Ecological Risk Index Research Articles

Heavy metal concentrations in soil and ecological risk assessment in the vicinity of Tianzhu Industrial Park, Qinghai-Tibet Plateau

Industrial parks in China are centers of intensive chemical manufacturing and other industrial activities, often concentrated in relatively small areas. This concentration increases the risk of soil pollution both within the parks and in surrounding areas. The soils of the Tibetan Plateau, known for their high sensitivity to environmental changes, are particularly vulnerable to human activity. In this study, we examined the concentrations (mg/kg) of 10 metal elements (As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Se, and Zn) in soils at depths of 0–10 cm, 10–20 cm, and 20–30 cm from the surface at three distances (500 m, 1000 m, and 1500 m from the park boundary) on the east, south, west, and north sides of the Tianzhu Industrial Park on the Qinghai-Tibet Plateau. The concentrations of As, Cr, Mn, and Pb were close to the standard reference values for the Qinghai-Tibet Plateau, while Cu, Ni, Se, and Zn levels were found to be 1.6-2.2 times higher than the reference values. Cd and Hg concentrations were particularly concerning, at 8.0 and 6.5 times higher than reference values, respectively. The potential ecological risk indexes indicated persistent risk levels for Cd and Se across various directions and distances. Variations in soil depth and direction were observed for the concentrations of As, Cd, Hg, Pb, Se, and Zn, underscoring the need for regular or long-term monitoring. Cd, in particular, presents a significant hazard due to its high concentration and its propensity for uptake by plants in the study area.

Spatial–temporal effect of sea–land gradient on landscape pattern and ecological risk in the coastal zone: A case study of Dalian City

Abstract Coastal zones have intense human activity and are ecologically fragile. Assessing ecological risks in coastal zones is crucial to promoting ecological safety and sustainable development for coastal cities. However, the relationship between ecological risk assessment and distance from the coastline is indeterminate in current research. To solve this problem, this study constructs the sea–land gradient and reconstructs the landscape pattern index and landscape ecological risk index (ERI) considering the sea–land gradient paradigm. This study aims to analyze the spatial–temporal variation characteristics and effects of the sea–land gradient on landscape pattern and ecological risk in Dalian City from 2000 to 2015. The results show the following: (1) between 2000 and 2015, a significant effect of coastline on the coastal landscape pattern in Dalian is reducing landscape fragmentation. The extent of this influence gradually diminished along the sea–land gradient. The landscape aggregation of urban building sites near the sea was relatively high and gradually increased over the years; (2) in Dalian, the landscape ERI has decreased near the sea and increased near the inland year by year; (3) the dominant pattern of landscape ecological risk was characterized by a transition from high to low levels within the [0, 2.5] km zone, while a transition from low to high levels predominated within the [2.5, Max] km zone; and (4) the northern region in Dalian primarily goes from high to low risk in the buffer zone near the landside, whereas the southern area has this changing pattern in the buffer zone near the seaside.

Integrated Assessment of Metal Contamination of Soils, Sediments, and Runoff Water in a Dry Riverbed from a Mining Area Under Torrential Rain Events

Dry riverbeds can transport mining waste during torrential rain events, disseminating pollutants from mining areas to natural ecosystems. This study evaluates the impact of these mine wastes on soils, sediments, and runoff/pore water in the La Carrasquilla dry riverbed (southeastern Spain). An integrated approach utilizing geochemical and mineralogical techniques was employed, analyzing water, soil, and sediment samples from both the headwater and mouth of the riverbed. Soil profiles and pore water were collected at 30 cm, 60 cm, and 90 cm deep, alongside sediment and runoff water samples. The assessment of metal(loid) contamination focused on arsenic, cadmium, chromium, copper, iron, nickel, manganese, zinc, and lead, utilizing sequential extraction to evaluate metal partitioning across soil phases. Various pollution indices, including the contamination factor (Cf), pollution load index (PLI), potential ecological risk index (RI), and metal(loid) evaluation index (MEI), were employed to classify contamination levels. The highest level of contamination was reported in the headwater, which suggested anthropogenic activities linked to the presence of mining residues as the major source of metal(loid)s. However, an active deposition of As, Cd, Cu, Fe, Mn, and Zn was reported in the topsoil at the mouth. In the headwater, a quartz and muscovite-rich zone exhibited the highest Cf for Pb (1022), primarily bound to the soil residual fraction (62.8%). At the headwater and mouth, pore water showed higher concentrations of sulfate, Ca, Na, Cl, Mg, and Mn and higher salinity than acceptable limits for drinking water or irrigation established by the World Health Organization. Runoff-water metal concentrations surpassed established guidelines, with MEI values indicating significant contamination by cadmium (36.1) and manganese (19.0). These findings highlight the considerable ecological risk of Pb and underscore the need for targeted remediation strategies to mitigate environmental impacts in the Mar Menor coastal lagoon.

Effects of Tide Dikes on the Distribution and Accumulation Risk of Trace Metals in the Coastal Wetlands of Laizhou Bay, China

Tide dikes play a key role in preventing seawater intrusion in coastal regions; however, their effects on trace metal distribution and accumulation remain unclear. This study explored the distribution and enrichment of trace metals (As, Cr, Cu, Ni, Pb, and Zn) inside and outside tide dikes in Laizhou Bay. The accumulative risk of these metals in the two habitats was analyzed by combining their sources. The results show that the average enrichment factor, geological accumulation index, and potential ecological risk index of As in the outside habitat are significantly higher than those in the inside habitat (p < 0.001), which indicates that the tide dike effectively reduces the migration of As from outside to inside habitats. For other trace metals, no statistical differences were found between the two habitats. Based on principal component analysis and redundancy analysis of trace metals and their correlations with soil physicochemical properties, we speculated that Cr and Zn may derive from soil parent material and rock weathering. Cu, Pb, and Ni may be related to atmospheric nitrogen deposition resulting from nearby agricultural activities, and As may come from industrial wastewater or transport through seagoing rivers. The findings suggest that tide dikes effectively block exogenous trace metals but not those from natural sources.

Evaluation of Health Risk and Heavy Metal Pollution Caused by Dust Storms in Zabol City.

This study investigated the concentrations and compositions of specific elements in total suspended particulate (TSP) samples and the associated ecological, carcinogenic, and non-carcinogenic risks related to the inhalation, ingestion, and dermal absorption of heavy metals. The study focused on adult and pediatric populations in the highly dust-polluted city of Zabol, Iran, during 2022-2023. The samples were analyzed by using inductively coupled plasma optical emission spectrometry (ICP-OES). The concentration of metals in milligram per kilogram (mg/kg) was as follows: Al (75053) > Ca (8206) > Fe (5439) > Mg (5323) > Zn (15.27) > Pb (3.66) > Cr (3.38) > Cd (0.011); according to the results, the highest amount of metals related to aluminum and calcium in dust particles. The calculated individual indices, including the ecological risk index (ERI), pollution factor (Cfi), and geographic accumulation index (Igeo), indicated that calcium exhibited minimal pollution, while the metal samples (Al, Mg, Fe, Cd, Cr, Pb, and Zn) were categorized as uncontaminated. The results revealed that the ecological risk factor (Er) is below 40, indicating a low level of contamination. Additionally, the pollution level determined by the ecological risk potential (RI) was less than 150, suggesting a low probability of contamination. Ingestion posed the highest average hazard quotient (HQ) values for both children and adults in terms of non-carcinogenic risk assessment, while cutaneous and inhalation exposures showed lower values. Furthermore, the hazard index (HI) for heavy metals remained below the safe threshold of 1. The risk index (RI) values for lead, cadmium, and chromium were all below 1 × 10-6 in both adult and pediatric populations. The United States Environmental Protection Agency (USEPA) guidelines suggest an acceptable level of carcinogenicity for all heavy metals, indicating a potential risk of cancer associated with the presence of these metals in suspended particles in Zabol.

Characterization and source apportionment of heavy metal pollution in soil around red mud disposal sites using absolute principal component scores-multiple linear regression and positive matrix factorization models.

In recent years, industrial waste and agrochemicals have reduced soil fertility and productivity, significantly impacting food security and ecosystems. In China, areas near red mud deposits from the aluminum industry show severe heavy metal contamination. This study examines agricultural soil near a red mud site in Shanxi Province, analyzing Cd, Cr, Hg, Ni, Pb, As, Cu, and Zn levels and distribution. Geostatistical methods and GIS are utilized to assess heavy metal pollution using the single factor index, the Nemerow integrated index, and the Hakanson potential ecological risk index. Absolute Principal Component Scores-Multiple Linear Regression (APCS-MLR) and Positive Matrix Factorization (PMF) models are used for quantitative analysis of pollution sources. Research indicates that the average concentrations of eight heavy metals exceed the natural background values of Shanxi, placing them at a severe pollution level with moderate ecological risk. Specifically, indices for As, Pb, and Cr are 3.79, 3.38, and 3.26, indicating severe pollution; Cd, Cu, and Hg at 2.36, 2.62, and 3.00 suggest moderate pollution; Ni at 1.87 shows mild pollution, while Zn at 0.97 is not polluted. Hg presents the highest ecological risk with a coefficient of 120.00, followed by Cd (70.69) and As (37.92). Spatial analysis shows significant correlations among Pb, Zn, Cu, and Ni, while Cr, Cd, Hg, and As show greater variability and weaker correlations. Both models identify five main sources: industrial activities, agricultural fertilizers, red mud leachate, energy combustion, and natural geological backgrounds, with respective contribution rates in the APCS-MLR model at 27.7%, 24.6%, 18.1%, 15.2%, and 14.4%, and in the PMF model at 29.2%, 21.5%, 16.9%, 16.7%, and 15.7%. This study offers a scientific basis for controlling soil pollution in the region, filling a literature gap.

Construction of Long-Term Grid-Scale Decoupling Model: A Case Study of Beijing-Tianjin-Hebei Region

Against the backdrop of rapid global economic development, the Beijing-Tianjin-Hebei (BTH) region, a pivotal economic hub and environmentally sensitive area in China, faces significant challenges in sustaining its landscape ecosystem. Given the region’s strategic importance and vulnerability to environmental pressures, this study investigated the intricate relationships between landscape ecological risk, urban expansion, and economic growth (EG) in the BTH region. Utilizing the landscape as the focal point, we constructed a decoupling model at the grid scale to explore the decoupling relationship between the landscape ecological risk index (ERI), construction area growth (CAG), and EG. The results showed that (1) distinct stages and regional disparities were observed in the trends of ERI, CAG, and EG within the BTH region. The hot and cold spot patterns for these factors did not align consistently. (2) From 1995 to 2019, the coupling relationship between ERI, CAG, and EG in the BTH region underwent a fluctuating transition, initially moving from an undesirable state to an ideal state, and subsequently reverting to an undesirable state. Although the overall trends in these relationships showed some convergence, there were notable spatial distribution differences. (3) The spatial heterogeneity of the two decoupling relationships in the BTH region was relatively poor. Further analysis revealed that the evolution of these decoupling relationships was closely intertwined with regional policy shifts and adjustments.

Innovative Perspectives on Ecological Assessment in the Agro-Pastoral Ecotone of Inner Mongolia: An Integrated Evaluation and Forecast of Landscape and Ecological Risks and Drivers

The agro-pastoral ecotone of Inner Mongolia, one of China’s most ecologically vulnerable regions, requires careful evaluation and prediction of landscape ecological risks to improve its environment and support sustainable development. Our study built a model to assess the landscape ecological risks from 1990 to 2020 using land use data from Google Earth Engine. We examined the changes in landscape ecological risks and their driving factors through spatial autocorrelation analysis and geographic detectors. Future ecological risks from 2025 to 2040 were predicted using the multi-criteria evaluation-cellular automata-Markov model. Results revealed a declining trend in both disturbance and loss intensity across land use types, with the overall ecological risk index also decreasing. Higher risk areas were concentrated in the east and southwest, while lower risks were observed in the north and center. Temperature and precipitation are key natural factors, while the impact of Gross Domestic Product (GDP), a human factor, on ecological risk is increasing and surpassed natural influences in 2015 and 2020. In the future, the highest risk areas will remain in the southwest and northeast. This study provides detailed evidence and guidance for ecological safety and sustainable development in the agro-pastoral ecotone of Inner Mongolia.

Characterization and ecological health risks of microplastics in the water and sediment of Xinyanggang River Estuary

ABSTRACT Microplastic (MP) pollution in aquatic environment has increased concerns. This study comprehensively examined properties and health risk to ecosystem of MPs in Xinyanggang River Estuary. Monthly sampling in 2023 detected MPs in water column (6.7 ± 0.55–11.6 ± 0.63 particles/L) and sediment (6.2 ± 0.78–10.2 ± 0.53 particles/g), with abundance peaking in summer, coinciding with the rainy season. The major features of the detected MPs included transparency and fiber, rayon, PVDF, PS, PE and PP composition. The dominant size fraction of detected MPs was 0.001–0.25 mm. Ecological risk assessment suggested relatively low load of MPs entering the Xinyanggang Estuary. However, polymer risk index (PRI) and potential ecological health risk index (PERI) suggested that MPs in Xinyanggang River are hazardous to ecosystem. This study firstly characterized MP contamination in Xinyangang River Estuary, and the provided results can guide the management of MPs in water environment more broadly.

Assessment of contamination levels, potential ecological and human health risks due to trace elements pollution in the vicinity of the Lolodorf uranium deposit, Southern Cameroon.

The current study assessed the contamination levels and associated ecological and health risks due to hazardous trace elements in soils from Awanda and Mvengue, located in the vicinity of the Lolodorf uranium deposit in Southern Cameroon. Qualitative and quantitative analyses of the soil samples were performed using energy-dispersive X-ray spectrometry. The results indicated that the mean concentrations of metallic and trace elements in soil samples increased in the following order: U < As < Th < Pb < Cu < Ni < Zn < Cr < Mn < Fe < Al. The average concentrations of U, As, Th, Pb, Cu, Ni, Zn, Cr, Mn, Fe, and Al ranged between 0.9-3, 2.9-3.8, 9.2-15, 13.1-20.3, 11.5-42.5, 31.1-60.7, 42.9-91.6, 94.50-170.9, 100.45-500.57, 4874.8-88340 and 226147.5-324240.0mg/kg, respectively. The contamination levels of trace elements were assessed and the human health risk of chemical elements was determined. The investigated elements' average contamination factors (CF) results showed the highest mean CF recorded for Al followed by Cr, Th, Pb, Zn, Cu, Ni, Fe, U, Mn, and As. Furthermore, the findings showed that 90% of soil samples can be classified as considerably contaminated with Al, 100%, and 60% as moderately contaminated with Cr and Th, respectively. The Geo-accumulation indices of Mn, Cr, Th, U, Ni, Zn, Cu, As, and Pb were lower than 1, suggesting low contamination levels for these elements. The ecological factors and risk indices indicated a low ecological risk in the investigated area. In terms of human health risk, ingestion was identified as the primary pathway for both carcinogenic and non-carcinogenic risks, with children found to be more exposed to both risks than adults. Al, Cr, and Fe were found to be the main contributors to non-carcinogenic health risks, while Cr and Ni were the main contributors to carcinogenic health risks.

Microplastics pollution in tropical estuary (Muttukadu Backwater), Southeast Coast of India: Occurrence, distribution characteristics, potential sources and ecological risk assessment

Around the world, microplastic pollution is pervasive and is regarded as the biggest threat to all ecosystems. We conducted the present study to determine the prevalence of microplastics (MPs), their polymer hazard risk (PHI), and any potential sources of these particles in the estuary of Muttukadu Backwater, Southeast Coast of India. Microplastics were extricated from surface water and sediment by the wet peroxide method, identified by a stereo zoom microscope (SM), and characterized by ATR-FTIR and SEM-EDS analysis. The average microplastic abundance in sediment and surface water was 815±158 particles Kg−1 and 195±38 particles m−3, respectively. The most common microplastics based on shapes were fibers and fragments in both sediment and surface water, with blue and green-colored microplastics being the most frequently observed colors. Type II polymer particles (<3.00 mm–1.00 mm) are dominant particles in sediment (36 %), and type I (5.00 mm–3.00 mm) particles dominate in surface water samples (49 %). Energy dispersive X-ray spectrometer (EDS) results showed that the following chemical elements, such as O, C, Cl, Fe, Na, Al, K, Ca, and Si, as well as the order of the trace metal Pb > Cr > Ni > Co > As > Cu > Cd > Zn, are observed by microplastics of all sediment sampling location. The pollution load index (PI), polymer hazard index (PHI), and potential ecological risk (PER) index models revealed varying level of risk. The polymer hazard index (PHI) reveals that both water and sediments are moderate to highly MP contamination. The hazards of polymers such as polyethylene, polystyrene, polyester, and polyamide significantly contributed to hazard level IV. Inadequate plastic waste management, human habitation and tourism, rapid industrialization, and coastal construction are the main sources of microplastic contamination in the study area. The proper guidelines, potential policies, and technological interventions are much needed to reduce the microplastic contamination along Southeast Coast of India.

Pollution assessment, ecological risk and source identification of heavy metals in paddy soils and rice grains from Salem, South India

The present study investigated concentrations of metals (Cu, Zn, Fe, Mn, Ni, Pb, and Cd) in paddy soils and rice tissues of nine different widely used indica rice varieties in Salem district, India. The order of DTPA soil available metal contents (mg kg-1) were Fe (33.50) > Mn (8.86) > Cu (2.58) > Pb (1.99) > Zn (1.67) > Ni (1.48) > Cd (0.13). Pollution load index (PLI) levels for Cd (1.28) were ‘moderately polluted’, contamination factor (CF) and enrichment factor (EF) values for all metals showed ‘medium contamination’ and ‘less enrichment’ except for Cu and Pb. Ecological risk factor (ERF) and potential ecological risk index (PRI) values of Cd (31.94 and 287.50) showed ‘moderate risk’ and ‘strong ecological risk’. Bio-accumulation factor (BAF) levels of Cd (48.12) and Pb (27.89) are classified as ‘high concentrators’. Translocation factor (TF) values of Pb (2.9), Cd (2.5) and Ni (1.7) were greater than one for roots to plants. Children had higher target hazard quotient (THQ) and hazard index (HI) values for Cd, Pb and Ni than adults. Principal component analysis (PCA) revealed with all parameters that they fell within the two primary factors 1 and 2, with an eigenvalue of 4.69 (33.52% variation) and 3.73 (26.66% variation), respectively. However, cluster analysis (CA) revealed three distinct groups between the metals studied. Although the soil metal contents were within the permissible levels, the grain Cd (6.07 mg kg-1), Pb (56.20 mg kg-1), and Fe (116.11 mg kg-1) contents in all the rice varieties exceeded the prescribed limits of 0.4, 0.2, and 15 mg kg-1, respectively. Our findings will provide important data for metal enrichment in soils to implement more effective measures to reduce the contamination of metals in paddy fields.

The influence of water conservancy project on microplastics distribution in river ecosystem: A case study of Lhasa River Basin in Qinghai-Tibet Plateau

Water conservancy projects affect the migration, suspension, and deposition of microplastic (MP). However, its impact on MP pollution of river ecosystem remains elusive. Herein, we investigated the MP characteristics and the influence of water conservancy projects on MPs in the Lhasa River Basin of the Qinghai-Tibet Plateau, China. The results demonstrated that the MPs concentration in surface water decreased from upstream to downstream, as more MPs in surface water were settling down and stored in reservoir sediments in the midstream. It is postulated that reservoir sedimentation of MPs occurs at a greater rate due to the barrier effect of reservoirs, steady hydrodynamics, and weak salinity-induced buoyancy. To evaluate the ecological risk of the Lhasa River Basin, the pollution load index, the polymer hazard index, and the potential ecological risk index were analyzed. The upstream exhibits elevated polymer hazard index values (>100), and the potential ecological risk index values in the Lhasa River Basin showed ecological risk similar to those of pollution load index values. This research represents the initial exploration of MP distribution within the entire Lhasa River basin, providing a foundational framework for investigating the impact of water conservancy projects on MP migration.

Potential ecological risk assessment of microplastics in environmental compartments in Mexico: A meta-analysis.

Microplastic (MP) environmental contamination has been widely studied in Mexico; however, the evaluation of the associated risk to MP in environmental compartments is scarce. Therefore, this study addresses this issue using diverse indicators such as the Pollution Load Index (PLI), the Polymer Risk Index (PRI), and the Potential Ecological Risk Index (PERI). The results of a meta-analysis revealed high MP contamination levels in most of the studied compartments, which included marine and estuarine waters, beach sand, freshwater, sediments, and biota. Regarding the risk assessment indicators, PLIs indicated low (56%), dangerous (22%), moderate (12%), and high (10%) levels across compartments. Meanwhile, PRIs displayed concerning values, with 36%, 35%, 20%, and 9% exhibiting dangerous, high, moderate, and low levels, respectively. Thus, high PRI values emphasized the significant rise in MP pollution, largely attributed to high-hazard polymer compositions. Otherwise, PERIs showed low (56%), very dangerous (29%), moderate (6%), high (5%), and dangerous (4%) levels. Thus, the ecological risk in Mexico is widespread and mainly linked to MP abundance, polymer type, environmental matrix, and organisms' characteristics. This study represents the first attempt at MP ecological risk assessment in Mexico, providing crucial insights for developing mitigation strategies to address concerns about MP contamination.

Conversion of recovered phosphorus tailings into high-value lightweight ceramic materials and evaluation of environmental safety

In recent years, the substantial production and underutilization of phosphorus tailings have prompted an intensified search for innovative strategies to mitigate their accumulation and the associated hazards they present. This investigation the utilization of phosphorus tailings as a raw material for the cost-effective production of lightweight ceramic materials using the foaming-gel casting method. The impact of the stirring process on lightweight ceramic materials was investigated, encompassing mineral composition, pore structure, properties, and environmental safety assessment. The investigation utilized slurry volumetric foaming rate, XRD, SEM, ICP-MS, and potential ecological risk index (RI) for analysis. The findings suggested that the lightweight ceramic material, obtained by stirring at 1300rpm for 15min, exhibited the densest structure and excellent properties. It had a porosity of 79.19%, a bulk density of 0.59g/cm3, and a compressive strength of 6.08MPa. Besides, the leaching concentration and RI of lightweight ceramic materials complied with national (GB 8978-1996) and US EPA standards. This study aimed to enhance the sustainable production capacity of lightweight ceramic materials and offered data support for the value-added application and performance optimization of phosphorus tailings in the production of lightweight ceramic materials.

Exploring the traits and possible ecological risks of heavy metals in biochars derived from rice husk and sugar beet pulp.

This research investigated the properties and potential environmental hazards associated with biochars derived from rice husk (RH) and sugar beet pulp (SBP), both of which are rich in heavy metals (HMs). The results indicated that the concentration of various HM fractions is significantly affected by the type of feedstock and the pyrolysis temperature. Specifically, the total concentrations of HMs in biochars produced at 600°C were found to be 10-140% higher than those in the original biomasses, a phenomenon attributed to the precipitation of HMs. Cd was a notable exception, exhibiting a reduction of 3-7% in the resultant biochars when compared to biomass, likely attributable to its volatilization. The results also revealed that the F1 + F2 fraction of HMs were largely transformed into F3 + F4 fraction during combustion, indicating that pyrolysis may reduce the ecotoxicity of HMs present in contaminated biomass. However, the process did not effectively diminish the F1 and F2 fractions of Cr and Cd. Elevated pyrolysis temperature significantly enhanced the reduction of HMs phytoavailability. Specifically, the phytoavailability of HMs in biochars produced at 600°C exhibited a decrease ranging from 10 to 92% when compared to the original biomass. Conversely, an unexpected rise in the phytoavailable fractions of Cr and Cd was noted in both RH and SBP biochars as the pyrolytic temperature increased, which correspondingly raised the potential ecological risk index (PERI). All materials analyzed exhibited a very high risk level, with PERI values exceeding 800, primarily due to the significant toxicity of Cd. Excluding Cd from consideration, the biomasses and their resultant biochars displayed PERI values ranging from 7 to 13. It is important to acknowledge that pyrolysis may not effectively diminish the environmental toxicity associated with HMs present in contaminated biomass, thereby limiting its safe application.

Spatiotemporal Distribution of Mercury in Tree Rings and Soils Within Forests Surrounding Coal-Fired Power Plants

The release of mercury (Hg) from coal-fired power plants (CPPs) into local ecosystems poses substantial environmental and health hazards. This study was conducted in Chungcheong-nam-do, South Korea, a region featuring over half of the country’s coal power facilities, to estimate the impacts of CPPs on Hg distribution in forest ecosystems. By analyzing Hg concentrations in pine tree rings and soil at 21 locations around CPPs and comparing them to control sites and industrial zones, we present a nuanced understanding of the effects of CPPs on Hg concentration. The analysis of Hg concentrations in tree rings showed a significant decrease in Hg levels as the distance from the power plants increased, suggesting that CPPs primarily influence Hg distribution in trees within a 25 km radius. In contrast, soil Hg concentrations did not exhibit a clear trend. This may reflect the limitations of this study in accounting for the physicochemical properties of the soil at each sampling site. Nevertheless, the Potential Ecological Risk Index for soil Hg contamination indicated a higher risk rating within a 1 km radius of the CPPs compared to other locations. Hg concentrations in tree rings have shown a steady decline since the 1970s, suggesting the positive effects of air pollution regulations. This also highlights the value of tree core samples as effective tools for monitoring historical Hg pollution. Furthermore, the higher historical concentrations of Hg in tree rings imply that trees may have acted as sinks for atmospheric Hg in the past.

Combined contamination of tire and road wear microplastics with heavy metals in expressway tunnels: occurrence characteristics and risk assessment

Tire and road wear microplastics (TRWMPs), as an important type of microplastics, have attracted increasing attention. However, current studies on their contamination within expressway tunnels remain limited. Therefore, we investigated the occurrence characteristics of TRWMPs in dusts from various tunnels, and combined contamination with heavy metals (HMs). The results showed that the abundance of TRWMPs in expressway tunnel dust (53,778 n/kg) was much higher than that sampled from other land use types (1360–4960 n/kg) in the same region. A large amount of polyamide was released into the environment along with wear particles from the vehicles. Also, the abundance of TRWMPs inside tunnels was greater than outside, and the proportion of large-size TRWMPs was higher inside tunnels. TRWMPs was symmetrically distributed with respect to the center of expressway tunnel. The pollution load index (PLI) and ecological risk index (H) indicated that study area was heavily contaminated with TRWMPs. There was a significant positive correlation between the abundance of TRWMPs and concentration of Cr (p < 0.01) in dust, and their risk assessment and health risk fluctuations were almost identical. Thus, the study is of great significance for elucidating the synergistic contamination and potential risk of TRWMPs and HMs in expressway tunnels.

Ecological and Human Health Risk Assessment Based on Stream Sediments from Coastal Oecusse (Timor)

Timor Island is located in a geologically complex region strongly affected by the collision of the Australian margin with the Banda volcanic arc. In Oecusse, an enclave of East Timor in the western part of Timor, crop out several lithological units of the Banda Terrane that are associated with the obduction of oceanic crust and upper mantle on the Australian continental crust. This study reports the geochemistry of stream sediments from the coastal region of the Oecusse enclave, where the Banda Terrane is best represented, employing statistical analyses to discern the sources of metal(oid)s and assessing ecological and health risks. Arsenic, Cr, and Ni are the elements with higher potential ecological risk factors. The potential ecological risk index (PERI), which combines single indexes of ecological risk factors for multiple elements, is very high in a stream sourced by the Lolotoi-Mutis Complex. Significant risks for human health were found for As (sourced by the Lolotoi-Multis Metamorphic Complex and basalts of the Barique Formation), Mn (sourced by the Maubisse and Barique formations), and V (sourced by the Manamas Formation). The highest values of hazard index (HI), however, were determined with Cr, in particular for children (HI higher than 10 in 12 sediments sourced by ultramafic units and their covering sedimentary units). This investigation shows that high geogenic concentrations of several elements, particularly those derived from the oceanic crust and the upper mantle, raise significant cancer and non-carcinogenic risks.

Spatial distribution, ecological and human health risks of potentially toxic elements (PTEs) in river Ravi, Pakistan: A comprehensive study

Significant quantities of potentially toxic elements have been and are still being discharged into Pakistan's rivers through natural sources and anthropogenic activities. The present study provides a comprehensive study of potentially toxic element contamination in the water and sediment of the Ravi River, Pakistan. The research aims to examine the extent of pollution, its ecological risks, and the potential human health impacts through detailed geospatial analysis and statistical correlation. Water and sediment representative samples were taken and analyzed for potentially toxic elements, including Cobalt (Co), Cadmium (Cd), Zinc (Zn), Nickel (Ni), Arsenic (As), Chromium (Cr), Lead (Pb), Copper (Cu), and Manganese (Mn). Various pollution indices, such as the “Geo-accumulation Index (Igeo), Modified degree of Contamination (mCd), Nemerow comprehensive pollution index (Pt), Contamination factor (CF), Enrichment factor (EF), Pollution Load Index (PLI), and Potential Ecological Risk Index (PERI),” were calculated to determine the contamination levels and ecological risks. The results indicated significant spatial variability in metal concentrations, with higher levels observed in industrial and urban areas (near Lahore). Cd and As were identified as the most critical pollutants, exhibiting high Igeo, CF, EF, and PERI values. The PLI revealed that several regions along the river are heavily polluted. Pt shows high comprehensive pollution near Lahore and moderate to high pollution in surrounding areas. According to mCd, most of the study area, especially sampling points near Lahore, ranges between 8 and 16, indicating a high degree of pollution. The Human Health Risk (HHR) assessment, considering ingestion, inhalation, and dermal contact pathways, highlighted that children are particularly vulnerable, showing higher Hazard Quotient (HQ) and Hazard Index (HI) values for several metals. Correlation analysis revealed significant relationships between certain metals, suggesting common sources of contamination, likely from industrial discharges and urban runoff. The comprehensive mapping and statistical analysis underscore the urgent need for implementing effective pollution control measures to mitigate the risks posed by potentially toxic element contamination in the Ravi River. This study provides critical insights for policymakers and environmental managers to prioritize areas for remediation and to develop strategies to protect both ecological and human health in the region.