Search Results (876)

Water security in rapidly urbanising river basins is increasingly threatened by untreated city effluents, industrial discharges, and legacy agricultural contamination. The Tula River basin in central Mexico illustrates this issue, absorbing the majority of Mexico City’s effluent while sustaining a heavily exploited aquifer beneath one of the nation’s largest irrigation districts. This study provides an integrated assessment of surface water and groundwater quality throughout the basin, including the Endhó Dam and its associated aquifer. Water quality analysis revealed severe surface water contamination (WQI > 300), driven by untreated sewage and inadequate sanitation infrastructure. Elevated COD, BOD, and nutrient concentrations indicate significant organic loading and eutrophication risk. Near Tula City, arsenic, copper, and zinc were detected at levels posing direct risks to human health. Groundwater quality was comparatively favourable, with 71% of wells recording WQI < 100; however, arsenic exceeded permissible limits more than twentyfold in select wells, attributed to geological sources. The detection of SVOCs in both hydrological compartments confirms cross-compartment contamination. Point-source reduction alone is insufficient for aquifer recovery; comprehensive sanitation strategies and long-term monitoring are urgently required. These findings carry direct relevance for water governance in megacity-dependent basins globally, where urban, agricultural, and geological stressors demand integrated management approaches. Full article

Plant species can significantly influence soil micronutrients. We assessed how soil micronutrients (B, Fe, Cu, Zn, Mn) and aluminum (Al) were affected by soil depth (SD) and plant species (PS) in a secondary forest at Masako Forest Reserve. Soil samples were collected in June 2022 and June 2023 along five PS (Entandrophragma utile, Hevea brasiliensis, Milettia laurentii, Musanga cecropoides, and Triculia africana). Four trees (replications) were selected per plant species. A completely randomized design was used with five PS and three SD (0–10 cm, 10–20, and 20–30 cm) and was replicated four times. To collect soil samples, a pit was dug at each sampling location (near a tree), and three soil samples were taken horizontally in the middle of each layer on one of the four faces of the pit, with a 5 cm height and 5 cm diameter cylinder. Soil samples were air-dried, mixed, and sieved to 2 mm, and a 20 g subsample was sent to Brookside Laboratories (OH, USA) for analyses of soil micronutrients. The results showed that most micronutrients were concentrated in the topsoil (0–10 cm). Plant species such as Treculia africana, Millettia laurentii, and Musanga cecropoides enhanced micronutrients in the soil in which they grew, especially iron (Fe) and zinc (Zn). The effect of the year of sampling on micronutrients was prevalent for many micronutrients, which remained significantly higher in 2022 than in 2023. These findings provide a foundational framework for developing nature-based biofortification strategies. By prioritizing key native plant species, local stakeholders can optimize soil health in the Congo Basin. Full article

This study investigates the environmental and health impacts of potentially toxic elements (PTEs) in solid and liquid wastes from phosphate beneficiation and fertilizer production in the Mdhilla area, Gafsa Basin, Tunisia. Solid wastes, including phosphate tailings (PTs) and phosphogypsum (PG), and associated industrial effluents from phosphate beneficiation (PBE) and fertilizer production (PFE), were characterized using physicochemical analysis, ICP-MS, SEM–EDX, and ion chromatography. Single and integrated pollution indices, along with conservative human health risk assessments, were applied to evaluate cumulative contamination and potential risks. PT exhibited near-neutral pH (7.64) and high PTE enrichment (Zn 350 mg kg⁻¹, Cr 329 mg kg⁻¹, Cd 38.8 mg kg⁻¹), whereas PG was strongly acidic (pH 3.13) and comparatively depleted in metals, reflecting process-dependent partitioning. Despite neutral pH, PBEs contained markedly higher metal concentrations than PFEs, with Fe (163 mg L⁻¹), Cr (3.09 mg L⁻¹), Cd (0.49 mg L⁻¹), and Pb (0.71 mg L⁻¹) exceeding discharge limits. Pollution indices indicated severe to extreme contamination, with PBE showing an exceptionally high contamination degree (C_deg = 63,659) compared to PFE (C_deg = 12,815), and elevated Toxic Element Pollution Index (PTEPI) values confirmed stronger cumulative pollution in PBE. Potential ecological risk indices (PERI > 600) revealed very high ecological risk for both effluents, primarily driven by Cd, Co, and Tl. Although dermal contact may represent the most frequent exposure route, risk assessment results indicated that accidental oral ingestion is the dominant pathway contributing to both non-carcinogenic and carcinogenic risks, with children being particularly vulnerable. Non-carcinogenic risk thresholds (HQ > 1) were exceeded for PBE, while total carcinogenic risks approached or exceeded regulatory limits (10⁻⁶–10⁻⁴), mainly due to Cd and Cr. Overall, phosphate beneficiation was the primary source of cumulative metal loading and associated ecological and health risks, while fertilizer production partially reduced contamination. These findings underscore the urgent need for improved management and mitigation of phosphate-processing wastes in industrial regions. Full article

The anthropogenic transformation of the steppe zone in the southern East European Plain has led to the destruction and catastrophic fragmentation of natural ecosystems. Due to the presence of highly fertile lands and the deposits of the Donetsk coal basin, up to 90% of the territory is occupied by agricultural and industrial activities, urban agglomerations, other settlements, and extensive transportation networks. The predominant use of introduced species in artificial plantings (within the city limits, the ratio of species to quantity is 7:3) leads to the widespread spread of alien species, further isolation of natural habitats, and their subsequent degradation. The problem of preserving natural ecosystems and restoring a stable balance in their functioning can be solved through the widespread introduction of native species into all types of plantings capable of serving as ecological corridors. In this regard, we analyzed the key characteristics of native tree and shrub species that determine their functional value. The results indicate that of the 85 native plant species, only two cannot be used because they carry pests and diseases dangerous to agricultural crops. The remaining 83 species are suitable for various planting types, based on a set of individual characteristics, and 29 of these are universal for all planting types. Outside urban ecosystems, these 83 native species can completely replace introduced species. Within urban ecosystems, the need for their combination remains. Despite a number of advantages identified in native species in conditions of anthropogenic pollution (relatively high viability, long lifespan, good resistance to mechanical stress), native species lack a number of categories of traits necessary for the more effective functioning of urban green infrastructure. Among them, there is an insufficient number of tall species (>25 m) and conifers, which are more effective in purifying and improving the health of the atmosphere, as well as beautifully flowering and generally highly decorative species necessary for recreational areas and other territories that, among other things, perform esthetic functions. Full article

The Souss-Massa basin, one of Morocco’s major agricultural regions, is increasingly affected by water scarcity and climatic stress. However, the long-term interactions between hydro-climatic change and farmers’ cropping system adjustments remain insufficiently documented. This study analyzes hydro-climatic trends and agricultural transformations over the period 1995–2021. The methodology combines statistical trend analysis of meteorological data (Mann–Kendall test and Sen’s slope estimator), diachronic land use/land cover mapping using Google Earth Engine, Crop Water Stress Index (CWSI) assessment, and groundwater piezometric analysis. Results reveal declining and highly variable precipitation, together with a significant warming trend reaching +0.116 °C/year. In parallel, cultivated cereal areas (rainfed and irrigated) declined, while irrigated forage crops expanded, particularly Berseem/Maize. Despite increasing aridity, CWSI results indicate maintained crop vigor in irrigated areas, suggesting growing dependence on groundwater extraction. These findings highlight an ongoing agricultural transition that increases pressure on already vulnerable water resources and underscores the need for integrated climate adaptation and groundwater management strategies in the basin. Full article

Under the influence of climate change and human activities, alpine grasslands in the Qinghai Lake basin have undergone a degradation trend over recent decades. In this context, investigating the distribution and stability of soil aggregates across varying degradation degrees of alpine grasslands, along with their driving factors, is critical for formulating sustainable management strategies to maintain grassland health and soil structural resilience in this ecologically sensitive region. In this study, plant and soil samples (0–20 cm) were collected at nine sites in the Qinghai Lake basin, each encompassing a non-degraded (ND), a lightly degraded (LD), and a heavily degraded (HD) grassland plot. The distribution and stability of mechanically stable aggregates and water-stable aggregates were evaluated using the dry-sieving and wet-sieving methods, respectively. The results showed that grassland degradation led to declines in plant above-ground and below-ground biomass, soil carbon, nitrogen, phosphorus, and microbial biomass carbon contents, and β-1,4-nacetylglucosaminidase activity, alongside an increase in soil pH. However, soil β-1,4-glucosidase and alkaline phosphatase activities exhibited no significant changes. The 2–0.25 mm fraction is the primary component of mechanically stable aggregates in alpine grasslands across three degradation levels. After degradation, neither the distribution nor the stability of mechanically stable aggregates exhibited significant changes. In terms of water-stable aggregates, the 2–0.25 mm fraction constituted the primary component in ND and LD, whereas the <0.053 mm fraction predominated in HD. Additionally, the mass proportions of the >2 mm and 2–0.25 mm size fractions were significantly lower in HD compared to ND, while the mass fraction of the <0.053 mm fraction was notably higher. The altered distribution of water-stable aggregates resulted in a significant decrease in mean weight diameter and a notable increase in the percentage of aggregate destruction, suggesting a reduced resistance of the soil to water erosion. Plant below-ground biomass, soil total organic carbon, and total nitrogen were identified as crucial factors modulating the dynamics of aggregate stability during grassland degradation. The findings of this study suggest that alpine grassland degradation in the Qinghai Lake basin reduces the water stability rather than the mechanical stability of soil aggregates. Full article

The quality of water for human consumption depends on the supply method and source type. Water may contain pathogens and excessive constituents that pose health risks, and timely monitoring and planned service provision help ensure its quality. This study assessed the supply system, quality, and health risks associated with the consumption of water from three sources in the high-elevation Andean city of Andahuaylas, Peru, managed by the Municipal Sanitation Service Provider Chanka (EMSAP). The sources were found to provide between 0.8 and 32 L/s, with consumption of about 17 m³ per connection per month, at a cost of 0.20 USD/m³. The system shows a current deficit and a projected deficit for 2027 due to increasing user debts and the absence of mechanisms for payment for ecosystem services (PESs), despite the existence of cross-subsidies. Water quality, assessed using the WQI-Pe, ranged from regular to excellent, although with high levels of heavy metals according to the Environmental Quality Standards for Water (EQS–Peru), which increases the non-carcinogenic health risk. Chronic non-carcinogenic exposure (HQ) from consumption and dermal contact exceeded one, mainly for arsenic (As), while the deterministically and probabilistically evaluated incremental lifetime cancer risk (ILCR) was linked to high levels of As, Cr, and Cd across all age groups (infants, children, adolescents, and adults). Overall, this study provides insight into the state of water in areas without conventional treatment, so the implementation of buffer zones in the basin’s headwaters in localities with similar characteristics is vital. Full article

Due to the destruction of natural aquatic ecosystems, developing comprehensive biological index evaluation methods is critical for river restoration and regeneration. However, research on spatial multiple-scale biological assessments remains lacking. This study used the biological integrity index methodology to examine the effectiveness of fish and macrobenthos in ecological assessments, as well as to analyze environmental factors impacting aquatic ecosystem health assessments. The Daning River basin in Chongqing was selected as the study area, and aquatic ecosystem health assessments were conducted at both regional and local scales. The results indicated that benthos were more abundant than fish, but there were no significant differences in species richness between sub-basins (p > 0.05). The assessment results for F-IBI and B-IBI showed partial discrepancies at the local fine-scale level but were nearly consistent at the regional broad-scale sub-basin level, with only small differences between the F-IBI and B-IBI ratings in one sub-basin. This discrepancy may be due to the diverse water environment. Woodland areas have significant negative relationships with F-IBI, while water areas have significant positive relationships with it. Comprehensively, the assessment findings of F-IBI beat those of B-IBI, implying that F-IBI may be better suited for regional assessments. However, the impact of local water quality issues remains unclear. To enhance ecological restoration, it is vital to conduct additional research into the degree of interference caused by water quality variables. Full article

The Yangtze River Economic Belt supports over 400 million people and contributes nearly half of China’s GDP, yet decades of industrialization, urbanization, and agricultural intensification have resulted in severe contamination and pressing environmental challenges. This systematic review synthesizes three decades of peer-reviewed and governmental data to examine the spatiotemporal distribution, sources, and ecological and human health risks of major pollutants, including heavy metals, microplastics, persistent organic pollutants, and excess nutrients. While point-source emission of heavy metals such as cadmium, lead, and mercury have decreased by 35–42% since 2013 following policy interventions like the 10-Point Water Plan and the Yangtze River Protection Law, legacy contaminants in sediments and diffuse agricultural inputs continue to pose significant risks. Cadmium levels in rice still exceed food safety standards, arsenic in groundwater surpasses health guidelines, and microplastic flux into the East China Sea has reached 8.3 × 10¹² particles per year. Nutrient surpluses also drive extensive algal blooms, causing substantial economic losses. This review evaluates remediation strategies such as dredging, phytoremediation, wetland restoration, and AI-enhanced monitoring, which show removal efficiencies of 60–90% at reduced costs. However, critical gaps remain in understanding chronic mixture toxicity, the long-term fate of emerging contaminants, and pollutant–climate interactions. We propose an integrated basin-wide roadmap combining zero-liquid-discharge mandates, green infrastructure, and adaptive, performance-based governance to secure the Yangtze’s ecological and economic sustainability. This framework offers a transferable model for large-scale watershed management worldwide. Full article

The Aksu River Basin oasis, a typical arid ecological environment, faces considerable ecological and public health risks from fluoride accumulation in soil and groundwater. However, systematic investigations integrating soil–groundwater co-enrichment mechanisms with multi-pathway health risk assessments under environmentally relevant conditions remain scarce. We examined spatial fluoride distribution in the soil–groundwater system, associated health risks, and key driving mechanisms. Based on 2009 soil and 264 groundwater samples, we applied radial basis function (RBF) interpolation, Getis-Ord G_i* hotspot analysis, the geo-accumulation index (I_geo), the ecological risk index (ER), and the U.S. EPA health risk assessment model to evaluate pollution levels, ecological risks, and health impacts on adults and children. Spearman’s correlation analysis revealed relationships with 12 environmental factors, including topography, climate, soil properties, and vegetation. Key results are as follows: (1) High-fluoride soils (>700 mg·kg⁻¹) clustered in the eastern basin, while groundwater fluoride increased along a west–east gradient, with RBF interpolation yielding the highest accuracy; (2) soil fluoride was generally “unpolluted–moderate risk” (mean I_geo = −0.14, ER = 1.40), whereas groundwater posed the primary health risk, with a mean hazard quotient of 1.83 for children via drinking water, indicating non-carcinogenic risk; (3) soil enrichment was driven by evaporation–concentration–alkaline activation, while groundwater enrichment followed a convergence–concentration–evaporation mechanism, being negatively correlated with elevation. Groundwater fluoride presents a clear health risk, particularly to children, arising from high geological background levels and intense evaporation. Managing fluoride pollution and safeguarding drinking water quality in arid oasis regions is consequential. These findings provide a scientific basis for sustainable groundwater management and public health protection in arid oases. Full article

Background: Malaria remains hyperendemic in the Democratic Republic of the Congo, while arboviral infections are increasingly reported but remain under-surveilled, particularly in remote regions. Overlapping ecological niches and non-specific clinical presentations complicate case management and surveillance. Methods: A cross-sectional door-to-door survey was conducted in December 2023 in Inkanamongo village (Lokolia Health Area, Boende Health Zone, Tshuapa Province). Blood samples were collected from 379 adults; malaria infection was assessed by using HRP2-based rapid diagnostic tests, and arboviral IgG antibodies were measured on dried blood spots using Luminex^® multiplex immunoassay. Sociodemographic data were collected via standardized questionnaires. Results: Malaria prevalence was 51.7% (95%CI: 46.7–56.7). Overall arboviral seroprevalence reached 78.4% (95%CI: 73.1–81.5), dominated by O’nyong-nyong virus, 42.8% (95%CI: 37.6–47.5), Rift Valley fever virus, 32.0% (95%CI: 26.9–36.2), and chikungunya virus, 23.4% (95%CI: 19.0–27.4). Concurrent malaria infection and arboviral exposure were observed in 40.4% (95%CI: 35.6–45.4) of participants. No sociodemographic factors were significantly associated with co-exposure in the multivariable analysis. Conclusions: Substantial co-exposure of malaria and multiple arboviruses occurs in this remote Congo Basin setting. Integrated surveillance and improved diagnostics are urgently needed to guide febrile illness management and preparedness in under-resourced regions. Full article

The Western Amazon is a global biodiversity hotspot, yet the Upper Napo River Basin (UNRB) remains understudied regarding aquatic ecosystem health along anthropogenic gradients. We integrated benthic macroinvertebrate assemblages with physicochemical and microbiological indicators across 45 sites to assess ecological quality under four impact scenarios: Few Threats (FT, reference sites; n = 6), Crop/Aquaculture (CA; n = 22), Gold Mining (GM; n = 10), and Wastewater Discharge (WD; n = 7). Analysis of 2285 individuals (62 families) revealed clear degradation across the anthropogenic gradient. Reference sites (FT) exhibited high integrity (q₀ = 24.3 families), establishing the regional baseline for Andean–Amazonian freshwater ecosystems. In stark contrast, GM sites showed catastrophic defaunation (q₀ = 9.9 families) coupled with extreme turbidity (1320 ± 1589 NTU) and heavy metal mobilization (Fe: 430 ± 229 µg/L; Cu: 338 ± 128 µg/L), placing these reaches in “Bad” ecological status (Ecological Quality Ratio, EQR ≤ 0.16). Wastewater sites reached critical fecal coliform levels (33,708 ± 58,047 CFU/100 mL)—165-fold higher than FT sites—indicating severe sanitary impairment and community collapse (EQR = 0.28, dominated by Chironomidae at 80%). The application of ASPT (Average Score Per Taxon) and EQR proved essential for detecting functional shifts toward tolerant assemblages even when raw biotic scores appeared moderate. Crop/Aquaculture sites showed intermediate degradation (EQR = 0.37–0.38), reflecting chronic pesticide exposure and habitat loss. We conclude that gold mining and wastewater discharge are the primary drivers pushing the UNRB toward ecological collapse, with GM exerting the most severe impact on aquatic biodiversity. Safeguarding this global freshwater stronghold requires immediate implementation of multimetric biomonitoring, enhanced mining regulation, wastewater treatment infrastructure, and establishment of Indigenous-led fluvial reserves to maintain long-term connectivity. Full article

Groundwater is a critical lifeline for ecosystems and human settlements in arid and semi-arid regions, yet it is increasingly vulnerable to the dual pressures of extreme climatic conditions and intensifying anthropogenic activities. This study investigated 24 groundwater and 4 river water samples to discuss the hydrogeochemical evolution and water quality suitability in the Tianjun Basin, a typical high-altitude arid basin on the northeastern Tibetan Plateau. The results indicate that groundwater is mildly alkaline (pH: 7.65–8.35) and predominantly fresh (TDS: 233.77–1061.42 mg/L). Hydrochemical facies evolve from HCO₃-Ca type in upstream areas to Mixed HCO₃-Na·Ca and Cl-Na types. Hydrochemical analysis suggests that silicate weathering and carbonate dissolution are the dominant natural processes, while cation exchange further modifies the ionic composition. Notably, anthropogenic nitrogen (NO₃⁻ and NH₄⁺) contamination, primarily from domestic sewage in the Tianjun Basin, has significantly impacted groundwater quality. Health risk assessment shows that infants are the most vulnerable group, with 16.67% of samples posing a non-carcinogenic risk via the oral pathway. Regarding irrigation suitability, while sodium hazards are generally low, a significant salinity hazard is identified due to elevated electrical conductivity in the arid environment. This poses a substantial risk of secondary soil salinization, necessitating strict salt management strategies to preserve long-term land productivity. These findings provide critical insights for the sustainable management of fragile groundwater resources in extreme arid environments. Full article

Groundwater contamination by dissolved metals and metalloids in the Chiang Mai Basin is an important drinking-water concern, yet the coupled depth patterns, hydrogeochemical controls, composite contamination status, and screening-level health implications have not previously been assessed in an integrated basin-scale framework. This study evaluated 120 groundwater samples from alluvial wells classified by depth as shallow (≤30 m, n = 40), intermediate (31–60 m, n = 35), and deep (>60 m, n = 45). Samples were analyzed for nine dissolved metals and metalloids (Fe, Mn, As, Cd, Pb, Cr, Zn, Hg, and Se) together with pH, Eh, and total dissolved solids (TDS). The highest exceedance frequencies were observed for Fe (72.5% of samples, >0.3 mg/L acceptability threshold), Mn (65.0%, >0.08 mg/L), and As (45.8%, >10 μg/L). Fe and Mn increased significantly with depth, whereas As was enriched in deep wells but showed no statistically significant depth dependence. Pearson correlation and principal component analysis consistently identified a dominant redox-associated component in which Fe, Mn, and As covaried negatively with Eh, supporting redox-sensitive co-enrichment in deeper groundwater. Contamination factors calculated relative to selected global groundwater background values were >6 for all seven evaluated metals (Fe, Mn, As, Cd, Pb, Cr, and Zn), and the overall pollution load index (PLI) was 9.11, with the highest depth-specific PLI in deep wells (10.42). These indices are interpreted here as background-relative screening tools rather than stand-alone regulatory measures. A screening-level ingestion risk assessment identified arsenic as the dominant toxicological driver, with hazard quotients (HQ) of 1.97 for adults and 4.60 for children, and an estimated lifetime cancer risk (LCR) of 8.87 × 10^–4. The results support targeted monitoring of deeper wells, routine screening for As and Mn, and treatment strategies that can address the co-occurring Fe–Mn–As assemblage in alluvial groundwater. Full article

The increasing consumption of fish has raised public health concerns regarding fish-borne zoonotic helminths (FBZHs), which are recognized as significant food-borne parasites worldwide. In freshwater environments, Clinostomum complanatum, Opisthorchis felineus, Pseudamphistomum truncatum, Dibothriocephalus latus and Eustrongylides excisus are of particular concern in Italy and neighbouring countries. This study aimed to assess the prevalence of these FBZHs in five commercially and ecologically relevant freshwater fish species from Lake Varese, a heavily anthropized and understudied basin in northern Italy. A total of 59 fish were examined via necropsy and stereomicroscopic inspection of skeletal muscles. Only Eustrongylides spp. larvae were detected, with a prevalence of 16.9%. Molecular analysis (ITS region) identified them as E. excisus. This study reports, for the first time in Western Europe, E. excisus in Sander lucioperca (p = 12.5%) and Esox lucius (p = 8.3%). The highest prevalence occurred in Silurus glanis (p = 37.5%), followed by Perca fluviatilis (p = 25.0%), while Tinca tinca showed no infection. These findings confirm that among the FBZHs considered, E. excisus is currently present and expanding both in host range and geography in Italian lakes, underscoring the need for updated epidemiological data to support risk assessment, food safety and zoonotic parasite control in freshwater fisheries. Full article