karst in Tianmeixin village were summarized, and the key detection areas were drawn. This conclusion was verified by several sets of cross-well seismic computed tomography profiles, which provided a reference for the layout of the subsequent cross-well seismic computed tomography imaging method and greatly reduced the workload of drilling, shortened the construction period, saved on detection costs, and reduced the impact on the production and life of residents. Full article

Extreme weather events and rising temperatures pose significant risks, not only in urban areas but also in metropolitan forests, that affect the well-being of the people who visit them. City forests are considered one of the best bets for mitigating high temperatures within civic areas. Such areas modulate microclimates in contemporary cities, offering environmental, social, and economic advantages. Therefore, comprehending the intricate relationships between municipal forests and the climatic changes of various destinations is crucial for attaining healthier and more sustainable city environments for people. In this research, the thermal comfort index (Modified Temperature–Humidity Index (MTHI)) has been analysed using Landsat images of six urban forests in London during July 2022, when the area first experienced record-breaking temperatures of over 40 °C. Our results show a significant growth in the MTHI that goes from 2.5 (slightly hot) under normal conditions to 3.4 (hot) during the heat wave period. This situation intensifies the environmental discomfort for visitors and highlights the necessity to enhance their adaptability to future temperature increases. In turn, it was found that the places most affected by heat waves are those that have grass cover or that have small associated buildings. Conversely, forested regions or those with lakes and/or ponds exhibit lower temperatures, which results in enhanced resilience. These findings are noteworthy in their concentration on one of the UK’s most severe heat waves and illustrate the efficacy of integrating spectral measurements with statistical analyses to formulate customized regional initiatives. Therefore, the results reported will allow the implementation of new planning and adaptation policies such as incorporating thermal comfort into planning processes, improving green and blue amenities, increasing tree densities that are resilient to rising temperatures, and increasing environmental comfort conditions in metropolitan forests. Finally, the applicability of this approach in similar urban contexts is highlighted. Full article

In early 2018, Cape Town, South Africa, experienced severe water shortages during the worst drought in nearly a century (2015–2017), underscoring the need to diversify water resources, including groundwater. This study evaluated infiltration rates and hydraulic properties of three representative stormwater ponds in the Zeekoe Catchment, Cape Town, to assess their feasibility as recharge basins for transferring detained stormwater runoff into the underlying aquifer. Field infiltration data were analysed to estimate hydraulic properties, while laboratory permeability tests and material classification on 36 soil samples provided inputs for numerical modelling using HYDRUS 2-D software. Simulations estimated recharge rates and indicated wetting front movement from pond surfaces to the water table (~5.5 m depth) ranged between 15 and 140 h. The results revealed field hydraulic conductivity values of 0.3 to 19.9 cm/h, with laboratory estimates up to 103% higher due to controlled conditions. Simulated infiltration rates were 67–182% higher than field measurements, attributed to idealised assumptions. Despite these variations, ponds in the central catchment exhibited the highest infiltration rates, indicating suitability for artificial recharge. Explicit recognition of pond-specific infiltration variability significantly contributes to informed urban water security planning, enabling targeted interventions to optimise groundwater recharge initiatives. Full article

In the face of acute water scarcity and sanitation challenges emblematic of arid and semi-arid regions (ASARs), this study investigated the transformative upgrade of the Aqaba Conventional Activated Sludge Wastewater Treatment Plant (CAS-AWWTP) in Jordan. The project, expanding capacity to 40,000 m³/day, integrated sustainable features including renewable energy and repurposed natural treatment ponds functioning as artificial wetlands. The plant’s treatment performance, byproduct valorization, and alignment with sustainable development goals (SDGs) were assessed. Comparative analysis revealed that the upgraded CAS-AWWTP consistently outperforms the previous natural and extended activated sludge systems. CAS-AWWTP average removal efficiencies of BOD₅, COD, TSS, and T-N were 99.1%, 96.6%, 98.7%, and 95.1%, respectively, achieving stringent reuse standards and supplying approximately 30% of Aqaba Governorate’s annual water budget, thus conserving freshwater for domestic use. Furthermore, the plant achieved 44% electrical self-sufficiency through renewable energy integration, significantly reducing its carbon footprint. The creation of artificial wetlands transformed the site into a vital ecological habitat, attracting over 270 bird species and becoming a popular destination for birdwatching enthusiasts, drawing over 10,000 visitors annually. This transformation underscores the plant’s dual role in wastewater treatment and environmental conservation. The AWWTP upgrade exemplifies a holistic approach to sustainable development, impacting multiple SDGs. Beyond improving sanitation (SDG 6), it enhances water reuse for agriculture and industry (SDG 6.4, 9.4), promotes renewable energy (SDG 7), stimulates economic growth (SDG 8), strengthens urban sustainability (SDG 11), fosters resource efficiency (SDG 12), and supports biodiversity (SDG 14/15). The project’s success, facilitated by multi-stakeholder partnerships (SDG 17), provides a replicable model for water-scarce regions seeking sustainable wastewater management solutions. Full article

Analyzing the soil carbon, nitrogen, and phosphorus content, along with their stoichiometric ratios across different urban-rural gradients, can offer essential insights into enhancing soil quality and the sustainable management of urban green space ecosystems. This study focused on Nanchang, China, examining two typical urban forest types (Pinus massoniana forests and Camphora officinarum forests), two typical urban wetlands types (river wetlands and pond wetlands), as well as urban natural and artificial grasslands. It analyzed the distribution characteristics of organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and their stoichiometric ratios along the “urban-suburban-rural” gradients in surface (0–20 cm) and deep (20–40 cm) soil. The results indicated that in the deep soil of Pinus massoniana forests, rural areas exhibited significantly higher SOC content compared to suburban areas. In the surface soil of Camphora officinarum forests, the TN content and N:P were significantly greater in urban areas compared to rural areas (p < 0.05). Both soil layers in river wetlands showed significantly higher soil TN levels in urban areas compared to rural areas. Additionally, in the deep soil of pond wetlands, urban areas showed significantly greater TN content, C:P, and N:P, compared to rural areas (p < 0.05). For natural grasslands, soil C:N was significantly more in suburban and rural areas than in urban areas for both soil layers. In artificial grasslands, the SOC content in deep soil was significantly greater in rural areas compared to urban areas (p < 0.05). In the deep soil of suburban areas, soil TP content in Camphora officinarum forests was highly significantly greater than that in Pinus massoniana forests (p < 0.01). The SOC, TN content, and C:P were considerably higher in pond wetlands compared to river wetlands (p < 0.05). The SOC content of natural grasslands was significantly higher compared to artificial grasslands (p < 0.05). Nitrate nitrogen was highly significantly and positively correlated with soil N:P in the deep soil of Pinus massoniana forests (p < 0.01), and soil pH was highly significantly and negatively correlated with soil N:P in the surface soil of pond wetlands (p < 0.01). The urbanization process has altered the SOC, TN, and TP nutrient status to some extent, exacerbating the imbalance of nutrient elements in green space soils along the “urban-suburban-rural” gradients. Full article

The inadequate collection and treatment of urban wastewater continue to pollute built environments, threaten public health, and contribute to epidemic outbreaks in many densely populated, underdeveloped regions. This study investigates whether algae-based wastewater treatment offers an optimal and efficient solution for drought-prone and underdeveloped cities. Given recent global challenges, such as the COVID-19 pandemic, nature-based wastewater treatment methods—particularly algae-based systems—have regained attention due to their feasibility, cost-effectiveness, and sustainability. Algae-based wastewater treatment presents an innovative approach to sustainable urban development, offering environmental, resource-efficient, energy-saving, and biodiversity benefits while supporting circular economy principles. This study evaluates recent advancements in wastewater treatment technologies and applies a case study methodology to Zahedan City, analyzing sewage canal networks, wastewater composition, and treatment feasibility. Three algae-based techniques were assessed, with waste stabilization ponds (WSPs) identified as the most suitable solution based on technical, economic, and environmental indicators. Key factors such as climate conditions, land-use policies, and cost-effectiveness were incorporated into the comparative analysis, enhancing the scientific rigor of this study compared to prior research. The findings provide actionable insights for urban planners, engineers, and policymakers to address simultaneous challenges in wastewater management, public health, and water scarcity. Full article

Urban parks are vital for providing cultural ecosystem services (CESs) to residents. However, few studies have explored sex-based differences in CES demand, particularly within mountainous urban parks. This study aimed to elucidate sex-based differences in the perceptions and preferences for CESs and landscape elements and explore their relationship in mountainous urban parks. Using value-labeled photographs from an equal number of male and female volunteer visits to Eling Park in Chongqing, China, the SolVES model was employed to investigate the relationship between sex-specific perceptions of CESs and landscape elements. The results showed that males preferred slopes and steps, garden facilities, and recreation facilities, whereas females preferred overlooks that offer multiple CES values, including science and ecological education, and aesthetic and cultural heritage values. Females perceived social relational value at the lotus pond and Kansheng Tower, whereas males perceived inspirational value at Kansheng Tower, the entrance, and the cliffside path. Males linked inspirational value to fort-like ridges and cliffs. Females associated inspirational value with slopes and steps. Based on the findings, the study recommends enhancing CESs specific to mountainous landscapes and incorporating sex-sensitive design elements. Ultimately, these efforts aim to position parks as key components of urban sustainable development, promoting overall resident well-being. Full article

Urban areas are expanding rapidly and experience diverse and complex contamination of their surface waters. Addressing these issues requires different tools to describe exposures and predict toxicological risk to exposed biota. We surveyed 21 stormwater management ponds in Brampton, Ontario using three types of sampling methods deployed concurrently: time-integrated water sampling, biofilms cultured on artificial substrates, and organic-diffusive gradients in thin films (o-DGT) passive samplers. Our objective was to compare pesticide occurrences and concentrations to inform monitoring in stormwater ponds, which reflect pesticide pollution in urban areas. We detected 82 pesticides across the three sampling matrices, with most detections occurring in o-DGT samplers. The in situ accumulation of pesticides in o-DGTs during deployment and the high analytical sensitivity achieved establishes o-DGTs as excellent tools for capturing the mixtures of pesticides present. Water and biofilm sampling demonstrated that pesticide concentrations available for uptake are relatively low, with most below toxicological thresholds. Yet our results demonstrate that urban areas are subject to a wide range of pesticides, including herbicides, insecticides, and fungicides, and underscores the urgency of research to quantify the risks of chronic exposure to this chemical mixture. Full article

This study examines historical water management practices as a means of addressing climate change, focusing on the Tyski Stream catchment in Upper Silesia, Poland, a region marked by extensive urbanization and industrial evolution. It investigates the effectiveness of historical hydrotechnical systems, such as bead-like ponds from the 15th to 18th centuries, in enhancing water retention, reducing flood risks, and supporting ecosystem services. In a critical period, over 54 years (1827–1881), the number of reservoirs decreased from 142 to 31 (the area of ponds decreased from 161 to 32 ha). Throughout the entire period, between 1748 and 2017, the surface area of the analyzed reservoirs decreased from 163 ha to 16.8 ha. This was related to progressive industrialization, urban sprawl, and changes in legal frameworks, such as land ownership laws, leading to ecosystem degradation, loss of biodiversity, and altered hydrological processes. The research emphasizes the potential of reviving historical water management systems on natural processes to mitigate the impacts of climate change. By analyzing historical cartographic resources, this study assesses the feasibility of reconstructing lake systems in areas with similar topographic and hydrological features. It also stresses the necessity of community engagement and securing widespread social and political support to ensure public acceptance and the success of renaturation initiatives. The findings indicate that restoring these systems can offer diverse benefits, including improved water management, enhanced biodiversity, and greater urban resilience, while addressing the socio-political complexities of implementing large-scale environmental restoration projects. The aim of this study is to utilize archival materials for engineering solutions to prevent flooding and enhance water retention. Full article

The urban water environment, an integral component of the terrestrial hydrosphere, is closely linked to human activities and serves as a fundamental resource for industrial and agricultural development. Sedimentary organic matter in water bodies contains rich biological, physical, and chemical information, playing a central role in nutrient cycling and serving as a primary reservoir for nutrient accumulation. This study assesses the water quality, chemical indicators, and sediment productivity of four typical urban water bodies (Canal, Pond, Lake, and River) in Shaoxing City, eastern China. The results show that artificial water bodies, particularly canals, have higher dissolved oxygen (DO) compared to natural water bodies. Stationary water bodies, such as lakes and ponds, generally have higher total dissolved solids (TDS) and electrical conductivity (EC) than flowing water bodies like rivers and canals. All four urban water body types slightly exceed China’s Class-V water quality standard for total nitrogen (TN), with canals, lakes, ponds, and rivers averaging 1.29, 1.22, 1.23, and 1.23 times the standard, respectively. Ponds exhibit the highest total dissolved nitrogen (TDN) content, while ammonium (NH₄⁺–N) and nitrate (NO₃⁻–N) levels are relatively consistent across the bodies, except for lower NO₃⁻–N in lakes. Higher organic matter in canals and lakes, indicated by chlorophyll-a (Chl-a) and permanganate index (COD_Mn), suggests greater eutrophication compared to ponds and rivers. Sediment total organic nitrogen (TON) content is relatively uniform across all water bodies, with slightly higher values in lakes and rivers. Total organic carbon (TOC) content is highest in lake sediments, 1.51 times that of canals. Carbon/nitrogen (C/N) ratios vary, with ponds and lakes showing the highest averages. Source quantification using isotopic analysis (δ¹³C and δ¹⁵N values) indicates that phytoplankton is the primary sedimentary organic matter source in rivers and canals, while terrestrial sources are significant in lakes and ponds. Sewage notably contributes to rivers and canals. These findings highlight the need for targeted pollution control strategies, focusing on phytoplankton and sewage as key sedimentary organic matter sources to mitigate eutrophication and enhance water quality in urban environments. Full article

The wetland ecosystem is one of the most important carbon sinks on Earth, the most biodiverse ecological landscape in nature, and one of the most important living environments for human beings. The Weihe River wetland is located in the Guanzhong Plain urban agglomeration, with extreme climate and urban expansion having a great impact on its dynamic changes. Revealing the characteristics of and trends in wetland dynamics in the Weihe River Basin is the key to protecting and maintaining the healthy development of the Weihe River wetlands. This paper analyzed the changing characteristics of land use types and landscape patterns in the wetlands of the Weihe River Basin using wetland land use data from six periods in the Weihe River wetland from 1980 to 2020 and explored the spatial and temporal distribution characteristics and dynamic changes in wetlands in the Weihe River Basin. The results showed the following: (1) Wetlands in the Weihe River Basin, dominated by rivers, saw area fluctuations with an initial decline followed by an increase. Land use changes followed a slow–fast–slow trend. (2) From 1980 to 2020, frequent conversions among wetland types were observed. The primary transformation was the conversion of marshes into lakes (18.05 km²) and reservoirs/ponds (17.98 km²). Approximately 0.06 km² of lakes were transformed into canals/channels. (3) River patches have the largest area, while canals/channels have the smallest. The patch density (PD) and landscape shape index (LSI) of wetlands fluctuate significantly, and the reduction in area leads to a 3.46% decrease in aggregation index (AI). Shannon’s diversity index (SHDI) has decreased by 5.41%. (4) The centroid of marshes experiences significant changes, while river changes are complex. The centroid changes in reservoirs/ponds are located along the southeast–northwest line. Canals/watercourses remain stable. Lakes exhibit the longest migration. This study provides robust scientific support for wetland ecological protection, policy formulation, and social sustainable development by conducting an in-depth analysis of the dynamic change characteristics of wetlands in the Weihe River Basin. Full article