Search Results (1,886)

This study investigated the contamination characteristics, sources, and ecological risks of organochlorine pesticides (OCPs) in surface sediments from three plateau lakes in southwestern China (Qilu Lake, Dianchi Lake, and Yangzonghai Lake). Significant differences in OCP pollution levels were observed among the three lakes. Hexachlorocyclohexanes (HCHs) were identified as the dominant contaminants, reflecting historical technical HCH input and subsequent long-term aging, whereas dichlorodiphenyltrichloroethanes (DDTs) exhibited generally low concentrations and originated primarily from historical technical use, with predominantly aerobic degradation. Principal component analysis (PCA) revealed that agricultural non-point source pollution was the main contributor to OCP residues. Ecological risk assessment demonstrated that most OCPs posed low or negligible risk; however, γ-HCH (lindane) ubiquitously presented moderate risk across all lakes, with one site exceeding the high-risk threshold. Endrin derivatives and methoxychlor further elevated combined risks at specific sites. Notably, the unique hydrological characteristics of plateau lakes may enhance OCP retention and accumulation in sediments. These findings provide a scientific basis for ecological risk management and pollution control in plateau lakes. Full article

Mangrove wetlands act as ecological buffers and important sinks for pollutants such as microplastics, yet their surface transformation processes remain unclear. This study examines changes in the surface composition of polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP) through ten field experiments in mangrove environments. The study indicates that the oxidation, hydrolysis and damage degree of PE, PP and PET all show that the exposed area above the sediment has a greater change compared to the buried area within the sediment. Spatial variation is evident, with the most severe degradation occurring in muddy seawater areas, and material susceptibility following the order PP > PE > PET. In muddy zones, damage decreases along the gradient: seawater > mudflat > mangrove > nearshore. Microbial analysis reveals that Proteobacteria and Bacteroidetes dominate microplastic biofilms. Specific genera are associated with different degradation patterns among microplastic types: Ruegeria, Sulfitobacter, and Neptuniibacter are positively correlated with PET degradation; Sulfurovum and Desulfobacter are positively correlated with PP degradation; and no positive correlation is observed between Sulfurimonas and PE degradation. These findings highlight the combined roles of environmental conditions and microbial communities in microplastic aging, offering insights for pollution mitigation strategies in mangrove ecosystems. Full article

Estuaries along South Africa’s coastline are increasingly subjected to anthropogenic pressures that disrupt their biogeochemical function and increase the risk of contamination. This study presents the first seasonal assessment of heavy metal contamination and water quality indices in the Qholora Estuary, Eastern Cape Province. Surface water samples collected during wet and dry seasons were analysed for physicochemical properties and heavy metals (As, Cd, Cu, Fe, Hg, and Pb). Multiple pollution metrics (Pollution Index (PI), Nemerow Pollution Index (NPI), Heavy Metal Evaluation Index (HEI), Heavy Metal Pollution Index (HPI)), ecological risk indices ((Ecological Risk Index (ERI), and Potential Ecological Risk Index (PERI)), and the Water Quality Index (WQI) were applied and supported by Principal Component and Cluster Analyses to identify dominant pollutant, contamination sources and seasonal hydro-geochemical controls. Results reveal strong seasonal contrasts: wet-season conditions showed elevated ionic concentrations and enhanced mobilisation of Cu, Pb, Cd, Hg, and Fe due to storm-driven runoff and sediment resuspension, while dry-season patterns reflected evapo-concentration, prolonged residence times, and pH-mediated metal partitioning. Across indices, heavy metal contamination remained low in the dry season but increased significantly in the wet season, especially for Hg, which posed moderate to considerable ecological risk at most sites, indicating emerging ecological pressure under high-flow conditions. These findings highlight a generally low risk under average conditions but a pronounced seasonally vulnerable estuarine system, underscoring the need for intensified monitoring during periods of increased runoff. The study establishes an important baseline for regional water resource management. Full article

The Yellow River Delta (YRD), a crucial ecotone, is becoming increasingly polluted by antibiotics, posing serious threats to aquatic ecosystems and human health. In this study, comprehensive investigations were conducted to explore the regional distribution, environmental risks, and source apportionment of antibiotics, with the aim of facilitating precise management and control of antibiotic pollution. The results show that the surge in runoff during the water–sediment regulation period (June and August) of the Yellow River drove a sharp rise in antibiotic concentrations in the surface water, peaking at 135.0 ng/L, whereas antibiotics were rarely detected in the sediments after multiple rounds of intense hydraulic scouring (0.2~12.6 ng/g in October). Furthermore, seven antibiotics (sulfadiazine, sulfamethoxazole, flumequine, ofloxacin, tetracycline, doxycycline, and lincomycin) in surface water and six antibiotics (norfloxacin, enrofloxacin, ofloxacin, doxycycline, oxytetracycline, and florfenicol) in sediments were identified as representative compounds according to the antibiotic pollution profiles. Environmental risk assessment coupled with spatial autocorrelation analysis revealed that sulfamethoxazole generally posed medium to high risk (0.12~1.27) in surface water. Sediments posed more serious ecological risks, with universally high risk levels (ranging from 1.11 to 280.00). More importantly, in both surface water and sediment, four core antibiotic sources—namely, human sewage, livestock farming, agricultural and aquaculture inputs, and hydrodynamic-driven resuspension processes—were consistently identified through the Positive Matrix Factorization model and Kriging interpolation. These findings provide crucial insights for establishing targeted antibiotic pollution control strategies in the YRD and advance the understanding of antibiotic fate in sediment-laden rivers. Full article

Vegetated coastal wetlands, especially mangroves, seagrass beds, and salt marshes, are biodiversity-rich ecosystems whose blue carbon outcomes depend on living communities, sediment dynamics, hydrological connectivity, and landscape context. Biodiversity conservation and blue carbon management are often assessed through separate scientific, monitoring, and policy frameworks. This review uses a staged literature search and thematic synthesis to examine biodiversity–blue carbon linkages across the three major vegetated coastal wetland types. It considers how taxonomic, genetic, functional, and habitat diversity influence productivity, sediment stabilization, trophic exchange, carbon stocks, carbon burial, and carbon retention. It also evaluates how climate change, habitat fragmentation, hydrological alteration, pollution, and anthropogenic disturbance weaken these linkages. The synthesis compares representative carbon-stock and burial-rate baselines, examines conservation and restoration synergies and trade-offs, and expands the discussion of seagrass regime shifts. Field surveys, remote sensing, unmanned aerial vehicles, environmental DNA, and AI-enabled data integration are placed within a tiered monitoring framework. The review further develops an operational decision pathway for biodiversity-centered blue carbon management. Persistent blue carbon benefits arise where conservation and restoration maintain native communities, hydrological exchange, sediment stability, habitat complexity, migration space, and long-term stewardship capacity. Full article

Polycyclic aromatic hydrocarbons (PAHs) represent a major class of ubiquitous environmental pollutants, posing significant risks to ecosystems and human health due to their persistence, toxicity, and potential for bioaccumulation. This review provides a comprehensive synthesis of current scientific knowledge on PAHs, integrating insights from chemical kinetics, environmental fate, and toxicological mechanisms. The fundamental structural chemistry of PAHs and its direct influence on their physicochemical properties and environmental properties are discussed. The major anthropogenic and natural sources of PAHs are detailed, alongside the chemical kinetics behind their formation during incomplete combustion and their transformation in environmental media. Unlike previous reviews that address PAH sources, remediation, or health effects as separate topics, this review uniquely traces the mechanistic continuum from molecular formation kinetics through physicochemical partitioning and environmental transport to toxicological endpoints, providing a causally linked framework for understanding how structural properties ultimately determine biological outcomes. A central focus is placed on the environmental fate and transport of PAHs across atmospheric, aquatic, and terrestrial compartments, highlighting processes such as gas–particle partitioning, sediment accumulation, and long-range transport. The review further elucidates the complex toxicological pathways of PAHs, including metabolic activation to reactive intermediates, DNA adduct formation, oxidative stress, and their roles in carcinogenesis and other systemic health effects. The analysis reveals strong scientific consensus on the carcinogenic mechanism of parent PAHs via CYP450-mediated metabolic activation to diol-epoxide intermediates while identifying critical areas of uncertainty: the current regulatory framework based on 16 priority PAHs underestimates total carcinogenic risk by a factor of 2–5, mixture toxicology remains poorly characterized, and dose–response relationships for non-cancer endpoints (cardiovascular, neurodevelopmental, immunotoxic) lack the quantitative data needed for robust risk assessment. Finally, human exposure pathways and health risk characterization approaches are discussed, highlighting the need for cumulative, mixture-based assessment frameworks. Full article

Transitional waters—such as estuaries, lagoons, deltas, and coastal wetlands—are dynamic environments where freshwater and seawater interact, forming highly productive and biologically diverse ecosystems. Shaped by temperature and salinity gradients, tidal influence, sediment transport, and nutrient-rich conditions, these habitats support diverse ecological functions. Their structural complexity—including seagrass beds, salt marshes, mudflats, and mangroves—provides essential habitats for many fish species. These areas are crucial for fish life cycles, serving as nurseries, spawning grounds, feeding zones, and refuges from predators. Many commercially important species depend on them during early life stages before moving offshore, making them vital for both commercial and recreational fisheries. Beyond food provision, they deliver key ecosystem services, including water purification, coastal protection, and carbon storage. Research on the fish community of the Ria Formosa lagoon in Portugal since the 1980s highlights long-term changes in the fish community and the dominant role of habitat structure and temporal dynamics. Subtidal seagrass beds support higher fish abundance and diversity than unvegetated areas, acting as key nursery habitats and provide important fish provisioning services. Seasonal variation is also central, driven by recruitment pulses of marine migrants in late winter–spring. Recent pressures on this system have been driven by human activity and environmental change. Seagrass loss reduces nursery and feeding areas, while pollution degrades water quality. Overfishing (including illegal fishing), recreational activities, and aquaculture expansion add stress. Climate warming and invasive species such as Caulerpa prolifera, further disrupt ecosystem balance and threaten biodiversity. Sustainable management—such as habitat restoration, protected areas, and integrated policies—is essential to preserve the ecological and economic value of this unique lagoon. Ongoing research, monitoring, habitat restoration, and stakeholder engagement remain critical for ensuring resilience. Full article

As an important port in the Beibu Gulf of the South China Sea, Tieshangang Bay is potentially at risk of PTE pollution, yet systematic research integrating multi-hydrological period data remains limited. By applying pollution indices (C_f, WQI, I_geo, RI) combined with PCA, and PMF, we investigated PTE distribution characteristics, risk assessment, and source apportionment across different hydrological seasons. The results indicate that average PTE concentrations in surface seawater meet Class II standards of the Sea Water Quality Standard, with Zn and As showing relatively high concentrations compared to other PTEs. High-concentration areas were mainly located in the inner and middle bay. In sediments, concentrations of Zn and Cr were relatively high, with values generally higher inside the bay than outside. Both C_f and WQI values for seawater PTEs were below 1, indicating an overall low pollution risk. However, Cd and Hg in sediments presented a moderate potential ecological risk. Source apportionment revealed that seawater PTEs primarily originated from an industrial–aquaculture composite source (44.60%), while sediment PTEs were mainly attributed to composite terrestrial inputs (53.16%). These findings provide a scientific basis for PTE pollution management and sustainable development in Tieshangang Bay. Full article

Introduction: Establishing baseline descriptions of inorganic elements in the early life stages of sharks and in their respective nursery areas is essential for assessing anthropogenic impacts and supporting conservation strategies. Objectives: This study presents the first baseline of plasma trace element concentrations (Al, Zn, As, Cu, Cr, Cd, Co, Mn, Ti, Ni, Hg, Pb) for four juvenile shark species (Carcharhinus limbatus, Paragaleus pectoralis, Rhizoprionodon acutus, and Sphyrna lewini) from Sal Rei Bay, Boa Vista Island, Cabo Verde—the first multi-species shark nursery area described in Atlantic Africa. Methodology: Seawater and sediment samples were collected from eight sites and analyzed along with plasma samples using total reflection X-ray fluorescence spectroscopy (TXRF). Sediment granulometry and pollution indices, including the enrichment factor (EF), ecological risk index (RI), and metal pollution index (MPI), were used to characterize habitat contamination. Data were analyzed using statistical models to explore spatial and element-specific patterns. Results: Overall, environmental contamination was low, with slight increases in Cd, Co, and Hg at sites 1 and 2, near the fishing port, and at site 5, likely reflecting natural transport, sediment redistribution, and enhanced nearshore deposition. Juvenile sharks exhibited generally low plasma trace element concentrations, although species-specific elemental signatures were evident: elevated levels of Al and Cu in C. limbatus, Zn in S. lewini, and As in R. acutus and P. pectoralis. Conclusions: These findings establish critical baseline reference values for trace elements in juvenile sharks from a key Atlantic nursery area. The results provide an essential framework for future biomonitoring efforts and contribute to the management and conservation of Cabo Verdean shark nursery habitats. Full article

Microplastics (MPs; <5 mm) represent a growing environmental concern that increasingly challenges environmental monitoring, governance, and evidence-based decision-making. This review critically examines how current scientific understanding of microplastic sources, classification, occurrence, and environmental behavior can support environmental governance. MPs are classified as primary and secondary particles; however, persistent inconsistencies in size definitions, shape descriptors, and polymer identification limit the comparability of monitoring data and constrain the development of coherent regulatory frameworks. Evidence on the occurrence of MPs in surface waters and sediments highlights widespread contamination and pronounced spatial variability, raising challenges for risk assessment and policy harmonization across regions. Key transport pathways, including atmospheric deposition, terrestrial runoff, and riverine fluxes, are analyzed to illustrate how local emissions translate into large-scale environmental impacts. Rivers emerge as key components linking sources to receptors, offering relevant points for policy intervention and management measures. The review evaluates current policy responses to microplastic pollution, identifying significant gaps in standardized monitoring, data integration, and risk assessment approaches. It emphasizes the need for stronger alignment between scientific outputs and policy requirements, including the co-production of knowledge involving scientists, regulators, and stakeholders. By outlining pathways through which scientific evidence can inform regulatory design and environmental management, this study provides actionable insights for improving policy effectiveness. Advancing harmonized methodologies and integrating science into decision-making processes are essential steps toward mitigating microplastic pollution and supporting sustainable environmental governance. Full article

Soil erosion (SE) is a constant, complex land degradation process, a common natural disaster that occurs all over the world and severely impacts soil fertility, food security, and environmental balance. Soil erosion depends on many factors, including soil properties, slope, vegetation, rainfall amount and intensity, and anthropogenic activities. There are two main natural erosive forces by which soil is eroded and transported—water and wind. Water erosion refers to the detachment, transportation, and deposition of soil particles (solid runoff) into river networks. These particles, varying in size and composition, are the main products of soil erosion and most strongly affect river ecosystems. Solid runoff, or sediment-laden runoff, affects water quality, destroying habitats, carrying pollutants, reducing reservoir storage, and causing flooding. Erosion control activities also influence river ecosystems in different ways. Hydrotechnical facilities, a major erosion control practice, can alter the composition of aquatic biota by disrupting longitudinal connectivity and isolating populations. Reforestation and afforestation are other erosion control practices that have a strong impact on ecosystems. Stormwater retention systems in urban and forest areas are also important measures addressed in this review. This review examines complex environmental interactions and the roles of erosion and erosion control activities in river ecosystems. During the research, several key points were established: erosion and erosion control activities significantly affect river ecosystems. There is a lack of quantitative analysis of erosion intensity and its influence on ecosystems. This is probably due to the exceptional complexity and diversity of river ecosystems, but such a study would provide important information about complex relationships in nature. Full article

Textural and geochemical analysis of intertidal sediments in the southern Atacama region makes it possible to identify sites primarily affected by mining-related pollution, based on a multivariate statistical analysis of the concentrations of five elements (Fe, Cu, Zn, As, Pb) and their geoaccumulation indices. These concentrations are not correlated with grain size, which is dominated by the sandy fractions. Spearman’s matrix and principal component analysis make it possible to distinguish between two groups of elements (group A: Fe-Cu-As; group B: Zn-Pb), with a strong correlation between them (ρ ≥ 0.51; p < 0.01) and the first two components explain 96.3% of the variance. Three heavily polluted sites (Playa Blanca, Bahía Sarco and Chañaral de Aceituno; I_geo Cu > 8) have been identified linked to waste from the washing of tailings, a copper smelter and frequent boat trips. In addition, four moderately polluted sites (Playa Grande, Balneario Caldera, the mouth of the Copiapó River and Carrizal Bajo; 1.7 < I_geo Cu < 8; 1.2 < I_geo Pb < 2.6), mainly due to activities associated with mining and oil refineries, have been identified. Full article

The Santiago River is a highly anthropogenically impaired lotic system globally, yet the mechanisms governing its contaminant transport remain poorly understood under static monitoring paradigms. This study evaluates how hydrological forcing dictates the mobilization and bioavailability of trace metals by integrating a 15-year public hydrochemical database from 10 monitoring nodes with SAR-derived discharge estimates and thermodynamic metal modeling (PHREEQC). To validate the structural integrity of the mass load estimates against hydrometric uncertainties, a deterministic boundary-sensitivity analysis was conducted. Results empirically refute the classical dilution paradigm, introducing the “Anthropogenic Pulse” to describe the non-linear acceleration of pollutant export during high-flow events (discharge Q surging from 36.62 to 286.13 m³/s). While climate-driven parameters follow seasonal cycles, industrial stressors (COD, Pb, Cd) remain in a chronic steady state, decoupling from volumetric dilution. Based on coupled × CQ × C (discharge × concentration) estimates, this dynamic induces a synchronized flushing of toxic burdens, exporting monthly peak loads exceeding 51,000 kg of Zinc, 6500 kg of Lead, and 3100 kg of Cadmium. Thermodynamic simulations reveal that this hydrological flushing functions as a chemical activator; the seasonal dilution of natural Alkalinity and Hardness suppresses the river’s theoretical buffered pH (from 8.5 to 7.0), maintaining metals in their uncomplexed free-ion states (Me²⁺). Modeling indicates that nearly 90% of the exported Cadmium remains in this highly labile, toxic form due to a dual coupling with both river Discharge (r_s = 0.87) and pH (r_s = 0.79). The identification of stochastic arsenic peaks 100 times above regulatory limits at Paso de Guadalupe (RS-08) underscores the failure of concentration-based monitoring. Our findings suggest that restoration strategies should shift toward mass-loading-based regulatory frameworks and targeted sediment management at critical nodes to mitigate the chronic export of bioavailable industrial waste. Full article

Radioisotopic techniques provide powerful tools for reconstructing the history of lake sediments, offering critical insights into past environmental changes and human impacts. These techniques have contributed significantly to our understanding of past environmental change and have implications for current environmental management practices. This review comprehensively examines various radiometric dating techniques used for lake sediments, with a focus on natural, cosmogenic, and artificial radionuclides, including ²¹⁰Pb, ¹³⁷Cs, ²⁴¹Am, ⁷Be, ³H, and ¹⁴C. The review highlights the widespread use of radionuclides in establishing sediment chronologies across different time scales, from short-term processes (days to decades) to long-term environmental reconstructions spanning thousands of years. Moreover, applications in limnological research are explored, including sedimentation rate estimation, reconstruction of pollution history of trace elements, nutrients, microplastics, and organic compounds, and assessment of anthropogenic impacts and catchment changes. The integration of radioisotopic methods with multiproxy paleolimnological approaches is emphasized as a powerful framework for reconstructing past environmental and ecological conditions. Despite their effectiveness, radioisotopic methods are exposed to several sources of uncertainty, including dispersion in atmospheric isotope flux, post-depositional processes, reservoir effects, and model assumptions. These challenges highlight the importance of careful methodological selection, site-specific evaluation, and rigorous uncertainty assessment in radioisotopic studies of lake sediments. Future research should emphasize refining sediment age-model calibration using region-specific sedimentation parameters and standardized validation procedures, and integrating radiometric techniques with geochemical, biological, and paleolimnological proxies to improve the reconstruction of environmental change in lacustrine systems. Such developments would enhance the interpretation of historical pollution records, sediment accumulation patterns, eutrophication history, and ecological variability, thereby providing scientifically robust information to support evidence-based lake management, restoration programs, and long-term conservation strategies. Full article

Microplastics, MPs, plastic particles with dimensions between 0.1 and 5 mm, represent an important environmental pollutant. The removal of microplastics from natural and wastewater is a challenging research topic. In this regard, high-performance technical solutions must be identified, which can be based on existing treatment and purification technologies, to ensure their removal at concentration values in accordance with the legislation in force. In this study, the efficiency of removing some fractions of polyurethane microplastics, with dimensions smaller than 500 µm, from aqueous synthetic solutions with a concentration of 0.2 g L⁻¹, i.e., around 175 NTU, was evaluated. In the first stage of the study, the doses of coagulants and flocculants effective for the removal of microplastics were identified through the Jar Test. The variation in turbidity and their removal efficiencies were evaluated in the presence of classic coagulants, such as aluminum sulfate, Al₂(SO₄)₃·18H₂O, SA; iron sulfate (ferrous sulfate), FeSO₄, IS; polyaluminum chloride, [Al₂(OH)_nCl_6−n], PAC; Aloe Vera, AV, a flocculant; and activated carbon, AC, of the Norit GAC 830 W type. Classic coagulants, such as aluminum sulfate, have a good efficiency in removing microplastics, being able to provide a residual turbidity in the range of 6–10 NTU after a retention time of 50–60 min. In the second stage of the study, the removal efficiency of microplastics was tested using a laboratory pilot plant—called in the study the Smart Decantation-Filtration System, SDFS. The efficiency of the decanter was studied using Response Surface Methodology (RSM) to identify mathematical models that characterize the influence of key process variables: flow rate (A), microplastic size (B) and aluminum sulfate concentration (C) on microplastic removal efficiency. Sedimentation in the specially constructed decanter can raise the optimal value of the removal efficiency of polyurethane microplastics to 98.98%, and filtration can ensure an efficiency that reaches over 99.5%. Through this research, we aimed to identify viable solutions that can be applied to remove microplastics, MPs, from natural and wastewater. A novel element is the fact that we chose to study the removal of polyurethane, which is studied little in the literature. We identified the optimal doses of coagulants and flocculants that help sedimentation of MPs. The efficiency of an installation called Smart Decantation-Filtration System, specially designed to ensure increased efficiency in the removal of microplastics, was determined. The results obtained were encouraging. Full article