Determination of multi-element profiles of street dust using energy dispersive X-ray fluorescence (EDXRF)

Mapping of heavy metal contamination associated to microplastics marine debris - A case study: Dubai, UAE

Microplastics (MPs) are ubiquitously detected in the environment. The adverse impact of microplastics on marine life is well documented. Previous research has shown that MPs can adsorb heavy metals, however, this fact has not been investigated along the coast of Dubai, UAE. Elemental composition of MPs debris was determined using X-ray fluorescence spectroscopic (XRF) analysis. The analyzed MPs were extracted from 80 sediment samples collected from the wrack lines of 16 Dubai, UAE beaches. A total of 480 MPs pieces extracted from the samples were analyzed in order to detect heavy metals. The polymer composition was previously confirmed by FTIR spectroscopy, showing that polyethylene (PE) and polypropylene (PP) were the most abundant MPs. 14 heavy metals were identified in the samples: Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Pb, Ce, Pr, Nd, Pd, and Co with different concentrations. Five of them (Cr, Ni, Cu, Zn, and Pb) are priority pollutants according to EPA. Their average concentrations in oxide form were Cr₂O₃ (2.96 %), NiO (0.32 %), CuO (0.45 %), ZnO (0.56 %), and PbO (1.49 %).

Combination of enrichment factor and positive matrix factorization in the estimation of potentially toxic element source distribution in agricultural soil

The study intended to assess the level of pollution of potential toxic elements (PTEs) at different soil depths and to evaluate the source contribution in agricultural soil. One hundred and two soil samples were collected for both topsoil (51), and the subsoil (51) and the content of PTEs (Cr, Cu, Cd, Mn, Ni, Pb, As and Zn) were determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The concentrations of Zn and Cd in both soil horizons indicated that the current study levels were higher than the upper continental crust (UCC), world average value (WAV), and European average values (EAV). Nonetheless, the concentration values of PTEs such as Mn and Cu for EAV, As, Cu, Mn, and Pb for UCC, and Pb for WAV were lower than the average values of the corresponding PTEs in this study. The single pollution index, enrichment factor, and ecological risk revealed that the pollution level ranged from low to high. The pollution load index, Nemerow pollution index, and risk index all revealed that pollution levels ranged from low to high. The spatial distribution confirmed that pollution levels varied between the horizons; that is, the subsoil was considered slightly more enriched than the topsoil. Principal component analysis identified the PTE source as geogenic (i.e. for Mn, Cu, Ni, Cr) and anthropogenic (i.e. for Pb, Zn, Cd, and As). PTEs were attributed to various sources using enrichment factor-positive matrix factorization (EF-PMF) and positive matrix factorization (PMF), including geogenic (e.g. rock weathering), fertilizer application, steel industry, industrial sewage irrigation, agrochemicals, and metal works. Both receptor models allotted consistent sources for the PTEs. Multiple linear regression analysis was applied to the receptor models (EF-PMF and PMF), and their efficiency was tested and assessed using root-mean-square error (RMSE), mean absolute error (MAE), and R² accuracy indicators. The validation and accuracy assessment of the receptor models revealed that the EF-PMF receptor model output significantly reduces errors compared with the parent model PMF. Based on the marginal error levels in RMSE and MAE, 7 of the 8 PTEs (As, Cd, Cr, Cu, Ni, Mn, Pb, and Zn) analysed performed better under the EF-PMF receptor model. The EF-PMF receptor model optimizes the efficiency level in source apportionment, reducing errors in determining the proportion contribution of PTEs in each factor. The purpose of building a model is to maximize efficiency while minimizing inaccuracy. The marginal error limitation encountered in the parent model PMF was circumvented by EF-PMF. As a result, EF-PMF is feasible and useful for apparently polluted environments, whether farmland, urban land, or peri-urban land.

Study on metal elements in indoor particulate matter: a case study of rural residential environment in Northeast China

The use of solid fuels for heating and cooking in rural Northeast China has led to severe indoor metal element pollution in particulate matter (PM), posing a direct threat to human health and creating immense pressure on the sustainability of residential environments. To investigate the levels, sources, and potential health hazards of indoor metal element pollution in this region, we conducted a year-long sampling and monitoring campaign in actual residential settings and used ICP-OES to measure six metal elements (Mn, Cr, Zn, Cu, Pb, and Ni). This study's findings reveal that indoor metal element pollution levels in PM (33,513.65 mg/kg per year) are higher in rural Northeast China compared to other rural areas. Straw burning is the primary source of metal element pollution, followed by motor vehicle emissions and natural soil sources. It is crucial to note that our results indicate a total carcinogenic risk greater than 10^-4 according to the US EPA health risk model assessment, highlighting the high risk posed to human health by indoor metal elements in rural areas. By using a seriously polluted area in Northeast China as a case study, this research provides initial insights into the characteristics and sources of indoor metal pollution in rural areas, offering a reference for future prevention and control of indoor pollution in these regions. Ultimately, this work can help improve the rural habitat and enhance the health of the rural population.

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.

Sources, toxicity potential, and human health risk assessment of heavy metals-laden soil and dust of urban and suburban areas as affected by industrial and mining activities

Sources and levels of heavy metals (HMs) in soil and dust of urban and suburban areas in Riyadh (industrial city) and Mahad AD’Dahab (mining area) cities in Saudi Arabia were reported in this study. Additionally, the concentrations of HMs in different soil particle size fractions (> 250, 63–250 and < 63 µm) were reported. Pollution extent, and ecological and human health risks associated with collected soil and dust samples were explored. Contamination levels of HMs were higher in dust as compared to soil samples at all sites. The average integrated potential ecological risk in dust samples of urban area of Mahad AD’Dahab was 139, and thus characterized as a very-high-risk criterion. Enrichment factor (EF), correlation analyses, and principal component analysis showed that aluminum (Al), cobalt (Co), chromium (Cr), iron (Fe), manganese (Mn), nickel (Ni), titanium (Ti), and zinc (Zn) had mainly the lithogenic occurrence (EF < 2). However, Zn, copper (Cu), and lead (Pb) in Riyadh, and cadmium (Cd), Cu, Zn, and Pb in the Mahad AD’Dahab were affected by industrial and mining activities, respectively, that were of anthropogenic origins (EF > 2). The hazard index values of dust and soil (< 63 µm) samples in both urban and suburban areas in Mahad AD’Dahab were > 1, suggesting non-carcinogenic risk. Therefore, the dust and soil samples from the mined area of Mahad AD’Dahab had a higher pollution levels, as well as ecological and human health risks than those from Riyadh. Hence, the pollution of such residential environments with HMs (especially Cd, Cu, Zn, and Pb) needs to be monitored.

Characteristics, source apportionment and health risk assessment of heavy metals in urban road dust of the Pearl River Delta, South China

To investigate the characteristics of heavy metals (As, Cd, Cr, Cu, Pb, Hg, Ni and Zn) in urban road dust from different cities and functional areas in the Pearl River Delta (PRD), South China, a total of 294 dust samples were analyzed. The contamination characteristics and health risk of heavy metals in the dust were assessed, their chemical speciation were distinguished, and their sources were identified by the correlations, cluster and principal component analysis (PCA). The mean concentrations of As (15.89 mg/kg), Cd (1.59 mg/kg), Cr (143.75 mg/kg), Cu (184.42 mg/kg), Pb (114.82 mg/kg), Hg (0.11 mg/kg), Ni (41.53 mg/kg) and Zn (645.94 mg/kg) in urban road dust were in high or moderate levels compare with other previous researches. In this case, the contamination of Cr, Cu, Ni and Zn in the industrial area (IA) and the contamination of Cd and Hg in the commercial area (CA) were significantly higher relative to other functional areas (P < 0.05), and the contamination of heavy metals in Foshan City was significantly higher than other cities (P < 0.01). The order of mobility of the heavy metals with higher concentration in urban road dust of the Pearl River Delta declined in the following order: Zn, Ni, Cu, Pb and Cr. Statistical analysis result showed the contaminated heavy metals in urban road dust were mainly contributed by industrial activities, traffic activities and building pollution. There were no significant carcinogenic and noncarcinogenic risks for adults, children however showed significant noncarcinogenic effect caused by As and Cr in partial points, albeit with low contamination level of the two metals. The ingestion was a principal pathway for heavy metals via urban road dust to exposure population. More protection measures should be considered to reduce children's exposure to the dust, especially in the CA and IA.

Pollution Indexing and Health Risk Assessment of Heavy-Metals-Laden Indoor and Outdoor Dust in Elementary School Environments in Riyadh, Saudi Arabia

The prevalence of potentially toxic heavy metals (HMs)-bearing dust in the environment is posing serious health risks to humans. Therefore, the occurrence of HMs in indoor and outdoor dust samples of elementary school’s environment in Riyadh, Saudi Arabia, were reported, and associated potential human health risks were estimated in this study. Dust samples were collected from outdoor and indoor environments from eighteen elementary schools using a soft plastic brush. The mean concentrations of Cd, Co, Cu, Ni, Pb, and Zn in collected indoor dust samples were much higher (0.08, 3.45, 59.20, 15.20, 4.99, and 94.10 mg kg−1, respectively) than that of outdoor dust samples (0.07, 3.07, 42.20, 13.60, 4.57, and 62.40 mg kg−1, respectively), due to fans operation, opened windows, and resuspension of dust by children’s activities. The values of estimated enrichment factor revealed that both the outdoor and indoor dusts were moderately contaminated with Zn and Cu, while highly contaminated with Cd and Pb. However, the estimated potential ecological risks associated with HMs were lower. Health risks (non-carcinogenic and carcinogenic) calculations exhibited no potential risks of HMs in the schools’ dust toward children. However, health risks for children were determined in the following order: up to 6 years > 6–12 years > adults. Therefore, assessing the potential health risks posed by HM-contaminated dust in school environments is necessary to avoid any possible children’s health concerns.

Concentrations, spatial distribution, sources and environmental health risks of potentially toxic elements in urban road dust across China

Potentially toxic element (PTE) pollution is widespread in road dust across China, and the effects of PTEs in road dust on health cannot be ignored. In this study, the concentrations of six PTEs (Pb, Cd, Cr, Cu, Zn and Ni) in 4336 road dust samples from 58 cities in 31 provincial regions of China taken after 2000 were obtained from the literatures. Based on these data, the spatial distribution, pollution sources, and ecological and human health risks of PTEs in road dust were comprehensively assessed and the main pollution factors and areas of high risk were identified. The results revealed that PTE levels are generally higher in eastern cities than western cities in China. The key driving factors are socioeconomic factors, including those related to transportation, industry, and population, for which the contribution rates are 57.80%, 55.39% and 37.19%, respectively. PTEs in the road dust with high ecological risks are mainly distributed in the southeastern coastal areas and the Beijing-Tianjin-Hebei region. No obvious noncarcinogenic risk was found for PTEs in road dust, but Cd and Pb may have potential noncarcinogenic risk, mainly distributed in cities in western China. Therefore, regions and pollution sources contributing to Pb and Cd levels should be monitored. The control of PTE pollution in China is a priority for ecological and environmental protection.

Heavy metals in water and surface sediments of the Fenghe River Basin, China: assessment and source analysis

This paper combines environmental science, inorganic chemistry, water quality monitoring and other disciplines to analyze and assess the heavy metals in the water bodies and sediments of the Fenghe River Basin (FRB) in Shaanxi Province, and reveal their sources. The Water Quality Index (WQI), Nemero Index (Pn), Geological Accumulation Index (I-geo) and Potential Ecological Risk Index (RI) are used to assess heavy metals in water and sediments. Pearson correlation analysis (CA), hierarchical cluster analysis (HCA), principal component analysis (PCA) and positive matrix factorization (PMF) models are used to study the relationship and source of heavy metals. The results show that most of the residual heavy metals in the water are below the corresponding environmental quality standards for surface water. Most of the heavy metals in the sediment exceed the background value of the soil. The factors or sources of heavy metals in water and sediment are revealed in detail through PMF models. The main sources of pollution in the region are urban construction and transportation, the electronics industry, machinery manufacturing and tourism. In water, the average contribution rates of these four sources to heavy metals were 36.8%, 11.7%, 9.4% and 42.0%, and in sediments were 8.0%, 29.2%, 23.9% and 38.9%. Therefore, these sectors should be given sufficient attention.

Risk and sources of heavy metals and metalloids in dust from university campuses: A case study of Xi'an, China

College students study and live at university for several years; however, the pollution levels, ecological health risks, and sources of heavy metals and metalloids (HMMs) in the dust found at university campuses are still unknown. In this study, dust samples from university campuses in Xi'an were collected and the Zn, Mn, As, Pb, V, Cr, Co, Cu, Ba, and Ni contents were measured using X-ray fluorescence spectrometry. The pollution levels and ecological health risks of these HMMs were evaluated using the geo-accumulation, pollution load, and potential ecological risk indices and a health risk assessment model while their sources were apportioned using positive matrix factorization. The mean HMM concentrations in the dust were higher than the corresponding background values in the topsoil of Shaanxi Province. The Mn, V, Co, As, and Ni concentrations in the dust samples analyzed were within the levels categorized as no pollution by the geo-accumulation index standard, whereas other HMMs caused pollution to different degrees. Assessment of the pollution load index indicated that the dust samples analyzed were moderate contamination with HMMs. Pb and Cu in the dust presented considerable and moderate ecological risks, respectively; the other HMMs presented low ecological risks. The combined ecological risk of the HMMs measured in the dust samples was considerable. The non-carcinogenic and carcinogenic risks to male and female college students were within the safe levels. This study found three main sources of the HMMs measured in the dust: traffic, natural, and mixed sources (the latter including automobile repair industry waste and paints and pigments), which accounted for 47.5%, 29.3%, and 23.2% of the total HMM concentration, respectively.

Study of Atmospheric Pollution and Health Risk Assessment: A Case Study for the Sharjah and Ajman Emirates (UAE)

Dust is a significant pollution source in the United Arab Emirates (UAE) that impacts population health. Therefore, the present study aims to determine the concentration of heavy metals (Cd, Pb, Cr, Cu, Ni, and Zn) in the air in the Sharjah and Ajman emirates’ urban areas and assesses the health risk. Three indicators were used for this purpose: the average daily dose (ADD), the hazard quotient (HQ), and the health index (HI). Data were collected during the period April–August 2020. Moreover, the observation sites were clustered based on the pollutants’ concentration, given that the greater the heavy metal concentration is, the greater is the risk for the population health. The most abundant heavy metal found in the atmosphere was Zn, with a mean concentration of 160.30 mg/kg, the concentrations of other metals being in the following order: Ni > Cr > Cu > Pb > Cd. The mean concentrations of Cd, Pb, and Cr were within the range of background values, while those of Cu, Ni, and Zn were higher than the background values, indicating anthropogenic pollution. For adults, the mean ADD values of heavy metals decreased from Zn to Cd (Zn > Ni > Cr > Cu > Pb > Cd). The HQ (HI) suggested an acceptable (negligible) level of non-carcinogenic harmful health risk to residents’ health. The sites were grouped in three clusters, one of them containing a single location, where the highest concentrations of heavy metals were found.

Potentially toxic elements in street dust from an urban city of a developing country: ecological and probabilistic health risks assessment

Anthropogenic activities in and around the urban highways followed by aerodynamic processing generate street dusts, which can cause adverse health effects through different exposure pathways. Hence, considering the high degree of industrialization, concomitant unplanned urbanization, and rapid demographic augmentation, street dust samples from an urban city (Gazipur, Bangladesh) were investigated in terms of potentially toxic elements (using ICP-MS) to evaluate their ecological and health risks. Mean concentrations (± SD) of lead (Pb), copper (Cu), chromium (Cr), cadmium (Cd), zinc (Zn), nickel (Ni), and arsenic (As) in the analyzed air-dried samples were 40.9 ± 13.6, 44.9 ± 15.4, 83.3 ± 19.0, 9.1 ± 5.4, 239.1 ± 34.7, 33.5 ± 10.4, and 2.1 ± 0.8 mg/kg, respectively with heterogeneous distribution which were 0.2 (As) to 82.7 (Cd) times higher than the available internationally recommended limits. Element-specific environmental indices revealed that contamination levels followed the descending order as Cd > Zn > Cu > Pb > Cr > Ni > As, whereas individual ecological risks followed the descending order as Cd > Cu > Pb > Ni > Zn > Cr > As. Sampling site-specific composite indices indicated that sampling sites with high loadings of traffic, population, industrialization, and urbanization were mostly polluted. Multivariate statistical approaches also deduced the similar origins of the studied elements. In terms of the investigated elements, the study site possessed high potential ecological risks, although non-carcinogenic and carcinogenic risks through different pathway's exposures seem insignificant, where children are more vulnerable than adults.

Assessment of Pollution Sources and Contribution in Urban Dust Using Metal Concentrations and Multi-Isotope Ratios (13C, 207/206Pb) in a Complex Industrial Port Area, Korea

The metal concentrations and isotopic compositions (13C, 207/206Pb) of urban dust, topsoil, and PM10 samples were analyzed in a residential area near Donghae port, Korea, which is surrounded by various types of industrial factories and raw material stockpiled on empty land, to determine the contributions of the main pollution sources (i.e., Mn ore, Zn ore, cement, coal, coke, and topsoil). The metal concentrations of urban dust in the port and residential area were approximately 85~112 times higher (EF > 100) in comparison with the control area (EF < 2), especially the Mn and Zn ions, indicating they were mainly derived from anthropogenic source. These ions have been accumulating in urban dust for decades; furthermore, the concentration of PM10 is seven times higher than that of the control area, which means that contamination is even present. The isotopic (13C, 207/206Pb) values of the pollution sources were highly different, depending on the characteristics of each source: cement (−19.6‰, 0.8594‰), Zn ore (−24.3‰, 0.9175‰), coal (−23.6‰, 0.8369‰), coke (−27.0‰, 0.8739‰), Mn ore (−24.9‰, 0.9117‰), soil (−25.2‰, 0.7743‰). As a result of the evaluated contributions of pollution source on urban dust through the Iso-source and SIAR models using stable isotope ratios (13C, 207/206Pb), we found that the largest contribution of Mn (20.4%) and Zn (20.3%) ions are derived from industrial factories and ore stockpiles on empty land (Mn and Zn). It is suggested that there is a significant influence of dust scattered by wind from raw material stockpiles, which are stacked near ports or factories. Therefore, there is evidence to support the idea that port activities affect the air quality of residence areas in a city. Our results may indicate that metal concentrations and their stable isotope compositions can predict environmental changes and act as a powerful tool to trace the past and present pollution history in complex contexts associated with peri-urban regions.

Source-specific risks of synchronous heavy metals and PAHs in inhalable particles at different pollution levels: Variations and health risks during heavy pollution

Synchronous heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) in inhalable particulate matter (PM₁₀) were measured during 2009-2012 and 2015-2016 in a Chinese megacity (Chengdu) to understand the variations in source-specific health risks during haze episodes. Samples were divided into four mass concentration levels: PM₁₀ ≤ 150 μg m^-3 (L1), 150 μg m^-3 < PM₁₀ ≤ 250 μg m^-3 (L2), 250 μg m^-3 < PM₁₀ ≤ 350 μg m^-3 (L3), and PM₁₀ > 350 μg m^-3 (L4). The percentages of some HMs and PAHs (accounting for PM₁₀) decreased from L1 to L4, indicating that they exhibited lower growth rates than other species during heavy pollution. The combined cancer risk (R) for HMs and PAHs was higher at L1 and L4, and the combined non-cancer risk (HQ) was significantly high at L4. The HMs and PAHs combined source-specific risk apportion (HP-SRA) model was employed to quantify the source-specific risks. The relative contributions of (i) diesel and gasoline vehicles to the R, and (ii) crustal dust to the HQ increased during heavy pollution (L3 and L4). The relative contribution of industrial source declined from 81% (L1) to 60% (L4) for the HQ, and from 49% (L1) to 36% (L4) for the R, implying that the control of industrial emissions during heavy pollution events could alleviate risk growth as a co-benefit of controlling PM mass concentration. However, the risks associated with industrial emissions should also be considered during 'clean' days.

Characterization of the contribution of road deposited sediments to the contamination of the close marine environment with trace metals: Case of the port city of Busan (South Korea)

We examined the concentrations of 12 trace metals in road-deposited sediments (RDS) and their contributions to the pollution of harbor/marine sediments in the port city of Busan, South Korea. The concentrations of Cr, Cu, Zn, Cd, Sn, Sb, and Pb in RDS affected by industrial and traffic activities were 6.7-25.7 times higher than those in marine sediments. The enrichment factors indicate that RDS are extremely polluted with Sb and moderately to strongly polluted with Cr, Cu, As, Sn, Pb, Zn, and Cd. The mean modified pollution index distinguished between unpolluted marine sediments, moderately to heavily polluted harbor sediments, and severely polluted RDS. Furthermore, harbor/marine sediments close to shipyards and the mouths of streams and rivers were found to be moderately polluted with Cu, Zn, Cd, Sb, and Pb. RDS containing trace metals accumulate on impervious surfaces and flow into the marine environment via untreated stormwater runoff.

Heavy metal pollution by road-deposited sediments and its contribution to total suspended solids in rainfall runoff from intensive industrial areas

Understanding the relationship between road-deposited sediments (RDS) and total suspended solids (TSS) is essential for managing non-point pollution. Studying the heavy metal concentrations of RDS and TSS in rainfall is important to the development of RDS management strategies and to the design of effective stormwater management practices. We investigated the heavy metal (V, Cr, Mn, Co, Ni, Cu, Zn, As, Mo, Cd, Sn, Pb) in RDS and TSS in rainfall runoff to assess the metal pollution level and to evaluate the contribution of RDS heavy metal pollution in the TSS. The heavy metal pollution in RDS and TSS in industrial areas was relatively higher in small particles (<125 μm), while TSS had a higher heavy metal concentration than RDS. In addition, the concentration of heavy metals in TSS increased rapidly during the initial rainfall. The amount of particles larger than 125 μm also increased, suggesting that large metal particles accumulated in industrial areas were also discharged in the form of non-point pollution. The amount of RDS per unit of industrial area (g/m²) and the accumulation of heavy metals (Pb, Cu, and Zn) (mg/m²) were 15- and 8-54-fold higher than those of urban areas, respectively. Considering particles <125 μm, which can be easily transported or discharged during rainfall, the contribution rate of RDS to TSS was 41.3%, but the average contribution rate to heavy metals in TSS was 22.1%. The average load of heavy metals from industrial areas in TSS was 77.9%. The load of Cu, Ni, As, Cd, and Sn exceeded 90%, indicating that most of these metals were attributed to industrial activities related to metal processing. Our results suggest the importance of efficient road cleaning and rainfall runoff management strategies to solve the heavy metal pollution problem caused by non-point sources in industrial areas.

Spatially resolved distribution, sources and health risks of heavy metals in size-fractionated road dust from 57 sites across megacity Kolkata, India

This work reports the first assessment of contamination levels, source contributions and health risks associated with heavy metals (HMs) in road dust from Kolkata, the second-most polluted metropolis in India. To this end, samples collected from 57 locations across 6 land-use categories: residential, roadside, traffic, railway, port and industrial areas in the city during 2018 were analyzed for 11 major and trace metals (Ca, Mg, Fe, Al, Mn, Ni, V, Cu, Zn, Cr, Pb) in three size fractions: <75 μm, 75-125 μm and 125-300 μm. Overall, Mn, Zn, Cr, Pb, V, Cu and Ni were enriched in the smallest fraction by factors of 1.2-2.7. Based on metal distribution across land-use categories, crustal dust (Fe, Al, V), construction activities (Ca, Mg), metallurgical processes (Pb), and non-exhaust abrasive emissions from brake, tire and paint wear (Cu, Zn, Cr) were found to be significant. HMs such as Cu, Zn, Cr and Pb were considerably enriched over background levels as suggested by three contamination indices: Enrichment Factor (EF; overall range: 2.4-12.0), Index of Geo-accumulation (I_geo; overall range: 1.1-3.4), and Pollution Index (PI; overall range: 3.1-15.6). Geospatial mapping identified HM contamination hotspots (integrated PI >4) in west-central and northern parts (the older sections) of the city represented by industrial, port, and traffic-congested residential areas. Using positive matrix factorization (PMF), the following sources were apportioned for the three size fractions: crustal dust (48-66%), construction activities (18-20%), vehicular abrasion (7-21%), industrial emissions (5-8%), a Cr-dominated mixed source (6%) and an unassigned source (7%). Finally, health risk assessment in the form of cumulative hazard index (HI) and incremental lifetime cancer risk (ILCR) found that children (mean HI_children: 1.29 and ILCR_children: 2E-04) are comparatively more vulnerable than adults (mean HI_adults: 0.22 and ILCR_adults: 8E-05) to HM exposure, with the ingestion exposure pathway dominating over dermal contact and inhalation.

Evaluation of microplastics in beach sediments along the coast of Dubai, UAE

Microplastic contamination in beach sediments along coast of Dubai is un-documented. In this study, microplastic contamination in beach sediments collected from the wrack lines of 16 beaches in Dubai was evaluated. Five samples were collected from each beach along a 100 m stretch using a 0.5 m by 0.5 m, quadrant. The number, color, and shape of microplastics were documented. The polymer types of large fibers and strings were identified through FT-IR analysis. 480 microplastics from each of the 16 beaches were selected to detect heavy metals using XRF analysis. The results showed that the average weight of microplastic is 0.33 mg per gram of dry sediment (or 953 mg·m^-2) and the number of microplastic is 59.71 items per kg of dry sediment (or 165 items·m^-2). Blue and fibrous microplastics were dominant. Polyethylene strings and fibers were abundantly found. 13 heavy metals were identified of which five are priority pollutants.

Street dust heavy metal pollution implication on human health in Nicosia, North Cyprus

The consequence of carcinogenic and non-carcinogenic health risks of the heavy metal concentrations in street dust of North Cyprus is yet to be reported. This study is aimed at investigating the concentration of six different heavy metals' concentration explicitly: As, Cu, Zn, Ni, Cr, and Pb, along leading highways in Nicosia. The result obtained was analyzed using an X-ray fluorescent machine. Multivariate and statistical methods were applied for the data analysis using xlstat MS-excel; furthermore, index of geo-accumulation (Igeo) and human health risk assessment using exposure pathways as defined by United State Environmental Protection Agency (USEPA) pollution mode were also used for level assessment and health risk implications. The average (M ± SD) concentrations of the metals in the dust are as follows: As (17.48 ± 1.53 mg/kg), Cu (51.86 ± 8.60 mg/kg), Cr (321.14 ± 8.20 mg/kg), Pb (35.62 ± 8.54 mg/kg), Ni (64.79 ± 8.72 mg/kg), and Zn (136.13 ± 30.85 mg/kg). Variation coefficient, Vc, and principle component analysis (PCA) suggested that As, Cr, Ni, and Pb have same source of pollution emission from both natural and anthropogenic activities, Zn from traffic emission while Cu from natural source. However, the result was compared with other nearby towns bordering North Cyprus; all the metal shows similar pattern of pollution with the exception of Cr which is 5 and 11 times higher than street dust of Amman (Jordan) and Tokat (Turkey), respectively. Additionally, Igeo result has the following decreasing order: Zn > Cr > Pb > Ni > Cu > As and also revealed that the As, Cu, and Ni have originated from natural source. Cr has mix source: one from traffic and the other one from atmospheric deposition. Also, Pb is emitted from industrial pollution, whereas 80% of Zn are from traffic-related emissions. The non-carcinogenic health risk (hazard quotient (HQ) and hazard index (HI)) follows the order Cr > As>Ni > Pb > Zn > Cu for children and adults. It is found that the HI of As, Cu, Ni, Pb, and Zn is less one; hence, the street dust does not exhibit non-carcinogenic health risk. But that of Cr content is greater than one, with HI values of Cr 1.44E+02 and 1.55E+01 for children and adults, respectively. The result for carcinogenic health risk (total cancer risk (TCR)) has the following order: Pb (1.42E-05) > Cr (4.81E-09) > (Ni 1.35E-09) > As (1.96E-10). With all the values less than threshed hole limit of TCR ≥ 10^-4, street dust does not possess carcinogenic health risk for the entire values of six heavy metals considered in this work.

Characterization and risk assessment of heavy metals in road dust from a developing city with good air quality and from Shanghai, China

To investigate the differences in characteristics of heavy metals associated with different levels of ambient air quality, we collected road dust samples from Beihai (BH) and Shanghai (SH). The mean concentrations of Ni, Cr, Zn, and Cu in BH samples were one to four times the background concentrations in soil, whereas the concentrations of Cd, Cr, Mn, Zn, Cu, and Pb in SH were one to three times the background concentrations. The geo-accumulation index (I_geo) indicated widespread moderate contamination by Zn and high contamination near industrial areas by Ni and Cr in BH, whereas in SH was partly moderately contaminated by Pb, Cu, and Zn. The potential ecological risk index ([Formula: see text]) indicated the low risk posed by all metals in both BH and SH. However, special attention should be given to the maximal [Formula: see text] values, such as considerable risk for Hg ([Formula: see text] = 148.7) and high risk for Ni (254.1) in BH, respectively. According to the health risk assessment results, there were no non-carcinogenic or carcinogenic risks (CR) posed by heavy metals in road dust collected from BH and SH. Non-carcinogenic risks due to Cr for children in both BH (0.36) and SH (0.24) were relatively high compared to other metals, and a maximal CR value for Cr (2.7 × 10^-6) was found to pose a potential carcinogenic risk near the industrial area in BH. Compared with those in developed cities, the health risks in BH related to Cu, Pb, and Zn from motor vehicle emissions were relatively low, but those related to Ni and Cr from local industrial activity in road dust were relatively high.

Ecological and Human Health Risk Assessment of Heavy Metal Content of Atmospheric Dry Deposition, a Case Study: Kermanshah, Iran

The present study was intended to investigate the ecological and human health risk of cobalt, nickel, and vanadium in the atmospheric dry deposition of the Kermanshah city, Iran, in 2015. Totally 54 samples of atmospheric dry deposition were collected from the three regions of the city with different traffic intensity, and after acid digestion of the samples with ultrapure concentrated HNO₃, the total contents of the metals were determined using inductively coupled plasma optical emission spectrometer (ICP-OES). Also, all statistical analyses were performed using the SPSS statistical package. The atmospheric dry deposition element contents increase according to the following descending order for both autumn seasons: Ni > Co > V. The results of potential ecological risk analysis demonstrated that metals in the samples are in low ecological risk levels, whereas the results of human health risk assessment showed that ingestion is the main exposure pathway of heavy metals in the dust to the local residents compared with inhalation and dermal pathways. Also, the upper limit of the 95% confidence interval (95% UCL) of hazard indices for non-carcinogenic risks of all analyzed metals in the dust samples was within the safe level for both children and adults. On the other hand, the carcinogenic risk levels of Co and Ni were all lower than the acceptable range (10^-6-10^-4) to local citizens. Consequently, the results advocate the necessity of understanding the heavy metal content of atmospheric dry deposition and regular monitoring of air pollution.

Characteristic contaminants in snowpack and snowmelt surface runoff from different functional areas in Beijing, China

Characteristics of physicochemical parameters, dissolved-phase heavy metals, and polycyclic aromatic hydrocarbons (PAHs) were investigated for 68 urban snowmelt surface runoff and snowpack samples collected from five different functional areas in Beijing, including a business area (BA), a cultural and educational area (CEA), a garden area (GA), a residential area (RA), and a roadside area (RSA). Both snowmelt surface runoff and snowpack were significantly polluted by organic matter, as indicated by their high concentrations of chemical oxygen demand (COD) and total organic carbon (TOC). Among the 11 heavy metals analyzed, Zn was the most enriched in all samples, followed by Mn, Fe, and Cu, whereas the concentrations of Pb, Cr, Cd, As, Ni, Sb, and Co were comparatively low. The results suggested that typical traffic emissions, natural events, industrial practices, and human activities were mainly sources of heavy metals. Low molecular-weight (LMW) PAHs were the dominant sources in snowmelt and snowpack. Anthracene (Ant) and fluorene (Flo) were the most enriched PAHs in both snowmelt surface runoff and snowpack. Coal burning for heating and traffic activities were the most important contributors of PAH pollutants in snowmelt surface runoff and snowpack in Beijing in the winter. Ecological risk assessment demonstrated, however, that heavy metals in snowmelt surface runoff pose little risk to downstream aquatic environments. A middle potential ecological risk could be caused by Ant, Flo, benzo[g, h, i]perylene (BghiP), and benzo[a]pyrene (BaA).

Contamination Level, Source Identification and Risk Assessment of Potentially Toxic Elements (PTEs) and Polycyclic Aromatic Hydrocarbons (PAHs) in Street Dust of an Important Commercial Center in Iran

The geochemical nature and health hazards of potentially toxic elements (PTEs) and polycyclic aromatic hydrocarbons (PAHs) in the street dust of Bandar Abbas, Iran, are investigated in this study based on 27 street dust samples. Mean concentrations of Cu, Pb, Zn, As, Sb, and Hg revealed elevated concentrations as compared to the world soil average. Calculated enrichment factors (EFs) indicated that there is very high contamination in dust particles owing to anthropogenic emissions. Two main sources of PTEs are traffic emissions (Cu, Pb, Zn, Co, Mn, Fe, As, Cd, Sb, and Hg) and resuspended soil particles (Al, Ti, Ni, and Cr). Statistical analysis shows that Al, Mn, Ni, Ti, Cr, Fe, and Co are geogenic, whereas PAHs are mainly derived from traffic emissions. Values of incremental lifetime cancer risk (ILCR), as derived from a modified model of the United State Environmental Protection Agency (USEPA), indicate that Bandar Abbas residents are potentially exposed to high cancer risk, especially via dust ingestion and dermal contact, whereas the level of hazard index (HI), hazard quotients (HQ), and cancer risk associated with exposure to the elements in street dust fall lower than threshold values representative of health risks.

Contamination characteristics and source apportionment of heavy metals in topsoil from an area in Xi'an city, China

As soil-extractable elements potentially pose ecological and health risks, identifying their contamination characteristics and sources is crucial. Therefore, to understand topsoil trace elements in the urban ring zone from the Second Ring Road to the Third Ring of Xi'an city in China, we determined the concentrations of Zn, Co, V, As, Cu, Mn, Ba, Ni and Pb, and analyzed the sources of the contamination. The results showed that the individual pollution indices of Pb, Co, Cu, Zn, Ba, Ni, Mn, As, and V were 1.79, 1.48, 1.41, 1.33, 1.20, 1.07, 1.04, 0.99, and 0.99, respectively. Evaluation with the aid of the pollution load index (PLI) indicated slight soil contamination by these elements in the study area. Using the positive matrix factorization (PMF) method, we identified four sources of contamination, namely (1) a natural source, (2) traffic emission source, (3) industrial emission source, and (4) mixed source. PMF is an effective tool for source apportionment of heavy metals in topsoil. The contribution rates of the natural source, traffic source, mixed source, and industrial source to the heavy metal contamination were specified as 25.04%, 24.71%, 24.99%, and 25.26%, respectively. Considering the above, any attempt to reduce the soil environmental cost of urban development, has to take into account the heavy metal contamination of the topsoil from industries, traffic, and other activities.

Rare earth elements in street dust and associated health risk in a municipal industrial base of central China

The content levels, distribution characteristics, and health risks associated with 15 rare earth elements (REEs) in urban street dust from an industrial city, Zhuzhou, in central China were investigated. The total REE content (∑REE) ranged from 66.1 to 237.4 mg kg^-1, with an average of 115.9 mg kg^-1, which is lower than that of Chinese background soil and Yangtze river sediment. Average content of the individual REE in street dust decreased in the order Ce > La > Nd > Y > Pr > Sm > Gd > Dy > Er > Yb > Eu > Ho > Tb > Tm > Lu. The chondrite-normalized REE pattern indicated light REE (LREE) enrichment, a relatively steep LREE trend, heavy REE (HREE) depletion, a flat HREE trend, a Eu-negative anomaly and a Ce-positive anomaly. Foremost heavy local soil and to less degree anthropogenic pollution are the main sources of REE present in street dust. Health risk associated with the exposure of REE in street dust was assessed based on the carcinogenic and non-carcinogenic effect and lifetime average daily dose. The obtained cancer and non-cancer risk values prompt for no augmented health hazard. However, children had greater health risks than that of adults.

Identification of sources of metal in the agricultural soils of the Guanzhong Plain, northwest China

A comprehensive survey was conducted to assess the possible sources and distribution of metals in the agricultural soils of the Guanzhong Plain in northwest China. In total, 227 samples of agricultural soil were collected to determine the content of Pb, Cr, Co, V, Ni, Zn, Cu, As, and Mn by X-ray fluorescence spectrometry. The mean concentrations of metals were 26.2 ± 10.8 mg kg^--1 , 71.5 ± 16.8 mg kg^-1 , 12.7 ± 1.81 mg kg^-1 , 85.1 ± 7.86 mg kg^-1 , 30.5 ± 6.17 mg kg^-1 , 71.1 ± 14.1 mg kg^-1 , 25.2 ± 5.58 mg kg^-1 , 12.5 ± 1.94 mg kg^-1 , and 635.4 ± 84.7 mg kg^-1 for Pb, Cr, Co, V, Ni, Zn, Cu, As, and Mn, respectively-slightly higher than the regional background values. Multivariate analysis was used to identify the metal sources, and it was found that Ni and Cr in the agricultural soils were mainly derived from lithological materials, and Pb, Zn, and Cu were mainly from traffic emissions; however, Zn and Cu also originated from mineral fertilizers or pesticides. The other metals originated from industrial emissions. The Nemerow index coupled with geographic information system technology was applied to assess the degree and spatial distribution of metal contamination; the soils studied were classified as slightly polluted, and the most contaminated regions were concentrated in the area surrounding Xi'an city, as well as areas in the southeast and north of the Guanzhong Plain. Environ Toxicol Chem 2017;36:1510-1516. © 2016 SETAC.

Characteristic comparison of heavy metal contamination between road-deposited and roof-deposited sediments in suburban area

Surface-deposited sediment in urban area is an essential environmental medium for assessing heavy metal contamination. A total of 10 sampling trips were conducted to collect road-deposited and roof-deposited sediments for the comparison of nickel (Ni), copper (Cu), cadmium (Cd), lead (Pb), zinc (Zn), and chromium (Cr) contamination characteristics. Results indicated that roof sediment appeared to have a finer size distribution than road sediments. Roof sediment indicated higher metal concentration and lower surface loading than road sediment. The impact of particle size on heavy metal contamination was quantified by using the developed pioneering term of finer particle effect factor; it differed according to surface types and grain size fraction. Particles in individual grain size fraction showed different contribution to the surface loading for bulk sediments. No consistent trend was found for the grain size fraction loading along with grain size for the studied heavy metals for road sediments. In contrast, an asymmetric "W" trend was observed for the roof sediments, and it had the following results: Fraction of <63 and 250-500 μm showed higher loading, while fraction of 90-125 and >850 μm indicated the smaller loading. Findings above facilitated the appropriate management practice selection for the treatment of surface-deposited sediments.

Pollution characteristics, source apportionment, and health risk of heavy metals in street dust of Suzhou, China

To analyze the pollution characteristics, source apportionment, and health risk of heavy metals (HMs) in street dust of Suzhou, China, 23 sampling sites were selected and periodically sampled for 12 months. A total of 276 samples were collected, and the concentrations of selected HMs (e.g., Cr, Cu, Fe, Mn, Pb, V, and Zn) were examined with an X-ray fluorescence spectrum analyzer. Results showed that the mean concentrations of Cr, Cu, Fe, Mn, Pb, V, and Zn in the street dust of Suzhou were 112.9, 27.5, 19941.3, 410.3, 45.2, 75.6, and 225.3 mg kg^-1, respectively. Cr, Cu, Pb, and Zn exceeded their background values in local natural soils by 1.3-3.6-fold, whereas Fe, Mn, and V were all within their background values. However, enrichment factor analysis revealed that Cr, Cu, Mn, Pb, V, and Zn, especially Cr, Cu, Pb, and Zn, were enriched in Suzhou street dust. The HMs showed no significant seasonal changes overall, but spatial distribution analysis implied that the high values of Cr, Cu, Mn, Pb, V, and Zn were mainly distributed in areas with frequent human activities. Results of multivariate techniques (e.g., Pearson correlation, hierarchical cluster, and principal components analyses) suggested that Pb and Zn had complicated sources; Cu and V mainly originated from traffic sources; Fe and Mn mainly came from natural sources; and Cr was dominantly related to industrial district. Health risk assessment revealed that a single heavy metal might not cause both non-cancer and carcinogenic risks to local residents. Nevertheless, the sum of the hazard index of all selected HMs for children slightly exceeded the safety value, thereby implying that the HMs from Suzhou street dust can possibly produce significant risk to children. Cr was the priority pollutant in the study area because of its high concentration, high enrichment, and high contribution to non-cancer risk values.

Distribution characteristics and sources of trace metals in sediment cores from a trans-boundary watercourse: An example from the Shima River, Pearl River Delta

Metal pollution in sediments from the Shima River, a typical transboundary watercourse in the Pearl River Delta area, was investigated. Sediment cores were collected at eight sites from the upper to the lower reaches crossing Shenzhen, Dongguan and Huizhou cities. Sediment physicochemical properties and the total concentrations of trace metals (V, Cr, Co, Ni, Cu, Zn, As, Cd and Pb) were determined. The results showed that riverine sediment was significantly polluted by Cr (content range: 13.8-469mgkg^-1), Ni (14.1-257mgkg^-1), Cu (10.8-630mgkg^-1), Zn (50.2-1700mgkg^-1) and Cd (0.172-2.26mgkg^-1). The geoaccumulation indices (I_geo) of trace metals decreased in the order Cd>Zn>Ni>Cu>Co>Cr>Pb>As>V. The pollution load indices and potential ecological risk indices (RI) at the sampling sites were similar, with more severe pollution and greater risk presenting in the upper and middle reaches (S1-S6) compared with the lower reaches (S7 and S8). Cd contributed significantly (77.2-87.6%) to the RI. Source identification based on multivariate statistical techniques, including principal component analysis (PCA), correlation analysis (CA) and hierarchical cluster analysis (HACA), was performed to differentiate the origins of trace metals. PCA and CA yielded similar results, indicating that As and V originated from natural sources (e.g., parent materials) and that the other metals were related to anthropogenic activities. HACA based on the I_geo showed that Cd was associated mainly with fertilizers, and the origins of Cr, Ni, Cu and Zn were probably industrial effluents, whereas Co and Pb were related to traffic activities. HACA of sediment cores suggested that Dongguan and Shenzhen cities contribute large quantities of metals to the riverine sediment, whereas few metals were discharged from Huizhou City.

Intra-urban biomonitoring: Source apportionment using tree barks to identify air pollution sources

It is of great interest to evaluate if there is a relationship between possible sources and trace elements using biomonitoring techniques. In this study, tree bark samples of 171 trees were collected using a biomonitoring technique in the inner city of São Paulo. The trace elements (Al, Ba, Ca, Cl, Cu, Fe, K, Mg, Mn, Na, P, Rb, S, Sr and Zn) were determined by the energy dispersive X-ray fluorescence (EDXRF) spectrometry. The Principal Component Analysis (PCA) was applied to identify the plausible sources associated with tree bark measurements. The greatest source was vehicle-induced non-tailpipe emissions derived mainly from brakes and tires wear-out and road dust resuspension (characterized with Al, Ba, Cu, Fe, Mn and Zn), which was explained by 27.1% of the variance, followed by cement (14.8%), sea salt (11.6%) and biomass burning (10%), and fossil fuel combustion (9.8%). We also verified that the elements related to vehicular emission showed different concentrations at different sites of the same street, which might be helpful for a new street classification according to the emission source. The spatial distribution maps of element concentrations were obtained to evaluate the different levels of pollution in streets and avenues. Results indicated that biomonitoring techniques using tree bark can be applied to evaluate dispersion of air pollution and provide reliable data for the further epidemiological studies.

Heavy metals in soils from a typical county in Shanxi Province, China: Levels, sources and spatial distribution

The concentrations of As, Cd, Cr, Cu, Pb, Ni, Zn, and Hg in 128 surface soil samples from Xiangfen County, Shanxi Province, China were measured. The concentrations of these eight heavy metals were lower than the critical values in the national soil quality standard. However, these concentrations were found to be slightly higher than their background values in soils in Shanxi Province, indicating enrichment of these metals in soils in Xiangfen County, especially for Hg and Cd. Principal component analysis coupled with cluster analysis was used to analyze the data and identify possible sources of these heavy metals; the results showed that the eight heavy metals in soils from Xiangfen County came from three different sources. Lead, Cd, Cu and Zn mainly arose from agricultural practices and vehicle emissions. Arsenic and Ni arose mainly from parent materials. Industrial practices were the main sources of Cr and Hg. The spatial distribution of the heavy metals varied greatly, and was closely correlated to local anthropogenic activities. This study will be helpful not only for improving local soil environmental quality but will also provide a basis for effectively targeting policies to protect soils from long-term heavy metal accumulation.

Human Health Risks Associated with Metals from Urban Soil and Road Dust in an Oilfield Area of Southeastern Algeria

Hassi Messaoud town is a recent city that is situated inside the oil field, which hosts an important petroleum extraction field and refinery. Large-scale and long-term oil refinery and corresponding industrial activities may contaminate the surrounding soil/dust and could lead to pollution levels that can affect human health. The soil and road dust samples were analysed for different trace elements: copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn). Geo-accumulation index (I(geo)), pollution index (PI), and integrated pollution index (IPI) were calculated to evaluate the heavy metal contamination level of urban soil and road dust. The I(geo) values indicate unpolluted to moderate polluted of investigated metals in the soil samples. The assessment results of PI support the results of I(geo), and IPI indicates heavy metals in road dust polluted seriously. The noncarcinogenic health risk assessment shows that ingestion of soil/dust particles is the route for exposure to heavy metals, followed by dermal adsorption. The human exposure risk assessment based on different exposure pathways showed that the hazard index (HI) was <1.0 for all of the elements. The relative exposure risk (noncarcinogenic) was greater for toddlers. Although the overall risk was within the acceptable limit of 1.00, the HI of Pb from the soil (0.103) and road dust (0.132) was close to the threshold limits, which over the long-term may pose a health risk.

Pollutant characteristics of road deposited sediments collected by road sweeping

Road deposited sediments (RDS) swept from highways in South Korea were characterized to quantitatively evaluate the reduction in non-point source pollutants by sweeping. The swept RDS consisted primarily of sand (63 μm to 2 mm) particles (80.34 ± 8.33% of total weight) highly contaminated by organics, nutrients and heavy metals. The average concentrations of total organic carbon (TOC), biochemical oxygen demand (BOD), volatile solids (VS), total nitrogen (T-N), and total phosphorus (T-P) were 20.17 ± 9.13, 1.04 ± 0.62, 39.92 ± 16.55, 1.99 ± 0.96, and 0.54 ± 0.19 g kg(-1) (±one standard deviation), respectively, for 63 μm to 2 mm RDS. The concentrations of the pollutants were high for RDS smaller than 63 μm, but most of the mass was associated with the 63 μm to 2 mm RDS. The results suggest that the pollutants associated with RDS swept from highways originated mainly from engine wear, exhaust emissions, and tire wear. These results were different from the RDS on roads in residential and commercial areas, where natural particles and brake wear contribute significantly to RDS. In addition, the reductions in TOC, BOD, VS, T-N, T-P, Cu, Pb, Zn, Fe, and As based on the swept RDS measurements were calculated to be 3,355.3, 175.1, 6,621.4, 323.0, 88.3, 30.3, 13.7, 1.0, 303.4, 11,198.7, and 0.4 g km(-1), respectively.

Influence of population density on the concentration and speciation of metals in the soil and street dust from urban areas

Street dust and soil from high, medium and low populated cities and natural area were analysed for selected physical-chemical properties, total and chemical speciation of Zn, Pb, Cu, Cr, Cd, Co, Ni to understand the influence of human activities on metal accumulation and mobility in the environment. The pH, salinity, carbonates and organic carbon contents were similar between soil and dust from the same city. Population density increases dust/soil salinity but has no influence on metals concentrations in soils. Increases in metal concentrations with population density were observed in dusts. Cu, Zn, Pb, Cr can be mobilized more easily from dust compared to the soil. In addition, population density increase the percentage of Pb and Zn associated to reducible and carbonate phase in the dust. The behaviour of metals except Cd in soil is mainly affected by physico-chemical properties, while total metal influenced the speciation except Cr and Ni in dusts.

Source identification and metallic profiles of size-segregated particulate matters at various sites in Delhi

A study of elemental composition in the ambient air of Delhi was carried out in the monsoon, winter and summer seasons at four different sites from August 2012 to April 2013 in the size ranges <1, 1-2.5, 2.5-10 and >10 μm using "Dekati PM10" impactor. At each site, three samples were collected and were analyzed by energy-dispersive X-ray fluorescence (EDXRF). The presence of elements was found to be very common and highly concentrated in aerosol particles at all the sites, which are Na, Al, Si, K, Ca, Zn and Ba. Total suspended particulate matters (TSPMs) of fine particles were found high in comparison to coarse particles at all seasons. The TSPM of fine particles was found to be varied in the range from 303.6 to 416.2 μg/m(3). Similarly, the range of coarse TSPM was observed from 162.9 to 262.8 μg/m(3). Correlation matrices were observed between fine (size ranges <1 and 1-2.5 μm) and coarse (size ranges 2.5-10 and >10 μm) size particles for all elements with seasons. Source apportionments of elements were carried out using MS Excel 2010 through XLSTAT software. The source apportionments between fine and coarse particles were carried out through factor analysis and dominated sources found to be crustal re-suspension and industrial activities.

Street dust: implications for stormwater and air quality, and environmental through street sweeping

Street dust represents a source of dual potential risk to stormwater and air quality. It has been well documented that street dust washes into local watersheds and can degrade water quality. Research has also demonstrated that ambient particulate matter (PM10) , which is associated with adverse health outcomes, can arise from resuspension of accumulated street dust. Furthermore, many contaminants, including metals, are present at higher concentrations in the smallest available particles, which are more likely to be resuspended in air and stormwater runoff. Although street cleaning is listed as a best management practice for storm water quality by the EPA, data are limited on the critical parameters (technology, environment, usage), which determine the effectiveness of any street cleaning program, particularly in the peer-reviewed literature. The purpose of the present study was to develop a comprehensive understanding of the efficacy of various street cleaning technologies and practices to protect both water quality and public health. Few studies have compared the effectiveness of street sweeping technologies to remove street dust. Unfortunately, the dearth of comprehensive data on exposure, contaminant concentrations, and efficacy of various sweeping technologies and strategies precludes developing quantitative estimates for potential risk to humans and the environment. Based on the few studies available, regenerative air street sweepers appear to provide the most benefit with regard to collection of small particles and prevention of re-entrainment. It is also clear from the available data that local conditions, climate, and specific needs are critical determinants of the ideal street sweeping strategy (technology, frequency, speed, targeted areas, etc.). Given the critical need for protection of water and air quality in rapidly expanding urban regions (e.g., megacities), further research is necessary to develop best practices for street dust management. Herein, we provide a framework for future experimental studies to support risk-based assessments of street cleaning technologies.

Assessment of mobility and bio-availability of heavy metals in dry depositions of Asian dust and implications for environmental risk

We assess the potential mobility and bio-availability of selected metals (As, Cd, Co, Cr, Cu, Ni, Mo, Pb, S, Zn, and Zr) in the dry depositions of Asian and non-Asian dust from the city of Daejeon, Korea. For this study, we applied Pb isotopes, total extraction and chemical sequential extraction methods to the dry depositions. In addition, microscopic analysis was performed using X-ray diffraction (XRD) and focused ion beam (FIB)-scanning electron microscopy (SEM-EDS). FIB-SEM cross-section observations and Pb isotope data showed a black carbon is an important carrier of associated heavy metals originating from China. A five-step sequential extraction performed on the dry depositions showed that S and Cd are the most abundant elements in the water-soluble and cation-exchangeable fraction. In addition, Zn and Pb appeared predominantly in the carbonate and reducible fractions. On the other hand, Cu, Mo and, to a lesser degree, As were significantly associated with the organic fraction, while Co, Ni, Cr and Zr were bound to the residual fraction. These results showed that S, Cd, Zn and Pb, which were highly concentrated in potentially mobile fractions, have potential environmental risk because potential changes in redox state and pH may remobilize these metals. In addition, the estimated remobilization concentrations of these metals were significant. Thus, this study shows that frequent and careful monitoring of S, Cd, Z, Pb and, to a lesser degree, Cu, Mo and As is very important for assessing environmental risk in Korea.

Seasonal concentrations of lead in outdoor and indoor dust and blood of children in Riyadh, Saudi Arabia

Because detrimental effects of exposure to lead (Pb) on human health have been observed, we previously investigated concentrations of Pb in water supplies and blood of adult residents of Riyadh, Saudi Arabia. The objectives of the present study were to: (1) examine seasonal rates of deposition of Pb in dust in several areas of Riyadh city, (2) measure concentrations of Pb in both outdoor and indoor dust, (3) compare concentrations of Pb in dust in Riyadh with those reported for other cities, and (4) quantify Pb in blood of children living in Riyadh. Mean, monthly deposition of PB in outdoor dust was 4.7 × 10(1) ± 3.6 tons km(-2), with a mean Pb concentration of 2.4 × 10(2) ± 4.4 × 10(1) μg/g. Mean, monthly deposition of Pb in indoor dust was 2.7 ± 0.70 tons km(-2), with a mean concentration of 2.9 × 10(1) ± 1.5 × 10(1) μg Pb/g. There was a significant (P < 0.01) correlation between concentrations of Pb in outdoor and indoor dust. There was no correlation between concentrations of Pb in indoor dust and that in blood of children of Riyadh, whereas there was a weakly significant (P < 0.05) correlation between concentrations of Pb in outdoor dust and that in blood of children. The mean (±SD) concentration of Pb in blood of children in Riyadh was 5.2 ± 1.7, with a range of 1.7-1.6 × 10(1) μg/dl. Concentrations of Pb in blood of 17.8 % of children in Riyadh were greater than 10 μg/dl, which is the CDC's level of concern.

Heavy metals in surface sediments of the Jialu River, China: their relations to environmental factors

This work investigated heavy metal pollution in surface sediments of the Jialu River, China. Sediment samples were collected at 19 sites along the river in connection with field surveys and the total concentrations were determined using atomic fluorescence spectrometer and inductively coupled plasma optical emission spectrometer. Sediment samples with higher metal concentrations were collected from the upper reach of the river, while sediments in the middle and lower reaches had relatively lower metal concentrations. Multivariate techniques including Pearson correlation, hierarchical cluster and principal components analysis were used to evaluate the metal sources. The ecological risk associated with the heavy metals in sediments was rated as moderate based on the assessments using methods of consensus-based Sediment Quality Guidelines, Potential Ecological Risk Index and Geo-accumulation Index. The relations between heavy metals and various environmental factors (i.e., chemical properties of sediments, water quality indices and aquatic organism indices) were also studied. Nitrate nitrogen, total nitrogen, and total polycyclic aromatic hydrocarbons concentrations in sediments showed a co-release behavior with heavy metals. Ammonia nitrogen, total nitrogen, orthophosphate, total phosphate and permanganate index in water were found to be related to metal sedimentation. Heavy metals in sediments posed a potential impact on the benthos community.

Human health risk assessment based on toxicity characteristic leaching procedure and simple bioaccessibility extraction test of toxic metals in urban street dust of Tianjin, China

The potential ecological and human health risk related with urban street dust from urban areas of Tianjin, China was quantitatively analyzed using the method of toxicity characteristic leaching procedure (TCLP) and simple bioaccessibility extraction test (SBET). In the study, Hakason index, Nemerow index (P), the hazard index (HI) and the cancer risk index (RI) were calculated to assess the potential risk. The sequence of potential ecological risk based on Hakason index was arsenic (As) > cadmium (Cd) > lead (Pb) > copper (Cu) > chromium (Cr), in particular, As and Cd were regarded as high polluted metals. While the results of extraction of TCLP were assessed using P, the sequence was As > Pb > Cd > Cr > Cu, which mean that As and Pb should be low polluted, and Cd, Cr and Cu would barely not polluted. For human health, total carcinogenic risk for children and adults was 2.01×10⁻³ and 1.05×10⁻³, respectively. This could be considered to be intolerable in urban street dust exposure. The sequence in the hazard quotient (HQ) of each element was As > Cr > Pb > Cu > Cd. The HI value of these toxic metals in urban street dust for children and adults was 5.88×10⁻¹ and 2.80×10⁻¹, respectively. According to the characters of chemistry, mobility, and bioavailability of metals in urban street dust, we estimated the hazards on the environment and human health, which will help us to get more reasonable information for risk management of metals in urban environment.

Level and contamination assessment of environmentally sensitive elements in smaller than 100 μm street dust particles from Xining, China

Concentrations of the environmentally sensitive elements (ESEs) As, Co, Cu, Mn, Ni, Pb, V and Zn in smaller than 100 μm street dust particles from Xining were measured using X-ray fluorescence spectrometry and their contamination levels were assessed based on enrichment factor (EF), geoaccumulation index (I_geo) and pollution load index (PLI). The concentrations of As, Co, Cu, Mn, Ni, Pb, V and Zn in smaller than 100 μm street dust particles from Xining are 0.1–0.8, 2.7–10.9, 0.7–5.2, 0.3–1.1, 0.6–2.5, 1.2–11.1, 0.7–1.3 and 0.4–2.9 times the background values of Qinghai soil, respectively. The calculated EF and I_geo values reveal the order Co > Pb > Cu > Zn > V > Ni > Mn > As. The EF and I_geo values of Co, Cu, Pb and Zn are higher indicating that there is considerable pollution by these elements in smaller than 100 μm street dust particles, especially for Co. The EF and I_geo of Mn, Ni and V are lower and the assessment results indicate an absence of distinct Mn, Ni and V pollution in the studied samples. The mean value of PLI_site is 1.14, indicating a slightly pollution in the whole city of Xining. The order of PLI_area for the five tested districts is Center District (CD) > East District (ED) > West District (WD) > North District (ND) > South District (SD), showing that ESEs pollution in the South District is the lightest while it is the highest in the Central District.

Dust fallout in Kuwait city: deposition and characterization

Dust fallouts in Kuwait city was monitored on monthly basis during the period from March 2011 to February 2012 at 10 locations. The results of this study reveal that: (1) monthly dust deposition rates ranged from 0.002 to 0.32 kg/m(2) with average deposition rate of 0.053 kg/m(2) and annual average deposition rate of 0.59 kg/m(2), ranking the first out of 56 dust deposition rates observed throughout the world; (2) on average, about 55.9% of the settled dust have fine to very fine sand fraction sizes, while silt and clay comprise an average of 37.4 and 1.4% of the total sample, respectively; (3) the concentrations for Zn and Mo out of 15 other elements analyzed from the dust were up to 11 times higher than their soil background values in Kuwait, while Pb and Ni were about seven times higher; (4) Mo, Ni, Pb and Zn show maximum enrichment relative to the upper continental crustal component (Mn); (5) Sr, Zr and Zn show highest concretions among all collected samples; and (6) quartz and calcite were the dominant minerals in the dust samples. The distribution of the heavy metals in dust seems to be controlled mainly by the land uses and the volume of traffic emissions.

Depth profile of major and trace elements in estuarine core sediment using the EDXRF technique

Distribution and enrichment of elements in sediment are influenced by their texture, mineralogical composition, and physical transport. The vertical concentration profiles of sixteen elements in core sediment samples, namely Na, Mg, Al, K, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br, Sr, and Pb were measured using the energy dispersive X-ray fluorescence (EDXRF) technique. To check the anthropogenic input various indices (enrichment factor, contamination factor, index of geoaccumulation and pollution load index) were calculated and compared.

Automated mineralogical analysis of PM10: new parameters for assessing PM toxicity

This work provides the first automated mineralogical/phase assessment of urban airborne PM10 and a new method for determining particle surface mineralogy (PSM), which is a major control on PM toxicity in the lung. PM10 was analyzed on a TEOM filter (Aug.-Sept. 2006 collection) from the London Air Quality Network Bexley, East London, U.K. A cross-section of the filter was analyzed using a QEMSCAN automated mineralogical analysis system which provided 381,981 points of analysis for 14,525 particles over a period of 9 h 54 min. The method had a detection limit for individual mineral components of 0.05 ppm (by area). Particle shape and mineralogical characteristics were determined for particles in the size ranges PM(10-4), PM(4-2.5), and PM(2.5-0.8). The PM(2.5-0.8) fraction contained 2 orders of magnitude more mineral particles than the PM(10-4) and PM(4-2.5) fractions, however the PM(10-4) fraction forms 94% and 79% of the mineral mass and surface area, respectively. PSM of the PM10 was dominated by gypsum (36%), plagioclase (16%), Na sulphates (8%), and Fe-S-O phases (8%) in the PM(10-2.5), which may be important in explaining the toxicity of the coarse fraction. The wider implications of the study are discussed.

Heavy metal concentrations and contamination levels from Asian dust and identification of sources: a case-study

The aims of this study were to determine concentrations of selected metals (As, Cd, Cr, Co, Cu, Ni, Sb, Pb and Zn) in Asian and non-Asian dust collected in Daejeon, Korea between February 2007 and December 2007 and to estimate the pollution sources. The geoaccumulation index (Igeo) and the enrichment factor (EF) show that the pollution levels of Cd, Pb, Zn, Sb, Cu, and As are much higher than those of Cr, Co and Ni. As, Cd, Cu, Sb, Pb, and Zn are the ones most strongly affected by anthropogenic inputs such as airborne pollutants. The (206)Pb/(207)Pb ratios of Asian and non-Asian dust are similar to those of the airborne particles in some heavily industrialized Chinese cities and the soils of the Alashan desert. To address the highly elevated levels of heavy metals found in Asian and non-Asian dust, studies should be performed to assess the potential impacts of settled particles on surface ecosystems, water resources, and human health in Korea.