Traffic emission dominates the spatial variations of metal contamination and ecological-health risks in urban park soil

Evaluation of Potential Toxic Elements in Soils from Three Urban Areas Surrounding a Steel Industrial Zone

The urban zone around the city of Volos, a Greek city with a historically industrialized profile, faces threats arising from Potential Toxic Element (PTE) contamination. The scope of this study is to determine the contamination levels of 10 PTEs in three urban areas which are located near the industrial zone in the city of Volos. For this purpose, a total of 30 soil samples from parks, playgrounds and roadsides were collected from the Agios Georgios, Velestino and Rizomilos areas (Magnesia, Central Greece). The sampling was conducted in June 2022 and the concentrations of chromium (Cr), nickel (Ni), copper (Cu), arsenic (As), cadmium (Cd), lead (Pb), iron (Fe), manganese (Mn), cobalt (Co) and zinc (Zn) were measured through inductively coupled plasma mass spectrometry (ICP-MS). The Contamination Factor (CF), Pollution Load Index (PLI) and Geo-accumulation Index (Igeo) revealed moderate pollution in most cases, whereas in some sites the contamination was significant for Ni or for As. Principal Component Analysis showed concomitant changes for some PTEs in Component 1 and for others in Component 2, explaining approximately 67% of the variation. K-means Cluster Analysis showed two distinct groups of PTE-impacted sites within these urban areas. It can be postulated that industrial activities may have a carry-over effect on the soil in residential areas. Frequent monitoring of areas deemed as "contaminated" and time-series data are needed to examine in depth the soil pollution in cities and its possible shifts in relation to the changes in industrialization status in the extended urban areas.

Local honey reflects environmental changes in metal concentrations and lead isotope ratios during COVID-19 restrictions in Brussels, Belgium, and Vancouver, Canada

Effective methods for measuring sudden environmental changes are crucial for understanding how cities respond to shifts in human activity. This study examines atmospheric metal outputs during the COVID-19 restrictions using honey samples collected from three land use types in Brussels Capital Region (BCR), Belgium, and Metro Vancouver Regional District (MVRD), Canada to study changes as the result of restrictions. By comparing these cities with distinct sizes, ages, and structures, we assess how urban environments responded to pandemic-induced restrictions. We present honey samples, analyzed for metal concentration and Pb isotope ratios, to provide insights into the impacts of reduced human activity in different land use types. In BCR, significant increases of Al, Cd, Cr, Cu, Fe, Ni, Pb, Ti, and V were observed in suburban sites, while in MVRD, significant decreases of Cr, Pb, Sb, Ti, and V were observed in suburban sites. The increase in metal concentrations in BCR suburban sites indicates a shift in metal emission patterns due to changes in human activity during the restrictions. Conversely, the decrease in metal concentrations in MVRD suburban areas aligns with expectations of reduced pollution during restrictions. Pb isotope ratios of BCR vary more widely and do not show any spatial trends by land use, suggesting that Pb concentrations in BCR may be more homogenized. In MVRD, significant differences in 208Pb/206Pb were observed during the restrictions, wherein honey sampled from rural sites had more radiogenic (lower 208Pb/206Pb) Pb isotope ratios. This difference suggests that honey may be more sensitive to Pb isotope ratio changes in environments with a less extensive history of metal use, such as rural British Columbia. This research demonstrates the potential of honey as a biomonitor for sudden environmental shifts. This study contributes to a global geochemical honey database, enabling tracking of environmental trends across diverse urban settings worldwide.

The use of sedimentary metals to assess anthropogenic change, ecological risk, model past and future impacts and identify contaminant sources in the eleven estuaries of Greater Sydney (Australia): A review and critical assessment

The Greater Sydney (Australia) region is dissected by eleven major estuaries comprising a wide range of sizes, sediment and contaminant types, while the catchments also vary in size, land use type, populations size and geology/soils. The magnitude and breadth of the current study are rare and offered an unusual opportunity to provide new information on interactions between source, fate and effect relationships of a highly diverse estuarine-catchment environment using sedimentary metals (Co, Cr, Cu, Ni, Pb and Zn). Advanced methodologies used in this study revealed that although metal concentrations were generally high, ecological risk was surprisingly reduced due to the presence of metal-poor coarse sediment. Stormwater was identified as the dominant source of metals to estuaries of Greater Sydney and relates to development of high-density road networks. Industrial sources, frequently identified as a major contributor to estuarine contamination, was significantly reduced due to the decline of industry through decentralisation and gentrification and because waste is discharged to the sewer system, which is released offshore, or tertiary-treated to the Hawkesbury. Groundwater leachate associated with shoreline reclamation and wetland infilling and metals related to boating activities were important sources of metals impacting local bays and coastal lagoons. Temporal monitoring and unique modelling approaches indicated that the concentration of sedimentary metals is generally declining in these estuaries, (especially for Pb), except for areas with rapidly increasing urban populations. Multivariate statistical modelling was able to differentiate the 11 estuaries on a chemical basis by aligning Cu, Pb, Zn vectors with metal-rich estuaries and also identified catchment attributes (percent area, total yield, anthropogenic yield and population density) normalised to catchment areas as having a major influence on estuarine condition. The new knowledge derived from this study should be used to assess the environmental status of estuaries and to prioritise management actions in future investigations.

Human health risk assessment of metal-contaminated soils in Sydney estuary catchment (Australia)

Sydney estuary catchment supports the largest city in Australia and provides essential eco-social and environmental services; however, the region has been influenced by extensive anthropogenic modification. Soil metal concentrations in the catchment had been studied previously; however, the current investigation was designed to determine the risk posed by these contaminants to human health. Soil metal concentrations were higher than observed in most global capitals and increased substantially in the south and south-east of the catchment and close to the central business district. Road-side soils and road dust contained the highest concentration of metals in the catchment. Lead in catchment soils was closely related to traffic density and sourced from the historic use of Pb in petrol. A human health assessment indicated that soil Cd, Ni and Zn posed no non-carcinogenic risk (NCR), or carcinogenic risk (CR) for children, or adults in Sydney estuary catchment and that Cu and Cr may pose minor NCR for children. Vehicle-related Pb raised the greatest human health risk in catchment soils and may pose NCR at 32% and 4.3% of sites for children and adults, respectively. Inconsistent analytical techniques used in CR and NCR evaluations produce incomparable assessments and a consistent` methodology is suggested to improve interpretation. Human health risk may well be higher than commonly calculated due to pollutants present in urban soil not being included in assessments.

Review and assessment of road-derived metals as a major contributor of metallic contaminants to urban stormwater and the estuarine environment (Sydney estuary, Australia)

Sydney Harbour (Australia). is one of the most metal-contaminated in the world and sediments are toxic over large areas. The major source of metals is stormwater, however there remains considerable debate regarding the source of metals in water entering the estuary. The current review and critical assessment of a large source of data accumulated from over three decades of research, supplemented by global studies, identified road-derived metals (RDMs) as the chief contributor of metals to stormwater and consequently to pollution of the estuary. Roads comprise almost 25% of a typical urban catchment and generate a considerable metal load from highly effective impervious surfaces and RDM is transported directly to the adjacent receiving basin with enhanced connectivity. In Sydney, industrial waste is delivered to the sewage system and is disposed of offshore, leaving RDM as a major contributor of metals to the stormwater system and estuarine environment. RDMs are modelled to be hazardous to the ecology and human health (carcinogenic and non-carcinogenic diseases) in the catchment environment driven by high metal concentrations, small size and elevated bioavailability. Remediation of RDMs is complex, requiring extensive knowledge and an experienced management team. The enormous potential for water re-use is often neglected.

Similarity in human health risk assessment using models of soil-blood lead levels (IEUBK) and non-carcinogenic condition (US EPA 2002)

Soil lead (Pb) concentrations in Sydney estuary (Australia) catchment are substantially elevated and strongly associated with traffic networks. This study compared the health risk predictions of blood Pb levels (BLL) in children using the soil IEUBK model and an independent, non-carcinogenic human health risk (NCR) assessment using the soil US EPA 2002 model. The predictions by the two models were significantly correlated (p < 0.001) and showed similar spatial distributions, but the NCR model may be more stringent in protection of human health when exposed to soil Pb in relation to adverse health effect, as the warning soil Pb concentration from the BLL was 4.6-fold higher than that from the NCR. The empirical IEUBK model considers gastric phase adsorption only and of the three exposure pathways (ingestion, inhalation and dermal) assessed by the theoretical NCR model, ingestion was the major exposure route. The reason for the similarity in outcomes of the two models is unknown, however the close correlation may be due to broadly similar formulations and, or that neurological and non-carcinogenic risks may be related to the adverse effects of Pb on bodily function. Parallel studies of human health risk based on BLL and NCR models have not been attempted previously and this opportunity to compare results from the two health risk assessments employing the same soil metal data is therefore unique.

Heavy metals contamination, receptor model-based sources identification, sources-specific ecological and health risks in road dust of a highly developed city

The present study quantified Ni, Cu, Cr, Pb, Cd, As, Zn, and Fe levels in road dust collected from a variety of sites in Tangail, Bangladesh. The goal of this study was to use a matrix factorization model to identify the specific origin of these components and to evaluate the ecological and health hazards associated with each potential origin. The inductively coupled plasma mass spectrometry was used to determine the concentrations of Cu, Ni, Cr, Pb, As, Zn, Cd, and Fe. The average concentrations of these elements were found to be 30.77 ± 8.80, 25.17 ± 6.78, 39.49 ± 12.53, 28.74 ± 7.84, 1.90 ± 0.79, 158.30 ± 28.25, 2.42 ± 0.69, and 18,185.53 ± 4215.61 mg/kg, respectively. Compared to the top continental crust, the mean values of Cu, Pb, Zn, and Cd were 1.09, 1.69, 2.36, and 26.88 times higher, respectively. According to the Nemerow integrated pollution index (NIPI), pollution load index (PLI), Nemerow integrated risk index (NIRI), and potential ecological risk (PER), 84%, 42%, 30%, and 16% of sampling areas, respectively, which possessed severe contamination. PMF model revealed that Cu (43%), Fe (69.3%), and Cd (69.2%) were mainly released from mixed sources, natural sources, and traffic emission, respectively. Traffic emission posed high and moderate risks for modified NIRI and potential ecological risks. The calculated PMF model-based health hazards indicated that the cancer risk value for traffic emission, natural, and mixed sources had been greater than (1.0E-04), indicating probable cancer risks and that traffic emission posed 38% risk to adult males where 37% for both adult females and children.

Contamination and source apportionment of metals in urban road dust (Jinan, China) integrating the enrichment factor, receptor models (FA-NNC and PMF), local Moran's index, Pb isotopes and source-oriented health risk

Contamination and source identifications of metals in urban road dust are critical for remediation and health protection. Receptor models are commonly used for metal source identification, whereas the results are usually subjective and not verified by other indicators. Here we present and discuss a comprehensive approach to study metal contamination and sources in urban road dust (Jinan) in spring and winter by integrating the enrichment factor (EF), receptor models (positive matrix factorization (PMF) and factor analysis with nonnegative constraints (FA-NNC)), local Moran's index, traffic factors and Pb isotopes. Cadmium, Cr, Cu, Pb, Sb, Sn and Zn were the main contaminants, with mean EFs of 2.0-7.1. The EFs were 1.0-1.6 times higher in winter than in spring but exhibited similar spatial trends. Chromium contamination hotspots occurred in the northern area, with other metal contamination hotspots in the central, southeastern and eastern areas. The FA-NNC results indicated Cr contamination primarily resulting from industrial sources and other metal contamination primarily originating from traffic emissions during the two seasons. Coal burning emissions also contributed to Cd, Pb and Zn contamination in winter. FA-NNC model-identified metal sources were verified via traffic factors, atmospheric monitoring and Pb isotopes. The PMF model failed to differentiate Cr contamination from other detrital metals and the above anthropogenic sources, largely due to the model grouping metals by emphasizing hotspots. Considering the FA-NNC results, industrial and traffic sources accounted for 28.5 % (23.3 %) and 44.7 % (28.4 %), respectively, of the metal concentrations in spring (winter), and coal burning emissions contributed 34.3 % in winter. Industrial emissions primarily contributed to the health risks of metals due to the high Cr loading factor, but traffic emissions dominated metal contamination. Through Monte Carlo simulations, Cr had 4.8 % and 0.4 % possibilities posing noncarcinogenic and 18.8 % and 8.2 % possibilities posing carcinogenic risks for children in spring and winter, respectively.

Biomonitoring trace metal contamination in Guangzhou urban parks using Asian tramp snails (Bradybaena similaris)

Anthropogenic activities have caused environmental metal contamination in urban areas. Biomonitoring using organisms such as invertebrates can evaluate metal pollution, supplementing chemical monitoring, which cannot comprehensively reflect how metals influence organisms in the urban environment. To assess metal contamination in Guangzhou urban parks and its source, Asian tramp snails (Bradybaena similaris) were collected from ten parks in Guangzhou in 2021. The metal concentrations (Al, Cd, Cu, Fe, Mn, Pb, and Zn) were measured by ICP-AES and ICP-MS. We evaluated the metal distribution characteristics and correlations among metals. The probable sources of metals were determined by the positive matrix factorization (PMF) model. The metal pollution levels were analysed using the pollution index and the Nemerow comprehensive pollution index. The mean metal concentrations were ranked Al > Fe > Zn > Cu > Mn > Cd > Pb; metal accumulation in the snails was ranked Al > Mn > CuFe > Cd > Zn > Pb. Pb-Zn-Al-Fe-Mn and Cd-Cu-Zn were positively correlated in all samples. Six major metal sources were identified: an Al-Fe factor corresponding to crustal rock and dust, an Al factor related to Al-containing products, a Pb factor indicative of traffic and industries, a Cu-Zn-Cd factor dominated by the electroplating industry and vehicle sources, an Mn factor reflecting fossil fuel combustion, and a Cd-Zn factor related to agricultural product use. The pollution evaluation suggested heavy Al pollution, moderate Mn pollution, and light Cd, Cu, Fe, Pb, and Zn pollution in the snails. Dafushan Forest Park was heavily polluted; Chentian Garden and Huadu Lake National Wetland Park were not widely contaminated. The results indicated that B. similaris snails can be used as effective biomarkers for monitoring and evaluating environmental metal pollution in megacity urban areas. The findings show that snail biomonitoring provides a valuable understanding of the migration and accumulation pathways of anthropogenic metal pollutants in soil‒plant-snail food chains.

Source Analysis and Contamination Assessment of Potentially Toxic Element in Soil of Small Watershed in Mountainous Area of Southern Henan, China

In this study, the concentrations of potentially toxic elements in 283 topsoil samples were determined. Håkanson toxicity response coefficient modified matter element extension model was introduced to evaluate the soil elements contamination, and the results were compared with the pollution index method. The sources and spatial distribution of soil elements were analyzed by the combination of the PMF model and IDW interpolation. The results are as follows, 1: The concentration distribution of potentially toxic elements is different in space. Higher concentrations were found in the vicinity of the mining area and farmland. 2: The weight of all elements has changed significantly. The evaluation result of the matter-element extension model shows that 68.55% of the topsoil in the study area is clean soil, and Hg is the main contamination element. The evaluation result is roughly the same as that of the pollution index method, indicating that the evaluation result of the matter-element extension model with modified is accurate and reasonable. 3: Potentially toxic elements mainly come from the mixed sources of atmospheric sedimentation and agricultural activities (22.59%), the mixed sources of agricultural activities and mining (20.26%), the mixed sources of traffic activities, nature and mining (36.30%), the mixed sources of pesticide use and soil parent material (20.85%).

Impact of change in traffic flow on vehicle non-exhaust PM2.5 and PM10 emissions: A case study of the M25 motorway, UK

This study quantifies the change in traffic flow on the M25 motorway in the UK due to the COVID-19 outbreak. Moreover, the impact of the change in traffic flow on non-exhaust PM_2.5 and PM₁₀ emissions for different categories of vehicle was explored. During the year of the COVID-19 outbreak (March 2020 to February 2021), the total traffic flows of passenger cars (PCs), light goods vehicles (LGVs), heavy goods vehicles (HGVs), and long HGVs on the M25 motorway decreased by 38.6%, 27.6%, 15.9% and 7.2%, respectively, in comparison to the previous year. Correspondingly, the total mass of non-exhaust emissions (PM_2.5 and PM₁₀) of PCs, LGVs, HGVs, and long HGVs reduced by 38.7%, 27.3%, 16.2% and 7%, respectively. The traffic flows per year before and during the COVID-19 outbreak of long HGVs were 87.2% and 80.7% less than those of PCs. Correspondingly, the long HGVs emitted 10.2% less but 36.3% more PM_2.5 emissions, as well as 10.9% and 66.7% more PM₁₀ emissions than the latter, indicating that long HGVs contribute much more to non-exhaust particles than PCs. In addition, it was found that resuspension of road dust on the M25 motorway was the largest contributor to air pollution among non-exhaust emissions, followed by road wear, tyre wear, and brake wear particles.