Source identification and implications of heavy metals in urban roads for the coastal pollution in a beach town, Busan, Korea

Exploring the environmental risks and seasonal variations of potentially toxic elements (PTEs) in fine road dust in resource-based cities based on Monte Carlo simulation, geo-detector and random forest model

The environmental pollution caused by mineral exploitation and energy consumption poses a serious threat to ecological security and human health, particularly in resource-based cities. To address this issue, a comprehensive investigation was conducted on potentially toxic elements (PTEs) in road dust from different seasons to assess the environmental risks and influencing factors faced by Datong City. Multivariate statistical analysis and absolute principal component score were employed for source identification and quantitative allocation. The geo-accumulation index and improved Nemerow index were utilized to evaluate the pollution levels of PTEs. Monte Carlo simulation was employed to assess the ecological-health risks associated with PTEs content and source orientation. Furthermore, geo-detector and random forest analysis were conducted to examine the key environmental variables and driving factors contributing to the spatiotemporal variation in PTEs content. In all PTEs, Cd, Hg, and Zn exhibited higher levels of content, with an average content/background value of 3.65 to 4.91, 2.53 to 3.34, and 2.15 to 2.89 times, respectively. Seasonal disparities were evident in PTEs contents, with average levels generally showing a pattern of spring (winter) > summer (autumn). PTEs in fine road dust (FRD) were primarily influenced by traffic, natural factors, coal-related industrial activities, and metallurgical activities, contributing 14.9-33.9 %, 41.4-47.5 %, 4.4-8.3 %, and 14.2-29.4 % to the total contents, respectively. The overall pollution and ecological risk of PTEs were categorized as moderate and high, respectively, with the winter season exhibiting the most severe conditions, primarily driven by Hg emissions from coal-related industries. Non-carcinogenic risk of PTEs for adults was within the safe limit, yet children still faced a probability of 4.1 %-16.4 % of unacceptable risks, particularly in summer. Carcinogenic risks were evident across all demographics, with children at the highest risk, mainly due to Cr and smelting industrial sources. Geo-detector and random forest model indicated that spatial disparities in prioritized control elements (Cr and Hg) were primarily influenced by particulate matter (PM10) and anthropogenic activities (industrial and socio-economic factors); variations in particulate matter (PM10 and PM2.5) and meteorological factors (wind speed and precipitation) were the primary controllers of seasonal disparities of Cr and Hg.

Risk assessment and source identification of soil heavy metals: a case study of farmland soil along a river in the southeast of a mining area in Southwest China

To investigate the heavy metals (HMs) contamination of surface farmland soil along the river in the southeast of a mining area in southwest China and identify the contamination sources, 54 topsoil samples were collected and the concentrations of seven elements (Zn, Ni, Pb, Cu, Hg, Cr, and Co) were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) and atomic fluorescence spectrometry (AFS). The geo-accumulation index ([Formula: see text]) and comprehensive potential ecological risk index ([Formula: see text]) were used for analysis to determine the pollution degree of HMs and the risk level of the study area. Meanwhile, the Positive Matrix Factorization (PMF) model was combined with a variety of statistical methods to determine the sources of HMs. To explore the influence of the river flowing through the mining area on the concentrations of HMs in the farmland soil, 15 water samples were collected and the concentrations of the above seven elements were determined. The results showed that the concentrations of Pb, Cu, and Zn in soil all exceeded the risk screening value, and Pb in soil of some sampling sites exceeded control value of "Agricultural Land Soil Pollution Risk Control Standard".[Formula: see text] showed that Pb was heavily contaminated, while Cu and Zn were moderately contaminated. RI showed that the study area was at moderate risk. PMF and various statistical methods showed that the main source of HMs was the industrial source. In the short term, the river flowing through the mine has no significant influence on the concentration of HMs in the soil. The results provide a reference for the local government to control contamination and identify the sources of HMs.

Application of Ionic Liquid Crosslinked Hydrogel for Removing Heavy Metal Ions from Water: Different Concentration Ranges with Different Adsorption Mechanisms

Heavy metal wastewater poses a significant environmental challenge due to its harmful effect on organisms and difficult biodegradation. To address this issue, hydrogel has been used as a promising solution for the adsorption of heavy metal ions in water, offering advantages such as low cost, simple design, and environmental friendliness. In this study, we synthetized a novel poly-acrylamide/acrylic acid/vinyl imidazole bromide (PAM/AA/[Vim]Br₂) hydrogel as an effective adsorbent for the removal of Ni^II, Cu^II, Zn^II, and Cr^III from water. The structure of the hydrogel was characterized by using techniques such as Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). By exploring various parameters such as monomer ratio, neutralization degree, crosslinking agent addition amount, and initiator addition amount, the highest swelling ratio of the PAM/AA/[Vim]Br₂ hydrogel reached 40,012%. One of the notable aspects of this study lay in the investigation of the adsorption behavior of the hydrogel towards heavy metal ions at different concentrations. The adsorption isotherm calculations and X-ray photoelectron spectroscopy (XPS) analysis revealed distinct adsorption mechanisms. At low concentrations, the hydrogel exhibits a multilayer physical adsorption mechanism, with heavy metal ion removal rates exceeding 80%; while at high concentrations, it demonstrates a monolayer chemical adsorption mechanism, with heavy metal ion removal rates above 90%. This dual mechanism approach distinguishes our study from previous reports on the removal of heavy metal ions using hydrogels and shows good ion adsorption efficiency at both high and low concentrations. To the best of our knowledge, this is the first report to explore the removal of heavy metal ions from water using hydrogels with such intriguing dual mechanisms. Overall, the utilization of the PAM/PAA/[Vim]Br₂ hydrogel as an adsorbent for heavy metal ion removal presents a promising and innovative approach, contributing to the development of environmentally friendly solutions for heavy metal wastewater treatment.

Multi-element features and trace metal sources of road sediment from a mega heavy industrial city in North China

As the primary carrier of harmful elements, road sediment poses severe hazards to human health and ecological environment, especially in megacities. Based on the industrial cities in North China, this research focused on the multi-element features and the pollution levels, sources, and spatial distributions of trace metals in road sediment of Shijiazhuang. The mean levels of P (928.4 mg kg^-1), S (1446.2 mg kg^-1), Cl (783.9 mg kg^-1), Br (5.3 mg kg^-1), Na₂O (2.0%), CaO (9.9%), Co (36.0 mg kg^-1), Pb (38.0 mg kg^-1), Cu (34.7 mg g^-1), Zn (149.1 mg kg^-1), Ba (518.1 mg kg^-1), and Sr (224.9 mg kg^-1) in road sediment were greater than their soil background values. Trace metals in most samples was moderately (75%) and heavily contaminated (15.6%). The industrial areas, congested roads, and residential areas in the northeast, middle and south of Shijiazhuang are the hotspots of trace metals pollution. A comprehensive analysis of trace metals sources indicated that Ni, V, Ga, Rb, Y, Sc, La, Ce, Zr, and Hf were mainly from natural source, which contributed to 34.2% of the total trace metals concentrations. Cu, Pb, Zn, Cr, Ba, Sr, and Mn primarily originated from mixed source, which accounted for 46.5%. Co principally came from building source, which accounted for 19.3%. This study shows that industrial discharges, construction dust and traffic emissions are the primary anthropogenic sources of trace metals in road sediment in the study area.

Trace metals in urbanized coasts: The central Atlantic of Morocco as a case study

This study describes the contamination, accumulation, and ecological risk assessment of five trace metals (Cd, Pb, Cu, Zn, and Cr) in sediments of an urbanized beach in the central Atlantic coastline of Morocco. The two-year investigation (2018 and 2019) included six sampling sites along a 6 km coastal reach. In both years, none of the studied trace metals exceeded the background or the sediment quality guidelines (SQGs). The eco-toxicological indices revealed low degree of contamination, unpolluted ecosystem, and low ecological risk of metals. However, Cd exceeded the background value and some SQGs following the increase of anthropogenic activities in 2019. Likewise, it indicated unpolluted to moderately polluted sediment as well as moderate ecological risk. Overall, it is highly recommended to mitigate the avoidable anthropogenic activities (marine litter generation, sewage discharge, intense urbanization, and vehicle traffic on the beach) that lead to the elevation of metal pollution in the study area.

Heavy Metal Pollution and Risk Assessment of Surface Dust in the Arid NW China

High concentrations of heavy metals (HMs) in urban surface dust (USD) can be extremely hazardous to urban ecology and human health. Oasis cities are located at the edge of deserts and are more exposed to salt/sandstorms, and they face a significantly higher accumulation of USD than wet or semi-humid areas. However, systematic studies on the pollution and risk assessment of HMs in USD in oasis cities have rarely been conducted. This study systematically analyzed the enrichment status, spatial distribution, pollution levels, health risks, and sources of HMs in USD in a typical oasis city (Changji city). The results showed that the average concentrations of Pb, Ni, As, Cd, Hg, and Cu in the USD of Changji city were 46.83, 26.35, 9.92, 0.21, 0.047, and 59.33 mg/kg, respectively, and the results of the pollution index evaluation showed moderate Pb, Hg, and Cu pollution, mild Cd pollution, and no Ni or As pollution. The spatial distribution of HM concentrations in the USD was substantially heterogeneous. High values of Pb, Hg, and Cu concentrations were mainly observed in areas with relatively intensive transportation and commercial activities, and high values of Cd and Ni were observed in industrial areas. The health risk assessment showed that HMs do not pose non-carcinogenic risks to humans at their current level, but they pose a carcinogenic risk to children, with As contributing the largest carcinogenic and non-carcinogenic risks. The source identification of HMs showed that the main pollution of HMs were traffic sources for Pb and Cu, industrial sources for Ni and Cd, natural sources for As, and coal-fired sources for Hg. According to the results of the quantitative analysis with the positive matrix factorization, the contribution of pollution sources followed this order: industrial sources (31.08%) > traffic sources (26.80%) > coal-fired sources (23.31%) > natural sources (18.81%).

Distribution of typical antibiotic resistance genes in underlying surface sediments from urban commercial public squares and their potential hosts

Increasing attention has been paid to antibiotic resistance genes (ARGs) in environments. However, no available literature could be found on ARGs contamination in urban underlying surface sediments. In this study, sediments from commercial public squares around Nanjing (China) were selected for the investigation of target ARGs distribution, showing that intracellular ARGs (iARGs) in particles were the dominant with their relative abundances in descending order of 4.82 × 10^-2 copies/16S rRNA (<0.063 mm), 4.18 × 10^-2 copies/16S rRNA (0.063-0.125 mm), 3.70 × 10^-2 copies/16S rRNA (0.25-0.5 mm), 3.44 × 10^-2 copies/16S rRNA (0.5-1 mm), 3.20 × 10^-2 copies/16S rRNA (0.125-0.25 mm) and 9.53 × 10^-3 copies/16S rRNA (1-2 mm), which was different with that of extracellular ARGs (eARGs). The influence of street sweeping on ARGs levels indicated that the species and relative abundances for both iARGs and eARGs in sediments from different sites were not consistent with the corresponding population densities. The correlation between ARGs and dominant bacterial communities implied that both Firmicutes and Bacteroidetes were positively correlated with ARGs (P < 0.01). The role of solar UV disinfection demonstrated that UV irradiation could inactivate antibiotic resistance bacteria (ARB) slightly with 0.5-1.0 log reduction, implying a considerable risk of ARB after solar irradiation. Our results suggested that it would need the more effective sweeping modes for the cleaning of small particles (<0.25 mm) and the higher disinfection to ARGs potential hosts (like Firmicutes and Blastocatella).

Risk assessment and spatial distribution of heavy metal in street dusts in the densely industrialized area

Street dust samples can be used as an indicator for pollution monitoring especially in big cities. Various environmental problems have been experienced in Dilovasi, Turkey, and studies have been carried out in many different areas; however, no study has been conducted to examine the heavy metal content in street dusts. Therefore, in this study, 20 heavy metals, namely Si, Fe, Al, Zn, Mn, Ti, Cr, Ba, Pb, Ni, Sr, V, Co, Cd, Sb, As, Sn, Mo, Sc and Ag, in the street dusts of Dilovasi were investigated at 40 sampling points. Samples were analyzed with ICP-MS and ICP-OES. The concentrations were from 0.01 mg/kg for Ag to 42,645.48 mg/kg for Si. The Igeo values were in the range of 0.02 for Ag and 8.03 for V. The average EF value was 29.67, which indicates a very high pollution level. ERI was found as 300.74. This value being 300-600 indicates a considerable ecological risk level for the region. According to PCA, the predominant anthropogenic contribution of metal pollution in this area was due to traffic and vehicle-related activities and industrial activities and their waste. Metal pollution from residential areas and natural resources was relatively low, but it was another source of pollution.

Biodiversity and Transportation Infrastructure in the Republic of Korea: A Review on Impacts and Mitigation in Developing the Country

The construction and continued use of transportation infrastructure, specifically roads, has had a significant global impact on biodiversity and the environment. The Republic of Korea, or South Korea, has a road density of 1.13 km/km2. So far, three nationwide studies about vertebrate road-killed species have been reported, showing bias towards medium to large mammals, the most common victims being the Korean water deer (Hydropotes inermis), Korean hare (Lepus coreanus), Siberian roe deer (Capreolus pygargus), and the common raccoon dog (Nyctereutes procyonoides). Road-kills, or wildlife-vehicle collisions (WVCs), tend to occur in or near preferred habitat types or in highly fragmented areas, with roads additionally being linked to habitat fragmentation and loss. Alongside WVCs and habitat effects, information about other adverse effects on biodiversity is scant, although there are reports that heavy metals and other pollutants from road runoff impact marine biodiversity, vegetation, soil, and groundwater. Furthermore, roads have been linked to a prevalence of invasive plant species. To mitigate road impacts, the South Korean government has constructed, with mixed results, 530 wildlife crossing structures, mainly including overpasses and tunnels. To mitigate road impacts more effectively, the country will need more construction, monitoring, and consistent management of wildlife crossing structures. Further, incorporating plans for wildlife crossing structures in early stages of road development will be required.

Identification of Metal Contamination Sources and Evaluation of the Anthropogenic Effects in Soils near Traffic-Related Facilities

Traffic-related facilities typically have much lower metal emissions than other sources; however, they can be numerous and widespread as well. Subdividing pollution sources is necessary to assess soil contamination characteristics and identify sources according to the contamination cause. Anthropogenic contamination by metals was quantitatively determined using contamination factor (Cf) and evaluated using multivariate analysis. More than half of the concentrations for Zn, Pb, and Cu in soils were higher than that in the natural background (NB). Cf of metals was, in decreasing order, Zn > Pb = Cu > Ni = As. Zn, Pb, and Cu were identified as anthropogenic contaminants in correlation analysis. Principal component analysis showed that the two main contamination causes were coarse particles from the maintenance or crushing activities of vehicles and nonexhaust/exhaust emissions. Clusters were classified according to those two anthropogenic and lithogenic causes and included Group I (Zn, Pb, and Cu in garages, auto repair shops, and auto salvage yards), Group II (Zn, Pb, and Cu in parking lots, driving schools, and roadsides), and Group III (As and Ni with high lithogenic properties). Anthropogenic input and sources of soil contamination by metals in traffic-related facilities were appropriately estimated through the combination of Cf and multivariate analysis.

Sources of and Control Measures for PTE Pollution in Soil at the Urban Fringe in Weinan, China

The environment of the urban fringe is complex and frangible. With the acceleration of industrialization and urbanization, the urban fringe has become the primary space for urban expansion, and the intense human activities create a high risk of potentially toxic element (PTE) pollution in the soil. In this study, 138 surface soil samples were collected from a region undergoing rapid urbanization and construction—Weinan, China. Concentrations of As, Pb, Cr, Cu, and Ni (Inductively Coupled Plasma Mass Spectrometry, ICP-MS) and Hg (Atomic Fluorescence Spectrometry, AFS) were measured. The Kriging interpolation method was used to create a visualization of the spatial distribution characteristics and to analyze the pollution sources of PTEs in the soil. The pollution status of PTEs in the soil was evaluated using the national environmental quality standards for soils in different types of land use. The results show that the content range of As fluctuated a small amount and the coefficient of variation is small and mainly comes from natural soil formation. The content of Cr, Cu, and Ni around the automobile repair factory, the prefabrication factory, and the building material factory increased due to the deposition of wear particles in the soil. A total of 13.99% of the land in the study area had Hg pollution, which was mainly distributed on category 1 development land and farmland. Chemical plants were the main pollution sources. The study area should strictly control the industrial pollution emissions, regulate the agricultural production, adjust the land use planning, and reduce the impact of pollution on human beings. Furthermore, we make targeted remediation suggestions for each specific land use type. These results are of theoretical significance, will be of practical value for the control of PTEs in soil, and will provide ecological environmental protection in the urban fringe throughout the urbanization process.

Traffic-related microplastic particles, metals, and organic pollutants in an urban area under reconstruction

In urban environments, particularly areas under reconstruction, metals, organic pollutants (OP), and microplastics (MP), are released in large amounts due to heavy traffic. Road runoff, a major transport route for urban pollutants, contributes significantly to a deteriorated water quality in receiving waters. This study was conducted in Gothenburg, Sweden, and is unique because it simultaneously investigates the occurrence of OP, metals, and MP on roads and in stormwater from an urban area under reconstruction. Correlations between the various pollutants were also explored. The study was carried out by collecting washwater and sweepsand generated from street sweeping, road surface sampling, and flow-proportional stormwater sampling on several occasions. The liquid and solid samples were analyzed for metals, polycyclic aromatic hydrocarbons (PAH), oxy-PAH, aliphatics, aromatics, phthalates, and MP. The occurrence of OP was also analyzed with a non-target screening method of selected samples. Microplastics, i.e. plastic fragments/fibers, paint fragments, tire wear particles (TWP) and bitumen, were analyzed with a method based on density separation with sodium iodide and identification with a stereo microscope, melt-tests, and tactile identification. MP concentrations amounted to 1500 particles/L in stormwater, 51,000 particles/L in washwater, and 2.6 × 10⁶ particles/kg dw in sweepsand. In stormwater, washwater and sweepsand, MP ≥20 μm were found to be dominated by TWP (38%, 83% and 78%, respectively). The results confirm traffic as an important source to MP, OP, and metal emissions. Concentrations exceeding water and sediment quality guidelines for metals (e.g. Cu and Zn), PAH, phthalates, and aliphatic hydrocarbons in the C₁₆-C₃₅ fraction were found in most samples. The results show that the street sweeper collects large amounts of polluted materials and thereby prevents further spread of the pollutants to the receiving stormwater.

Potentially toxic elements pollution in road deposited sediments around the active smelting industry of Korea

Potentially toxic elements (PTEs) were investigated in the different sizes of road deposited sediments (RDS) around the active smelting industry to understand their sources and to assess the pollution and ecological risk levels. The highest PTEs concentrations was shown near the raw materials import port and the smelting facilities. The fine particles of RDS showed extremely high PTEs concentrations. Zn has the highest mean concentration in the < 63 μm particle size of RDS, followed by Pb > Cu > As > Cr > Ni > Cd > Hg. The PTEs concentrations of this study were the highest values compared to the soils around the smelter and the RDS in urban and industrial areas in the world. This indicates that these PTEs pollution in RDS were mainly attributed to the transportation of raw materials for the smelting industry. According to nemerow pollution index calculation, RDS at all sampling sites with particles of less than 250 mm was seriously polluted with PTEs. The ecological risk was also found to be very high in all RDS fractions and highly toxic elements such as Cd, Pb and Hg pose extremely risk. Given the total amounts PTEs in the road surface, it is necessary to apply RDS removal management plan to reduce the PTEs pollution.

The Equilibrium Concept, or…(Mis)concept in Beaches

Beaches, as deposits of unconsolidated material at the land/water interface, are open systems where input and output items constitute the sediment budget. Beach evolution depends on the difference between the input/output to the system; if positive the beach advances, if negative the beach retreats. Is it possible that this difference is zero and the beach is stable? The various processes responsible for sediment input and output in any beach system are here considered by taking examples from the literature. Results show that this can involve movement of a volume of sediments ranging from few, to over a million cubic meters per year, with figures continuously changing so that the statistical possibility for the budget being equal can be considered zero. This can be attributed to the fact that very few processes are feedback-regulated, which is the only possibility for a natural system to be in equilibrium. Usage of the term “beach equilibrium” must be reconsidered and used with great caution.

Identification of Soil Heavy Metal Sources in a Large-Scale Area Affected by Industry

Heavy metals (HMs) in soil are some of the most serious pollutants due to their toxicity and nonbiodegradability. Especially across large-scale areas affected by industry, the complexity of pollution sources has attracted extensive attention. In this study, an approach based on zoning to analyze the sources of heavy metals in soil was proposed. Qualitative identification of pollution sources and quantification of their contributions to heavy metals in soil are key approaches in the prevention and control of heavy metal pollution. The concentrations of five HMs (Cd, Hg, As, Pb and Cr) in the surface soil of the Chenzhou industrial impact area were the research objects. Multiple methods were used for source identification, including positive matrix factorization (PMF) analysis combined with multiple other analyses, including random forest modeling, the geo-accumulation index method and hot spot analysis. The results showed that the average concentrations of the five heavy metals were 9.46, 2.36, 2.22, 3.27 and 1.05 times the background values in Hunan soil, respectively. Cd was associated with moderately to strongly polluted conditions, Hg, As and Pb were associated with unpolluted to moderately polluted conditions and Cr was associated with practically unpolluted conditions. The mining industry was the most significant anthropogenic factor affecting the content of Cd, Pb and As in the whole area, with contribution rates of 87.7%, 88.5% and 62.5%, respectively, and the main influence area was within 5 km from the mining site. In addition, we conducted hot spot analysis on key polluting enterprises and identified hot spots, cold spots, and areas insignificantly affected by enterprises, used this information as the basis for zoning treatment and discussed the sources of heavy metals in the three subregions. The results showed that Cd originated mainly from agricultural activities, with a contribution rate of 63.6%, in zone 3. As originated mainly from sewage irrigation, with a contribution rate of 65.0%, in zone 2, and the main influence area was within 800 m from the river. This element originated mainly from soil parent materials, with a contribution rate of 69.7%, in zone 3. Pb mainly originated from traffic emissions, with a contribution rate of 72.8%, in zone 3, and the main influence area was within 500 m from the traffic trunk line. Hg was mainly derived from soil parent materials with a contribution rate of 92.1% in zone 1, from agricultural activities with a contribution rate of 77.5% in zone 2, and from a mixture of natural and agricultural sources with a contribution rate of 74.2% in zone 3. Cr was mainly derived from the soil parent materials in the whole area, with a contribution rate of 90.7%. The study showed that in large-scale industrial influence areas, the results of heavy metal source analysis can become more accurate and detailed by incorporating regional treatment, and more reasonable suggestions can be provided for regional enterprise management and soil pollution control decision making.

Environmental monitoring of toxic metals in roadside soil and dust in Ulsan, South Korea: pollution evaluation and distribution characteristics

This study investigated toxic metal distribution in roadside soil and dust in the metropolitan city of Ulsan, South Korea, and the factors affecting distribution, using Korean waste-leaching tests, determination of total concentrations, sequential extraction, and statistical analysis. Composite grab samples were collected from high-traffic roads (7 sites), low-traffic roads (2 sites), and an uncontaminated control area (2 sites) in Ulsan. The pH of roadside soil and dust was slightly alkaline. The concentrations of copper, lead, and zinc in soil as determined by Korean waste-leaching tests decreased as soil depth increased, while those of arsenic, nickel, and chromium increased. Leaching concentrations in dust were lower than in soil, with the exception of copper. Total concentrations decreased as soil depth increased, and total concentrations of metals in dust were higher than in soil. The sampling sites that exceeded the regulation levels of soil contamination in South Korea were 7 points in topsoil, 3 points in middle soil, and 9 points in dust. TCLP tests showed that the concentrations of arsenic, cadmium, and lead in topsoil and dust at Duwang and Myeongchon intersections were higher than regulatory levels. The maximum correlation coefficient among two metals in soil and dust was 0.987 (p < 0.01), for cadmium and lead. Concentrations of cadmium, copper, arsenic, lead, nickel, and mercury, mostly from tire and brake-pad abrasion, were highly correlated. The strong positive correlation between traffic volume and metals in dust suggests that vehicle emissions may be responsible for metal contamination of soil and dust. Pollution indices of topsoil at 4 sites and all dust at 7 high-traffic sites were higher than 1.0, which is consistent with an effect of vehicle traffic on metal contamination in soil and dust.