Source apportionment and spatial-temporal variations in the metal content of surface dust collected from an industrial area adjoining Delhi, India

A comparative study on metal pollution from surface dust of informal and formal e-waste recycling sectors in national capital region of New Delhi and associated risk assessment

Electrical and electronic waste (e-waste) is considered as resource and secondary source of metals, and is being recycled for recovery of precious and base metals. But the processes of recycling and the waste generated during e-waste recycling in informal and formal sectors contribute toxic metals in to the environment. This work aimed to compare the environmental and health impacts of informal and formal e-waste recycling facilities at New Delhi and Bhiwadi Industrial area in India, respectively. Here, concentrations of Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sn, V, Zn, and Ag, and As in surface dust collected from informal and formal recycling sectors and their associated pollution, human health and ecological risk are presented. Metal concentrations were higher than the background levels in both sectors. Contamination factor (Cf), contamination degree (Cdeg), pollution load index (PLI), geo-accumulation index (Igeo) and enrichment factor (EnF) of metals indicated severe pollution levels in both sectors. However, contamination in informal sector was comparatively higher than the formal sector. Sampling sites in both sectors had very high ecological risk. Storage, dismantling/shredding and recycling techniques were contributors of metals in surface dust in formal sector whereas fumes deposition, re-suspension, and dried by-products during acid bath treatments were additional sources in informal sector. Metal pollution depends on metal(s), e-waste type(s) and recycling sector(s). Total non-carcinogenic health risk due to metals was 6.5E+00 and 6.0E+01 and 6.2E+00 and 5.5E+01 in adult and children in informal and formal sectors, respectively. Total carcinogenic risk was 3.3E-03 and 7.2E-03 in informal and formal sectors, respectively. Ingestion was major pathways of metals followed by dermal and inhalation and children were more prone to risk compared to adults. Formal sectors too cause metal pollution but to lesser degree compared to informal. More effective pollution control measures are required in formal sector to control environmental pollution.

Geochemical fractionation, bioavailability, ecological and human health risk assessment of metals in topsoils of an emerging industrial cluster near New Delhi

Urban spaces have become sink for metal-rich waste, particularly in unorganized industrial clusters and metro-cities. Geochemical distribution of metals in different forms and their mobility and bioavailability in topsoils of Bhiwadi Industrial Cluster (BIC) near New Delhi are studies following m-BCR-SEP. Contamination factor (Cf), risk assessment code (RAC), ecological risk assessment (Er), and carcinogenic and non-carcinogenic health risk (HRA) were calculated to assess health and environmental risks. Residual fraction (F4) contained considerable amounts of Cd (57.2%), Cr (81.5%), Fe (86.1%), Mn (62.5%), Ni (58.3%), and V (71.4%). Pb was present in reducible fraction (F2; 52.8%), whereas Cu was distributed in F2 (33.3%) and F4 (31.6%). Zn showed equal distribution in acid exchangeable (F1; 33.9%) and oxidizable fraction (F3; 32.5%). High Cf was observed for Zn (0.9-20.9), Cu (0.46-17) and Pb (0.2-9.9). RAC indicated high risk of Cd, Cu, Mn, Ni, and Zn due to their high mobility and toxicity. High potential bioavailability of Cu, Pb, and Zn (> 65%) was found in samples collected near to metal casting, electroplating, and automobile part manufacturing industries. Considerable to extremely high ecological risk was observed for Cd, low to high risk for Cu, low risk to moderate risk for Cr, Mn, Ni, Zn, and Pb. All topsoil samples were in low to very high-risk range for metals. Ingestion was major pathway of metals followed by dermal and inhalation. Children were more prone to non-carcinogenic risks (hazardous index: 3.6). Topsoils had high carcinogenic risk to exposed population for Cd, Cr, Ni, and Pb.

Accumulation degree and risk assessment of metals in street dust from a developing city in Central Taiwan

Due to the numerous industrial parks and high traffic density in Miaoli, Taiwan, large amounts of metals may be released into the atmosphere, accumulating in street dust. Therefore, this study aimed to collect street dust in Miaoli to quantify the metals and assess the accumulation degree, sources, and potential risks. The enrichment factor (EF), geological accumulation index (Igeo), ecological risk, and non-carcinogenic and lifetime carcinogenic risk were estimated to assess the accumulation degree and the potential environmental and health risks. Pearson correlation analysis, principal component analysis, and positive matrix factor model were used to clarify the relationship between levels of metals and identify possible sources. The levels of metals in street dust in order were Fe > Zn > Mn > Cu > Cr > Ni > Pb > Sr > Co > Sb. According to Igeo, the level of Ni indicated moderately polluted. The levels of Zn, Cu, and Pb showed moderate to strong pollution, strong pollution, and very strong pollution, respectively. Results of average ecological risk analysis pointed out that Pb and Cu represent a very high risk, while other metals posed low-to moderate-level ecological risks. Excluding the Steel Enterprise area, based on the EF value and source identification, it might be concluded that Co, Sr, Fe, Mn, and Sb were mainly from natural sources, while Cu, Pb, and Zn come from anthropogenic pollution sources. Based on the results of the risk assessments, most metals pose no serious adverse health risk to humans. But, in comparison to Miaoli townships, the health risks of residents living in the Steel Enterprise area were higher. However, given that children and adolescents exposure to Co, Cr, Pb, and Ni together constitute a relatively higher carcinogenic risk (CR > 10-6), more attention needs to be paid to the populations most susceptible.

Spatial distribution, sources and health risk assessment of heavy metals in topsoil around oil and natural gas drilling sites, Andhra Pradesh, India

Soils are usually the interface between human activity and environmental components that must be conserved and protected. As a result of rising industrialization and urbanization, activities such as exploration and extraction operations lead to the release of heavy metals into the environment. This study presents distribution of six heavy metals (As, Cr, Cu, Ni, Pb and Zn) in 139 top soil samples collected in and around oil and natural gas drilling sites at a sampling density of 1 site/12 km2. The results indicated the concentration ranged from 0.1 to 16 mg/kg for As, 3-707 mg/kg for Cr, 7-2324 mg/kg for Cu, 14-234 mg/kg for Ni, 9-1664 mg/kg for Pb, and 60-962 mg/kg for Zn. The contamination of soil was estimated on the basis of Index of geo accumulation (Igeo), enrichment factor (Ef), and contamination factor (Cf). Further, spatial distribution pattern maps indicated that the pollution levels for Cu, Cr, Zn, and Ni were higher around drilling sites of the study area relative to other regions. Using exposure factors for the local population and references from the USEPA's integrated database, potential ecological risk indices (PERI) and health risk assessments were made. The hazard index (HI) values of Pb (in adults) and Cr, Pb (in children) exceeded the recommended limit of HI = 1, indicating the non-carcinogenic risks. Total carcinogenic risk (TCR) calculations revealed Cr (in adults) and As, Cr (in children) levels in soils exceeded the threshold value of 1.0E - 04, indicating significant carcinogenic risk due to high metal concentrations in the study area. These results may assist in determining the soil's present state and its effect due to extraction strategies used during drilling process and initiate few remedial techniques, particularly for proper management strategies in farming activities to decrease point and non-point source of contamination.

Chemical Speciation, Bioavailability and Human Health Risk Assessment of Metals in Surface Dust from an Industrial Cluster in India

In this study, distribution of metals in different geochemical forms, their mobility and bioavailability in bulk surface dust samples of Bhiwadi industrial cluster (BIC) in Rajasthan, India, was assessed by modified Community Bureau of Reference (m-BCR) sequential extraction procedure. Potential risk of metals in surface dust to environment and human health was evaluated using Contamination factor (C_f), Mobility Factor (MF) and Risk Assessment Code (RAC), and carcinogenic and non-carcinogenic health risk. Residual fraction contained significant amount of metals as Cd(55.86%), Cr(86.05%), Fe(90.06%), Mn(69.94%), Ni(66.08%), and V(71.80%). Pb(52.43%) was present in reducible fraction, while Cu was equally distributed in reducible (27.66%) and oxidizable (28.20%) fractions. Zn was equally distributed in acid exchangeable (33.15%) and reducible (35.01%) fractions. High C_f values were observed for Zn (1.32-16.98), followed by Pb (0.38-11.23) and Cu (0.26-8.22). RAC indicated high risk of Cd, Mn, Ni and Zn to environment due to their high mobility and toxic nature. Zn, Pb, Cu and Cd showed highest mobility (potential bioavailability) in samples collected around metal casting, electroplating, and automobile part industries. Data indicated that metals can bio-available with the changes in redox conditions in environment. Ingestion was major pathway for carcinogenic and non-carcinogenic health risks followed by dermal and inhalation. Hazardous Index value (6.32) indicated higher susceptibility of children for non-carcinogenic risk as compared to adults. Carcinogenic risk of Cr, Cd, Ni and Pb was higher than acceptable levels in surface dust, suggesting a high risk of cancer to exposed population.

Health implications, distribution and source apportionment of heavy metals in road deposited dust of Jammu City in northern India

Road deposited dust (RDD) is an important indicators of heavy metal contamination in urban areas. In this study, we measured eight heavy metals (V, Cr, Mn, Fe, Ni, Cu, Zn, and Pb) in RDD collected from 34 different locations in Jammu city represented by different land uses such as industrial, urban-residential, high-density traffic, and sub-urban locations, and evaluated their ecological and health risks. The ratio of metal concentrations in RDD to their respective background levels varied as: Cu (3.94) > Pb (3.75) > Zn (3.01) > Cr (1.75) > Ni (1.51) > Mn (1.40) > V (1.35) > Fe (1.1) suggesting Cr, Ni, Cu, Zn and Pb were enriched anthropogenically. Geospatial maps revealed a heterogeneous distribution of metals in Jammu city with metal(s) specific hotspots primarily localized around high traffic density locations and industrial clusters. The index of geoaccumulation indicated 32%, 26%, 20%, 9%, and 8%, of samples belonged to "moderately polluted" category for Zn, Cu, Pb, Cr, and Ni respectively. Health index (HI) showed low non-carcinogenic hazards of metal contamination to adults but a high hazard to children. Though the values of total carcinogenic risks (TCR) (6.53E-05 to 3.71E-04) considerably exceeded the USEPA acceptable levels (1 × 10^-6 ≤ TCR <1 × 10^-4) suggesting high carcinogenic risks of metal contamination to both adults and children. Besides potential ecological risk index (PERI) revealed that 56% of samples had PERI >40 suggesting "moderate to high ecological risk" of metal contamination in the Jammu city RDD.

10 years long-term assessment on characterizing spatiotemporal trend and source apportionment of metal(loid)s in terrestrial soils along the west coast of South Korea

Long-term trends in the spatial distributions and sources of metal(loid)s in soils adjacent to the west coastal areas of South Korea have been systematically investigated for 10 years (2010-2019). Monitoring in 17 sites clearly showed site- and region-specific distributions, being associated with land use type (significant differences, as road > agriculture > wild) (P < 0.05), rather than temporal variation. The great concentrations of all metal(loid)s were found near Lake Shihwa (LS) and Geum River (GG), near the road, indicating that transportation activity was the main source of metal(loid)s contamination in soil. Especially, Cd (0.5 mg kg^-1), Hg (0.04 mg kg^-1), Pb (65 mg kg^-1), and Zn (184 mg kg^-1), related to the transportation activity near the road, showed twice greater than other land use types, on average. The concentration of metal(loid)s in each site and with the same land use type did not greatly vary over the years, with no significant annual difference (P > 0.05). The degree of metal(loid)s contamination compared to the background levels was identified in the order of Pb > Zn > Cr > Cu > As>Cd > Ni > Hg, with the contaminated hotspots mostly in LS or GG. The potential ecological risk was evidenced for Cd and Hg, but such a trend was temporally irregular over the years, indicating site-specificity. The sources of metal(loid)s were carefully determined as natural (20%), fuel combustion & agricultural pollution (43%), and vehicular emissions (37%) using the Positive Matrix Factorization model. The relative contribution of each source to contamination over the last decade was found to be similar, supporting that site-dependent lesser variation in metal(loid)s contamination in the coastal areas of South Korea. Overall, the distribution of metal(loid)s in the soil near the west coastal areas over the last decade largely depended on land use activities, and contamination degree was associated with non-point sources, such as transportation and fuel combustion.

Gridded distribution of total suspended particulate matter (TSP) and their chemical characterization over Delhi during winter

In the present study, total suspended particulate matter (TSP) samples were collected at 47 different sites (47 grids of 5 × 5 km² area) of Delhi during winter (January-February 2019) in campaign mode. To understand the spatial variation of sources, TSP samples were analyzed for chemical compositions including carbonaceous species [organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC)], water-soluble total nitrogen (WSTN), water-soluble inorganic nitrogen (WSIN), polycyclic aromatic hydrocarbons (16 PAHs), water-soluble inorganic species (WSIS) (F^-, Cl^-, SO₄^2-, NO₂^-, NO₃^-, PO₄^3-, NH₄⁺, Ca²⁺, Mg²⁺, Na⁺, and K⁺), and major and minor trace elements (B, Na, Mg, Al, P, S, Cl, K, Ca, Ti, Fe, Zn, Cr, Mn, Cu, As, Pd, F, and Ag). During the campaign, the maximum concentration of several components of TSP (996 μg/m³) was recorded at the Rana Pratap Bagh area, representing a pollution hotspot of Delhi. The maximum concentrations of PAHs were recorded at Udhyog Nagar, a region close to heavily loaded diesel vehicles, small rubber factories, and waste burning areas. Higher content of Cl^- and Cl^-/Na⁺ ratio (>1.7) suggests the presence of nonmarine anthropogenic sources of Cl^- over Delhi. Minimum concentrations of OC, EC, WSOC, PAHs, and WSIS in TSP were observed at Kalkaji, representing the least polluted area in Delhi. Enrichment factor <5.0 at several locations and a significant correlation of Al with Mg, Fe, Ti, and Ca and C/N ratio indicated the abundance of mineral/crustal dust in TSP over Delhi. Principal component analysis (PCA) was also performed for the source apportionment of TSP, and extracted soil dust was found to be the major contributor to TSP, followed by biomass burning, open waste burning, secondary aerosol, and vehicular emissions.

Particle-bound organic and elemental carbons for source identification of PM < 0.1 µm from biomass combustion

Atmospheric nanoparticles (PM < 0.1 µm) are a major cause of environmental problems and also affect health risk. To control and reduce these problems, sources identification of atmospheric particulates is necessary. Combustion of bituminous coal and biomass including rubber wood, palm kernel, palm fiber, rice stubble, rice straw, maize residue, sugarcane leaves and sugarcane bagasse, which are considered as sources of air quality problems in many countries, was performed. Emissions of particle-bound chemical components including organic carbon (OC), elemental carbon (EC), water-soluble ions (NH₄⁺, Cl^-, NO₃^-, SO₄^2-), elements (Ca, K, Mg, Na) and heavy metals (Cd, Cr, Ni, Pb) were investigated. The results revealed that PM < 0.1 µm from all samples was dominated by the OC component (>50%) with minor contribution from EC (3%-12%). The higher fraction of carbonaceous components was found in the particulates with smaller sizes, and lignin content may relate to concentration of pyrolyzed organic carbon (PyOC) resulting in the differences of OC/EC values. PM emitted from burning palm fiber and rice stubble showed high values of OC/EC and also high PyOC. Non-carbonaceous components such as Cl^-, Cr, Ca, Cd, Ni, Na and Mg may be useful as source indicators, but they did not show any correlation with the size of PM.

Ecological and human health risks from pseudo-total and bio-accessible metals in street dusts

Street dust samples were collected from industrial and commercial cities (Jamshedpur and Ranchi during monsoon and post-monsoon seasons) for detecting the levels of Cr, Cd, Cu, Ni, Pb, Zn, As, Co, Al, and Mn. The industrial city recorded higher metal concentrations compared to commercial. Similar trend of pseudo-total metal concentrations was observed in both the seasons at industrial city (Al > Mn > Zn > Cr > Pb > Cu > Ni > Cd) and only monsoon season at commercial city (Al > Mn > Zn > Cu > Cr > Pb > Ni > Cd). Zn > Cd was the most bioaccessible metal throughout the cities (monsoon and post-monsoon). The geochemical parameters (Igeo, EF, CF) were highest for Cd and lowest for Ni (both cities for the two seasons). Pollution Load Indices (PLI zone) were highest during the post-monsoon season in the industrial city. The highest carcinogenic risk was posed by Cr ranging from 1.87E-05 to 4.80E-05, in both the cities through ingestion and inhalation pathways. Children were found at higher risks, while the bioaccessible fractions posed neither carcinogenic nor non-carcinogenic threats to the population. Principal component analysis and correlation analysis indicated the influence of vehicular and industrial emissions, especially steel industry and coal-based thermal power plants as the major source of metals in street-dust. The outcomes of this work will be useful in providing baseline information of pollution along with their consequent environmental and human health risks of Jharkhand state.

Polycyclic aromatic hydrocarbons in fine road dust from a coal-utilization city: Spatial distribution, source diagnosis and risk assessment

Coal combustion can release large amounts of polycyclic aromatic hydrocarbons (PAHs), which persist in various environment matrices (e.g., road dust) and hence cause the carcinogenic risk to human health. In this study, an exhaustive characterization of road dust samples coupling their physicochemical characteristics and stable isotope compositions (δ¹³C and δ¹⁵N) was conducted to evaluate the source, level, spatial distribution, and carcinogenic risk of PAHs in a typical coal-utilization city. Concentrations of Σ₁₆ PAHs ranged from 605.5 to 25,374.3 ng/g with a mean concentration of 4083.0 ng/g. Pollution levels of sites around the coal-fired power plant (Zone 1) were significantly higher than those in other zones (p < 0.05). PAH concentration showed significant correlations with both C and N fractions (p < 0.01). Compositions of δ¹³C and δ¹⁵N in road dust coupled to principal component analysis and the partitions and diagnostic ratios of PAHs contributed to associating road dust to several local sources of contamination. Coal combustion and vehicular exhaust were major sources of PAHs around the power plant and urban area. Results of incremental lifetime cancer risk showed 81.5% of all sampling sites suffered potential risk (>10^-6) for both adults and children, while children around the power plant suffered the highest risk. Despite the estimation of only potential risk being posed by PAHs in road dust, human exposure to the various environmental matrices, scientific and systematic assessment of carcinogenic risks by PAHs in the total environment warrants further investigations.

Comprehensive screen the lead and other toxic metals in total environment from a coal-gas industrial city (NW, China): Based on integrated source-specific risks and site-specific blood lead levels of 0-6 aged children

A new integrated source-specific risk model and site-specific blood lead levels (BLLs) of 0-6 children were introduced to comprehensive understand the status of the toxic metals in soil-dust-plant total environment from a Coal-Gas industrial city, NW China. 144 samples were collected and ten toxic metals (As, Ba, Co, Cr, Cu, Mn, Ni, Sr, Pb, and Zn) were screened by XRF and ICP-MS. It was found that the occurrences of toxic metals deferred in the different medium, such as Co, Cu, Pb, and Zn observed the trend of accumulating in soil and plant compared to clustered distributions of Cr, Mn and Ni preferred to accumulate in dust. However, few bioaccumulations observed in Ulmus pumila L. Toxic metals distributions in majority of sites influenced by coal combustion mixed sources and industrial activities posed the high integrated ecological risks and caused significant non-carcinogenic and carcinogenic integrated risks for local 0-6 children identified by new integrated source-specific risk model, especially observed in the priority contaminants Co and Pb. The site-specific BLLs confirmed that younger children fewer than 4 lived in the north region were more vulnerable to priority Pb pollution as their BLLs above 50 μg/L, almost up to 80 μg/L. Although proportions of source-specific risks to toxic metals changed in soil and dust, the critical sources from coal combustions and industrial activities posed the most important contribution to the local risks. Therefore, effective strategies targeting at critical sources on coal industries should be conducted to reduce risks, and mostly emphasize on the north hotspot areas.

Health risk assessment of heavy metals in dust particles precipitated on the screen of computer monitors

Dust is an important factor to indoor pollution that contains suspended particles and heavy metals. Since today, use of computer has become an essential part of human life. Therefore, this study aimed to compare the amount of heavy metals deposited on CRTs and LCDs and their risk assessment. Ten dust samples for each type of monitor were collected from CRT and LCD screens in accordance with the standard OSHA ID-125 and ID-206, wet filter wipe method. Concentrations of Pb, Hg, Cd, Cr, and Cu were measured by inductively coupled plasma-optical emission spectrometer. Exposure and risk assessment of these elements were estimated using USEPA's exposure parameters. The average concentrations of heavy metals in the dust on CRTs (0.82 mg/kg) were higher than LCD screens (0.69 mg/kg). Cr with 62.824% and Hg with 0.849% had the highest and lowest average concentration in both types of monitors. The non-carcinogenic risk and carcinogenicity indexes of CRT monitors were 0.0009, and 3.94 × 10^-11 and for LCD monitors were 0.0008 and 2.94 × 10^-11. In both monitors, ingestion is the main route to exposure with heavy metals. The average concentration of heavy metals in CRT dust. HI values for studied metals in dust of CRTs and LCDs were less than safe limit of 1. Because RI < 10^-4, cancer risk of studied elements in dust can be ignored.

Assessment of heavy metal content, distribution, and sources in Nansi Lake sediments, China

Much attention has been paid to the heavy metal contamination of lake sediments in rapidly developing regions. In this study, heavy metal (Cd, Cr, Co, Ni, Mn, Pb, As, Cu, and Zn) concentrations in sediment surface samples and cores from the Nansi Lake were investigated to ascertain the potential sources and environmental risks of heavy metals. The average concentration of heavy metals was 0.16-16.04 times background concentrations. The enrichment factor, Tomlinson pollution load index, geo accumulation index, positive definite matrix factor analysis (PMF), and potential ecological risk index were used to assess heavy metal concentrations and explore the evolution of heavy metal sources, and result indicated that Cd reached moderate pollution levels, which is the most polluted heavy metal in the history and present, while the remaining heavy metals are at low or no pollution levels. The contribution of Cd to RI exceeded 76%, which is the decisive factor in the ecological risk of Nansi Lake. The result of ecological risk showed that the risk level for most of Nansi Lake is medium, and some areas of Zhaoyang Lake and Weishan Lake reach high levels. The PMF results showed that there are four main factors influencing heavy metal concentrations in Nansi Lake sediments, including industrial sources, fertilizers, and herbicides used in agricultural production, traffic-related emissions, and mineral mining. Among these factors, industrial and mineral mining sources were found to be the most important, and the highest contribution rate occurred in the -10cm (1960s). Although the contribution of fertilizers and herbicides is lower than that of other sources, increasing trend should be a warning sign that Cd has reached a high ecological risk level in Nansi Lake sediments.

Pollution characteristics and risk assessment of surface sediments in the urban lakes

The objective of the manuscript was to evaluate the concentration and distribution of nutrients and heavy metals (HMs) in the sediments of urban lakes, as well as the potential ecological risk to the lake. This paper discusses the risk assessment and its management via potential nature-based solutions (NBS), which are lessons learnt from nature. The HM pollution and potential ecological risk were evaluated using conventional geo-accumulation index (GI) and geo-accumulation vector (GV) model. So urban lakes are usually more of a source of pollution than non-urban lakes, and more widely based on the literature on lake sediment pollution assessments in China over the past 10 years, 42 urban lakes, and 5 typical non-urban lakes (five representative freshwater lakes in China) were selected. The average concentrations of total nitrogen (TN); total phosphorus (TP); and Cu, Zn, Pb, Cr, Cd, Ni, As, and Hg were 2382, 712, 33.10, 118.05, 38.30, 66.40, 0.82, 32.38, 11.33, and 0.12 mg/kg, respectively. The pollution levels of nutrients and HMs in sediments were evaluated using a single pollution index, a comprehensive pollution index, a ground accumulation index, a potential ecological risk index, and a sediment quality index. The evaluation results showed that the overall pollution level of urban lake sediments in China was higher than that of the selected five typical non-urban lakes, and the problem of nitrogen pollution in sediments was more prominent. There was no significant difference in the potential risk assessment of HMs between urban lakes and typical non-urban lakes, but the probability of negative biological effects was significant. The surface sediments from the estuaries of the tributaries flowing downtowns and heavy industrial parks showed high heavy metal pollution levels and potential ecological risk. The HM pollution and environmental risk assessment of the sediments from urban lakes is of great significance.

Fast removal of heavy metals from water and soil samples using magnetic Fe3O4 nanoparticles

Heavy metal discharge from anthropogenic sources on open soil surfaces and in natural water bodies poses serious environmental and health concerns. In addition to the contamination reduction of metals at the source, post-discharge removal of metals using nanoparticles is one of the remediation technologies being explored nowadays due to its cost-effectiveness, being environment-friendly, and easy application as a technique. In this work, magnetic iron oxide (Fe₃O₄) nanoparticles were synthesized chemically and then used for the removal of heavy metals (Cd, Cr, Cu, Fe, Ni, Pb, and Zn) from water and soil samples. The heavy metal removal efficiency of these iron oxide nanoparticles for different metals in water was best observed at a pH of 4.5 and varied between 63.5 and 98.3%. However, the removal efficiency of these nanoparticles from the soil sample was only measured at a pH of 0.7, and heavy metal removal efficiency varied between 69.6 and 99.6%. In both soil and water samples, the most efficient remediation time was less than 20 min, after which desorption and even dissolution of the nanoparticles can occur at a highly acidic pH. Among all selected metals for removal, lead showed the best adsorption and hence removal efficiency. The nanoparticles were characterized using the TEM, XRD, and FTIR techniques. The adsorption efficiency of various metals was estimated by using atomic absorption spectroscopy. The results suggest that the removal efficiency and stability of adsorbed products can further be improved by adjusting the pH higher towards 7 and also perhaps by modifying the nanoparticles with functional groups. The primary advantage of the magnetic un-coated nanoparticles is easy and efficient removal of the nanoparticles from the treated solutions by using an ordinary magnet.

Investigating the seasonal variability in source contribution to PM2.5 and PM10 using different receptor models during 2013-2016 in Delhi, India

The present work deals with the seasonal variations in the contribution of sources to PM_2.5 and PM₁₀ in Delhi, India. Samples of PM_2.5 and PM₁₀ were collected from January 2013 to December 2016 at an urban site of Delhi, India, and analyzed to evaluate their chemical components [organic carbon (OC), elemental carbon (EC), water-soluble inorganic components (WSICs), and major and trace elements]. The average concentrations of PM_2.5 and PM₁₀ were 131 ± 79 μg m^-3 and 238 ± 106 μg m^-3, respectively during the entire sampling period. The analyzed and seasonally segregated data sets of both PM_2.5 and PM₁₀ were used as input in the three different receptor models, i.e., principal component analysis-absolute principal component score (PCA-APCS), UNMIX, and positive matrix factorization (PMF), to achieve conjointly corroborated results. The present study deals with the implementation and comparison of results of three different multivariate receptor models (PCA-APCS, UNMIX, and PMF) on the same data sets that allowed a better understanding of the probable sources of PM_2.5 and PM₁₀ as well as the comportment of these sources with respect to different seasons. PCA-APCS, UNMIX, and PMF extracted similar sources but in different contributions to PM_2.5 and PM₁₀. All the three models extracted 7 similar sources while mutually confirmed the 4 major sources over Delhi, i.e., secondary aerosols, vehicular emissions, biomass burning, and soil dust, although the contribution of these sources varies seasonally. PCA-APCS and UNMIX analysis identified a less number of sources (besides mixed type) as compared to the PMF, which may cause erroneous interpretation of seasonal implications on source contribution to the PM mass concentration.

Heavy metals in urban road dusts from Kolkata and Bengaluru, India: implications for human health

Air pollution and dust pollution are major urban environmental issues, with road dust being a potential source and a pathway for human exposure. The developing megacities of India, where the population may spend a significant portion of their working lives close to the roadside, including consuming street food, have obvious source-pathway-receptor linkages. The aim of this study in Kolkata and Bengaluru, India, was to evaluate the risk to human health from inorganic components of road dust. Samples were collected and analysed from a cross section of urban environments for a wide range of anthropogenic and geogenic elements, some such as antimony showing an increase in response to vehicle activity. Calculated enrichment factors relative to crustal abundance demonstrated significant enrichment in common heavy metals and less commonly reported elements, e.g. molybdenum, antimony, that may be used as contaminant markers. Factor analysis gave multielement signatures associated with geography, vehicle traffic and local industry. The bio-accessibility of road dusts in terms of ingestion was determined using the BARGE method with more than 50% of zinc and lead being available in some cases. A formal human health risk assessment using the US EPA framework showed that lead in Kolkata and chromium in Bengaluru were the elements of most concern amongst chromium, nickel, copper, zinc and lead. However, the only risk combination (hazard index) shown to be significant was lead exposure to children in Kolkata. Ingestion dominated the risk pathways, being significantly greater than dermal and inhalation routes.

Spatio-temporal variation of air pollutants around the coal mining areas of Jharia Coalfield, India

Jharia Coalfield (JCF) is one of the oldest coalfields in the eastern part of India and falls under critically polluted areas as per CPCB/MoEFCC Notification. Therefore, a study of air pollution and its management is the demand of the day. This study had been undertaken to know the current status of JCF concerning air quality. Ambient air quality monitoring with reference to particulate matter (PM₁₀ and PM_2.5), SO₂, NO_x and trace elements had been conducted in the coal mining areas of JCF. The study area was divided into two groups, mainly fire and non-fire for the sampling of air. Principal component analysis (PCA) identified coal mine fire as a major source of air pollution in the mining areas of JCF. Air quality index (AQI) was calculated which revealed that the air quality index of coal mine fire-affected areas was nearly 1.5 times higher than that of the non-mine fire areas. Graphical abstract.

Characterization and health risk assessment of indoor dust in biomass and LPG-based households of rural Telangana, India

Indoor dust is one of the key sources contributing to indoor air pollution (IAP) in rural households. It acts as a media for various toxicants like heavy metal depositions and causes severe health risks. The present study deals with investigation of metal concentrations and morphological characteristics of indoor dust generated in varied fuel types followed by estimation of health risks for women and children in rural households in Telangana, India. Indoor floor dust samples were collected from households using biomass and liquefied petroleum gas (LPG) as their cooking energy during winter to evaluate the morphological and chemical characteristics in the aforementioned dust samples. A morphological (SEM-EDX) analysis revealed the presence of carbonaceous particles in biomass-based households and mineral-rich crustal sources in LPG-based households. As observed from ICP-OES analysis, there is a significant difference in mean concentrations of Al, Co, Cr, Fe, Zn, and Ni based on fuel type, except for Mn and Pb. From Pearson's correlation analysis and principal component analysis, it was observed that the biomass households were dominated by Zn, Al, Mn, Cr, and Pb, which could have been contributed from biomass burning deposits, crustal sources, and unpaved roads, while Cr, Pb, Fe, and Mn dominated in LPG households, indicating their origin from leaded paints (Pb and Cr) and crustal sources. The health risks associated with these heavy metals to women and children were investigated using an EPA health risk model. The values from the model indicated that both non-carcinogenic and carcinogenic risks were within the safe levels for both subjects. This study not only establishes chemical and morphological characteristics of indoor dust, but also quantifies the role of fuel type.Implications: The present study provides the latest geographical evidence of chemical and morphological characterization of indoor dust particles in varied fuels; i.e, biomass- and LPG-based households and associated health risk assessment in a sub-tropical rural site in Telangana, India. Nevertheless, further research is essential from various regions across the country for more heavy metal analysis and factors impacting these levels. One of the major limitations of the present study is the analysis of few metals and measurements in only living area locations. Future studies can include soil and road dust, as well as kitchens and bedrooms, to provide more comprehensive analysis of dust compositions in varied environments.

Pollution characteristics, sources, and health risk assessment of human exposure to Cu, Zn, Cd and Pb pollution in urban street dust across China between 2009 and 2018

Since heavy metal pollution is widespread in street dust in China, the effects of heavy metals in street dust on human health cannot be ignored. However, studies estimating heavy metal pollution in street dust nationwide are limited. In this study, the concentrations of Cu, Zn, Cd and Pb in street dust at 3877sites throughout China were obtained from the published scientific literature. Based on these data, the contamination levels, spatial distributions, sources and potential health risks of heavy metals in street dust were comprehensively estimated. The results revealed that Cu, Zn, Cd and Pb levels are generally higher in the southeast provinces than in northwest China. In addition, traffic emissions and industrial activities are determined to be the two main sources of heavy metal pollution in street dust. The health risk assessment indicated that ingestion is the most important pathway of exposure to metal pollution in street dust for both children and adults, followed by dermal contact and inhalation. The spatial distribution of health risks suggested that the health risks are more serious in southeast China than in northwest China. The noncarcinogenic risks posed by Pb are relatively higher than those posed by the other three metals for both children and adults. Meanwhile, none of the hazard index (HI) values exceeded the safe level (1.0), with the exception of Pb in Daye city for children (HI = 1.074). The HI values for children were higher than those for adults. Therefore, children should be prioritized for protection from heavy metal pollution.

A systematic review on global pollution status of particulate matter-associated potential toxic elements and health perspectives in urban environment

Airborne particulate matter (PM) that is a heterogeneous mixture of particles with a variety of chemical components and physical features acts as a potential risk to human health. The ability to pose health risk depends upon the size, concentration and chemical composition of the suspended particles. Potential toxic elements (PTEs) associated with PM have multiple sources of origin, and each source has the ability to generate multiple particulate PTEs. In urban areas, automobile, industrial emissions, construction and demolition activities are the major anthropogenic sources of pollution. Fine particles associated with PTEs have the ability to penetrate deep into respiratory system resulting in an increasing range of adverse health effects, at ever-lower concentrations. In-depth investigation of PTEs content and mode of occurrence in PM is important from both environmental and pathological point of view. Considering this air pollution risk, several studies had addressed the issues related to these pollutants in road and street dust, indicating high pollution level than the air quality guidelines. Observed from the literature, particulate PTEs pollution can lead to respiratory symptoms, cardiovascular problems, lungs cancer, reduced lungs function, asthma and severe case mortality. Due to the important role of PM and associated PTEs, detailed knowledge of their impacts on human health is of key importance.

Evaluation of heavy metal pollution in the sediment of Poyang Lake based on stochastic geo-accumulation model (SGM)

The uncertainties introduced by sampling errors, measurement errors, and sediment heterogeneity in the evaluation of heavy metal pollution in the sediment of Poyang Lake are inevitable. The conventional geo-accumulation index (IGeo) cannot overcome these uncertainties. Thus, a stochastic geo-accumulation model (SGM) is established to solve this problem. In the SGM, the distribution of the heavy metal's concentration is stimulated by maximum entropy principle. Then, a membership vector is designed to quantify the pollution condition of each pollutant. Finally, a synthetic membership vector is generated to represent the comprehensive situation of heavy metal pollution in the sediment. SGM is applied in the evaluation of heavy metal pollution in four wetlands of Poyang Lake. Results show that (i) the SGM exhibits better capabilities in uncertainty analysis, risk recognition, and comprehensive pollution evaluation than the conventional IGeo and Hakanson index (HI) models. (ii) The pollution grade of heavy metals in the sediment of Longkou Wetland is "moderately contaminated," whereas the pollution categories in Nanjishan, Wucheng, and Baishazhou wetlands are "uncontaminated to moderately contaminated." (iii) Copper and lead are the key risk factors in Poyang Lake.

Spatial Distribution, Chemical Speciation and Health Risk of Heavy Metals from Settled Dust in Qingdao Urban Area

Settled dust samples were collected from Qingdao urban area to analyze the spatial distribution, chemical speciation and sources of metals, and to evaluate the health risk of metals from atmospheric dust. The average contents of Hg, Cd, Cr, Cu, Ni, Pb and Zn in the atmospheric settled dust of Qingdao were 0.17, 0.75, 153.1, 456.7, 60.9, 176.0 and 708.3 mg/kg, respectively, which were higher than soil background values. The mean exchangeable metal and carbonated-associated fraction proportions of Cd, Zn and Pb were 43.6%, 26.1% and 15%, which implies that they have high mobility and bioavailability. Higher contents of heavy metals appeared in old city areas because of the historical accumulation of metals. Principal component analysis showed that combustion sources partially contributed to Pb, Zn and other trace metals. Hg, Pb and Zn mainly originated from business, human activities and municipal construction. Cd and Cu from settled dust of the old city originated from the erosion and ageing of construction materials. The non-carcinogenic risk rankings for the seven determined heavy metals were ingestion > dermal > inhalation. Cd, Cr and Ni from settled dust showed a low carcinogenic risk. The health risks of Cr, Cu and Pb were higher in old city areas and, therefore, need special attention.

Environmental impact assessment of industrial activities on heavy metals distribution in street dust and soil

Street dust and soil are important materials for evaluating the contaminants level in industrial areas. Detailed size-resolved distribution of metal(loid)s in street dusts and soils influenced by industrial activities has rarely been investigated. This study was carried out to understand how industrialization might affect the size distribution of metal(loid)s concentration and contamination level in the street dust and soil from Murcia, southern Spain. An industrial and a natural areas were selected and surface soil and street dust samples were taken. They were fractionated into eleven size classes and total concentrations of Pb, Zn, Cu, Cd, Cr, Ni, As and Fe were determined in both the bulk samples and their fractions. Enrichment factor, geoaccumulation index, and mass loading of different heavy metal(loids) were calculated. The results indicated that the street dust from natural and industrial areas had almost the same particle size distribution, both containing higher percentage of coarse-sized particles than the soil. Industrialization seems to have only slightly affected the concentration of most elements studied in the soil. In contrast, the concentrations of the heavy elements in bulk industrial dust samples and all their size fractions were extremely higher than those from the natural area. This means that the industrial activities only affected the size dependency of the concentration (contamination level) of certain elements (Pb, Zn, Cu, Cd, and Cr) in the street dust, but not in the soil.

Seasonal and spatial variations of magnetic susceptibility and potentially toxic elements (PTEs) in road dusts of Thessaloniki city, Greece: A one-year monitoring period

A one-year sampling campaign of road dusts was carried out at 10 distinct sites in the broader area of the city of Thessaloniki, Greece and concentrations of heavy metals (HMs) along with magnetic susceptibility were evaluated. The concentrations of HMs in road dusts were higher than their local background values, while magnetic parameters indicated a significant anthropogenic load. Principal component analysis (PCA) identified non-exhaust vehicular emissions, oil/fuel combustion and industrial activities as major sources of heavy metals accounted for approximately 73% of the total variance. A significant seasonal variability for Cr, Cu, Mn, and χ_lf was observed with constantly higher values during summer. Moreover, variations among urban and industrial sites were more pronounced for Cr, Cu, Zn, and χ_lf, while they displayed insignificant variations across all urban sites. On the contrary, concentration peaks in the urban cluster were observed for Cd, Mn, and Ni coinciding with the port area. Based on multiple pollution indices, a severe polluted area was revealed, while potential ecological risk index (RI) indicated a high potential ecological risk with Cd being regarded as the pollutant of high concern. The health risk assessment model indicated ingestion as the major exposure pathway. For both adults and children, Cr and Pb had the highest risk values, mainly recorded in the urban cluster underscoring the need of potential measures to reduce road dust in urban environments.

Contamination levels and human health risk assessment of toxic heavy metals in street dust in an industrial city in Northwest China

This study investigated the content, distribution, and contamination levels of toxic metals (Cd, Cr, Cu, Pb, and Zn) in street dust in Lanzhou, an industrial city in Northwest China. Meanwhile, the risk these metals posed to the urban ecosystem and human health was also evaluated using the potential ecological risk index and human exposure model. Results showed that concentrations of these metals in the dust are higher than the background value of local soil, with Cu having the highest levels. The districts of Anning and Xigu had the most extreme levels of contamination, while Chengguan and Qilihe districts were lightly contaminated, which can be partly attributed to human activities and traffic densities. In comparison with the concentrations of selected metals in other cities, the concentrations of heavy metals in Lanzhou were generally at moderate or low levels. Heavy metal concentration increased with decreasing dust particle size. The pollution indices of Cr, Cd, Cu, Pb, and Zn were in the range of 0.289-2.09, 0.332-2.15, 1.38-6.21, 0.358-2.59, and 0.560-1.83 with a mean of 1.37, 1.49, 3.18, 1.48, and 0.897, respectively. The geo-accumulation index (I _geo) suggested that Zn in street dust was of geologic origin, while Cd, Cr, Pb, and Cu were significantly impacted by anthropogenic sources. The comprehensive pollution index showed that urban dust poses a high potential ecological risk in Lanzhou. Non-carcinogenic and carcinogenic effects due to exposure to urban street dust were assessed for both children and adults. For non-carcinogenic effects, ingestion appeared to be the main route of exposure to dust particles and thus posed a higher health risk to both children and adults for all metals, followed by dermal contact. Hazard index values for all studied metals were lower than the safe level of 1, and Cr exhibited the highest risk value (0.249) for children, suggesting that the overall risk from exposure to multiple metals in dust is low. The carcinogenic risk for Cd and Cr was all below the acceptable level (< 10^-6).

Accumulation degree and source apportionment of trace metals in smaller than 63 μm road dust from the areas with different land uses: A case study of Xi'an, China

Finer urban dusts have more serious environmental detriment and health risk than coarser urban dusts. The trace metals Pb, Cu, Zn, Cr, Co, Ba, Mn, Ni, V, Y, Rb, Ga, Hf, and Zr were analyzed using X-ray fluorescence spectrometry in smaller than 63 μm road dust collected from the areas with different land use types and human activities in Xi'an city. The purposes of this study were to reveal the impact of human activities on the environment through element enrichment factor, and to determine the sources of trace metals measured by multivariate statistical analysis and multiple liner regression of absolute principal component scores. The results indicated that the smaller than 63 μm road dust in Xi'an, in comparison to the element background value of local soil, had higher Cu, Pb, Zn, Cr, Y, Hf and Zr concentrations. Trace metals had different variations in the dusts, while the anthropogenic trace metals had no significant difference in the four areas owing to the wide existing of human activities. The accumulation level of Pb was the highest, followed by Cr, Cu and Zn, and then was Hf and Zr, while the other trace metals were deficient or deficient to minimal enrichment in the finer road dust. Source analysis results indicated that Co, Ga, Mn, Ni, V, Rb and Y mainly originated from natural source, which accounted about 57%-87% for these metals' concentration. Ba, Cr, Pb, Cu and Zn primarily derived from traffic source, which contributed approximately 59%-79% to these metals' content. Hf and Zr were mainly from construction source, which contributed 74.6% to Hf concentration and 78.2% to Zr concentration. The study indicated that traffic and construction activities had a predominant influence on local environment.

Energy Dispersive X-ray (EDX) microanalysis: A powerful tool in biomedical research and diagnosis

The Energy Dispersive X-ray (EDX) microanalysis is a technique of elemental analysis associated to electron microscopy based on the generation of characteristic Xrays that reveals the presence of elements present in the specimens. The EDX microanalysis is used in different biomedical fields by many researchers and clinicians. Nevertheless, most of the scientific community is not fully aware of its possible applications. The spectrum of EDX microanalysis contains both semi-qualitative and semi-quantitative information. EDX technique is made useful in the study of drugs, such as in the study of drugs delivery in which the EDX is an important tool to detect nanoparticles (generally, used to improve the therapeutic performance of some chemotherapeutic agents). EDX is also used in the study of environmental pollution and in the characterization of mineral bioaccumulated in the tissues. In conclusion, the EDX can be considered as a useful tool in all works that require element determination, endogenous or exogenous, in the tissue, cell or any other sample.

Risk Assessment and Implication of Human Exposure to Road Dust Heavy Metals in Jeddah, Saudi Arabia

Data dealing with the assessment of heavy metal pollution in road dusts in Jeddah, Saudi Arabia and its implication to human health risk of human exposure to heavy metals, are scarce. Road dusts were collected from five different functional areas (traffic areas (TA), parking areas (PA), residential areas (RA), mixed residential commercial areas (MCRA) and suburban areas (SA)) in Jeddah and one in a rural area (RUA) in Hada Al Sham. We aimed to measure the pollution levels of heavy metals and estimate their health risk of human exposure applying risk assessment models described by United States Environmental Protection Agency (USEPA). Using geo-accumulation index (Igeo), the pollution level of heavy metals in urban road dusts was in the following order Cd > As > Pb > Zn > Cu > Ni > Cr > V > Mn > Co > Fe. Urban road dust was found to be moderately to heavily contaminated with As, Pb and Zn, and heavily to extremely contaminated with Cd. Calculation of enrichment factor (EF) revealed that heavy metals in TA had the highest values compared to that of the other functional areas. Cd, As, Pb, Zn and Cu were severely enriched, while Mn, V, Co, Ni and Cr were moderately enriched. Fe was considered as a natural element and consequently excluded. The concentrations of heavy metals in road dusts of functional areas were in the following order: TA > PA > MCRA > SA > RA > RUA. The study revealed that both children and adults in all studied areas having health quotient (HQ) < 1 are at negligible non-carcinogenic risk. The only exception was for children exposed to As in TA. They had an ingestion health quotient (HQing) 1.18 and a health index (HI) 1.19. The most prominent exposure route was ingestion. The cancer risk for children and adults from exposure to Pb, Cd, Co, Ni, and Cr was found to be negligible (≤1 × 10-6).

Pollution characteristics and risk assessment of human exposure to oral bioaccessibility of heavy metals via urban street dusts from different functional areas in Chengdu, China

Urban street dusts were collected in commercial area (CA), traffic area (TA), educational area (EA), residential area (RA) and parks area (PA) of Chengdu, China, to investigate the concentrations of heavy metals (Pb, Zn, Cu, Ni, Cd and Cr), and analyzed to evaluated possible sources and health risk assessment. The average concentrations (mg/kg) of Pb (82.3), Zn (296), Cu (100), Cd (1.66) and Cr (84.3) in urban street dusts were all higher than the local soil background values. The concentrations of heavy metals in each functional area could be classified as follows: CA>TA>RA>EA>PA. Principal component analysis and Cluster analysis showed mainly derived from the mixed sources of nature and traffic (51.7%). The results of health risk assessment showed no non-carcinogenic and carcinogenic risks of the metals for inhabitants. However, higher concentrations and oral bioaccessibility of the heavy metals in the dusts from CA and TA, indicating there was more health risks to the inhabitants in than that in other functional areas.

Contamination and health risks of heavy metals in street dust from a coal-mining city in eastern China

We collected street dust from Huainan, a typical coal-mining city in China, to investigate the contamination features and health risks of heavy metals. Concentrations of Co, Cr, Cu, Pb, As, and Sb were generally low to moderate, while pollution levels of Cd and Hg were moderate to high. Concentrations of Cd and Hg were associated with considerable health risks at 64.3% and 58.6% of sites, respectively. In particular, about a fifth of samples had associated high risks as a result of Hg contamination levels. Relative to other urban areas, the street dust from the mining area had no more severe metal pollution, which might be partly attributed to the deposition of coal dust onto street dusts. A source assessment indicated that metals in dust form Huainan were mainly derived from vehicular-related activities, industrial emissions, weathering of coal dust and natural soils, and coal combustion. Although the health risk levels from exposure to individual metals in dusts were low, the non-carcinogenic risks from multiple metals to local children exceeded the acceptable level (1.0), suggesting that the overall risk from exposure to multiple metals in dust is concerning.

Identification of soil heavy metal sources and improvement in spatial mapping based on soil spectral information: A case study in northwest China

In a sewage irrigation area of northwest China, 52 topsoil samples were collected to measure the contents of arsenic (As), chromium (Cr), copper (Cu), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn). To identify their sources, multivariate statistics and geostatistics were applied to separate pedogenic elements (As and Mn) from anthropogenic elements (Cr, Cu, Hg, Ni, Pb and Zn). The accumulation of soil Hg was mainly attributed to long-term sewage irrigation, whereas Cr, Ni and Zn were mainly from industrial activities and dust deposition. In addition to the impacts of industry and dust, traffic-related factors were the main sources of Pb and Cu contamination. Based on the relationships of heavy metals with various soil properties and reflectance spectra, co-kriging (CK) was used to improve the interpolation of heavy metals. Comparatively, soil spectra were more suitable as covariates due to their ease and low-cost of collecting as features.

Heavy metals in road dust from Xiandao District, Changsha City, China: characteristics, health risk assessment, and integrated source identification

The physicochemical properties and the contents of metals (Cu, Zn, Pb, Cd, Cr, and Fe) in 51 road dust samples from Xiandao District (XDD) were investigated. Enrichment factor (EF), multivariate statistics, geostatistics, and health risk assessment model were adopted to study the spatial pollution pattern and to identify the priority pollutants and regions of concern and sources of studied metals. The mean EFs revealed the following order: Cd > Zn ≈ Pb ≈ Cu > Cr. For non-carcinogenic effects, the exposure pathway which resulted in the highest levels of exposure risk for children and adults was ingestion, followed by dermal contact and inhalation. Hazard index (HI) values for the studied metals at each site were within the safe level of 1 except maximum HI Cr (1.08) for children. The carcinogenic risk (CR) for Cd and Cr at each site was within the acceptable risk level (1E-06) except CR Cr (1.08E-06) for children in the road intersection between the Changchang highway and the Yuelin highway. Cr was identified as the priority pollutant followed by Pb and Cd with consideration of the local population distribution. Spatially, northwest and northeast of XDD were regarded as the priority regions of concern. Results based on the proposed integrated source identification method indicated that Pb was probably sourced from traffic-related sources, Cd was associated with the dust organic material mainly originated from industrial sources, and Cr was mainly derived from both sources.

Assessment of Heavy Metal Pollution in Topsoil around Beijing Metropolis

The topsoil around Beijing metropolis, China, is experiencing impacts of rapid urbanization, intensive farming, and extensive industrial emissions. We analyzed the concentrations of Cu, Ni, Pb, Zn, Cd, and Cr from 87 topsoil samples in the pre-rainy season and 115 samples in the post-rainy season. These samples were attributed to nine land use types: forest, grass, shrub, orchard, wheat, cotton, spring maize, summer maize, and mixed farmland. The pollution index (PI) of heavy metals was calculated from the measured and background concentrations. The ecological risk index (RI) was assessed based on the PI values and toxic-response parameters. The results showed that the mean PI values of Pb, Cr, and Cd were > 1 while those of Cu, Ni, and Zn were < 1. All the samples had low ecological risk for Cu, Ni, Pb, Zn, and Cr while only 15.35% of samples had low ecological risk for Cd. Atmospheric transport rather than land use factors best explained the seasonal variations in heavy metal concentrations and the impact of atmospheric transport on heavy metal concentrations varied according to the heavy metal types. The concentrations of Cu, Cd, and Cr decreased from the pre- to post-rainy season, while those of Ni, Pb, and Zn increased during this period. Future research should be focused on the underlying atmospheric processes that lead to these spatial and seasonal variations in heavy metals. The policymaking on environmental management should pay close attention to potential ecological risks of Cd as well as identifying the transport pathways of different heavy metals.

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.

Ultrafine particles in cities

Ultrafine particles (UFPs; diameter less than 100 nm) are ubiquitous in urban air, and an acknowledged risk to human health. Globally, the major source for urban outdoor UFP concentrations is motor traffic. Ongoing trends towards urbanisation and expansion of road traffic are anticipated to further increase population exposure to UFPs. Numerous experimental studies have characterised UFPs in individual cities, but an integrated evaluation of emissions and population exposure is still lacking. Our analysis suggests that the average exposure to outdoor UFPs in Asian cities is about four-times larger than that in European cities but impacts on human health are largely unknown. This article reviews some fundamental drivers of UFP emissions and dispersion, and highlights unresolved challenges, as well as recommendations to ensure sustainable urban development whilst minimising any possible adverse health impacts.