Heavy metals in airborne particulate matter of urban Coimbatore

Common weeds as heavy metal bioindicators: a new approach in biomonitoring

Environmental pollution by heavy metals affects both urban and non-urban areas of Europe and the world. The use of bioindicator plants for the detection of these pollutants is a common practice. An important property of potential bioindicators is their easy availability and wide distribution range, which means that they can be practically used over a wide area. Therefore, common and widely distributed weeds: Trifolium pratense L., Rumex acetosa L., Amaranthus retroflexus L., Plantago lanceolata L., ornamental species Alcea rosea L., and Lolium multiflorum L. var. Ponto were selected as a potential bioindicators of heavy metals (Cd, Pb, Cu, Zn). Plants were exposed in the same soil conditions in three sample sites in the Poznań city. It was found that all species had heavy metal accumulation potential, especially A. rosea, P. lanceolata and L. multiflorum for Zn (BCF = 6.62; 5.17; 4.70) and A. rosea, P. lanceolata for Cd (BCF = 8.51; 6.94). Translocation of Cu and Zn was the most effective in T. pratense (TF_Cu = 2.55; TF_Zn = 2.67) and in A. retroflexus (TF_Cu = 1.50; TF_Zn = 2.23). Cd translocation was the most efficient in T. pratense (TF_Cd = 1.97), but PB was the most effective translocated in A. retroflexus (TF_Pb = 3.09).. Based on physiological response to stress, it was detected an increasing level of hydrogen peroxide (H₂O₂) in roots and leaves of all samples, with the highest in all organs of A. rosea. Enzymatic activity levels of CAT, APOX, and also the marker of polyunsaturated fatty acid peroxidation MDA, were higher after 6 weeks of exposure in comparison to control samples and varied in time of exposure and between species and exposure. After the experiment, in almost all samples we detected a reduction of chlorophyll content and relative water content, but in efficiency of photosynthesis parameters: net photosynthesis rate, intercellular CO₂ concentration and stomatal conductance, we noted increased values, which proved the relatively good condition of the plants. The examined weeds are good bioindicators of heavy metal contamination, and their combined use makes it possible to comprehensively detection of environmental threats.

Evidences of microplastics in aerosols and street dust: a case study of Varanasi City, India

Microplastics (MPs) are ubiquitous in our environment. Its presence in air, water, and soil makes it a serious threat to living organisms and has become a critical challenge across ecosystems. Present study aimed to assess the abundance of MPs in aerosols and street dust in Varanasi, a typical urban city in Northern India. Airborne particulates and street dust samples were collected from various sampling sites around Varanasi City. The physical identification of MPs was conducted by binocular microscopy, fluorescence microscopy, and scanning electron microscopy (SEM), while elemental analysis was made by energy-dispersive X-ray (EDX). Finally, Fourier-transform infrared spectroscopy (FTIR) was used for chemical characterization of MPs. Presence of MPs in both aerosols and street dust from all selected sampling sites was confirmed, however with varying magnitude. MPs of different colors having the shape of fragments, films, spherules, and fibers were recorded in the study while fragments (42%) in street dust and fibers (44%) dominated in aerosols. Majority of the MPs were < 1 mm in size and were primarily polypropylene, polystyrene, polyethylene, polyethylene terephthalate, polyester, and polyvinyl chloride types. The EDX spectra showed the presence of toxic inorganic contaminants like metallic elements on MPs, especially elements like aluminum, cadmium, magnesium, sodium, and silicon found to adsorb on the MPs. Presence of MPs in the airborne particulates and street dust in Varanasi is reported for the first time, thus initiating further research and call for a source-specific management plan to reduce its impact on human health and environment.

A statistic comparison of multi-element analysis of low atmospheric fine particles (PM2.5) using different spectroscopy techniques

Over the past few decades, the metal elements (MEs) in atmospheric particles have aroused great attention. Some well-established techniques have been used to measure particle-bound MEs. However, each method has its own advantages and disadvantages in terms of complexity, accuracy, and specific elements of interest. In this study, the performances of inductively coupled plasma-optical emission spectrometry (ICP-OES) and total reflection X-ray fluorescence spectroscopy (TXRF) were evaluated for quality control to analyze data accuracy and precision. The statistic methods (Deming regression and significance testing) were applied for intercomparison between ICP-OES and TXRF measurements for same low-loading PM_2.5 samples in Weizhou Island. The results from the replicate analysis of standard filters (SRM 2783) and field filters samples indicated that 10 MEs (K, Ca, V, Cr, Mn, Fe, Ni, Cu, Zn, and Pb) showed good accuracies and precision for both techniques. The higher accuracy tended to the higher precision in the MEs analysis process. In addition, the interlab comparisons illustrated that V and Mn all had good agreements between ICP-OES and TXRF. The measurements of K, Cu and Zn were more reliable by TXRF analysis for low-loading PM_2.5. ICP-OES was more accurate for the determinations for Ca, Cr, Ni and Pb, owing to the overlapping spectral lines and low sensitivity during TXRF analysis. The measurements of Fe, influenced by low-loading PM_2.5, were not able to determine which instrument could obtain more reliable results. These conclusions could provide reference information to choose suitable instrument for the determination of MEs in low-loading PM_2.5 samples.

Monitoring Air Quality with Transplanted Bryophytes in a Neotropical Andean City

Air pollution is one of the main global environmental problems, where bryophytes, due to their high capacity to retain metals and other pollutants, have been widely used in active air quality monitoring studies in temperate and tropical zones. Thus, in this study, we analyzed for the first time the concentrations of eight metals (cadmium, copper, nickel, aluminum, iron, manganese, lead and zinc) in three species of transplanted mosses (Rhacocarpus purpurascens (Brid.) Paris, Sphagnum sp. and Thuidium delicatulum (Hedw.) Schimp.) from Ecuador. Significant differences were found for the three species in the concentrations of Al, Mn, Fe and Zn between urban and control areas, pointing to the Central zone as the main source of contamination with the highest concentrations of Al, Fe, Mn and Zn, related to vehicular traffic. Lead did not differ between zones for Rhacocarpus purpurascens and Sphagnum sp.; however, Thuidium delicatulum accumulated different concentrations between urban areas and the control areas. The three species of mosses provided valuable information on the contamination of Al, Fe, Mn, Pb and Zn in the urban area of the city of Loja, and therefore can be used in future air quality monitoring programs over time in tropical cities.

Extremely high concentrations of zinc in birch tree leaves collected in Chelyabinsk, Russia

Zinc is an essential trace element and a vital microelement for human health. Zinc can be toxic when exposures exceed physiological needs. Toxic effects in humans are most evident from inhalation exposure to high concentrations of Zn compounds. Urban air pollution can be especially dangerous due to the Zn content in airborne dust. Tree leaves can absorb significant levels of zinc. In this study, leaf deposition of Zn was investigated in Chelyabinsk, Russia. Russian zinc production plant and metallurgical plant are located in Chelyabinsk. Extremely high concentrations of Zn (316-4000 mg kg^-1) were found in the leaves of birch trees. It is well known that traffic also is Zn source in an urban environment. Trees, growing at the different distances from zinc production and metallurgical plants and road to identify the contribution of each source (road or industry), were studied. Through SEM analysis, the prevalence of small particulates (PM10 and less), containing Zn, illustrated leaf Zn deposition from the air by passing root accumulation. It was shown that emission of zinc production plant and the metallurgical plant is the main source of leaf Zn deposition in Chelyabinsk.

Source Analysis and Human Health Risk Assessment Based on Entropy Weight Method Modification of PM2.5 Heavy Metal in an Industrial Area in the Northeast of China

In this study, PM2.5 was analyzed for heavy metals at two sites in industrial northeast China to determine their sources and human health risks during heating and non-heating periods. A positive matrix factorization (PMF) model determined sources, and US Environmental Protection Agency (USEPA) and entropy weight methods were used to assess human health risk. PM2.5 heavy metal concentrations were higher in the heating period than in the non-heating period. In the heating period, coal combustion (59.64%) was the primary heavy metal source at Huagong Hospitals, and the contribution rates of industrial emissions and traffic emissions were 21.06% and 19.30%, respectively. Industrial emissions (42.14%) were the primary source at Xinqu Park, and the contribution rates of coal combustion and traffic emissions were 34.03% and 23.83%, respectively. During the non-heating period, coal combustion (45.29%) and industrial emissions 45.29% and 44.59%, respectively, were the primary sources at Huagong Hospital, and the traffic emissions were 10.12%. Industrial emissions (43.64%) were the primary sources at Xinqu Park, where the coal combustion and traffic emissions were 25.35% and 31.00%, respectively. In the heating period, PM2.5 heavy metals at Xinqu Park had noncarcinogenic and carcinogenic risks, and the hazard index of children (5.74) was higher than that of adult males (5.28) and females (4.49). However, adult males and females had the highest lifetime carcinogenic risk (1.38 × 10−3 and 1.17 × 10−3) than children (3.00 × 10−4). The traditional USEPA and entropy weight methods both produced reasonable results. However, when there is a difference between the two methods, the entropy weight method is recommended to assess noncarcinogenic health risks.

Study on the Characteristics of Size-Segregated Particulate Water-Soluble Inorganic Ions and Potentially Toxic Metals during Wintertime in a High Population Residential Area in Beijing, China

Airborne particulate matter (PM) pollution often occurs in the wintertime in northern China, posing a potential threat to human health. To date, there are limited studies about the metals and inorganic ions to link source apportionments and health risk assessments in the different size-segregated PM samples. In this study, our samples were collected by a high-volume air sampler from 26 December 2018 to 11 January 2019 in a high population residential area (Beijing). Water-soluble inorganic ions, metal elements in the different size-segregated PM samples were determined for health risk assessments by inhalation of PM. During the sampling period in Beijing, the average concentrations of PM1.1 and PM1.1–2.0 were 39.67 ± 10.66 μg m−3 and 32.25 ± 6.78 μg m−3. Distinct distribution profiles characterized the different elements. The markers of coal combustion Pb, As, and Se had >52% of their mass concentration in PM1.1. The average mass ratios of (NO3− + NO2−)/SO42−, Cl−/Na+, Cl−/K+, and Cl−/(NO3− + NO2−) were 1.68, 6.58, 6.18, and 0.57, which showed that coal combustion and vehicle emissions were the main anthropogenic sources of PM in Beijing in winter. PM1.1 was the major contributor of Pb, Cd, and As for carcinogenic risks (CR) and hazard quotient (HQ). It was indicated that PM1.1 is more harmful than coarse PM. The toxic elements of Cr (VI) (1.12 × 10−6), V (0.69 × 10−6), and As (0.41 × 10−6) caused higher CR for children than Ni, Cd, Co, and Pb. Meanwhile, Pb (35.30 × 10−6) and Ni (21.07 × 10−6) caused higher CR for adults than As, Cr (VI), V, Co, and Cd, especially PM1.1. This study provides detailed composition data and the first report on human health in a high population residential area in Beijing.

Monitoring and evaluating the control effect of dust suppressant on heavy metals based on ecological and health risks: a case study of Beijing

Dust suppressant is widely applied to control the road dust pollution, while the unified statement on its control effect has not been obtained. To fill this gap, an experiment was conducted at four typical sites in Beijing, where dust suppressant and water were sprayed at test and control sites, respectively. Samples were collected to analyze the concentrations of PM_2.5, PM₁₀, and heavy metals. With the application of potential ecological risk index and probabilistic health risk assessment, the ecological and health risks of heavy metals were obtained. Results showed that compared with control sites, the total concentrations of heavy metals in PM₁₀ and PM_2.5 at test sites decreased by 1555.40 and 784.95 ng/m³ in 14 days, with the suppression rate of 11.95% and 12.06%. Especially, the total ecological risks of heavy metals in PM₁₀ reduced from 165.77 to 143.64, with their ecological hazard level changed from medium to slight. The carcinogenic risks of PM_2.5 and PM₁₀ reduced by 0.60E-05 and 1.52E-06, respectively. As for the non-carcinogenic risks, there were a reduction of 5.78% and 12.28% for PM_2.5 and PM₁₀, respectively. Notably, the ecological risk of Pb was the highest; Cr and Zn contributed the most to carcinogenic and non-carcinogenic risk. Finally, to mitigate road dust pollution from an integration perspective, some preventive measures were proposed.

Assessment of foliar dust deposition and elemental concentrations in foliar dust and long rows of grand tamarind leaves along two major roads of Coimbatore, India

In this study, the concentration of foliar dust and 23 elemental concentrations in foliar dust and foliar tissues were studied using long rows of grand tamarind trees grown in two major roads in Coimbatore, India. Twenty-four sampling sites were chosen and categorized as urban (n = 5), suburban (n = 14), and rural (n = 5) areas based on the local population. In the case of foliar dust concentration, a significant difference was noted between the sites of urban (range between 3.06 and 6.68 μ/cm²) and suburban areas (range between 0.56 and 5.75 μ/cm²) but not for rural areas (range between 0.40 and 0.47 μ/cm²). When comparing the urban, suburban, and rural, either significantly or insignificantly, 17 elements (Al, Ba, Bi, Ca, Cd, Co, Cu, Fe, Ga, In, K, Mg, Mn, Ni, Sr, and Zn) in urban and five elements (Ag, B, Cr, Na, and Pb) in suburban were higher. However, in the case of elements in tamarind laves, almost all elements except Na and K were higher in the urban area. Furthermore, the study results suggest that the elements in both foliage dust and in tamarind leaves are not evenly distributed between the sites of urban, suburban, and rural areas. This uneven distribution might be due to the construction being performed on a stretch of a four-lane highway during sampling, heavy transportation in three small junctions of suburban sites, and a rail over-bridge construction in one suburban site. However, comprehensive studies are needed to confirm this conclusion.

Ecotoxicology of Heavy Metal(loid)-Enriched Particulate Matter: Foliar Accumulation by Plants and Health Impacts

Atmospheric contamination by heavy metal-enriched particulate matter (metal-PM) is highly topical nowadays because of its high persistence and toxic nature. Metal-PMs are emitted to the atmosphere by various natural and anthropogenic activities, the latter being the major source. After being released into the atmosphere, metal-PM can travel over a long distance and can deposit on the buildings, water, soil, and plant canopy. In this way, these metal-PMs can contaminate different parts of the ecosystem. In addition, metal-PMs can be directly inhaled by humans and induce several health effects. Therefore, it is of great importance to understand the fate and behavior of these metal-PMs in the environment. In this review, we highlighted the atmospheric contamination by metal-PMs, possible sources, speciation, transport over a long distance, and deposition on soil, plants, and buildings. This review also describes the foliar deposition and uptake of metal-PMs by plants. Moreover, the inhalation of these metal-PMs by humans and the associated health risks have been critically discussed. Finally, the article proposed some key management strategies and future perspectives along with the summary of the entire review. The abovementioned facts about the biogeochemical behavior of metal-PMs in the ecosystem have been supported with well-summarized tables (total 14) and figures (4), which make this review article highly informative and useful for researchers, scientists, students, policymakers, and the organizations involved in development and management. It is proposed that management strategies should be developed and adapted to cope with atmospheric release and contamination of metal-PM.

Trends in ambient air pollution levels and PM2.5 chemical compositions in four Chinese cities from 1995 to 2017

An in-depth analysis of the specific evolution of air pollution in a given city can provide a better understanding of the chronic effects of air pollution on human health. In this study, we reported trends in ambient concentrations of particulate matter (PM) and gaseous pollutants [sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and ozone (O₃)] from 1995 to 2017 and PM_2.5 composition for the period of 2000–2017 in Guangzhou, Wuhan, Chongqing, and Lanzhou. We provided socio-economic indicators to help explain the pollution trends. SO₂ and PM (including PM₁₀ and PM_2.5) concentrations showed a downward trend in recent years with the most notable reduction in SO₂ in Chongqing and PM_2.5 in Guangzhou. There was an overall flat trend for NO₂, while O₃ showed an upward trend in recent years except in Lanzhou. The majority of PM_2.5 mass was SO₄²⁻ (6.0–30 µg/m³) and organic carbon (6.0–38 µg/m³), followed by NO₃⁻ (2.0–12 µg/m³), elemental carbon (2.1–12 µg/m³), NH₄⁺ (1.0–10 µg/m³), K⁺ (0.2–2.0 µg/m³), and Cl⁻ (0.2–1.9 µg/m³). Except for secondary inorganic aerosols in Wuhan, annual average concentrations of all PM_2.5 constituents showed a declining trend after 2013, corresponding to the trend of PM_2.5. The secondary sources in PM_2.5 were found to be most prominent in Wuhan, while the most abundant EC and Cl⁻ in Lanzhou was attributed to the use of coal. Despite temporal and spatial variabilities across the four cities, coal combustion, traffic emissions, and secondary pollution have been the major sources of PM_2.5 pollution. These trends in ambient air pollution levels and PM_2.5 composition may help understand changes in health outcomes measured at different times within the time period of 1995–2017 in the four cities.

Modelling air quality levels of regulated metals: limitations and challenges

Toxic metals as arsenic (As), cadmium (Cd), nickel (Ni), and lead (Pb) exist in the atmosphere as particulate matter components. Their concentration levels in the European Union (EU) are regulated by European legislation, which sets target and limit values as annual means, and by the World Health Organization (WHO) that defines guidelines and reference values for those metal elements. Modelling tools are recommended to support air quality assessment regarding the toxic metals; however, few studies have been performed and those assessments rely on discrete measurements or field campaigns. This study aims to evaluate the capability of air quality modelling tools to verify the legislation compliance concerning the atmospheric levels of toxic elements and to identify the main challenges and limitations of using a modelling assessment approach for regulatory purposes, as a complement to monitoring. The CAMx air quality model was adapted and applied over Porto and Lisbon urban regions in Portugal at 5 × 5-km2 and 1 × 1-km2 horizontal resolution for the year 2015, and the results were analysed and compared with the few measurements available in three locations. The comparison between modelled and measured data revealed an overestimation of the model, although annual averages are much lower than the regulated standards. The comparison of the 5-km and 1-km resolutions' results indicates that a higher resolution does not necessarily imply a better performance, pointing out uncertainties in emissions and the need to better describe the magnitude and spatial allocation of toxic metal emissions. This work highlighted that an increase of the spatial and temporal coverage of monitoring sites would allow to improve the model design, contribute to a better knowledge on toxic metals atmospheric emission sources and to increase the capacity of models to simulate atmospheric particulate species of health concern.

Particulate matter (PM10) induces cardiovascular developmental toxicity in zebrafish embryos and larvae via the ERS, Nrf2 and Wnt pathways

Particulate matter (PM10) is one of the most important indicators of the pollution that characterizes air quality. Epidemiological studies have shown that PM10 can cause cardiovascular-related diseases in the population. And, we studied the developmental toxicity of PM10 and the underlying mechanism of its effects on the cardiovascular system of zebrafish embryo/larva. Changes in cardiac morphology, sinus venosus and bulbus arteriosus (SV-BA) distance, heart rate, vascular subintestinalis, blood flow, returned blood volume, and reactive oxygen species (ROS) level were measured, and changes in the expression levels of certain genes were assessed via RT-PCR. The results showed that PM10 caused a significant increase in pericardial sac area and SV-BA distance, a decrease in heart rate, inhibition of vascular subintestinalis growth, blood flow obstruction, reduced venous return, and other cardiovascular toxicities. PM10 induced an increase in the ROS level and significant increases in the expression levels of ERS signalling pathway factors and Nrf2 signalling pathway factors. The expression levels of the Wnt pathway-related genes also showed significant changes. Furthermore, ROS inhibitor N-Acetyl-l-cysteine (NAC) could ameliorate the cardiovascular toxicity of PM10 in zebrafish larvae. It is speculated that PM10 may result in cardiovascular toxicity by inducing higher ROS levels in the body, which could then induce ERS and lead to defects in the expression of genes related to the Wnt signalling pathway. The Nrf2 signalling pathway was activated as a stress compensatory mechanism during the early stage of PM10-induced cardiovascular injury. However, it was insufficient to counteract the PM10-induced cardiovascular toxicity.

Exposure to respirable and fine dust particle over North-Central India: chemical characterization, source interpretation, and health risk analysis

This study enhances the understanding of the particulate matters (PM_2.5 and PM₁₀) and their physical and chemical behavior over the Taj Mahal, Agra, in North-Central India. The mass concentration was determined, and the shape and size of the particles and chemical characterizations have been carried out using SEM-EDX. The high level and significant variation of PM₁₀ (162.2 µg m^-3) and PM_2.5 (83.9 µg m^-3) were observed. The exceedance factor of the present study region is in critical and moderate condition. Morphological characterization reveals the particles of different shapes and sizes, while elemental analysis shows the presence of Si, Al, Fe, Ca, K, Cl, Mg, Na, Cu, and Zn. The dominance of Si indicated the contribution of natural sources, i.e., soil over this region. Three significant sources, viz. soil/road paved dust/vegetative emissions, vehicular/industrial emissions, and intermingling of dust and combustion particles, have been identified using principal component analysis over North-Central India. Health risk analysis of particulate matter identified carcinogenic and non-carcinogenic metals in the present study, which comes in contact with human beings during inhalation. The non-carcinogenic risk was much higher than the acceptable level. The high carcinogenic risks were found in Zn in PM₁₀ and Cu in PM_2.5 for both children and adults.

An Investigation into the Accumulation of Air Borne Trace Metals in the Lungs of Common Myna Acridotheres tristis and Bank Myna Acridotheres ginginianus Captured from Urban and Semi Urban Areas of Lahore and Pattoki, Pakistan

With increasing urbanization and industrialization, clean air is becoming a scarce resource. During the present investigation, concentrations of metals (Pb, Ni and Zn) in the atmosphere and their subsequent deposition in the lungs of two common avian species, common myna, Acridotheres tristis (n = 30) and bank myna, A. ginginianus (n = 20), captured from urban areas of Lahore city and semi-urban areas of Pattoki city 80 km away from main city of Lahore were determined. The obtained results were analyzed statistically using Independent sample t test and Pearson's correlation. A comparison of trace metal concentrations in air of both the cities was also carried out. Statistically, significant variations were recorded for Pb (t (7) = - 4.276, p = 0.001) while non-significant differences were observed for both Ni (t (7) = 0.049, p = 0.962) and Zn (t (7) = 1.555, p = 0.146).

Perspective of mitigating atmospheric heavy metal pollution: using mosses as biomonitoring and indicator organism

Mosses were proved as an ideal and reliable biomonitor as well as an indicator of atmospheric trace metal pollution. They are used as model indicator species of air pollution since long back due to their simple structure, genetic diversity, totipotency, rapid colony-forming ability, and high metal resistance behavior. Bryomonitoring technique is gradually being popularized as an economically viable procedure for estimating the degrees of environmental health and evaluating the toxic pollutants in biosphere. Thus, in the present scenario, many parts of the world use these organisms for monitoring the air pollution. This article describes an overview of the relationship of terrestrial mosses with trace metals with respect to their uptake, accumulation, and toxification as well as detoxification and tolerance mechanisms. The review article explicitly expresses the caliber of the cryptogamic mosses in establishing the pristine environment around the world. It also highlights the underpinning mechanisms and potential for future research directions. We have referred more than 250 articles, which deals with the assessment and impact of different heavy metals on 52 numbers of different moss species belongs to different climatic zones. The present review covers the research work in this area carried out worldwide since 1965.

Seasonal Levels, Sources, and Health Risks of Heavy Metals in Atmospheric PM2.5 from Four Functional Areas of Nanjing City, Eastern China

Aerosol pollution is a serious environmental issue, especially in China where there has been rapid urbanization. To identify the intra-annual and regional distributions of health risks and potential sources of heavy metals in atmospheric particles with an aerodynamic diameter less than or equal to 2.5 μm (PM2.5), this work collected monthly PM2.5 samples from urban, industrial, suburban, and rural areas in Nanjing city during 2016 and analyzed the heavy metal compositions (Cu, Pb, Cd, Co, V, Sr, Mn, Ti, and Sb). Enrichment factors (EFs) and principal component analysis (PCA) were applied to investigate the sources. The atmospheric PM2.5 pollution level was highest in the industrial area, followed by the urban and suburban areas, and was the lowest in the rural area. Seasonally, the concentrations of PM2.5 and associated heavy metals in spring and winter were higher than those in summer and autumn. Besides natural sources, heavy metal pollution in PM2.5 might come from metallurgical dust in the industrial area, while it mainly comes from automobile exhaust in urban and suburban areas. Health risk assessments revealed that noncancerous hazards of heavy metals in PM2.5 were low, while the lifetime cancer risks obviously exceeded the threshold. The airborne metal pollution in various functional areas of the city impacted human health differently.

Levels of trace elements in PM10 collected at roadsides of Addis Ababa, Ethiopia, and exposure risk assessment

Estimation of personal exposure to air pollution is needed to identify high-risk population and to develop mitigation strategies. In this study, an assessment of the potential effects of short-term exposure to PM₁₀ and the elements bound within PM₁₀ was conducted. Samples were obtained from the ten sub-cities of Addis Ababa (three sampling points from each) during the commuting time (traffic congestion and taxi queues). A particle counter consisting of a portable sampling unit with multi-fraction dust samplers was used for sample collection. The elemental composition was analyzed by inductively coupled plasma-optical emission spectroscopy (ICP-OES). The mean concentrations of PM₁₀ ranged from 206 to 308 μg m^-3. The highest concentrations of pollutants were found in the major open-market part of the city, Addis Ketema. The lowest concentrations were found at the old-town, Arada sub-cities. The concentration of trace elements (Fe, Cd, As, Cr, Pb, B, Ni, Co, Sn, Cu, and Zn) bound in PM₁₀ ranged from below detectable limit to 0.981 μg m^-3. Regardless of the sampling sub-city, the overall patterns of the mean concentration of elements bound in PM₁₀ were found in the following increasing order of Cr < Cd < As < Co < Ni < Cu < Fe < Pb < Sn < B < Zn < Mn. The results showed that the primary source of Zn, Cr, and Cd may be emissions from on-road vehicles, tire and brake wear. Pb originates mainly from industries and suspended soil dust at the roadside, whereas As, Mn, and B are associated with dust resuspension and biomass and biofuel combustion, respectively. The carcinogenic and non-carcinogenic risks due to chronic exposure to trace elements bound in PM₁₀ at the roadside were assessed in accordance with the U.S. Environmental Protection Agency (US EPA) guidelines. It was determined that Mn, As, and Cd contributed substantially to the inducement of non-carcinogenic health problems to children and adults as a result of exposure while in close proximity to the roadsides.

Microclimate simulation and model optimization of the effect of roadway green space on atmospheric particulate matter

Urban green spaces have the potential to mitigate and regulate atmospheric pollution. However, existing studies have primarily focused on the adsorption effect of different plants on atmospheric particulate matter (PM), whereas the effect of green space on PM has not been adequately addressed. In this study, the effect of different urban green space structures and configurations on PM was investigated through the 3D computational fluid dynamics (CFD) model ENVI-met by treating the green space as a whole based on field monitoring, and at the same time, the regulatory effect of green space on PM was examined by integrating information about the forest stand, PM concentration, and meteorological factors. The results show that the green space primarily affected wind speed but had no significant effect on relative humidity, temperature, or wind direction (P > 0.05). The PM concentration was significantly positively correlated with the relative humidity (P < 0.01), significantly negatively correlated with temperature (P < 0.05), but not significantly correlated with wind speed and direction (P > 0.05). Comparison with the measured values reveals that the ENVI-met model well reflected the differences in PM concentrations between different green spaces and the effect of green space on PM. In different green space structures, the uniform-type structure performed rather poorly at purifying PM, the concave-shaped structure performed the best, and the purifying effectiveness of the incremental-type and convex-shaped structure of green space was higher in the rear region than in the front region; in contrast, the degressional-type green space structure was prone to cause aggregation of the PM in the middle region. Broadleaf and broadleaf mixed forests had a better purifying effectiveness on PM than did coniferous forests, mixed coniferous forests, and coniferous broadleaf mixed forests. The above results are of great significance for urban planning and maximizing the use of urban green space resources.

Heavy metals and their source identification in particulate matter (PM2.5) in Isfahan City, Iran

The presence of heavy metals (HMs) in particulate matters (PMs) particularly fine particles such as PM_2.5 poses potential risk to the health of human being. The purpose of this study was to analyze the contents of HMs in PM_2.5 in the atmospheric monitoring stations in Isfahan city, Iran, in different seasons between March 2014 and March 2015 and their source identification using principle component analysis (PCA). The samples of PM_2.5 were taken using a high volume sampler in 7 monitoring stations located throughout the city and industrial zones since March 2014 to March 2015. The HMs content of the samples was measured using ICP-MS. The results showed that the concentrations of As, Cd and Ni were in a range of 23-36, 1-12, and 5-76ng/m³ at all the stations which exceeded the US-EPA standards. Furthermore, the concentrations of Cr and Cu reached to 153 and 167ng/m³ in some stations which were also higher than the standard levels. Depending on the potential sources of HMs, their concentration in PM_2.5 through the various seasons was different. PCA illustrated that the different potential sources of HMs in the atmosphere, showing that the most important sources of HMs originated from fossil fuel combustion, abrasion of vehicle tires, industrial activities (e.g., iron and steel industries) and dust storms. Management and control of air pollution of industrial plants and vehicles are suggested for decreasing the risk of the HMs in the region.

Chemical partitioning of fine particle-bound As, Cd, Cr, Ni, Co, Pb and assessment of associated cancer risk due to inhalation, ingestion and dermal exposure

The bioavailability and human health risks of As, Pb, Ni, Co, Cr and Cd in fine particulate matter (PM_2.5) at an urban site on a National highway in Agra, India were investigated. Inductively coupled plasma-optical emission spectrometer was used for metal analysis in sequentially extracted samples to ascertain the highly mobile, reducible, bioavailable and immobile fractions of the metals. Cancer risk resulting from inhalation, dermal and ingestion exposure to each metal in these fractions was calculated according to US EPA models. The average mass concentration of PM_2.5 was 87.16 ± 62.51 μg/m³. Cr, Ni and Pb were the most abundant metals. The results showed that Pb and Cr were higher in the mobile fraction. Cd and Co had high bioavailability. Ingestion is the major exposure pathway for all heavy metals except Cr to infants, children and adults followed by inhalation and dermal contact. The cumulative risk for Cr(VI) due to dermal and inhalation routes exceed the maximum acceptable limit for children of age 1-7 years, 8-15 years and adults when total concentration is considered, but the estimated risks are within the acceptable limit when the bioavailable, water soluble and mobile fraction are taken into account. Hence the study shows that children and adults living in the vicinity of this site are more susceptible, hence more attention should be paid to protect them from pollution hazards. The study indicates the importance of metal speciation in assessing associated human health risks.

Hydrocarbons and heavy metals in fine particulates in oil field air: possible impacts on production of natural silk

Analyses of fine particulates (PM2.5) from the upper Assam oil fields of India indicated considerable presence of higher hydrocarbons (C22-C35) and heavy metals, Cd, Co, Cr, Cu, Ni, Pb, and Zn. This has raised serious concern for the sustainability of the exotic Muga (Antheraea assama) silk production, which has been a prime activity of a large number of people living in the area. The Muga worm feeds on the leaves of Machilus bombycina plant, and the impacts of air quality on its survival were further investigated by analyzing the leaves of the plant, the plantation soil, and the Muga cocoons. PM2.5 content in the air was much more during the winter due to near calm conditions and high humidity. Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), and gas chromatography-mass spectrometer (GC-MS) analysis of PM2.5 showed the presence of higher alkanes (C22-C35) that could be traced to crude oil. Cr, Ni, and Zn were found in higher concentrations in PM2.5, M. bombycina leaves, and the plantation soil indicating a common origin. The winter has been the best period for production of the silk cocoons, and the unhealthy air during this period is likely to affect the production, which is already reflected in the declining yield of Muga cocoons from the area. SEM and protein analyses of the Muga silk fiber produced in the oil field area have exhibited the deteriorating quality of the silk. This is the first report from India on hydrocarbons and associated metals in PM2.5 collected from an oil field and on their possible effects on production of silk by A. assama.

Seasonal concentrations, contamination levels, and health risk assessment of arsenic and heavy metals in the suspended particulate matter from an urban household environment in a metropolitan city, Beijing, China

The levels and health risks of arsenic and heavy metals (As, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) in the suspended particulate matter (SPM) collected from an urban household environment in Beijing of China for 12 months were investigated. The mean concentrations of the studied toxic elements were higher and lower than crustal abundance and PM2.5 in the urban outdoors of Beijing. The concentrations of the studied elements displayed significant seasonality. The highest concentrations of the total elements occurred in winter, followed by autumn, while the lowest concentrations were recorded in summer. Based on the calculated values of enrichment factor (EF) and geoaccumulation index (Igeo), the levels for As and Cu were heavily contaminated, while those for Cd, Pb, and Zn were extremely contaminated. As and Pb might pose risks to children and adults via ingestion exposure. The accumulative risks of multi-elements resulted from dermal contact and inhalation exposures were not negligible. More attention should be paid to reducing the non-carcinogenic and carcinogenic health risks posed by the toxic elements bound to urban household SPM particles via ingestion, inhalation, and dermal contact exposure.

Biomonitoring of heavy metals in feathers of eleven common bird species in urban and rural environments of Tiruchirappalli, India

Heavy metals continue to remain as a major environmental concern in spite of emission control measures. In this study, we analyzed the concentrations of heavy metals (Fe, Cr, Mn, Ni, Cu, Zn, and Cd) in the feathers of 11 species of birds collected from urban and rural areas of Tiruchirappalli, Southern India. Metal concentrations followed the order: Fe > Cu > Zn > Cr > Mn > Ni > Cd. Irrespective of sample locations, heavy metals such as Fe, Cr, Ni, Zn, and Cu were detected in high concentrations, while Cd and Mn were observed in lower concentrations. In contrary to our assumption, there were no statistically significant intraspecific and urban-rural differences in the metal concentrations except for Zn. Pairwise comparisons among species irrespective of metal type showed significant interspecific differences between Acridotheres tristis and Centropus phasianinus, A. tristis and Milvus migrans, C. phasianinus and M. migrans, M. migrans and Eudynamys scolopaceus, and Psittacula krameri and E. scolopaceus. Principal component analysis carried out for urban data extracted Ni, Mn, Zn, Fe, and Cu accounting for 48% variance implying dietary intake and external contamination as important sources for metals. In the rural, association of Zn, Cd, Ni, and Cr suggests the impact of metal fabrication industries and leather tanning operations.

Outdoor air particle-bound trace metals in four selected communities in Ibadan, Nigeria

Trace metal concentrations were determined in particulate matter (PM10) in ambient air of four purposively selected residential areas in Ibadan, Nigeria namely Bodija market (BM), Ojo Park (OP), Oluyole Estate (OE) and University of Ibadan (UI). PM10 was determined in the morning (7-10 a.m.) and afternoon (2-5 p.m.) for 12 weeks in the dry season months of January-March using a volumetric sampler following standard procedures and levels compared with WHO guideline limits. Glass-fibre filter papers exposed to the particulate matter were digested using appropriate acid mixtures, and the digest analysed for trace metals including Ni, Cr, Mn, Zn, and Pb using ICPMS method and levels compared with WHO limits. Data was analysed using ANOVA and Pearson correlation test at 5 % level of significance. The highest mean PM10 concentrations 502.3 ± 39.9 μg/m(3) were recorded in the afternoon period at BM, while the lowest concentration 220.6 ± 69.9 μg/m(3) was observed in the morning hours at UI. There was a significant difference between the PM10 levels across the various locations (p < 0.05), and all the levels were higher than WHO limit of 50 μg/m(3). The highest levels of Ni, Zn and Pb were recorded at BM, which also had the highest PM10 burden. The trend in Pb levels across the locations was BM > UI > OP > OE with the highest level 5.70 μg/m(3) in BM nearly fourfolds WHO limits of 1.5 μg/m(3). There was a significant correlation between PM10 and Ni (p < 0.05).Urban communities with increased human activities especially motor traffic recorded both higher levels of PM10 and toxic trace metals. There is need to carry out source apportionment to establish the origin of these trace metals in future studies.

The Research Progress of Heavy Metals in PM2.5

PM2.5 is one of the most important components in air pollution. It is also the focus of the most closely watched at home and abroad. Based on its small size, complex components, and strongenvironmental activity, it can be used as a carrier for chemicals, heavy metals, bacteria, toxins and carcinogens into the body. Then, as a result, it will affect Human Body Health. Heavy metals are important components of PM2.5, and the long-term accumulation of heavy metals in PM2.5 poses a great threat on human health and the environment. This paper reviewed the sources, distribution methods,chemical form, detection methods, disposal way, research progress of heavy metals in PM2.5. As a result, it provided a reference for in-depth study on the future.

Temporal distribution of fine particulates (PM₂.₅:PM₁₀), potentially toxic metals, PAHs and Metal-bound carcinogenic risk in the population of Lucknow City, India

Ubiquitous fine particulates can readily be bound to toxic metals and polycyclic aromatic hydrocarbons and are considered to be a great threat to human health. The purpose of this study was to assess the magnitude of air pollution risks to public health by determining four crucial parameters- inhalable particulates, metals in particulates and PAHs which are associated with PM₁₀ in the air environment of Lucknow, India during 2007-09. The values of PM₁₀ and PM₂.₅ ranged between 102.3-240.5 and 28.0-196.9 μg/m³ whilst the average PM₁₀ was 1.7 times and PM was 1.5 times higher than their respective NAAQS of 100 and 60 μg/m³ respectively. The estimated relative death rate and hospital admissions for each increase in the PM₁₀ levels of 10 μg/m³ ranged from 1.5-8% and from 3.9-8.0% (as per APHEA2 1990) respectively in persons > 65 yrs. Among the locations; AQ, AQ and AQ (with diversified activities and heavy traffic) recorded higher concentrations of both the particulate fractions than the AQ (residential area with low traffic). The average concentrations of Fe, Pb, Ni, Cu, Cr, Cd in PM₁₀ were 219.4, 40.6, 35.1, 27.3, 22.2 and 16.2 ng/m³ and that in PM₂.₅ were 54.3, 33.9, 38.5, 29.4, 8.4, and 1.17 ng/m³ respectively Regression analysis revealed that correlation of metals with PM₂.₅ was stronger than PM. The ratio of metals adsorbed on surface of particles (PM₂.₅:PM₁₀) reveals that PM₂.₅ has more affinity for Ni, Cu and Pb and PM₁₀ for Cd, Fe and Cr. Health risk due to carcinogenic metals bound to respirable particulates was predicted by estimating excess cancer risk (ECR). The highest ECR value was estimated for Cr, 266.70 × 10⁻⁶, which was associated with PM10 and 100.92 × 10⁻⁶ which was associated with PM₂.₅, whereas lead has the lowest ECR value. Amongst PAHs, benzo(a)pyrene (51.96 ± 19.71 ng/m) was maximum in PM₁₀ samples. Maximum concentrations of PM₁₀, PM₂.₅, metals and PAHs were detected during winter, and the lowest was during monsoon. The higher prevalence of diseases among the population may be due to high concentration of particulates coated with toxic metals and PAHs present in air environment.

Polycyclic aromatic hydrocarbons bound to PM 2.5 in urban Coimbatore, India with emphasis on source apportionment

Coimbatore is one of the fast growing industrial cities of Southern India with an urban population of 1.9 million. This study attempts to evaluate the trends of airborne fine particulates (PM 2.5) and polyaromatic hydrocarbons (PAH) on them. The PM 2.5 mass was collected in polytetra fluoroethylene filters using fine particulate sampler at monthly intervals during March 2009 to February 2010. PAHs were extracted from PM 2.5 and estimated by high-performance liquid chromatography. It is alarming to note that PM 2.5 values ranged between 27.85 and 165.75 μg/m(3) and exceeded the air quality standards in many sampling events. The sum of 9 PAHs bound to PM 2.5 in a single sampling event ranged from 4.1 to 1632.3 ng/m(3). PAH diagnostic ratios and principal component analysis results revealed vehicular emissions and diesel-powered generators as predominant sources of PAH in Coimbatore.

Investigating Jacaranda mimosifolia tree as biomonitor of atmospheric trace metals

Studies on the use of tree bark as biomonitors for environmental pollutants are still very scarce. We evaluated the reliability of using Jacaranda mimosifolia, a common tree in Tshwane City of South Africa, as a suitable biomonitor of atmospheric trace metals. Bark samples were collected from ten different locations during two sampling periods. The concentrations of the metals were determined by inductively coupled plasma mass spectrometry. The concentrations of the metals were 33.2-1,795 microg/g (Pb), 21.4-210 microg/g (Cu), 68.4-490 microg/g (Zn), 30.6-2,916 microg/g (Cr), 0.12-1.34 microg/g (Cd), and 6.04-68.0 microg/g (V), respectively. The differences obtained for the results from different sites were significant (p < 0.05). A significant difference was also observed between the two sampling periods. The trace metals concentrations suggested that automobile emissions are a major source of these metals. The study also confirms the suitability of J. mimosifolia as a biomonitor of atmospheric deposition of these metals.

Levels, chemical composition and sources of fine aerosol particles (PM1) in an area of the Mediterranean basin

Daily samples of fine aerosol particles (i.e., PM1, aerosol particles with an aerodynamic diameter less than 1.0mum) were collected in Tito Scalo - Southern Italy - from April 2006 to March 2007. Measurements were performed by means of a low-volume gravimetric sampler, and each PM1 sample was analyzed by means of Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or Atomic Absorption Spectrometry (GFAAS and FAAS) techniques in order to determine its content in fourteen trace elements (Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Ti and Zn). During the period examined, PM1 daily concentrations ranged between 0.3microgm(-3) and 55microgm(-3) with a mean value of 8 microg m(-3), a standard deviation of 7microgm(-3) and a median value of 6microgm(-3). As far as PM1 chemical composition is concerned, the mean values of the trace element concentrations decreased in the following order: Ca>Fe>Al>Na>K>Cr>Mg>Pb>Ni approximately Ti approximately Zn>Cd approximately Cu>Mn. Principal Component Analysis (PCA) allowed the identification of three probable PM1 sources: industrial emissions, traffic and re-suspension of soil dust. Moreover, the results of a procedure applied to study the potential long-range transport contribution to PM1 chemical composition, showed that trace element concentrations do not seem to be affected by air mass origin and path. This was probably due to the strong impact of the local emission sources and the lack of the concentration measurements of some important elements and compounds that could better reveal the long-range transport influence on PM1 measurements at ground level.