Chemical speciation and human health risk of trace metals in urban street dusts from a metropolitan city, Nanjing, SE China

Underestimated or overestimated? Dynamic assessment of hourly PM2.5 exposure in the metropolitan area based on heatmap and micro-air monitoring stations

Spatio-temporal distributions of air pollution and population are two important factors influencing the patterns of mortality and diseases. Past studies have quantified the adverse effects of long-term exposure to air pollution. However, the dynamic changes of air pollution levels and population mobility within a day are rarely taken into consideration, especially in metropolitan areas. In this study, we use the high-resolution PM_2.5 data from the micro-air monitoring stations, and hourly population mobility simulated by the heatmap based on Location Based Service (LBS) big data to evaluate the hourly active PM_2.5 exposure in a typical Chinese metropolis. The dynamic "active population exposure" is compared spatiotemporally with the static "census population exposure" based on census data. The results show that over 12 h on both study periods, 45.83% of suburbs' population-weighted exposure (PWE) is underestimated, while 100% of rural PWE and more than 34.78% of downtown's PWE are overestimated, with the relative difference reaching from -11 μg/m³ to 7 μg/m³. More notably, the total PWE of the active population at morning peak hours on weekdays is worse than previously realized, about 12.41% of people are exposed to PM_2.5 over 60 μg/m³, about twice as much as that in census scenario. The commuters who live in the suburbs and work in downtown may suffer more from PM_2.5 exposure and uneven environmental resource distribution. This study proposes a new approach of calculating population exposure which can also be extended to quantify other environmental issues and related health burdens.

Characterization, Spatial Variation and Management Strategy of Sewer Sediments Collected from Combined Sewer System: A Case Study in Longgang District, Shenzhen

In the urban drainage system, the formation of sewer sediments is inevitable, and the removal of sewer sediments is necessary for system maintenance. Disposal of arisings from sewer sediment removal is becoming a serious environmental issue. The current knowledge of sewer sediments is limited, which is restrained to sewer sediments management. To better understand this municipal waste, the sewer sediments of a combined sewer system in Longgang District, Shenzhen were collected and characterized, and the spatial distribution characteristics of contaminants were analyzed. Based on the bivariate correlation analysis, it is found that many contaminants in sewer sediments have a strong relationship with spatial variables. Compared to the sewer sediments in industrial areas, those in residential areas contain higher concentrations of Hg and phosphorus. The sediments in the sewage conduit also contain more organic matter (OM), phosphorus, Cu, and Ni, and the sediments in the rainwater conduit contain a higher concentration of Cd. Moreover, the sediments produced in different catchments also show huge differences in the content of contaminants. These spatial distribution characteristics may provide help for the further classification of sewer sediments, thereby making the disposal of sediments more targeted. According to the local standards of sludge disposal, land application and incineration are not suitable for managing sewer sediments due to the low OM content and poor lower heating value (LHV). Although sanitary landfill is feasible for sewer sediments disposal, the complicated composition of sewer sediments still poses the risk of polluting the surrounding environment. The management of sewer sediments via the production of building materials is a promising technical route that can avoid the migration of hazardous contaminants and produce valuable products. This study may improve our understanding of sewer sediments and provide a reliable recommendation for sewer sediment management.

Assessment of heavy metal pollution in soils and health risk consequences of human exposure within the vicinity of hot mix asphalt plants in Rivers State, Nigeria

This study evaluated the level of heavy metal pollution in soils within the vicinity of hot mix asphalt (HMA) plants and the health risk consequences of human exposure to the heavy metals. Soil samples collected from two asphalt plants during dry and rainy seasons were analyzed for Cr, Co, Cu, Ni, Mn, Cd, Pb, and Zn with atomic absorption spectrophotometer (AAS). Health risk indices were assessed as chronic daily intake (CDI), hazard quotient (HQ), hazard index (HI), and carcinogenic risk (CR) while the degree of pollution was assessed with geo-accumulation index (Igeo) and contamination factor (CF). The pollution assessment revealed that the soil samples were moderately to highly polluted with Cd. In both seasons, Zn and Mn, respectively, had the highest CDI values for ingestion, inhalation, and dermal route for both asphalt plants while Cd has the least CDI values for all the routes in both plants. The HQ and HI values for all the metals were less than 1.00E + 00 indicating no non-carcinogenic risk from exposure to any of the metals. Furthermore, the dermal route was found to be the least likely model for health risks associated with human exposure to soil heavy metals within the vicinity of the plants. The CR values for the metals were also within threshold value indicating non-significant cancer risk from exposure to the metals. Though no significant health risks were observed in the study, clean and efficient production of hot mix asphalt should be encouraged to minimize health risks and environmental pollution during production and usage.

Bioavailability of heavy metals bounded to PM2.5 in Xi'an, China: seasonal variation and health risk assessment

Studying the characteristics and health risks of heavy metals in atmospheric fine particulate matter (PM_2.5) is a crucial component of understanding atmospheric pollution in China. Integrated 24 h PM_2.5 samples were collected in winter and summer 2016 in Xi'an, China. The pollution levels, speciation, and health risks of seven PM_2.5-bound metal elements (Al, As, Cd, Cr, Ni, Pb, and Zn) were investigated in this study. The average concentration of PM_2.5 was 50.1 ± 30.4 μg m^-3 and was higher in winter than in summer. Significant seasonal variations in the elements were also observed. The average concentration ratios of Al, As, Cd, Cr, and Pb decreased in summer by 17.5%, 6.4%, 42.5%, 34.1%, and 61.4% compared with their concentrations in winter, respectively, whereas Ni and Zn increased by 37.7% and 7.6% in summer. The soluble and exchangeable fraction (F1) accounted for large proportions of Cd and Pb concentrations, indicating their greater hazard to the environment and human health. Al, As, and Cr mainly existed in the residual state (F4), which had relatively high stability in particulate matter. Ni was consistently distributed in different forms (F1-F4). The bioavailability evaluation indicated that Pb, Cd, Ni, and Zn were potential bioavailable element which exhibited strong biological toxicity. Although the concentration of Pb was very low, its BI value was the highest. The carcinogenic and non-carcinogenic risks of Cr and As were relatively high, and thus require attention from the government and environmental management departments.

Effect of Different Pollution Parameters and Chemical Components of PM2.5 on Health of Residents of Xinxiang City, China

The present study was planned to explore the pollution characteristics, health risks, and influence of atmospheric fine particulate matter (PM2.5) and its components on blood routine parameters in a typical industrial city (Xinxiang City) in China. In this study, 102 effective samples 28 (April-May), 19 (July-August), 27 (September-October), 28 (December-January) of PM2.5 were collected during different seasons from 2017 to 2018. The water-soluble ions and metal elements in PM2.5 were analyzed via ion chromatography and inductively coupled plasma-mass spectrometry. The blood routine physical examination parameters under different polluted weather conditions from January to December 2017 and 2018, the corresponding PM2.5 concentration, temperature, and relative humidity during the same period were collected from Second People's Hospital of Xinxiang during 2017-2018. Risk assessment was carried out using the generalized additive time series model (GAM). It was used to analyze the influence of PM2.5 concentration and its components on blood routine indicators of the physical examination population. The "mgcv" package in R.3.5.3 statistical software was used for modeling and analysis and used to perform nonparametric smoothing on meteorological indicators such as temperature and humidity. When Akaike's information criterion (AIC) value is the smallest, the goodness of fit of the model is the highest. Additionally, the US EPA exposure model was used to evaluate the health risks caused by different heavy metals in PM2.5 to the human body through the respiratory pathway, including carcinogenic risk and non-carcinogenic risk. The result showed that the air particulate matter and its chemical components in Xinxiang City were higher in winter as compared to other seasons with an overall trend of winter > spring > autumn > summer. The content of nitrate (NO3-) and sulfate (SO42-) ions in the atmosphere were higher in winter, which, together with ammonium, constitute the main components of water-soluble ions in PM2.5 in Xinxiang City. Source analysis reported that mobile pollution sources (coal combustion emissions, automobile exhaust emissions, and industrial emissions) in Xinxiang City during the winter season contributed more to atmospheric pollution as compared to fixed sources. The results of the risk assessment showed that the non-carcinogenic health risk of heavy metals in fine particulate matter is acceptable to the human body, while among the carcinogenic elements, the order of lifetime carcinogenic risk is arsenic (As) > chromium(Cr) > cadmium (Cd) > cobalt(Co) > nickel (Ni). During periods of haze pollution, the exposure concentration of PM2.5 has a certain lag effect on blood routine parameters. On the day when haze pollution occurs, when the daily average concentration of PM2.5 rises by 10 μg·m-3, hemoglobin (HGB) and platelet count (PLT) increase, respectively, by 9.923% (95% CI, 8.741-11.264) and 0.068% (95% CI, 0.067-0.069). GAM model analysis predicted the maximum effect of PM2.5 exposure concentration on red blood cell count (RBC) and PLT was reached when the hysteresis accumulates for 1d (Lag0). The maximum effect of exposure concentration ofPM2.5 on MONO is reached when the lag accumulation is 3d (Lag2). When the hysteresis accumulates for 6d (Lag5), the exposure concentration of PM2.5 has the greatest effect on HGB. The maximum cumulative effect of PM2.5 on neutrophil count (NEUT) and lymphocyte (LMY) was strongest when the lag was 2d (Lag1). During periods of moderate to severe pollution, the concentration of water-soluble ions and heavy metal elements in PM2.5 increases significantly and has a significant correlation with some blood routine indicators.

Exposure of street sweepers to cadmium, lead, and arsenic in dust based on variable exposure duration in zinc smelting district, Northeast China

Street dust is an important contributor to heavy metal exposure in street sweepers. In this work, the levels of cadmium (Cd), lead (Pb), and arsenic (As) in street dust were evaluated, and the corresponding health implications for street sweepers in the smelting district of Huludao city northeast China were assessed. The contributions of dietary sources and dust to total metal exposure in street sweepers were compared. Because street sweepers are exposed to street dust both during work and nonwork hours, the health risks faced by street sweepers are uncertain. Therefore, variable exposure duration was considered using a deterministic model. A probabilistic risk assessment model was developed to explore the health effects of street dust on street sweepers via Monte Carlo simulation. The various exposure parameters that affect risk were analyzed using sensitivity analysis. The average Cd, Pb, and As levels in the hair of street sweepers were 2.04, 20.12, and 0.52 mg·kg^-1, respectively. These values were higher than those for residents (i.e., not street sweepers) of Huludao. Strong correlations were found between the logarithms (base 10) of the Cd, Pb, and As contents in dust and hair (r_Cd = 0.581, p < 0.01; r_Pb = 0.428, p < 0.01; r_As = 0.378, p < 0.01; n = 62). Based on analysis using deterministic models, the maximum exposures to Cd and Pb via dust through the alimentary canal were nearly three and six times higher than the dietary exposures, respectively. Sensitivity analysis indicated that exposure duration is an important parameter.

Trace metal fractions, sources, and risk assessment in sediments from Umurbey Stream (Çanakkale-Turkey)

Trace metal contamination has become a worldwide problem for aquatic systems, as sediments act as a sink for trace metals. This study was conducted to assess geochemical fractions, sources and potential risks of trace metals (Cd, Cr, Cu, Ni, Pb, and Zn) in sediments of Umurbey stream (Çanakkale-Turkey). Sediment samples were taken from seven different locations of Umurbey stream. Aqua regia wet digestion procedure was applied to determine total contents of trace metals and BCR sequential extraction procedure was applied to determine geochemical fractions of trace metals. Trace metal total values were ordered as Zn > Pb > Cr > Cu > Ni > Cd. Just because of topography, geology, and agricultural practices, S4, S5, S6, and S7 sampling points had greater total trace metal concentrations than the other locations. Potential mobility of trace metals in sediment samples was ordered as Cd (62.1%) > Zn (60.8%) > Pb (54.8%) > Cu (46.1%) > Cr (43.0%) > Ni (29.7%). Cd, Zn, Pb, and partially Cu were encountered mostly in mobile phases. Multivariate analyses revealed that pollution in sediment samples was originated from not only anthropogenic but also natural factors. Except for Zn, trace metal concentrations were found to be at tolerable levels of biota. When the contamination factor and risk assessment code results were assessed together, it was observed that Cd, Zn, and partially Pb were weakly adsorbed onto sediments, thus might pose risks on environment in the long run.

Source and risk assessment of heavy metals and microplastics in bivalves and coastal sediments of the Northern Persian Gulf, Hormogzan Province

The objectives of the current study are to investigate the concentration, biological risks, chemical speciation, and mobility of of heavy metals and also the determination of their distribution, physicochemical characteristics, and abundance of microplastics in coastal sediments and edible bivalves in the Persian Gulf, the coastal area of Hormozgan Province. Sampling points were selected considering the location of industrial, urban and Hara forest protected areas. In November 2017, a total of 18 sediment samples from coastal sediments (top 0-10 cm) and the most consumed bivalve species in the region were collected from two stations, Lengeh and Bandar Abbas Ports. The average concentration of heavy metals (except for Ni and Cd) in the sediments were lower than their average shale and the upper continental crust. Enrichment factors revealed significant enrichment of Ni, Mn, Cr, Cd and As. The fractionation of heavy metals using the Community Bureau of Reference (BCR) sequential extraction scheme indicated the high bioavailability of Zn, As, Mn, and Co. In general, the highest concentration of Mo, Cd, Pb, Zn, Cr, Cu, Mn, Hg, and Sb was detected in areas with frequent human activities including Shahid Rajaee Port, Shahid Bahonar Port, and Tavanir station. Shahid Rajaee and Shahid Bahonar Ports are the most important ports on the coast of Hormozgan province. The Risk Assessment Code calculated for the study elements indicates that As, Co, Zn, and Cu pose a moderate environmental risk a threat to the aquatic biota. Health risks of most heavy metals arising from bivalves consumption were safe, except for As which is associated with the high target cancer risk values. With reference to the type of microplastics found, they were mainly fibeours with lengths ranging between 100 and 250 μm in sediments and bivalves. Most of the microfibers found in the sediments were made of polyethylene terephthalate (PET) and polypropylene (PP), and the fibers found in the bivalves were made of PP.

Temporal variations of levels and sources of health risk associated with heavy metals in road dust in Beijing from May 2016 to April 2018

To analyze the temporal variations of heavy metals, health risk, and source-specific health risk, 24 road dust samples were collected from Beijing in each month in two years. The temporal variations of Hg, Pb, and Ni were higher than other heavy metals. Most heavy metals reached their highest concentrations either in winter or in spring, then the concentrations decreased and reached the lowest values in autumn. Human health risk assessment (HHRA) model showed that As, Cr, and Ni might pose cautionary carcinogenic risk (CR) to children (CR > 10^-6). CR for adults were only 0.15 to 0.19 times of that for children. Four sources were identified based on positive matrix factorization model and HHRA model, they were traffic exhaust, fuel combustion, construction, and use of pesticides and fertilizers. Influenced by the difference of carcinogenicity of heavy metals, traffic exhaust contributed the largest to heavy metals (36.02%, over 42.24% higher than other sources), while contributions of fuel combustion to CR (36.95%) was similar to traffic exhaust (37.17%). Monte-Carlo simulation showed that the 95th percentile of probability density functions of CR posed by Cr and Ni from each source were 9.90 × 10^-5 to 2.64 × 10^-4, posing cautionary carcinogenic risk to children. The seasonal change of CR varied among different sources. CR from use of pesticides and fertilizers in spring was 35.06 times of that in winter, and that from fuel combustion in winter was 1.15-2.40 times of that in other seasons. CR from each source was sensitive to ingestion rate and skin adherence factor.

A survey of heavy metal contents of rural and urban roadside dusts: comparisons at low, medium and high traffic sites in Central Scotland

Roadside dust can contain particulates enriched with potentially toxic elements (PTEs) as a result of the degradation of mechanical vehicular parts, tyre wear and combustion processes. To assess the potential accumulation of these metals in roadside areas, a snapshot study was carried out, investigating metal content at rural and urban locations in central Scotland. Samples of road dust were collected at six sites representing low, medium and high traffic intensity at rural and urban locations. The samples were separated based on particle size and analysed for heavy metal content using inductively coupled plasma optical emission spectroscopy (ICP-OES) after acid digestion. The metals analysed were aluminium (Al), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), lead (Pb) and zinc (Zn). The rural area measurements were carried out in West Lothian, approximately 13 to 17 miles west of the city of Edinburgh (UK). The urban area measurements were carried out in the southern part of the Edinburgh city district (UK). Concentrations of Cu, Cr and Zn were found to correlate with traffic intensity, although only Cu and Zn concentrations exceed recommended EC directive 86/278/EEC guidelines for urban runoff materials. The metal concentrations of small particles (0.45-20 μm) were exceedingly high in both Cu and Zn at areas of high traffic intensity, indicating potential areas of concern regarding health impacts for pedestrians and cyclists who are exposed to roadside dust on a regular basis.

Comparison of two non-specific flow-through sequential extraction approaches to identify the physico-chemical partitioning of potentially harmful elements in a certified reference material

Two non-specific sequential extraction methods utilising chemometric data processing (chemometric identification of substrates and element distribution, CISED) have been developed and used to determine the physico-chemical partitioning of potentially harmful elements (PHE) in certified reference material BCR CRM 701 (lake sediment). A miniaturized centrifugation method in which the sample was extracted on a filter insert in a polypropylene centrifuging tube, and a quasi-flow through method in which the sample was supported on a TX40 filter in a 47 mm in-line polycarbonate filter holder, gave similar results. The CISED data processing identified nine components. Seven of these were of geochemical origin - two carbonate components, an Al/Fe oxide/hydroxide component, three Fe-dominated components and one Si-dominated component - while the others represented the TX40 filter blank. The overall extraction capabilities of the methods were similar to that of the well-established BCR sequential extraction (Σsteps 1-3). However, whilst the BCR extraction is operationally defined, the CISED provides information on associations between PHE and the geochemical components identified. The flow through CISED procedure has potential applications in investigating the chemical speciation of PHE associated with urban airborne particular matter.

Potentially toxic elements and polycyclic aromatic hydrocarbons in street dust of Yazd, a central capital city in Iran: contamination level, source identification, and ecological-health risk assessment

Contamination level, source, and ecological-health risk of potentially toxic elements (PTEs) and polycyclic aromatic hydrocarbons (PAHs) in the street dust of Yazd, a central capital city in Iran, were investigated for the first time regarding samples collected from 21 sites. Geochemical indices pointed out an enrichment trend of [Formula: see text] and an ecological risk trend of [Formula: see text]. The ecological risk indices of PAHs reflected high ecological risk for pyrene (Pyr). The statistical approach along with the isomeric ratios of PAHs suggested that the traffic-related sources, such as wearing of tires and brake pads, and the vehicular exhaust emissions were greatly responsible for the elevated concentrations of Pb, Cu, Sb, and PAHs, while Al, Ni, Co, V, Mn, As, and, to a lesser extent, Fe, Zn, Mo, and Cr were mainly influenced by geogenic sources. The human health risk assessment of PTEs and PAHs reflected that As, Cr, and Pb pose the highest non-carcinogenic risk in adults and children, compared with other PTEs and also PAHs. The carcinogenic health risk of Pb in the children and PAHs in both subpopulations was high for cancer development.

Is mercury in fluorescent lamps the only risk to human health? A study of environmental mobility of toxic metals and human health risk assessment

Although fluorescent lamps (FL) are extensively used worldwide, recycling rates in some countries are still low. If disposed of inappropriately and broken, FL can cause soil contamination. Hg toxicity in FL is extensively discussed in the literature; however, few studies address the other toxic metals present in the phosphorous powder of FL (PPFL). This paper presents a characterization of the environmental mobility with sequential extraction scheme (SES) of Cd, Cu, Hg, Mn, Ni, Pb, and Zn in PPFL, and modeling the potential risks to human health, in case of direct disposal in soils. An after thermal treatment waste was used for safety reasons. The SES method included five fractions, and the quantification was performed by flame atomic absorption spectrometry (FAAS). Human health risk assessment (HHRA) was conducted using RISC4® software. The PPFL showed the following mobility sequence: Cu (85%) > Ni (81%) > Hg (80%) > Zn (77%) > Cd (75%) > Mn (6%) > Pb (2%), which suggests that Cu, Ni, Zn, and Cd, besides Hg, could be of environmental concern in terms of availability. HHRA showed the potential hazard of Cd, for both children and adults, in the hypothetical scenario of vegetable ingestion, considering vegetables grown in soils contaminated with FL waste. The thermal treatment does not completely remove Hg from the matrix, and the residual Hg still poses a risk to children. These results show that Hg and Cd can be hazardous to humans and reinforce the importance of the correct disposal and treatment of PPFL.

Assessment of bioavailability and mobility of major and trace elements in agricultural soils collected in Port St Johns, Eastern Cape, South Africa using single extraction procedures and pseudo-total digestion

PURPOSE

The aim of this study was to evaluate the applicability of ultrasound assisted single extraction and pseudo-total digestion procedures to investigate the bioavailability and mobility of major and trace elements collected from agricultural soil collected in Mzimvubu farmstead area located in Port St Johns, Eastern Cape Province (South Africa).

MATERIALS AND METHODS

The potential metal availability was assessed using complexing agent (ethylenediaminetetraacetic acid (EDTA)), mild (cacium chloride (CaCl2) and ammonium nitrate (NH4NO3)), deionized water and acidic (CH3COOH) extractants with the assistance of ultrasound to evaluate mobility and bioavailability of metals. The ultrasound radiation was used to assist the single extraction of major and trace metals from agricultural soils as well shortening the extraction time. The pseudo-total metal content in agricultural soils was obtained using pseudo-total digestion employing aqua-regia.

RESULTS AND DISCUSSION

The results obtained using different solvents for single extraction procedures, revealed that higher extraction of Al (256-681 mg kg-1), Fe (172-430 mg kg-1) and Mn (35-136 mg kg-1), was observed compared to other metals. Among the investigated solvents, deionized water, acetic acid and EDTA proved to be the most aggressive extractants. The geo-accumulation index (2-6) and contamination factor (3-6) demonstrated that Fe, Cr, Mn, Co, Cu, Ni, and Zn could pose significant environmental contamination risk.

CONCLUSIONS

Based on the results obtained, it can be concluded that the high levels of some studied metals was due to anthropogenic activities.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40201-020-00581-x.

Pollution characteristics and toxicity of potentially toxic elements in road dust of a tourist city, Guilin, China: Ecological and health risk assessment☆

Road dust samples from industrial, urban, and tourist areas of the international tourist city of Guilin, China, were collected to study the concentration, spatial distribution, pollution level, and health risk of potentially toxic elements (PTEs) using an array-based risk assessment model from the United States Environmental Protection Agency. The geoaccumulation index (I_geo), ecological risk index, and spatial interpolation were used to investigate the road dust pollution level. The results indicated that apart from Ni and Al, the concentration of all the heavy metals (Pb, Zn, Ni, Cu, Cr, Cd, Fe, Mn, and As) were markedly higher than the corresponding background values in the three functional areas. Based on the I_geo, the study area had an uncontaminated to moderate pollution level, and the industrial area was slightly more polluted and posed a greater ecological risk than the urban and tourist areas. Comparatively, Pb, Zn, and Cu exhibited higher pollution levels in the three functional sites. Hotspots of PTEs were more concentrated in urban and industrial areas than in tourist areas. Furthermore, the health risk model revealed significant non-carcinogenic risks to children from As in urban, industrial, and tourist areas as the hazard quotients (1.64, 2.04, and 1.42, respectively) exceeded the threshold standard of 1.00. The carcinogenic risk via ingestion (RI_ing) illustrated significant risks to children from Cr, As, and Ni because the RI_ing values were considerably higher than the threshold standard (1.00E-6 to 1.00E-4) in the three functional areas. However, no cancer risk was observed from the dermal and inhalation pathways.

Trace metals in indoor dust from a university campus in Northeast India: implication for health risk

This study reports concentrations of trace metals and the associated health risks in settled dust of different microenvironments of a university in Northeast India. Settled dust samples were collected from the most accessible indoor locations by the students of Tezpur University, a rural-residential university of mid Brahmaputra Valley of Assam. Collected samples were digested in an aqua regia-assisted microwave digestion system and analyzed for iron (Fe), nickel (Ni), zinc (Zn), cadmium (Cd), and lead (Pb) using atomic absorption spectroscopy (AAS). The highest concentration was obtained for Fe with a mean value of 1353.51 ± 123 mg/kg. Cadmium showed the lowest concentration with a mean value of 0.75 ± 0.57 mg/kg. Cadmium was the highly enriched element followed by Pb, Zn, and Ni. The metals mostly fall in the "extremely high enrichment" category. The study revealed that infiltrated soil or street dust, eroding wall paints, and automotive sources were the main contributing sources of the metals. The calculated Hazard Index (HI) value, 0.39, was lower than the acceptable HI value of 1 indicating no significant non-cancer risk to the students from exposure to these heavy metals at present. The study also found no carcinogenic risk on exposure to the metals present in the indoor dust samples.

Heavy metals analysis in chalk sticks based on ICP-AES and their associated health risk

The purpose of this study was to determine the contents of 12 metals in obtainable chalk sticks and assess their associated health risk. Chalk stick samples from 16 factories were analyzed by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The results showed that 12 metals were detectable in white and colored chalks. The contents of Al, Fe, and Mg were in the range of 646.2-3909 μg/g, 408.8-2075.1 μg/g, and 125-6825.7 μg/g, respectively. Additionally, the levels of Cu, Pb, Mn, and Cr were ranked in the order of Cu>Cr>Pb>Mn, while the maximum levels of As, Ni, Cd, and Sn in all samples (9.90, 10.14, 7.27, and 6.08 μg/g, respectively) were relatively lower than those of other metals. Furthermore, the cumulative hazard index (HI) values of all metals and carcinogenic risk (CR) of As (1.12E-4), Ni (1.39E-4), and Cr (1.15E-4) for children were also higher than the threshold value (1.0E-6 to 1.0E-4), suggesting that chalk dust particles may exert adverse effects on children.

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.

Investigation of road dust characteristics and its associated health risks from an urban environment

Globally, road dust is a major source of inhalable particulate matter in any urban environment. This research seeks to assess the elemental composition of road dust at Vellore city, India, and to evaluate its health risks. For this, dust samples are collected from 18 locations in the study region. The collected samples are digested and analysed for about 25 elements using inductively coupled plasma-optical emission spectroscopy, of which 19 elements have concentration greater than the detection limit of the instrument (Al, Ba, Ca, Mg, Sr, Co, Cr, Cu, Fe, Ga, Zn, In, K, Li, Mn, Na, Ni, Pb and Rb). The highest mean concentration is noted for Fe (22,638.23 mg/kg) followed by Ca (13,439.47 mg/kg), Al (8445.89 mg/kg) and Mg (3381.20 mg/kg). Enrichment factor (EF) and contamination factor (CF) are calculated for 10 trace elements: Cu, Co, Cr, Ga, Mn, Ni, Pb, Rb, Sr and Zn. Elements Ga and Zn show the highest EF and CF. Source identification recognized that crustal material and traffic as the major sources of potentially toxic elements (PTEs). Further, the health risk assessment is performed for nine PTEs and identifies that Fe, Pb, Cr and Co are elements with the highest health index. Health index of these elements suggests a possible health risk. Ingestion is the major pathway, and children are found to be at a higher risk compared to adults.

Chemical fractionation and bioaccessibility of potentially toxic elements in area of artisanal gold mining in the Amazon

Artisanal mining may have modified the mobility, bioavailability and bioaccessibility of potentially toxic elements (PTEs) in the Serra Pelada gold mine, eastern Amazon, Brazil, which has not yet been studied. The objectives were to perform chemical fractionation of barium (Ba), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn), and to determine the bioaccessibility of these elements in soils and mining wastes collected in agriculture, forest, mining, and urban areas from the influence zone of the Serra Pelada gold mine. Pseudo total concentrations were obtained by acid digestion, chemical fractionation was performed using the Bureau Community of Reference (BCR) sequential extraction, oral bioaccessibility was obtained by the Simple Bioaccessibility Extraction Test (SBET) and lung bioaccessibility was obtained through Gamble's solution. The pseudo total concentrations indicated contamination by Ba, Cu and Ni. The sequential extraction revealed the predominance of all elements in the residual fraction. However, Ba is in high concentrations in the greater mobility forms, ranging from 166.36 to 1379.58 mg kg^-1. Regardless of the area, Cr and Cu are more oral bioaccessible in the intestinal phase, and Zn in the gastric phase. Ba, Cr and Zn are not lung bioaccessible, while Cu, Ni and Pb are bioaccessible via inhalation. The PTEs studied deserve attention not only due to the high pseudo total concentrations found (which indicate potential risk), but also the concentrations in high mobility forms and bioaccessible fractions, especially in the areas of greatest anthropogenic occupation.

Source identification and pollution degree of deposited dust on green space in Tehran

The information about concentration, sources, and pollution degree of heavy metals belong to deposited dust (DS) can be used for decision-making in air quality control, removal role of green space, and urban forest management. The objectives of the study were to identify and evaluate DS pollution degree with the introduction of a new index. DS samples were collected from five tree species. The concentration of heavy metals and pollution degree of DS were evaluated by enrichment factors (EF), geoaccumulation index (I_geo), modified degrees of contamination (mC_d), and a new comprehensive index as weighted degree of contamination factor (wC_d). The values of EF showed that all samples were significant to extremely high enrichment and DS samples were emitted from anthropogenic activities. I_geo values indicated that DS samples were polluted by Cd (80-97%) and Pb (100%). In addition, mC_d results showed more than 67% of samples were unpolluted. There was a clear fact that I_geo results showed high pollution levels for Pb, Cd, and low for Ni, and the mCd results were incompatible with them. When all heavy metals were used without their importance to mC_d, calculation can cause bias from reality. For this reason, the new index was suggested as wC_d for all heavy metals that its results showed high to very high degree of pollution and that it was compatible with other indices results.

Health risk assessment of heavy metals in street dust around a zinc smelting plant in China based on bioavailability and bioaccessibility

In order to investigate pollution level, chemical speciation and health risk of exposure to heavy metals in street dust from smelting district, we carried the following studies: (a). the differences in the morphology of street dust in smelting and non-smelting districts using a scanning electron microscope; (b). the chemical speciation and bioavailability of heavy metals in <100 μm and <63 μm particles near a smelting district using a modified three-stage BCR sequential extraction procedure and in vitro digestion test, respectively; (c). the evaluation of the non-carcinogenic risk of children and adults exposure to dust based on bioaccessibility. The results showed that most of the dust particles near Huludao Zinc Plant (HZP) were relatively solid with less porosity, which might originate from incompletely burned mineral particles from the smelting process. The concentrations of Pb, Cd and Cu were much higher than the background levels: 1560, 178.5 and 917.9 mg kg^-1 in <100 μm dust samples, and 2099, 198.4, 1038 mg kg^-1 in <63 μm dust samples, respectively. Pb was mostly present in the reducible fraction and the acid exchangeable fraction, while Cd and Cu were the most common heavy metals in the acid exchangeable fraction and oxidizable fraction, respectively. The rank order of bioaccessibility for the gastric and intestinal phase was Cd (58.13%) > Pb (50.00%) > Cu (19.19%) and Cd (20.36%) > Cu (15.67%) > Pb (5.08%), respectively. Hand-to-mouth ingestion poses the greatest non-carcinogenic exposure risk compared with other exposure pathways. When bioavailability is taken into account, children experienced higher non-carcinogenic and carcinogenic risks of dust exposure compared with adults, and the <63 μm particles posed greater risks than <100 μm particles.

Risks related to heavy metal pollution in urban construction dust fall of fast-developing Chinese cities

Urban construction is a major contributor to air pollution, but few studies have examined heavy metal pollution in urban areas caused by construction dust fall. We measured the concentrations of Cr, Ni, Cu, Zn, Pb, Cd, and Hg and particle size distribution in dust fall from various construction activities in seven fast-developing cities in China and conducted a health risk assessment. Mean metal concentrations in construction dust fall were on the order of Zn (246.3 mg/kg) > Cr (94.2 mg/kg) > Pb (56.5 mg/kg) > Cu (53.6 mg/kg) > Ni (22.8 mg/kg) > Cd (0.68 mg/kg) > Hg (0.08 mg/kg). Cu and Zn were positively correlated in areas of subway and building construction, and Pb and Cd were positively correlated in areas of road construction, likely because of the materials specific to these activities. Enrichment factors for heavy metals at all sampling sites were on the order of Cd (10.4) > Zn (6.37) > Cu (4.25) > Pb (3.84) > Hg (2.41) > Cr (2.02) > Ni (1.32). The enrichment factors for all metals except Zn indicated that heavy metal pollution was highest in road construction, followed by building and subway construction. Non-carcinogenic risks to children (hazard index >1) were 1.01-1.08 in four of the seven sampling sites, indicating possible risk from deposition of construction dust fall. In contrast, the hazard index for adults was <1 at the seven cities and total carcinogenic risks (<1 × 10^-6) were at acceptable levels. An integrated ecological risk assessment demonstrated that heavy metal particles in construction dust fall in two of the cities (Shijiazhuang and Qingdao) were likely to be suspended in the atmosphere. Our study of heavy metal pollution in construction dust fall provides data on ecological and human health impacts and suggests that extensive measures are required to control construction dust fall in China.

Heavy metal pollution and health risk assessment of agricultural soil near a smelter in an industrial city in China

To assess heavy metal pollution and human health risk, a total of 28 topsoil samples were collected during four seasons from seven agricultural soil sites near a famous smelter in Jiyuan, China. The maximum concentrations of Cd, Pb, Hg, As, Zn, Cu, Ni, and Cr were 26.00, 2601.00, 3.29, 65.00, 410.00, 156.30, 54.80, and 73.60 mg kg^-1, respectively. Compared with the sampling site nearest to the smelter, the concentrations of six metals at the farthest site were decreased significantly (P < 0.05). All sites were heavily contaminated, with Nemerow index (P) >3.0, and all sites had very high ecological risks related to Cd and Hg. The non-carcinogenic risk for children (based on combined exposure to the eight metals) was above the safety level. The carcinogenic risk of As for adults (8.98 × 10^-6) and children (1.49 × 10^-5) exceeded the acceptable level (1 × 10^-6). Results suggest a serious health risk in the polluted areas, particularly for children.Abbreviation Cd: Cadmium; Pb: Lead; Hg: Mercury; As: Arsenic; Zn: Zinc; Cu: Copper; Ni: Nickel; Cr: Chromium; P: Nemerow index; RI: Potential ecological risk index; E_i: Monomial potential ecological risk of a specific heavy metal; HI: non-carcinogenic hazard index; CR: Carcinogenic risk; TN: Total nitrogen; TP: Total phosphorus; OM: Organic matter; MC: Moisture content; ADD: Average daily dose.

Fractionation analysis and health risk assessment of heavy metals in six traditional Chinese medicines

Traditional Chinese medicines (TCMs) are widely used to treat various diseases in China and some countries, and TCM products are becoming increasingly available and popular worldwide. But TCMs are facing the challenge of heavy metal pollution. In this work, we examined the total contents and fractionations of Pb, Cd, Hg, and Cu in six TCMs (Angelicae Sinensis Radix (ASR), Chuanxiong Rhizoma (CR), Polygonati Rhizoma (PR), Astragali Radix (AR), Carthami Flos (CF), and Paeoniae Radix Rubra (PRR)) and evaluated the health risk of four heavy metals in these TCMs. The results showed that Cd, Pb, and Cu contents were considerably high and the amount of Cd in six TCMs, Pb in CR, ASR, AR, and CF, and Hg in ASR, PR, and PRR exceeded the limit values. The predominant fractions of Pb, Cd, and Cu were exchangeable and carbonate fractions in six TCMs; Hg mainly existed in organic and residual fractions. The average daily intake dose (ADD) and target hazard quotient (THQ) of Pb based on total content and total THQ of four heavy metals based on bioaccessible fractions in AR and PRR exceeded the safety guideline. These results indicated that the potential health risk could occur by taking these TCMs.

Health risk assessment and bioaccessibilities of heavy metals for children in soil and dust from urban parks and schools of Jiaozuo, China

Urban parks and schools sever as the mainly activity areas for children, but risk assessment posed by heavy metals (HMs) from soil and dust in these area has rarely been investigated. In this study, six urban parks and seven schools in Jiaozuo, China, were taken as research objects to understand the contamination level and bioaccessibility of HMs from soil and dust in urban parks and schools. The results indicated that Zn, Cu, Pb, Cd, As, Ni and Co from soil and dust were above the background values, especially Zn and Cd in dust, and As and Cd in soil. Serious Cd pollution was discovered, and respective Cd concentrations in soil and dust were 17.83 and 7.52 times the background value. Additionally, the average concentration and bioaccessibility of Zn, Mn, Pb, Cd, Cr, Ni and Co in dust were both higher than in soil. High concentration and high bioaccessibility of HMs in dust suggested that HMs contamination were serious and universal in Jiaozuo. The concentrations of most HMs were higher in the gastric phase, except for Cu and Cd which remained higher in the intestinal phase. Both in the gastric phase and intestinal phase, Mn, As and Cd in soil and dust both have high bioaccessibility which all exceed 10%. The carcinogenic and non-carcinogenic risks base on the total HMs for children (soil: 7.93, 1.96E-05; dust: 6.44, 3.58E-05) were greater than those for adults (soil: 6.35E-01, 1.32E-05; dust: 5.06E-01, 2.42E-05), and urban parks and schools posed high potential risk for children. Therefore, assessment the risk posed by HMs contamination of soil and dust in urban parks and schools is vital and urgent for children.

Metallic elements in human hair from residents in smelting districts in northeast China: Environmental factors and differences in ingestion media

The health of residents in Huludao City is affected by the emissions of heavy metals from smelting, diet and atmospheric precipitation. This study investigated the concentrations of Hg, Cd, Pb, Cu and Zn in scalp hair samples from 259 residents of different ages and genders from five districts in Huludao City and examined the main factors for heavy metal exposure. Cd and Pb concentrations in hair samples exceeded the normal concentration ranges for human hair (Cd < 0.3 mg/kg; Pb < 9.3 mg/kg), and the highest Pb concentrations were found in subjects in the age range 0-15 years. Samples from men were higher in Cd and Pb compared to those for women. Workers from the Huludao zinc plant (HZP) had higher concentrations of all metals in their hair relative to other occupations except for Cu. Geographically, the highest Cd and Pb concentrations in hair were found for residents living in Daochi district (DCD) and the Zn plant district (ZPD), respectively. In smelting regions, the effects of dust ingestion on heavy metal exposure were more important than in non-smelting regions.

Characterizing pollution indices and children health risk assessment of potentially toxic metal(oid)s in school dust of Lahore, Pakistan

Toxic metal pollution is a renowned environmental concern, especially to sensitive environments like school classrooms and their association with children's health. The study was planned to determine the pollution characteristics of 13 potentially toxic metal (oid)s (PTMs) and their associated children's health risk assessment from school dust samples of considerably three land-use types (residential, roadside, and industrial areas) of Lahore, Pakistan. Geo-accumulation (I_geo), pollution (PI), integrated pollution (IPI) and pollution load (PLI) indexes were used to determine the PTMs contamination and USEPA health risk assessment models were employed to assess the health risks in children. The mean concentrations of Cd, Cr, Cu, Ni, Pb, and Zn for three land-use types were found much higher than the permissible limits. Results of pollution indices revealed that school dust was strongly contaminated with Cd, Pb, and Zn whilst moderately contaminated with Cr and Cu. Moreover, the health risk assessment models revealed no significant non-cancerous risks in children with predominantly highest hazardous index (HI) of Cr in industrial (4.61E-01) and Pb in both roadside (4.30E-01) and residential (2.26E-01) area schools. According to cumulative HI of all PTMs and exposure routes, the land-use areas were in descending order as industrial > roadside > residential. The calculations of hazardous quotient (HQ) showed ingestion was the leading pathway of PTMs exposure through school dust. For carcinogenic health risk (CR), the most prominent PTM was Cr with values of 1.53E-06 in industrial area schools, found close to the tolerable range (1.0E-06). Hence, school dust of Lahore prominently contaminated with eminent PTMs triggering slight health risks predominantly by ingestion exposure to children.

Fast and effective simultaneous determination of metals in soil samples by ultrasound-assisted extraction and flame atomic absorption spectrometry: assessment of trace elements contamination in agricultural and native forest soils from Paraná - Brazil

This study proposes a simple and effective method for determination of Al, Cd, Cu, Ni, and Zn in soil samples, associating ultrasound-assisted extraction and flame atomic absorption spectrometry (FAAS). Ultrasound-assisted extraction conditions were optimized using a central composite design. This method required small volumes of HCl, HNO₃, and HF as an extraction solvent blend to ensure effective analyte extraction. Limits of detection and quantification were determined to assess the minimum accurate concentration of the studied elements that can be detected and quantified in a soil sample. Therefore, the ultrasound-assisted extraction was concluded as a simple and straightforward pretreatment technique to determine Al, Cd, Cu, Ni, and Zn concentrations in soil samples. Eight sites of agricultural and native forest areas of the city of Ponta Grossa and Guarapuava, State of Paraná, Brazil, were evaluated for metals, and compared with the reference values for trace elements provided by the Brazilian National Environment Council. Environmental assessment of soils from those eight sites was accomplished through I_geo, EF, CF, and PLI parameters, which aimed at the evaluation of agricultural sites in comparison with adjacent natural forest sites with no history of anthropogenic mobilization to determine the degree of the contribution of anthropogenic sources to metal concentrations. According to the I_geo, EF, and CF parameters, all sites were classified as unpolluted to moderately polluted and none or minor enrichment due to anthropogenic activities were noticed. PLI parameter evaluated the concentration of all studied metals in soils to stipulate an order of contamination, which was concluded as site 8 <site 4 <site 3 <site 7 <site 2 <site 6 <site 1 <site 5 for the sites under study.

Fate and partitioning of heavy metals in soils from landfill sites in Cape Town, South Africa: a health risk approach to data interpretation

The fate and persistence of trace metals in soils and sludge from landfill sites are crucial in determining the hazard posed by landfill, techniques for their restoration and potential reuse purposes of landfill sites after closure and restoration. A modified European Community Bureau of Reference's (BCR) sequential extraction procedure was applied for partitioning and evaluating the mobility and persistence of trace metals (As, Cd, Cr, Cu, Ni, Pb, Sb, Se, Zn) in soils from three landfill sites and sludge sample from Cape Town, South Africa. Inductively coupled plasma optical emission spectroscopy was used to analyze BCR extracts. The mobility sequence based on the BCR mobile fraction showed that Cu (74-87%), Pb (65-80%), Zn (59-82%) and Cd (55-66%) constituted the mobile metals in the soils from the three sites. The mobility of Cu, Zn and Ni (> 95%) was particularly high in the sludge sample, which showed significant enrichment compared to the soil samples. Geo-accumulation index (I_geo) and risk assessment code were used to further assess the environmental risk of the metals in the soils. Exposure to the soils and sludge did not pose any non-cancer risks to adult and children as the hazard quotient and hazard index values were all below the safe level of 1. The cancer risks from Cd, Cr and Ni require that remedial action be considered during closure and restoration of the landfill sites.

Daily exposure to toxic metals through urban road dust from industrial, commercial, heavy traffic, and residential areas in Petaling Jaya, Malaysia: a health risk assessment

Human health is threatened by significant emissions of heavy metals into the urban environment due to various activities. Various studies describing health risk analyses on soil and dust have been conducted previously. However, there are limited studies that have been carried out regarding the potential health risk assessment of heavy metals in urban road dust of < 63-μm diameter, via incidental ingestion, dermal contact, and inhalation exposure routes by children and adults in developing countries. Therefore, this study evaluated the health risks of heavy metal exposure via ingestion, dermal contact, and inhalation of urban dust particles in Petaling Jaya, Malaysia. Heavy metals such as lead (Pb), chromium (Cr), zinc (Zn), copper (Cu), and manganese (Mn) were measured using dust samples obtained from industrial, high-traffic, commercial, and residential areas by using inductively coupled plasma mass spectrometry (ICP-MS). The principal component and hierarchical cluster analysis showed the dominance of these metal concentrations at sites associated with anthropogenic activities. This was suggestive of industrial, traffic emissions, atmospheric depositions, and wind as the significant contributors towards urban dust contamination in the study sites. Further exploratory analysis underlined Cr, Pb, Cu, and Zn as the most representative metals in the dust samples. In accommodating the uncertainties associated with health risk calculations and simulating the reasonable maximum exposure of these metals, the related health risks were estimated at the 75th and 95th percentiles. Furthermore, assessing the exposure to carcinogenic and non-carcinogenic metals in the dust revealed that ingestion was the primary route of consumption. Children who ingested dust particles in Petaling Jaya could be more vulnerable to carcinogenic and non-carcinogenic risks, but the exposure for both children and adults showed no potential health effects. Therefore, this study serves as an important premise for a review and reformation of the existing environmental quality standards for human health safety.

Simultaneous Health Risk Assessment of Potentially Toxic Elements in Soils and Sediments of the Guishui River Basin, Beijing

Simultaneous ecological and health risk assessments of potentially toxic elements in soils and sediments can provide substantial information on their environmental influence at the river-basin scale. Herein, soil and sediment samples were collected from the Guishui River basin to evaluate the pollution situation and the ecological and health risk of potentially toxic elements. Various indexes were utilized for quantitatively assessing their health risks. Pollution assessment by geo-accumulation index showed that Cd had “uncontaminated to moderately polluted” status in the soils and sediments. Potential ecological risk index showed that the Guishui River basin was at low risk in general, but Cd was classified as “moderate or considerable ecological risk” both in the soils and sediments. Health risk assessment calculated human exposure from soils and indicated that both non-carcinogenic and carcinogenic risks of the selected potentially toxic elements were lower than the acceptable levels. Health risks posed by potentially toxic elements bio-accumulated in fish, stemming from sediment resuspension, were also assessed. Non-carcinogenic hazard index indicated no adverse health effects on humans via exposure to sediments; however, in general, Cr contributed largely to health risks among the selected potentially toxic elements. Therefore, special attention needs to be paid to the Guishui River basin in the future.

Effects of biodegradable chelator combination on potentially toxic metals leaching efficiency in agricultural soils

Soil washing with chelators, a viable method for treating soils contaminated with potentially toxic metals, has drawn increasing attentions. The objective of this study was to determine a new generation of mixed degradable chelating agents from N, N-bis (carboxymethyl) glutamic acid (GLDA), [S, S]-stereoisomer of ethyleneiaminedisucc--inic acid (EDDS), nitrilotriacetic acid (NTA), and citric acid (CA), and to evaluate its effectiveness and feasibility to reduce toxic metals contamination in two different agricultural soils. A comparative leaching test conducted on the four individual degradable chelating agents showed that the capacity of single chelator in mobilizing copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) varied significantly. Using a combination of GLDA and NTA was more advantageous than using a single chelating agent in extracting potentially toxic metals. The removal efficiencies of Cu, Zn, Cd, and Pb reached 38.2, 9.8, 71.4, and 19.5% for soil 1, and 25.0, 5.2, 59.7, and 18.5% for soil 2, respectively, at mixed chelator (MC) concentrations of 3 mmol/L (GLDA) and 2 mmol/L (NTA), pH of 6.0, and a contact time of 4.0 h. The effects of washing conditions, chelator concentration, pH values, and contact time on the removal efficiencies of target toxic metals were investigated. The results showed that the combined chelating agent has a lower pH dependence, making it feasible for a wider range of applications. The effects of the chelating agents on the morphological distribution of potentially toxic metals and the soil enzyme activity before and after the treatments were also studied. After washing, the content of the water-soluble, acid-soluble, reducible, and oxidizable target metals showed a certain degree of decrease. Although the activities of catalase, urease, and invertase appeared to be inhibited during a short period of time, their activities were stimulated and later promoted with the degradation of the chelating agent. In general, the chelating agent combination has a great potential for toxic metals leaching.

Characteristics and health risk assessment of heavy metals in indoor dust from different functional areas in Hefei, China

Metals in indoor dust pose potential health risks to humans. Dust deposition on air conditioner filters can represent the resuspended particulate matter in indoor air. However, few studies have examined this until now. This study investigated the total concentrations and different chemical fractionations of Cd, Cr, Mn, Ni, Pb, Sb, V, and Zn in indoor dust from three different functional zones (the Chief District, Commercial District (CmD), and Industrial District) in Hefei. The mean metal concentrations in indoor dust decreased in the following order: Zn > Mn > Pb > Cr > Ni > V > Cd > Sb. Cd, Pb, and Zn mainly existed in the mobile fraction. Cr and V mainly existed in the residual fraction. The enrichment factor and geo-accumulation index values of heavy metals were all ranked in the order of Cd > Zn > Pb > Sb > Ni > Cr > V, and these values in indoor dust were larger than those in outdoor dust. In addition, the enrichment patterns of these elements were similar in the three functional areas. The orders of non-carcinogenic risk (hazard index; HI) for the different functional areas for children were roughly the same, but there were clear differences for adults. In general, all the HIs were less than 1, which were within the internationally recognized safe range. The total carcinogenic risk (TR) was in the order of Cr > Pb > Cd for both children and adults in the three functional zones. The TRs from Cr exposure were not negligible. The TRs were significantly higher in the CmD.

First Assessment of Metals Contamination in Road Dust and Roadside Soil of Suva City, Fiji

Studies have claimed that road dust and roadside soil are potential banks of pollutants generally in urban areas. Thus, quantifying the concentrations of metals in an urban area is a prerequisite for assessing pollution and their health effects. Hence, this study reports the concentration of the metals, such as Cd, Co, Cr, Ni, Cu, Pb, Zn, and Fe, in the road dust and the roadside soil of Suva City. A total number of 45 road dust and 36 roadside soil samples were collected at 18 different locations around Suva City with potential traffic influence and analysed. The respective metals concentration in the road dust and roadside soil samples of Suva City were Cd (3.7 and 3.1 mg/kg), Co (35.0 and 33.2 mg/kg), Cr (40.0 and 34.0 mg/kg), Ni (54.3 and 32.4 mg/kg), Cu (172.3 and 265.7 mg/kg), Pb (71.0 and 59.3 mg/kg), Zn (685.0 and 507.0 mg/kg), and Fe (41,010.4 and 39,525.5 mg/kg) and showed the decreasing order as Fe > Zn > Cu > Pb > Ni > Cr > Co > Cd and Fe > Zn > Cu > Pb > Cr > Co > Ni > Cd for road dust and roadside soil, respectively. Furthermore, the mean values of the metals surpassed their background levels, except for Fe, whereas the mean values of Cd, Ni, Cu, and Zn have exceeded their permissible limits in road dust. Similarly, Cd, Cu, and Zn have exceeded their permissible limit in roadside soil except for Ni. The geo-accumulation index (I_geo) assessment of Suva City road dust thus indicated nonpolluted to moderate pollution by Ni and Cu and moderate pollution by Zn. The I_geo assessment of the roadside soil showed moderately polluted by Cu and Zn but no pollution from the remaining studied metals. Overall, the study indicated that the sampling locations at an industrial site of Suva City is highly predominated with almost all of the studied metals and is a concern to the general public who live and work within the vicinity of Walu Bay industrial area.

Accumulation, temporal variation, source apportionment and risk assessment of heavy metals in agricultural soils from the middle reaches of Fenhe River basin, North China

The Fenhe River basin is the main agricultural and industrial developed area in Shanxi province, China. In recent years, agricultural non-point source pollution in the Fenhe River basin intensified, threatening soil quality and safety in the area. Accumulation of eight heavy metals (HMs) including chromium (Cr), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg) has been detected in soil samples from 50 agricultural sites (0-20 cm) from the middle reaches of the Fenhe River basin. The ecological and human health risk and potential sources of the eight HMs were investigated. In addition, the human health and ecological risks imposed by the possible sources of the eight HMs were quantitatively apportioned. The enrichment factor (EF) values of Cr, Ni, Cu, Pb and Zn were lower than 2, indicating minimal enrichment, while values for As, Cd and Hg were between 2 and 5, exhibiting moderate enrichment. Temporal variation analysis suggested that most HMs in the study area exhibited low concentrations after 2015, except As. The potential ecological risk index was 174.09, indicating low ecological risk. The total hazard index and cancer risk values were 0.395 and 5.35 × 10-4 for adults and 2.75 and 3.63 × 10-4 for children, indicating the accepted standard levels were exceeded for non-carcinogenic risk for children and carcinogenic risks for both adults and children. Four potential sources were identified: (1) natural sources, (2) farming activities, (3) coal combustion, and (4) exhaust emissions. Natural sources represented the largest contributor to ecological risk, accounting for 57.42% of the total. Coal combustion was the major contributor to human health risks, accounting for 43.27% and 43.73% of the total non-carcinogenic risk and carcinogenic risk for adults, respectively, and 42.72% and 43.88% for children, respectively.

Speciation analysis and dynamic absorption characteristics of heavy metals and deleterious element during growing period of Chinese peony

The heavy metals and deleterious element (Pd, Cd, Cu, As, and Hg) in Chinese peony (Paeonia lactiflora Pall.) were determined by Tessier's sequence extraction method. Pb mainly existed in carbonate fraction. The main fraction of Cd in different tissues and different month is quite different. Cu mainly exists as exchangeable carbonate fractions. Five forms of Hg all exist in leaf, stem, and root. The total absorbable fraction of Pd, Cd, Cu, As, and Hg was different in different tissues. The total content of heavy metals can migrate from different tissues and the content of different speciation of heavy metal also can change during the growing period of plants. The results showed that different parts of plants and different elements resulted in different distribution and mobility. Base on this, it is more scientific and reasonable to clarify the migration and enrichment and to analyses the speciation of heavy metals during growing period of plant medicine. It is more scientific and reasonable to clarify the migration and enrichment, and to analyses the speciation of heavy metals during growing period of plant medicine.

Chemical fractionation, bioavailability, and health risks of heavy metals in fine particulate matter at a site in the Indo-Gangetic Plain, India

In the present study, the distribution and chemical fractionation of heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in PM_2.5 collected at Sikandarpur in Agra from September 2015 to February 2016 were carried out to evaluate their mobility potential, environmental, and human health risk through inhalation. Sequential extraction procedure was applied to partition the heavy metals into four fractions (soluble and exchangeable fraction (F1); carbonates, oxides, and reducible fraction (F2); bound to organic matter, oxidizable, and sulphidic fraction (F3); and residual fraction (F4)) in PM_2.5 samples. The metals in each fraction were analyzed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Daily PM_2.5 concentration ranged between 13 and 238 μg m^-3 during the study period. For more than 92% of the days, the mass concentrations were greater than the National Ambient Air Quality Standard (NAAQS) set at 60 μg m^-3. The total mass concentration of the eight metals was 3.3 μg m^-3 that accounted for 2.5% of the PM_2.5 mass concentration and followed the order Fe > Zn > Cu > Mn > Pb > Ni > Cd > Cr in dominance. The carcinogenic metals (Cd, Cr, Ni, and Pb) comprised 10% of the total metal determined. Almost all the metals had the highest proportion in the residual fraction (F4) except Ni, which had the highest proportion in the reducible fraction (F2). Chemical fractionation and contamination factor (CF) showed that Pb and Ni are readily mobilized and more bioavailable. Risk assessment code (RAC) showed that Cd, Cu, Mn, Ni, Pb, and Zn had medium environmental risk, while Cr and Fe had low risk. When the bioavailable (F1 + F2) concentrations were applied to calculate non-carcinogenic and carcinogenic risk, the results showed that the value of hazard index (HI) for toxic metals was 1.7 for both children and adults through inhalation. The integrated carcinogenic risk was 1.8 × 10^-6 for children and 7.3 × 10^-6 for adults, with both values being higher than the precautionary criterion (1 × 10^-6). Enrichment factor (EF) calculations showed that Cd, Pb, Zn, and Ni were enriched being contributed by anthropogenic activities carried out in the industrial sectors of the city.

Fine road dust contamination in a mining area presents a likely air pollution hotspot and threat to human health

The road dust found in mining areas is composed of dust from multiple sources, including wind transported mineral dust from mines and tailings as well as uncovered trucks leakage. Collectively, these are then distributed via wind and traffic activity, becoming an important source of particulate matter (PM) and subsequently inhaled by pedestrians. A common practice in previous road dust risk assessments has regarded them as soil, which likely led to a significant underestimation of the actual inhaled amount. To more accurately understand the inhalation risk presented by road dust in mining areas, the study applied a detailed pollution analysis and dust dispersion model to assess the inhaled amount of road dust. Road dust samples located at different distances to the mine and tailings were collected and sieved to 10 μm (RD10). Enrichment factors (EFs) of Ce, As, Cd, and Mo exceeded 20 across most sampled sites, suggesting extreme pollution. Source analysis indicated that most of the collected RD10 had greater than half of its mass originating from the mine. To assess the risk presented by inhalation exposure to local populations, we built a method using Gaussian diffusion model and two exposure scenarios for both adults and children were considered. The level of simulated particle concentrations was comparable to that described in the literature; the inhalation of potential toxic elements (PTEs) in RD10 led to health risks for both adults and children (adult and child HI > 1, with adults CR in industrial areas >10^-4). Results also indicated that a ten-fold reduction of silt load resulted in a >4-fold decrease in risk. Collectively, the results suggest that fine road dust is a potential hotspot for mineral exposure in populations living around a mine and its tailings; moreover, that effective prevention measures like road cleaning and truck regulation are urgently needed.

Mobility and bioaccessibility of risk elements in the area affected by the long-term opencast coal mining

The potential environmental hazards of risk elements in the area affected by the opencast coal mine and/or coal combustion for plants and animals was assessed by using a suite of laboratory bioaccessibility tests. The chosen sampling area was in the vicinity of the largest coal mine spoil in the Sokolov coal basin (Czech Republic). For an estimation of the oral bioaccessibility of the risk elements in soils, the physiologically based extraction tests were applied. Among the available methods for estimating the pulmonary bioaccessibility of elements, the Gamble's and Hatch's tests were chosen. The results showed elevated pseudo-total soil contents of As, Be, Cd, Cu, Pb, V, and Zn. Among these elements, only Cd showed substantial bioaccessibility for plants, as documented by the high Risk Assessment Code, reaching up to 47%, and the highest plant-availability, where the maximum Bioaccumulation Factor in plants reached up to 4.5. The simulated body fluids showed the highest bioaccessibility of Cd, but also substantial bioaccessible pools of As and Be, the elements frequently found at the brown coal mining and processing areas. For better understanding of the risk element bioaccessibility under the specific conditions, the released element pools should be related to the particular soil physicochemical parameters.

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.

Chemical speciation, pollution and ecological risk of toxic metals in readily washed off road dust in a megacity (Nanjing), China

Pollution of potentially toxic metals (PTMs) in road dust (RD) is becoming an important threat to the urban environmental quality and human health. The chemical speciation of PTMs is an important index charactering the risks, which may also closely relate to the pollution level and source but it was poorly understood. In this study, the chemical speciation of Cd, Cr, Cu, Ni, Pb and Zn in the RD of a megacity (Nanjing), China was determined following an optimized BCR (proposed by the European Community Bureau of Reference) sequential extraction procedure to assess their pollution and potential eco-risk and to explore the variations of metal chemical speciation with the pollution levels and sources. Total concentrations of the PTMs in the RD were enriched 1.4- to 123-fold relative to the subsoil with median contamination factors (CF) of 6.7 (Pb), 6.0 (Cu), 5.5 (Cd), 4.0 (Zn), 2.0 (Cr) and 1.9 (Ni). Pollution of the PTMs should be mainly from industrial and traffic emissions and showed high CF values in the northern industrial zone. Whereas, the chemical percentages of each metal showed relatively narrow spatial variations and were not statistically correlated with the pollution levels (p = 0.05). Comparing of similar studies indicates that no regular patterns existed in chemical percentages for each metal in RD polluted by the traffic and/or both the industrial and traffic sources. In the RD of Nanjing, Pb was mostly associated with reducible phase, Cd and Zn were mainly present in acid-soluble phase, Cu was mostly concentrated in oxidizable phase, while Cr and Ni were predominantly present in residual phase. As the typical pollutants, anthropogenic Cd, Cu, Pb and Zn were mostly associated with the potential mobile phases but also with the residual phase in the RD of Nanjing, causing 1.4- to 3.0-fold increase in the mobility. Combining the assessments from eco-risk index, risk assessment code and sediment quality guidelines with the pollution levels and chemical speciation, we deduced that Cd, Cu, Pb and Zn may pose certain eco-risk upon transport into the aquatic system and soil, and Cd should be primarily concerned.

Winter chemical partitioning of metals bound to atmospheric fine particles in Dongguan, China, and its health risk assessment

To analyze the relationship between nanoparticles and the chemical forms in an urban atmospheric environment, metallic particles with different diameters were collected using a nanoparticle sampling system and analyzed for chemical and morphological characteristics, bioactivity, and the risk of carcinogenic and non-carcinogenic effects. The source of the atmospheric particles was analyzed based on the enrichment factor method, and the carcinogenicity of the atmospheric particles was analyzed using the health risk model. The partition contents of metals extractable by a weak acid, including As, Ca, Cd, Cs, Pb, Sr, and Zn, were in a range of 32.17-71.4%, with an average value of 47.07%. The content of oxides and reducible metals of all of the elements was generally low. Potassium was distributed mainly in the residual and weak-acid-extractable fractions. Barium had a high proportion of the oxidation state. Each fraction of Zn was basically the same, while the content of the weak-acid-extractable fraction was slightly higher. We found bio-access potential to be positively correlated with a high proportion of the weak acid extracts such as Mg, Sr, and Zn. We also found there to be a large weak-acid-extractable fraction (F1) and residual fraction (F4) and relatively enriched elements and strongly enriched elements, which means F1 and F4 may be the cause of enrichment. The hazard index (HI) and the total cancer risk (TCR) were far beyond the safety threshold when the diameter of the particle was in the range of 0.1-0.5 μm, indicating that the residents in Dongguan city were experiencing obvious non-carcinogenic and carcinogenic risks.

Predicting future contents of soil heavy metals and related health risks by combining the models of source apportionment, soil metal accumulation and industrial economic theory

Enriched and bio-refractory soil heavy metals (SHMs) originate from the underground mineral, which supplies energy and materials for the development of economy and industry. Investigating soil metal contents and their adverse health impacts is the principal concern associated metal contaminated industrial areas, including both current assessments and future projections. In this research, we create a novel spatiotemporal model of SHMs prediction and risk characterization for future by citing a rigorous theory of industrial economics, and time series of activity intensity changes of various pollution sources are forecasted. The dynamic change of source contributions is quantitatively resolved and the mean SHMs concentrations are estimated by classical formulas for heavy metal accumulation. Human health risk in the future is described in a manner of time series. The results of the case study show that contribution rates of the five sources of the six metals change continuously over time. Pb, Cd and As assume the highest growth rates (400%, 500% and 165%), while Zn, Ni, Cr possesses relatively lower growth (< 130%), compared to their corresponding background values. Health risk of local sensitive population (children) is estimated at exceeding threshold in 2022 (non-carcinogenic) and 2012 (carcinogenic), and the upward trend will continue. Traffic emission, agriculture and household garbage are identified as major risky sources in the coming decades at the studied area, and improvement measures are recommended. Although a degree of uncertainties exists, the overall tendency is a conservative bias for chemical risk. Additionally, this paper is the first to explore a methodology of predicting future SHMs and associated human health risk, based on industrial economics and temporal source apportionment.

Health risk assessment of heavy metals in soil samples from an abandoned industrial waste dumpsite in Ibadan, Nigeria

This study was carried out to determine the concentrations of heavy metals in the soil samples collected from an abandoned lead acid battery (LAB) industrial waste dumpsite in Ibadan, southwestern Nigeria. This was to assess the potential risks of the heavy metals on human due to exposure among local residents (children and adults) of the area. Forty (40) soil samples were collected over the entire dumpsite at 0-20 cm depth. The elemental concentrations of Pb, Cr, Cd, Zn, Cu, and Ni were measured using an atomic absorption spectrophotometer (AAS) technique. The contamination load was estimated by employing index of geoaccumulation (I_geo) and potential human health risks due to multiple exposure pathways (inhalation, dermal absorption, and ingestion) were estimated using the risk-based equations and exposure parameters developed by the United States Environmental Protection Agency (USEPA). The average concentrations (± standard deviation) of Pb, Cr, Cu, Mn, Cd, Ni, and Zn were 3.79 ± 2.16, 8.36 ± 3.90, 7.77 ± 2.70, 7.75 ± 3.10, 4.31 ± 0.82, 3.09 ± 2.29, and 3.07 ± 1.74 μg/g, respectively. The mean values of I_geo follow the order of Mn < Cr < Pb = Ni < Zn < Cu < Cd. The dermal contact with the heavy metals appeared to be the major route of exposure to children followed by inhalation and ingestion. Inhalation is the main route of exposure for the adults. The hazard quotients (HQ) of all the heavy metals are lower than 1, implying that the adverse health impact on the children and adult exposed to heavy metals from the dumpsite was relatively moderate. The hazard index (HI) values of Cd were 2.0 and 1.2 for exposed adults and children, respectively. The carcinogen risks for inhalation exposure ranged from 2.3 × 10^-6 to 6.4 × 10^-6, which falls within the acceptable limit of 10^-4 to 10^-6. There is concern over the potential health risk of the local residents, most especially the children living in the vicinity of the dumpsite due to the possibility of dispersal of heavy metals to the entire community, leading to long-life exposure and residents' detrimental health.

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.

In vitro bioaccessibility of potentially toxic metals (PTMs) in Baoji urban soil (NW China) from different functional areas and its implication for health risk assessment

In order to better understand both the conceptual and operational aspects of bioaccessibility and phytobioavailability of PTMs (Co, Cr, Cu, Li, Mn, Ni, Pb, Zn) in different urban soils, a total of 30 soil samples from agricultural region, entertainment district, education area, traffic area, residential area and industrial area (IA) in Baoji urban city (NW China) were collected and the bioaccessibility and phytobioavailability were measured by multi-in vitro models of PBET, SBET, citric acid leaching and Tessier sequential extraction procedure, respectively. The suitable in vitro measurement of bioaccessibility and phytobioavailability for each PTM was selected and would be reliably applied for health risk assessment. The results indicated that the bioaccessibility and phytobioavailability for each PTM evaluated by in vitro models depended on PTM total concentration and anthropologic activity influence. The health risks associated with bioaccessibility of PTMs exposure showed that the carcinogenic and non-carcinogenic risks in all areas for children and adults were below the threshold or acceptable risk levels except lead exposure on children in IA, indicating there were more health risks to the children in than that in other functional areas. It was worth that the highest observation of Pb in IA would strongly correlate with lead-acid battery industries, which the emissions would influence on the occurrences of Pb distributing in the other functional areas, which were supported from the analysis results of XPS. Therefore, the continuous monitoring and attention to the health risk of inhabitants in different functional areas should be paid.

Uncertainty analysis in source apportionment of heavy metals in road dust based on positive matrix factorization model and geographic information system

Based on 36 road dust samples from an urbanized area of Beijing in September 2016, the information about sources (types, proportions, and intensity in spatial) of heavy metals and uncertainties were analyzed using positive matrix factorization (PMF) model, bootstrap (BS), geographic information system (GIS) and Kriging. The mean concentration of most heavy metals was higher than the corresponding background, and mean concentration of Cd was six times of its background value. Types and proportions of four sources were identified: fuel combustion (33.64%), vehicle emission (25.46%), manufacture and use of metallic substances (22.63%), and use of pesticides, fertilizers, and medical devices (18.26%). The intensity of vehicle emission and the use of pesticides, fertilizers, and medical devices were more homogeneous in spatial (extents were 1.285 and 0.955), while intensity of fuel combustion and the manufacture and use of metallic substances varied largely (extents were 4.172 and 5.518). Uncertainty analysis contained three aspects: goodness of fit, bias and variability in the PMF solution, and impact of input data size. Goodness of fit was assessed by coefficient of determination (R²) of predicted and measured values, and R² of most species were higher than 0.56. Influenced by an outlier, R² of Ni decreased from 0.59 to 0.11. Result of bootstrap (BS) showed good robust of this four-factor configuration in PMF model, and contributions of base run of factors to most species were contained in the small interquartile range and close to median values of bootstrap. Size of input data also had influence on results of PMF model. Residuals changed largely with the increase of number of site, it varied at first and then kept stable after number of site reached 70.