Comprehensive study of lead pollution in Shanghai by multiple techniques

The Metabolomics Response of Solanum melongena L. Leaves to Various Forms of Pb

Due to activities like mining and smelting, lead (Pb) enters the atmosphere in various forms in coarse and fine particles. It enters plants mainly through leaves, and goes up the food chain. In this study, PbXn (nano-PbS, mic-PbO and PbCl2) was applied to eggplant (Solanum melongena L.) leaves, and 379 differential metabolites were identified and analyzed in eggplant leaves using liquid chromatography-mass spectrometry. Multivariate statistical analysis revealed that all three Pb treatments significantly altered the metabolite profile. Compared with nano-PbS, mic-PbO and PbCl2 induced more identical metabolite changes. However, the alterations in metabolites related to the TCA cycle and pyrimidine metabolism, such as succinic acid, citric acid and cytidine, were specific to PbCl2. The number of differential metabolites induced by mic-PbO and PbCl2 was three times that of nano-PbS, even though the amount of nano-PbS absorbed by leaves was ten times that of PbO and seven times that of PbCl2. This suggests that the metabolic response of eggplant leaves to Pb is influenced by both concentration and form. This study enhances the current understanding of plants' metabolic response to Pb, and demonstrates that the metabolomics map provides a more comprehensive view of a plant's response to specific metals.

Pollution revealed by stable lead isotopes in recent snow from the northern and central Tibetan Plateau

Lead (Pb) isotopes are less fractionated than those from different sources, and thus were used to trace the sources of Pb in the environment. To investigate the sources of Pb in the atmosphere of the Tibetan Plateau, stable Pb isotopes (206Pb, 207Pb and 208Pb) in acidified snow pit samples collected from five glaciers (i.e., Qiyi-QY, Meikuang-MK, Yuzhufeng-YZF, Hariqin-HRQ and Xiaodongkemadi-XDKMD) in May 2016 of the northern and central Tibetan Plateau were measured. The results showed narrow ranges of 1.158-1.187 for 206Pb/207Pb and 2.450-2.489 for 208Pb/207Pb respectively. The 206Pb/207Pb ratios in all samples were obviously lower than the environmental background value of 1.196, indicating the primary contributions of anthropogenic sources. At least 60% of Pb was contributed by various human activities, which was supported by the Pb isotopes in the snow pit samples from the QY, MK, YZF, HRQ and XDKMD glaciers. By comparing Pb isotope data, we found that the primary anthropogenic sources are coal combustion, mining and smelting activities in northwestern China and mixed emissions from cities located in western China and close to the glaciers. These sources contributed to the Pb in the northern glaciers (QY and MK) in particular. Coal combustion in India probably contributes to the central glaciers (HRQ and XDKMD). Another potential source could be parts of central Asia (e.g., Kyrgyzstan and Uzbekistan) through long range transport. The above potential source areas of contaminants were traced further by the air mass back-trajectory tracing method.

Lead pollution-related health of children in China: Disparity, challenge, and policy

Lead (Pb) is a neurotoxic metal, and no level of lead exposure is safe for children. China has still experienced problems on child lead poisoning even though the Chinese government has phased out leaded gasoline since 2000. The underlying problem affecting the lead pollution-related health of children in China remains to be comprehensively investigated. It is found that although the significant decline of BLLs, as the Geometric Mean (GM), from 91.40 μg/L^GM in 2001 to 37.52 μg/L^GM in 2018 is observed, the average BLLs of children are still above 50 μg/L or more [average 59.70 (60.50-65.02, 95 % CI) μg/L^GM] after phasing out leaded gasoline since 2000 in China. Lead exposure causes 29.67 MID per 1000 children with a loss of 98.23 (59.40-146.21, 95 % CI) DALYs per 1000 in China, which is greater than the levels reported from the Western Pacific Region and other low- and middle-income countries. A significant correlation is observed between the number of child crimes (NoCCs) and the outcomes of long-term lead exposure for children in China. Although the disparities in BLLs in China are strongly influenced by unequal distributions of potential multi-lead related sources (soil lead, PM2.5 lead, dust lead), unbalance development of local industrialization and economies, as well as incorrect health care for younger children, the notable emissions from coal combustion (CC) and non-ferrous metals (NMS) exploitation dominate the crucial sources of low-level lead exposure to children after phasing out leaded gasoline in China currently. Faced with the unequal and disparate distribution of BLLs in China, the big bottleneck is to decrease the BLLs exertions of 36-45 μg/L in the next few decades. The Chinese government needs to make more efforts on developing more strict guidelines, implementing more policy strategies on prevention and management of blood Pb poisoning, and monitoring the nationwide changes in children's BLLs continuously.

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

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

Slight transition in Chinese atmospheric Pb isotopic fingerprinting due to increasing foreign Pb

Atmospheric lead (Pb) pollution negatively affects human health and ecosystem, and extensive research is required to identify its sources and develop robust mitigation methods. In this study, the concentration and isotopic composition of Pb in fine particulate matter (PM_2.5) at five sites in the China's Beijing-Tianjin-Hebei (BTH) region were analyzed. The results showed that the Pb concentration in the BTH region declined along the northwest direction in winter owing to the East Asian monsoon. Pb isotopic signatures confirmed that anthropogenic activities significantly contributed to Pb pollution, compared with natural sources. With the increasing import of foreign Pb (with a relatively lower ²⁰⁸Pb/²⁰⁶Pb ratio) to China, we hypothesized that the unique isotopic signature of Pb in Chinese aerosols may decline over time. Therefore, the application of the isotopic approach for quantifying Pb transported from China should be carefully appraised in future research to provide a realistic estimate of the contribution of local sources and the transboundary effect consistent with air mass trajectories analysis. This study provides a theoretical reference for supporting the utilization of Δ²⁰⁸Pb values for better clarify the transboundary impact of Pb pollution and to reduce international disputes.

Source apportionment of soil heavy metals with PMF model and Pb isotopes in an intermountain basin of Tianshan Mountains, China

A boom in tourism may lead to the enrichment in heavy metals (HMs) in soils. Contamination with HMs poses a significant threat to the security of the soil environment. In this study, topsoil samples were collected from a tourist area of Sayram Lake, and the concentrations of HMs (Cr, Cu, Ni, Pb, Zn and Cd) were determined. With contamination and eco-risk assessment models, correlation analysis, Pb isotope ratios, redundancy analysis and positive matrix factorization (PMF) model, the risks and sources of HMs in the soil were studied. The I_geo results suggested that Cd was the primary pollutant in the tourist area of Sayram Lake. The potential ecological risk index (PERI) showed that the study area was at low risk, and the pollution load index (PLI) indicated that the study area had a moderate contamination level. Qualitative and quantitative analyses apportioned three sources of HMs, namely, natural sources (38.5%), traffic sources (27.2%) and mixed sources (tourist waste and atmospheric deposition) (34.3%). Redundancy analysis results showed that the HMs content was related to SiO₂, Al₂O₃, TiO₂, P₂O₅, MnO, K₂O, Fe₂O₃ and SOC, and heavy metals tended to be stored in soil particles of grain sizes < 32 µm. These findings are expected to provide useful insights into the source identification of HMs in the soils of mountain tourism areas and provide a scientific decision-making basis for sustainable tourism development and for the assessment of ecological service values in the Tianshan Mountains.

Metal(loid) concentrations, bioaccessibility and stable lead isotopes in soils and vegetables from urban community gardens

Community gardens are "green oases" of recent cities with many benefits for human society. From a human health perspective, these benefits can be damaged by chemical contamination of soil and cultivated vegetables. Using geochemical approaches, this study characterised (i) total metal(loid) concentrations in soils and two commonly grown vegetables in urban community gardens (Bratislava, Slovakia), (ii) gastrointestinal bioaccessibility using a modified physiologically based extraction test (PBET), and (iii) stable lead (Pb) isotopes in order to identify sources of metal(loid)s, solubilisation in the human body and migration of Pb from soil to vegetables. While some soils could be considered contaminated when compared to the Slovak legislation for agricultural soil, the bioaccessibility of metal(loid)s did not exceed 20% in the intestinal phase, with the exception of cadmium (Cd). Tomatoes and lettuce contained low total and bioaccessible concentrations of metal(loid)s, being safe for people who consume their own grown vegetables. There were differences in Pb isotope composition among bulk soils, vegetables and bioaccessible Pb, with less radiogenic Pb being preferentially mobilised. Statistical methods considering the compositional nature of the geochemical data and the enrichment factor (EF) distinguished well metal(loid)s of natural origin (As, Co, Cr, Fe, Mn, Ni, V) from those with anthropogenic contributions. This research has shown the usefulness of integrating different methodologies to better understand the geochemistry of metal(loid)s in urban soils with their highly diversified sources.

Co-Effects of Hydrological Conditions and Industrial Activities on the Distribution of Heavy Metal Pollution in Taipu River, China

In Taipu River, after being transformed from a drainage channel to a drinking water supply river in 1995, heavy metals that have accumulated in sediments have become an environmental issue. Herein, we collected sediments of Taipu River in 2018, 2020, and 2021 and analyzed the distribution of Sb, As, Cd, Cu, Pb, Cr, and Zn to identify their sources. The results revealed that the mean concentrations of heavy metals were above the background values, except for Cr and As. During the non-flood season, the midstream of Taipu River becomes a heavy metal hotspot, with their concentrations 2-5 times higher than those in upstream sediment. There were significant correlations (r = 0.79-0.99) among drainage, precipitation and flow rate, which indicated that drainage caused by both the opening of Taipu Gate and precipitation control the flow rate and, then, possibly influenced the distribution of heavy metals. Moreover, three sources (industrial sources, particle deposition sources, and natural sources) were characterized as the determinants for the accumulation of heavy metal by the Positive Matrix Factorization model, with the contribution rates of 41.7%, 32.9%, and 25.4%, respectively. It is recommended that the influence of hydrological conditions and industrial activities should be a key consideration when developing regulations for the management of heavy metals in rivers.

Record of heavy metals in Huguangyan Maar Lake sediments: Response to anthropogenic atmospheric pollution in Southern China

The historical atmospheric heavy metal pollution of southern China over the past 200 years was explored by analyzing radiometric dating, heavy metals, and Pb isotopes from a sediment core in Huguangyan Maar Lake. Zn, Cd, Sb, Tl, and Pb in the lake are closely related to anthropogenic activities, while Cr and Ni are mainly derived from the weathering of basalt surrounding the lake. Atmospheric Zn, Cd, Sb, and Tl increased rapidly after 1980, consistent with the local industrial development. The increase of atmospheric Pb in southern China occurred earlier than in other regions of China, with the increase after 1850. War and the use of leaded gasoline were the main causes for the rapid increase in atmospheric Pb during 1910-1950. From 1950 to 2000, the input of Pb from anthropogenic activities decreased gradually due to the stable social environment. After 2000, atmospheric Pb continued to rise due to continued industrial development. The three-end-member model of Pb isotopes indicates that coal combustion is the main source of current atmospheric Pb. The proportion of Pb derived from vehicle exhaust emissions reached a peak in the 1960s, then gradually decreased and further reduced with the ban on leaded gasoline after 2000. These results are important in identifying the sources of atmospheric heavy metal pollution and in formulating pollution control strategies.

Characteristics and sources of Pb exposure via household dust from the urban area of Shanghai, China

Household dust has been considered as an important pathway for children's environmental Pb exposure. Shanghai was one of the first cities in China that removed Pb from petrol and has been shown in our previous study to have the lowest childhood blood Pb levels in China. This study therefore examines household dust Pb (Pb^HD) in Shanghai in order to determine the extent and exposure risks of Pb^HD. Household vacuum cleaner dust samples (n = 40) were collected and analyzed for total Pb concentration, bio-accessible Pb concentration and Pb isotopic compositions (Pb^IC). The mean concentration of Pb^HD was 195 mg/kg, which is between 7 and 10 times the Pb concentration of background soil samples from Shanghai. Among the investigated homes, those living in neighborhoods with lower average estate prices have higher dust Pb exposure risks for children. Bio-accessibility of Pb in household dust ranged between 53 and 91%, with a mean value of 71%. Analysis of Pb^IC of household dust samples (²⁰⁸Pb/²⁰⁶Pb: 2.1096 ± 0.0054; ²⁰⁷Pb/²⁰⁶Pb: 0.8648 ± 0.0025) are a close match to Pb^IC of coal combustion and solid waste incineration and fit well with those of outdoor air Pb^IC and urban surface soil Pb^IC of Shanghai. The study shows that children living in Shanghai are subject to Pb^HD exposure, with children living in the homes with lower average price having increased susceptibility to Pb^HD exposure. The data indicate that Pb^HD is derived primarily from contemporary coal combustion and solid waste incineration rather than common legacy Pb sources (e.g., Pb petrol and paint). Practices including closing doors and windows on days with poor air quality or high wind and preventing shoe wearing inside homes will aid in minimizing outdoor surface soil and ambient particulate intrusion indoors.

Study on the risk of soil heavy metal pollution in typical developed cities in eastern China

Enrichment of heavy metals in urban soils has become a major regional environmental risk. At present, research on the soil heavy metals in cities lacks risk spatial correlation analyses between different heavy metals, and there is a relative lack of assessments of the ecological and health risks. We selected Wuxi, a typical developed city of eastern China, collected and tested the contents of heavy metals in the urban soils of Wuxi in May 2020. Combined with Pb isotope analysis, ecological and health risk assessment, we found that the high heavy metal concentrations in Wuxi are mainly located in the central and western regions, and that the changes in spatial fluctuation are relatively small. The Pb isotopes in the urban soils of Wuxi are distributed in areas, such as those are related to coal combustion, automobile exhaust and urban garbage, indicating that the heavy metals in the urban soils of Wuxi are affected by human activities such as coal combustion and automobile exhaust. The average value of the potential ecological risk index of soil heavy metal Cd is 80.3 (the threshold: 40), which represents a high-risk state. Whether adults or children, the risk of soil heavy metals via ingestion is much higher than that through skin exposure. High health risk values are present in the central area of Wuxi and decrease in a ring-shaped pattern, which is similar to the population distribution of Wuxi and greatly increases the potential risk from soil heavy metals, which should be given close attention. We should develop and use clean energy to replace petroleum fossil fuels, especially in densely populated areas. This study provides technical support for the prevention and control of urban heavy metal pollution.

Concentrations and isotopic analysis for the sources and transfer of lead in an urban atmosphere-plant-soil system

Lead pollution has attracted significant attention over the years. However, research on the transfer of lead between urban atmospheric particles, soils, and plants remains rare. We measured lead concentrations and lead isotope ratios in total suspended particles (TSP), soil, and plants in an urban wetland in Beijing. The study period was September 2016-August 2017- covering all four seasons. The concentrations of lead in the atmospheric particles vary from 3.13 to 6.68 mg/m3. It is significantly higher in autumn than that in spring and summer (P < 0.05). There is also a significant difference between summer and winter (P < 0.05). The soil lead concentrations range from 57 to 114 mg/kg, with the highest concentration in spring, followed by summer, winter and autumn. The lead concentrations are 1.28-7.75 mg/kg in plants. The concentration was highest in spring and significantly higher than in summer. The bioaccumulation factor of Phragmites australis was 0.064 (<0.1), indicating that lead is not easily transferred to plants. Unlike the bioaccumulation factors, translocation factors have much higher values, indicating a higher transfer within the plants. Results also indicate an interesting seasonal pattern with almost 97% of lead in plants during spring being of atmospheric origin, whereas in autumn, soilborne sources contribute almost 94%. The isotopic compositions of lead in the urban atmosphere-soil-plant system show that lead pollution results from the mixing of geogenic and anthropogenic materials. Vehicle exhaust, crustal rocks and ore deposits are likely primary sources of lead pollution within the study domain.

Temporal and spatial changes of Pb in soils in Cuihu wetland, Beijing, China

Protecting soil from Pb contamination has been a programme for a long time in China. However, research on lead pollution in wetlands remains rare. To understand the characteristics of Pb pollution in Beijing and the sources of contamination of different soil samples in wetlands, we collected samples during all four seasons from two soil horizons and analyzed their Pb concentrations and Pb isotope ratios. The average concentrations of Pb varied from 65.44 mg/kg in spring to 106.11 mg/kg in winter. Concentrations in autumn were significantly lower than those in spring and summer and were notably different between A and B Horizons (59.42 and 71.47 mg/kg, respectively). The Pb isotopic compositions show that Pb pollution results from a mixing of geogenic and anthropogenic materials. The ratios of ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁶Pb/²⁰⁸Pb evidenced that coal combustion and vehicle exhaust are the main sources of lead contamination in the two horizons. These results will help in reducing lead contamination in soil by knowing the temporal and spatial variations and sources of lead in Beijing.

Mechanism of Pb accumulation in Chinese cabbage leaves: Stomata and trichomes regulate foliar uptake of Pb in atmospheric PM2.5

Chinese cabbage (Brassica rapa ssp. pekinensis) is one of the most popular and frequently consumed leafy vegetables. It was found that atmospheric PM_2.5-Pb contributes to Pb accumulation in the edible leaves of Chinese cabbage via stomata in North China during haze seasons with high concentrations of fine particulate matter in autumn and winter. However, it is unclear whether both stomata and trichomes co-regulate foliar transfer of PM_2.5-Pb from atmospheric deposition to the leaf of Chinese cabbage genotypes with trichomes. Field and hydroponic experiments were conducted to investigate the effects of foliar uptake of PM_2.5-Pb on Pb accumulation in leaves using two genotypes of Chinese cabbage, one without trichomes and one with trichomes. It was verified that open stoma is a prominent pathway of foliar PM_2.5-Pb transfer in the short-term exposure for 6 h, contributing 74.5% of Pb accumulation in leaves, whereas Pb concentrations in the leaves of with-trichome genotype in the rosette stage were 6.52- and 1.04-fold higher than that of without-trichome genotype in greenhouse and open field, respectively, which suggests that stomata and trichomes co-regulate foliar Pb uptake of from atmospheric PM_2.5. Moreover, subcellular Pb in the leaves was distributed in the following order of cytoplasm (53.8%) > cell wall (38.5%)> organelle (7.8%), as confirmed through high-resolution secondary ion mass spectrometry (NanoSIMS). The Leadmium™ Green AM dye manifested that Pb in PM_2.5 entered cellular space of trichomes and accumulated in the basal compartment, enhancing foliar Pb uptake in the edible leaves of cabbage. The results of these experiments are evidence that both stomata and trichomes are important pathways in the regulation of foliar Pb uptake and translocation in Chinese cabbage.

Continental-scale spatial distribution, sources, and health risks of heavy metals in seafood: challenge for the water-food-energy nexus sustainability in coastal regions?

Rare information on the seafood safety and the coastal water-food-energy nexus sustainability in terms of seafood safety is available. This study investigated the distribution of heavy metals in 3 kinds of seafood (bivalve molluscs, fish, and crustaceans) collected from coastal areas along the 18,000 km coastline of China. Risk assessment and source apportionment of heavy metals, and the coastal water-food-energy nexus sustainability in terms of heavy metal pollution were also performed. The results showed that total concentrations of 8 heavy metals (Cu, Pb, Zn, Cd, Cr, Hg, As, and Ni) in seafood varied with sampling sites and species by following the order of bivalve molluscs > crustaceans > fish. Estimated daily intake (EDI) analysis indicated that it was safe for humans to consume seafood in all sampling sites. Non-cancer risks posed by heavy metals were acceptable for 99.1% of adult and 97.7% of children. However, Cr and As in 72% of fish samples caused high cancer risks for children. The farmed fish posed relatively low risk in comparison with the wild fish suggested that it might be safer to consume farmed fish than wild fish. Source apportionment demonstrated that the fossil energy consumption (coal combustion and vehicle exhaust), seawater, and metallurgic dust might serve as the possible main sources of heavy metals in seafood. Based on the policy scenario analysis, the fossil-energy-controlling policy and clean coastal water action were beneficial to the seafood safety by reducing target heavy metals in seafood. These findings provided comprehensive information on seafood safety and the water-food-energy nexus sustainability in coastal regions at continental-scale in terms of heavy metal pollution.

Temporal and spatial distributions and sources of heavy metals in atmospheric deposition in western Taihu Lake, China

Heavy metals in atmospheric dust can directly pollute the soil, water and sediment, causing serious harm to human health. In this study, the temporal and spatial distribution characteristics of heavy metals in atmospheric deposition in western Taihu Lake were studied. We established 10 sampling sites to collect atmospheric deposition for two years in different seasons. The atmospheric deposition flux follows the order urban area (95.6 g m^-2·a^-1) > suburban area (80.2 g m^-2·a^-1) > forestland (56.8 g m^-2·a^-1). The concentrations of heavy metals in atmospheric deposition show trends of high values in the winter and low values in the summer and are significantly negatively correlated with distance from the city. The pollution level of I_geo-Cd is 6, which is very high, and that of E-Cd is 219, which means high risk. Heavy metals in atmospheric deposition are mainly taken up via hand-mouth intake, and the harm to children is significantly higher than the harm to adults. The highest health risk assessment values for the four analyzed heavy metals in atmospheric deposition are located near the city and in suburbs (within 5 km of the city center), that is, in areas where human activities are concentrated. The health risk assessment values in areas outside the suburbs are low; these areas are less affected by human activities. The health risk assessment values of heavy metals in the winter and spring are higher than those in the summer and autumn. The Pb isotope ratios show that the main sources of heavy metals in atmospheric deposition and local soil are human activities, such as industry and coal combustion, with less input from natural sources. Heavy metals in atmospheric deposition in the western part of Taihu Lake not only directly threaten local human health but also enter Taihu Lake, posing a serious threat to the Taihu Lake ecosystem.

Atmospheric lead pollution in a typical megacity: Evidence from lead isotopes

Atmospheric lead (Pb) pollution has adverse health effects on humans, while the sources and atmospheric process of Pb are key scientific problems. In this study, the concentrations and isotopic composition of Pb in fine particulate matter (PM_2.5), coal and street dust samples collected from a typical megacity Beijing were analyzed to identify the sources of atmospheric Pb. Results showed that the Pb concentrations in PM_2.5 were high in winter (168.1 ± 32.0 ng/m³) and low in summer (27.7 ± 9.1 ng/m³), whereas Pb isotopic values presented opposite variation trends. The abnormally elevated Pb concentrations in winter were probably related to coal combustion, while declined Pb concentration in summer may be attributed to favorable meteorological parameters such as high temperature, high wind speed, and frequent rain events. Pb isotopic ratios indicated that anthropogenic sources (coal combustion and vehicle exhaust) and natural sources were the main contributors to Pb in PM_2.5. Combined with the binary model, the anthropogenic sources predominantly contributed to Pb in the Beijing atmosphere by approximately 85% annually, while the natural sources accounted for the rest of 15%. More specifically, the contribution of natural sources was about 9.4% in spring, 29.7% in summer, 16.0% in autumn and 6.1% in winter, suggesting that natural sources might contribute more lead into the atmosphere during clear days. Furthermore, the contribution of the vehicle exhaust to atmospheric Pb was nonnegligible in megacity, highlighting that the ownership of motor vehicles in megacity should be regulated and more efforts should be paid to strengthen vehicle emission standard. This study may enrich the reservoir of Pb isotopic composition in nature and provides a new method to investigate the Pb migration and transformation in the environment, and also serve as a theoretical reference for pollution control measures.

Blood lead levels and their associated risk factors in Chinese adults from 1980 to 2018

In China, studies on lead exposure to grownup are scarce compared to children, although relevant disease burdens for adults are much severe than that in developed countries. The present study evaluated blood lead levels (BLLs) in Chinese adults by data mining using Monte Carlo simulation. A total of 115 scientific studies published between January 1980 and March 2021 reflecting 45,514 Chinese adults were included in the study. After a continuous increase in Chinese adult BLLs from 1980-1983 (GM 74.84 μg/L) to 1994-1996 (GM 92.27 μg/L), BLLs began to decline from 2000--2002 (GM 80.32 μg/L) to 2016-2018 (GM 21.57 μg/L). This decline implied that the lead phase-out policy in gasoline was effective over the past two decades. The study indicated that North, South, and Southwest China were still relatively high compared to other regions in the past decade. Statistical analysis showed that BLLs of males (GM 68.45 μg/L) were higher than females (GM 56.51 μg/L), smokers (GM 80.96 μg/L) higher than nonsmokers (GM 58.95 μg/L), and populations over 40 (GM 40.43 μg/L) higher than younger populations (GM 40.37 μg/L). The significantly positive correlation between the concentrations of PM2.5 and topsoil lead and BLLs in Chinese adults indicated that air and soil pollution affect adult BLLs. Taken together, our results showed that strict lead control strategies and regular bio-monitoring are needed to maintain low BLLs in the population.

In vitro assessments of bioaccessibility and bioavailability of PM2.5 trace metals in respiratory and digestive systems and their oxidative potential

Air pollution is a serious environmental issue. As a key aerosol component, PM_2.5 associated toxic trace metals pose significant health risks by inhalation and ingestion, but the evidences and mechanisms were insufficient and not well understood just by their total environmental concentrations. To accurately assess the potential risks of airborne metals, a series of in vitro physiologically based tests with synthetic human lung and gastrointestinal fluids were conducted to assess both the bioaccessibility and bioavailability of various PM_2.5 bound metals in the respiratory and digestive systems from both urban and industrial areas of Nanjing city. Moreover, the chemical acellular toxicity test [dithiothreitol (DTT) assay] and source analysis were performed. Generally, the bioaccessibility and bioavailability of investigated metals were element and body fluid dependent. Source oriented metals in PM_2.5 showed diverse bioaccessibility in different human organs. The PM_2.5 induced oxidative potential was mainly contributed by the bioaccessible/bioavailable transition metals such as Fe, Ni and Co from metallurgic dust and traffic emission. Future researches on the toxicological mechanisms of airborne metals incorporating the bioaccessibility, bioavailability and toxicity tests are directions.

Tracing local sources and long-range transport of PM10 in central Taiwan by using chemical characteristics and Pb isotope ratios

Central Taiwan is among the most heavily polluted regions in Taiwan because of a complex mixing of local emissions from intense anthropogenic activities with natural dust. Long-range transport (LRT) of pollutants from outside Taiwan also contributes critically to the deterioration of air quality, especially during the northeast monsoon season. To identify the sources of particulate matter < 10 μm (PM10) in central Taiwan, this study performed several sampling campaigns, including three local events, one LRT event, and one dust storm event, during the northeast monsoon season of 2018/2019. The PM10 samples were analyzed for water-soluble ion and trace metal concentrations as well as Pb isotope ratios. Local sediments were also collected and analyzed to constrain chemical/isotopic signatures of natural sources. The Pb isotope data were interpreted together with the enrichment factors and elemental ratios of trace metals in PM10, and reanalysis data sets were used to delineate the sources of PM10 in central Taiwan. Our results suggested that Pb in PM10 was predominantly contributed by oil combustion and oil refineries during the local events (48-88%), whereas the lowest contributions were from coal combustion (< 21%). During periods of high wind speed, the contribution from natural sources increased significantly from 13 to 31%. Despite Pb represented only a small portion of PM10, a strong correlation (r = 0.89, p  < 0.001, multiple regression analysis) between PM10 mass and the concentrations of Pb, V, and Al was observed in the study area, suggesting that the sources of PM10 in central Taiwan can be possibly tracked by using chemical characteristics and Pb isotopes in PM10. Moreover, the Pb isotopic signals of PM10 collected during the LRT event confirmed the impact of LRT from Mainland China, and the chemical characteristics of the PM10 significantly differed from those of the PM10 collected during local events. This study demonstrates the robustness of using a combination of Pb isotopic compositions and chemical characteristics in PM10 for source tracing in complex and heavily polluted areas.

Concentrations of selected trace elements in surface soils near crossroads in the city of Bratislava (the Slovak Republic)

It is well known that road transport emits various trace elements into the environment, which are deposited in soils in the vicinity of roads, so-called roadside soils, and thus contributes to the deterioration of their chemical state. The aim of this work was to determine concentrations of some metals and metalloids (arsenic (As), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), antimony (Sb), vanadium (V), and zinc (Zn)) in soils from crossroads with traffic signals, which are characterized by deceleration of vehicles and increased emissions of elements related mainly to brake and tyre wear. The results confirmed a moderate enrichment of soils with Cu, Pb, and Zn (enrichment factor (EF) values > 2) and significant enrichment for Sb (EF > 5), while the other elements showed no or minimal enrichment. The age of crossroads proved to have a positive influence on the accumulation of some elements in soils with the largest differences for Cu, Fe, Pb, Sb, and Zn (p < 0.001). Traffic volumes expressed as the average daily traffic intensity (ADTI) also positively influenced soil concentrations of Cr, Cu, Pb, Sb, and Zn, while distance to the crossroad had a significant negative effect on the soil concentration of Cu, Sb, and Zn (p < 0.001). The stable isotopic ratios of Pb, ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁶Pb, ranging from 1.1414 to 1.2046 and from 2.0375 to 2.1246, respectively, pointed to the mixed natural-anthropic origin of Pb in the soils of crossroads with a visible contribution of traffic-related sources. Based on the above findings combined with covariance among the studied elements using statistical methods applied to compositionally transformed data, it was possible to show that Cu, Pb, Sb, and Zn clearly originated from road traffic.

Naturally growing grimmiaceae family mosses as passive biomonitors of heavy metals pollution in urban-industrial atmospheres from the Bilbao Metropolitan area

In analytical chemistry, biomonitoring is known as the methodology, which consider the use of living organisms to monitor and assess the impact of different contaminants in a known area. This type of monitoring is a relatively inexpensive method and easy to implement, being a viable alternative to be developed in sites where there is no infrastructure/instruments for a convenctional air quality monitoring. These organisms, having the capability to monitor the pollution, are also known as passive biomonitors (PBs), since they are able to identify possible contamination sources without the need of any additional tool. In this work, a multianalytical methodology was applied to verify the usefulness of naturally growing Grimmia genus mosses as PBs of atmospheric heavy metals pollution. Once mosses were identified according to their morphology and taxonomy, thei ability to accumulate particulate matter (PM) was determined by SEM. EDS coupled to SEM also allowed to identify the main metallic particles deposited and finally, an acid digestion of the mosses and a subsequent ICP-MS study define more precisely the levels of metals accumulated on each collected moss. The study was focused on six sampling locations from the Bilbao Metropolitan area (Biscay, Basque Country, north of Spain). The experimental evidences obtained allowed to propose naturally growing Grimmia genus as PB of atmospheric heavy metals pollution and to identify the anthropogenic sources that contribute to the emission of the airborne particulate matter rich in metals, evaluating in this sense the atmospheric heavy metals pollution of the selected locations.

Metallic elements and Pb isotopes in PM2.5 in three Chinese typical megacities: spatial distribution and source apportionment

Heavy metal pollution in fine particulate matter (PM_2.5) is a serious environmental and health concern in China, particularly during winter. Here, we detected 40 elements in 24 h integrated daily PM_2.5 samples collected in January 2014 from three typical Chinese metropolises (Beijing, Changchun, and Chengdu) to reflect elemental spatial variations, local sources, and regional transport. The measured elemental concentrations in Changchun were 11.1% and 48.4% higher than those in Beijing and Chengdu, respectively. Thus, PM_2.5 from Changchun exhibited high levels and diversity in the elemental profile (characterized by high concentrations of industrial emission elemental markers). The results of elemental ratios and Pb isotopes proved that, except for a coal combustion source, vehicular emissions contributed more to PM_2.5 heavy metals in Beijing than in the other two cities; Changchun PM_2.5 elements received large contributions from industrial sources, including iron and steel manufacturing, and automobile industry. Moreover, crustal dust from long-range transport of regional air masses from the northwest regions of China played a crucial role in determining elemental levels in Beijing and Changchun, accounting for more than 50% of source intensity. However, a specific dominant source was not determined in Chengdu; the contribution of anthropogenic dust, mainly from construction activities, needs to be paid attention in Chengdu eastern area. This study contributed to enhancing our understanding of elemental spatial distribution characteristics and sources and to setting more judicious standards and strategies for PM_2.5 bound heavy metals in China.

Metal(loid) and isotopic tracing of Pb in soils, road and house dusts from the industrial area of Volos (central Greece)

This study examines the metal(loid) contents (As, Cd, Cr, Cu, Mn, Ni, Pb, Sb, Tl and Zn) and Pb isotopes in different environmental compartments (soil, road dust, house dust) from the industrial vicinity of Volos, central Greece. The area surrounding two steel factories, a cement plant, an industrial area and the city core were considered as potential hot spots of metal(loid) contamination. Significant anthropogenic enrichments of Cd, Pb and Zn in relation to local baseline were identified for the soil (median Enrichment Factors of 7, 15 and 8, respectively) and road dusts around the steel factory located at Velestino area. The high contents of As, Sb and Tl in the soil and road dust around the cement plant are attributed to natural sources of contamination associated with adjacent mineralization. The soil samples in the city core exhibited moderate enrichments with respect to typical tracers (Pb, Zn) of anthropogenic contamination in urban areas. Anthropogenic influences in terms of metal(loid) concentrations were more pronounced for the road and house dust material. The Pb isotopic ratios of soil (²⁰⁶Pb/²⁰⁷Pb = 1.154 to 1.194), road dust (²⁰⁶Pb/²⁰⁷Pb = 1.144 to 1.174) and house dust (²⁰⁶Pb/²⁰⁷Pb = 1.129 to 1.171) were between those of the local bedrock and anthropogenic Pb sources. Industrial Pb from the steel plant was the predominant anthropogenic Pb source with relative contributions of ~49% for the soil, ~42% for the road dust and ~44% for the house dust samples. For the road and house dust material, the geochemical signature obtained from Pb isotopic compositions and elemental ratios suggests additional contributors from vehicular emissions. The results of this study demonstrate the suitability of soil to trace natural and anthropogenic impacts in industrial areas and the sensitivity of the road and house dust material to record anthropogenic (industrial and vehicular-derived) contamination in such environments.

A comprehensive review of biogeochemical distribution and fractionation of lead isotopes for source tracing in distinct interactive environmental compartments

Lead (Pb) is a non-essential and extremely noxious metallic-element whose biogeochemical cycle has been influenced predominantly by increasing human activities to a great extent. The introduction and enrichment of this ubiquitous contaminant in the terrestrial-environment has a long history and getting more attention due to its adverse health effects to living organisms even at very low exposure levels. Its lethal-effects can vary widely depending on the atmospheric-depositions, fates and distribution of Pb isotopes (i.e., ²⁰⁴Pb, ²⁰⁶Pb, ²⁰⁷Pb &²⁰⁸Pb) in the terrestrial-environment. Thus, it is essential to understand the depositional behavior and transformation mechanism of Pb and the factors affecting Pb isotopes composition in the terrestrial-compartments. Owing to the persistence nature of Pb-isotopic fractions, regardless of ongoing biogeochemical-processes taking place in soils and in other interlinked terrestrial-compartments of the biosphere makes Pb isotope ratios (Pb-IRs) more recognizable as a powerful and an efficient-tool for tracing the source(s) and helped uncover pertinent migration and transformation processes. This review discusses the ongoing developments in tracing migration pathway and distribution of lead in various terrestrial-compartments and investigates the processes regulating the Pb isotope geochemistry taking into account the source identification of lead, its transformation among miscellaneous terrestrial-compartments and detoxification mechanism in soil-plant system. Additionally, this compendium reveals that Pb-pools in various terrestrial-compartments differ in Pb isotopic fractionations. In order to improve understanding of partition behaviors and biogeochemical pathways of Pb isotope in the terrestrial environment, future works should involve investigation of changes in Pb isotopic compositions during weathering processes and atmospheric-biological sub-cycles.

Phosphorus Speciation in Atmospherically Deposited Particulate Matter and Implications for Terrestrial Ecosystem Productivity

Chemical forms of phosphorus (P) in airborne particulate matter (PM) are poorly known and do not correlate with solubility or extraction measurements commonly used to infer speciation. We used P X-ray absorption near-edge structure (XANES) and ³¹P nuclear magnetic resonance (NMR) spectroscopies to determine P species in PM collected at four mountain sites (Colorado and California). Organic P species dominated samples from high elevations, with organic P estimated at 65-100% of total P in bulk samples by XANES and 79-88% in extracted fractions (62-84% of total P) by NMR regardless of particle size (≥10 or 1-10 μm). Phosphorus monoester and diester organic species were dominant and present in about equal proportions, with low fractions of inorganic P species. By comparison, PM from low elevation contained mixtures of organic and inorganic P, with organic P estimated at 30-60% of total P. Intercontinental PM transport determined from radiogenic lead (Pb) isotopes varied from 0 to 59% (mean 37%) Asian-sourced Pb at high elevation, whereas stronger regional PM inputs were found at low elevation. Airborne flux of bioavailable P to high-elevation ecosystems may be twice as high as estimated by global models, which will disproportionately affect net primary productivity.

Contamination identification, source apportionment and health risk assessment of trace elements at different fractions of atmospheric particles at iron and steelmaking areas in China

China has the largest share of global iron and steel production, which is considered to play a significant contribution to air pollution. This study aims to investigate trace element contamination at different fractions of particulate matter (PM) at industrial areas in China. Three PM fractions, PM2.1-9.0, PM1.1-2.1 and PM1.1, were collected from areas surrounding iron and steelmaking plants at Kunming, Wuhan, Nanjing and Ningbo in China. Multiple trace elements and their bioavailability, as well as Pb isotopic compositions, were analysed for identification of contaminants, health risk assessment and source apportionment. Results showed that PM particles in the sites near industrial areas were associated with a range of toxic trace elements, specifically As, Cr(VI), Cd and Mn, and posed significant health risks to humans. The isotopic Pb compositions identified that coal and high temperature metallurgical processes in the steelmaking process were the dominant contributors to local air pollution in these sites. In addition to iron and steelmaking activities, traffic emissions and remote pollution also played a contributing role in PM contamination, confirmed by the differences of Pb isotopic compositions at each PM fraction and statistical results from Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE) and Geometrical Analysis for Interactive Aid (GAIA). The results presented in this study provide a comprehensive understanding of PM emissions at iron and steelmaking areas, which helps to guide subsequent updates of air pollution control guidelines to efficiently minimise environmental footprint and ensure long term sustainability of the industries.

PM2.5-bound potentially toxic elements (PTEs) fractions, bioavailability and health risks before and after coal limiting

Fractions, bioavailability, health risks of fine particulate maters (PM_2.5)-bound potentially toxic elements (PTEs) (Pb, Cd, Cr, Cu and Zn) were investigated before and after coal limiting in Baoding city. The winter PM_2.5 samples were collected at different functional areas such as residential area (RA), industrial area (IA), suburb (SB), street (ST) and Botanical Garden Park (BG) in 2016 (coal dominated year) and 2017 (gas dominated year). The fractions and bioavailability of PTEs were determined and evaluated based on BCR sequential extraction. Health risks through inhalation exposure were evaluated by US EPA health risk assessment model. The results from different years and functional areas were compared and discussed. The fractions and bioavailability of PM_2.5-bound PTEs varied with functional areas. The percentages of cadmium (Cd) and zinc (Zn) in acid-soluble fraction (F1-Cd and F1-Zn) to the total amount of Cd and Zn were low in BG samples (p < 0.05). Bioavailability of Cd were high in SB samples (p < 0.05). Total contents of PM-bound PTEs in 2017 generally decreased compared with 2016. The differences of fraction and bioavailability between 2016 and 2017 depended on the elements and areas. Higher proportions of copper (Cu) in acid-soluble fraction (F1-Cu) and bioavailability of Cu (p < 0.05) were found in 2017 samples. Significant differences were found just at IA and RA for Pb, Cd and Zn. Our results indicated that the health risks from inhalation exposure for PTEs in PM_2.5 declined about 11%-52% after the coal limiting in this city.

Seasonal disparities in airborne lead (Pb) and associated foliar uptake by ryegrass (Lolium perenne L.): A Pb isotopic approach

Foliar uptake of airborne lead (Pb) may be particularly important for Pb accumulation in plant organs. However, the aerosol bioconcentration factor (BCF) in different seasons has seldom been reported. In the present study, we collected ryegrass (Lolium perenne L.) and size-segregated aerosols (SSA) during the corresponding growing seasons, and analyzed these for both Pb concentrations and isotopic ratios. Airborne Pb showed a seasonally varying concentration that was approximately 20% higher in winter than in spring. The bioavailability index, however, was higher in spring. Coupling the stable isotope technique with the bioavailable Pb of aerosol was more reliable in identifying airborne Pb accumulation in leaves than the total determination, suggesting that the hydrophilic absorption pathway was probably dominant for the foliar uptake of Pb in ryegrass. Contributions of airborne Pb accumulation were 88%-92% for washed ryegrass growing outdoors, indicating that the foliar uptake of Pb in the field was mainly from atmospheric deposition. The aerosol BCF of Pb for ryegrass was 6.4-11.4 m³/g in winter and 22.9-31.5 m³/g in spring. The increased aerosol BCF in spring was due to the suitable temperature, abundant rainfall, and increased Pb solubility of the aerosol. Therefore, our results indicate that, for the foliar uptake of Pb, both the aerosol Pb concentration, composition, and seasonal influence should be considered.

Lead Isotopes Combined with Geochemical Baseline in Sediments: A Novel Tool to Trace Anthropogenic Pb Sources

Traditional Pb isotopic identification only based on total Pb concentration and Pb isotopic ratios, resulted in difficulty for tracing Pb sources in the complex environmental medium, especially for sediment. Herein, a novel approach combining with regional geochemical baseline (RGB) and Pb isotopic ratios are used to directly trace anthropogenic Pb sources and calculate Pb source appointments in sediment. In this study, total Pb concentrations and isotopic ratios were analyzed for a 7-m long sediment core (92 sediment samples) collected from a reservoir. RGB of Pb was used to calculate anthropogenic Pb concentrations (R_d), their contributions (C_Rd) and screen the sediments influenced by anthropogenic activities. Among those sediments influenced by anthropogenic activities, a positive correlation was found between ²⁰⁶Pb/²⁰⁷Pb ratios and R_d, indicating there were two anthropogenic Pb sources in sediment. Further source identification using ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb indicated that these two anthropogenic Pb sources originated from coal consumption and aerosol input. Finally, C_Rd and Pb isotopic ratios were used to calculate these two Pb source appointments (1.13% for coal consumption and 7.53% for aerosol input). This study demonstrated that source identification using RGB and Pb isotopes could be a novel attempt for identifying anthropogenic Pb sources in sediment.

Does atmospheric processing produce toxic Pb-containing compounds? A case study in suburban Beijing by single particle mass spectrometry

A single particle aerosol mass spectrometry (SPAMS) was deployed to investigate the mixing state and chemical processing of Pb-rich particles in suburban Beijing. Based on a large dataset of mass spectra, Pb-rich particles were classified into Pb-O-Cl-N-S (55%), Pb-N (17%), Pb-N-S (15%), and Pb-EC (7%). Residual coal combustion, industrial activities, and meteorological conditions were identified as main factors regulating the variations of Pb-rich particles in the atmosphere. The highest abundance of the Pb-rich particles was observed during heating period (HP) primarily due to the increase in coal usage. Pb in Pb-O-Cl-N-S type was identified in forms of PbO, PbCl_2, and Pb(NO₃)₂. Dominantly presented in the form of Pb(NO₃)₂, Pb-N type represented the completely transformed Pb-rich particles from PbO/PbCl₂ by atmospheric processes. It is found that PbCl₂ and PbO could be transformed to Pb(NO₃)₂, highly dependent on the amount of NO₂ and RH. Significant enhancement of nitrate in Pb-O-Cl-N-S particles was observed when the RH was greater than 60%, emphasizing the importance of heterogeneous hydrolysis of N₂O₅ on the formation of Pb(NO₃)_2. Compared with non-carcinogenic PbCl₂/PbO and insoluble PbO, soluble and carcinogenic Pb(NO₃)₂ produced by atmospheric processes may significantly enhance negative effects of Pb-rich particles on human health and the ecosystem.

Concentration, fluxes, risks, and sources of heavy metals in atmospheric deposition in the Lihe River watershed, Taihu region, eastern China

This study investigated ecological and human-health risks associated with heavy-metal pollution arising from deposition in the Lihe River region of eastern China. Ecological risk assessment was based on the geoaccumulation index and health risk using a US Environmental Protection Agency health risk assessment model. Pollution source contributions were assessed through enrichment factors, positive matrix factor analysis, and Pb isotopic analyses. Mean concentrations of Cd, Cr, Cu, Ni, Pb, and Zn measured in deposited particulates were 8.842, 79.92, 150.3, 46.86, 231.7 and 1920 mg kg^-1, respectively. Deposition fluxes of these six heavy metals were 0.6, 6.0, 10.9, 3.3, 16.4, and 157 mg m^-2 a^-1, respectively. The order of ecological risk was Cd > Zn ≈ Pb > Cu > Ni > Cr. Ingestion is the main pathway of human exposure, however hazard quotient and hazard index values of the heavy metals studied were <1, indicating little or minimal risk to human health. The contributions to atmospheric deposition of coal-fired industries were Cd 82.4%, Cu 51.9%, Ni 51.2%, and Pb 68.3%. Zn was derived mainly from vehicular emissions (75.7%), and Cr concentrations (66.3%) were controlled mainly by natural sources. The qualitative and quantitative methods employed here resulted in improved accuracy of source apportionment. The results provide insights into the management of heavy-metal pollution in atmospheric deposition and serve as a reference for other regions of China.

The vertical migration and speciation of the Pb in the paddy soil: A case study of the Yangtze River Delta, China

Migration of Pb in the soil can be enhanced by acidification and frequent change of environmental condition. The paddy soil, where the environmental condition such as redox fluctuates frequently due to soil submergence and drainage, may offer a favorable condition for Pb migrating to deeper soil and further contaminate groundwater by leaching or irrigation. To date, not much is known about how quickly Pb migrates in the soil and the relevant transformation of Pb. We use long-term soil profile monitoring, sequential extraction and isotopic measurement to examine the temporal change of concentrations and isotopic ratios of Pb associated with different soil components in the paddy soil profile in the Yangtze River Delta area during 2011-2017. We find that Pb vertical migration in the paddy soil is faster. Pb in the shallow soil may migrate downward up to 60 cm during six years. The migration of Pb is dominated by the carbonate, and secondarily influenced by Fe/Mn oxides. Our results also imply that the mechanism of Pb migration in soils is changing. The mechanism which is now characterized as the carbonate-dominating will be replaced as the Fe/Mn oxides-dominating in the near future as the carbonate in shallow soil is becoming depleted.

Quantifying the elemental composition of mosses in western Washington USA

Major and trace element deposition across western Washington, USA was assessed in 2016 and 2017 by analyzing tissue metal concentrations in the epiphytic mosses Isothecium stoloniferum (Bridel) and Kindbergia praelonga (Hedw.) Ochyra. We used an intensive, vertically stratified sampling approach in Acer macrophyllum canopies in the Hoh Rainforest on the Olympic Peninsula, WA and in Seattle, WA to collect 214 samples of I. stoloniferum. An extensive, ground-based sampling approach was used across an urban-to-wildland gradient to collect 59 K. praelonga samples. Intensive samples were collected four times (April, July, and October of 2016 and in January 2017) and extensive samples three times (April, July, and October 2016) to assess seasonal differences in metal concentrations across sampling locations. A total of 273 moss samples were analyzed for Cd, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb, Sr, Ti, and Zn concentrations. Elevated concentrations of these elements were found in moss samples from both intensive and extensive sampling efforts across all seasons. Sampling location for both intensive and extensive sampling efforts was found to be a significant factor in determining moss metal concentrations. Metal deposition in and around Seattle appears to be derived from the regional transportation sector and other industrial sources. Ten I. stoloniferum samples from Seattle and the Hoh Rainforest were analyzed for Pb and Sr isotope ratios to help differentiate between natural and industrial-based emission sources. Hoh Rainforest Pb isotopes appear to be explained by a mixture of long-range Asian Pb influences and natural Pb sources, whereas Seattle Pb isotopes appear driven by industrial and road dust sources.

Lead isotope trends and sources in the atmosphere at the artificial wetland

With the rapid development of industry, studies on lead pollution in total suspended particulate matter (TSP) have received extensive attention. This paper analyzed the concentration and pollution sources of lead in the Cuihu Wetland in Beijing during the period of 2016–2017. The results show that the lead contents in TSP in the Cuihu Wetland were approximately equal in summer and spring, greater in winter, and greatest in autumn. The corresponding lead concentrations were 0.052, 0.053, 0.101, and 0.115 ng/m³, respectively. We compared the ²⁰⁶Pb/²⁰⁷Pb data with other materials to further understand the potential sources of atmospheric lead. The mean values of ²⁰⁶Pb/²⁰⁷Pb from spring to winter were 1.082, 1.098, 1.092, and 1.078, respectively. We found that the lead sources may be associated with coal burning, brake and tire wear, and vehicle exhaust emissions. We also calculated the enrichment factor values for the four seasons, and the values were all much greater than 10, indicating that the lead pollution is closely related to human activities.

Comprehensive Evaluation and Source Apportionment of Potential Toxic Elements in Soils and Sediments of Guishui River, Beijing

This study investigated the concentrations and spatial distributions, ecological risks, and potential pollution sources of potential toxic elements (PTEs) in the soils and sediments collected from the Guishui River (GSR) in Beijing, China. Multiple methods for pollution assessment and source identification of PTEs in the sediments/soils were used, including analysis of the physicochemical properties, Geo-accumulation index (Igeo), potential ecological risk index (RI), Pearson correlation, principal component analysis (PCA), and Pb isotopic ratio analysis. The results showed that PTE concentrations in the sediments/soils were similar to the soil background values (BV) of Beijing, except for Cd. Maximum Cd concentrations in soils were far below the guideline of the Environmental Quality Standard for Soils in China. PTE concentrations in the soils were slightly higher than those in the sediments. Upstream to downstream of GSR, PTEs concentrations in the soils and sediments remained stable. Pollution assessment based on Igeo and RI indicated that Cd was the main contaminant with moderate pollution levels. PCA results showed that Cd originated from anthropogenic sources, mainly including pesticide and fertilizer residues, while other metals mainly originated from natural sources. Further source identification using Pb isotopic ratios and PCA indicated that Cu, Pb, and Zn in GSR originated from anthropogenic sources (aerosols and coal combustion) and atmospheric deposition was considered as the primary input pathway.

Speciation and bioaccessibility of heavy metals in PM2.5 in Baoding city, China

The health risks and toxicity of heavy metals (HMs) in PM_2.5 are not only associated with their total amounts, but also with their species and bioaccessibility. In this study, the speciation (fractions) and bioaccessibility of HMs (Pb, Cd, Cr, Cu and Zn) as well as their correlations in fine particulate matter (PM_2.5) samples from four seasons were studied. A sequential extraction procedure was applied to divide the studied HMs into four fractions: acid-soluble fraction (F1), reducible fraction (F2), oxidative fraction (F3) and residual fraction (F4). The simulated body fluids (gastrointestinal and lung phases) were used for in vitro tests in order to evaluate the bioaccessibility of HMs. The distribution of HMs in PM_2.5 was season and element dependent. It was found that Zn was the most abundant element among the five measured metals and followed by Pb, Cu, Cr and Cd. The total contents of each HM in different seasons were in the following order: winter > autumn > spring > summer. The studied HMs were mainly concentrated in acid-soluble fraction (F1) with high bioaccessibility (p < 0.05) except for Cr. Zn, Pb and Cu possessed the highest bioaccessibility in summer while Cd and Cr were the highest in winter. In vitro tests indicated that HMs in PM_2.5 were much more accessible to gastrointestinal fluids rather than lung phase (Gamble's solution). A significant correlation was found between the results from the optimized BCR sequential extraction and solubility bioaccessibility research consortium (SBRC). The fractions extracted by SBRC were consistent with the first two fractions extracted by the sequential extraction method.

Impact of municipal solid waste incineration on heavy metals in the surrounding soils by multivariate analysis and lead isotope analysis

Municipal solid waste (MSW) incineration has become an important anthropogenic source of heavy metals (HMs) to the environment. However, assessing the impact of MSW incineration on HMs in the environment, especially soils, can be a challenging task because of various HM sources. To investigate the effect of MSW incineration on HMs in soils, soil samples collected at different distances from four MSW incinerators in Shanghai, China were analyzed for their contents of eight HMs (antimony, cadmium, chromium, copper, lead, mercury, nickel, and zinc) and lead (Pb) isotope ratios. Source identification and apportionment of HMs were accomplished using principal component analysis and Pb isotope analysis. Results indicated that the relatively high contents of cadmium, lead, antimony, and zinc in the soils at 250 m and 750-1250 m away from the MSW incinerators were related to MSW incineration, while the elevated contents of the other four HMs were associated with other anthropogenic activities. Based on Pb isotope analysis, the contribution ratio of MSW incineration (which had been operated for more than 14 years) to the accumulation of Pb in soil was approximately 10% on average, which was lower than coal combustion only. Incinerator emissions of Pb could have a measurable effect on the soil contamination within a limited area (≤1500 m).

Lead Pollution and Isotope Tracing of Surface Sediments in the Huainan Panji Coal Mining Subsidence Area, Anhui, China

In this study, the provenance of anthropogenic lead, a major pollutant of surface sediments, was determined in Huainan Panji coal mining area. The lead concentrations and the pollution degree were investigated by the enrichment factor. Tessier five-step morphology extraction method was used to discuss its potential hazard. By comparing the lead isotope ratios of surface sediments and surrounding potential polluted end-members, the lead isotope ternary mixture model was appropriated to explore the sources and relative contribution fractions. The results showed that: (1) The lead concentrations ranged from 31.44 to 64.07 mg/kg which was mild-moderate pollution. (2) The chemical forms of lead were residue state > iron-manganese oxidation state > exchangeable state > organic state > carbonate state. (3) The anthropogenic lead in surface sediments originated from soil, vehicle exhaust, coal gangue. And the relative contribution fractions were 51.70%, 30.90%, and 17.40%.

Blood lead, bone lead and child attention-deficit-hyperactivity-disorder-like behavior

BACKGROUND AND OBJECTIVE

Mounting evidence showed that lead exposure increased the risk of child attention-deficit-hyperactivity disorder (ADHD). Epidemiologic studies have typically used the blood-lead as a biomarker of lead exposure; blood-lead levels mostly reflect recent lead exposure. However, few studies have examined the relationship between bone-lead, a biomarker of cumulative exposure, and ADHD. Therefore, we aimed to compare the associations of bone-lead vs blood-lead levels with child ADHD symptoms and comorbidities.

METHODS

A total of 164 children aged 3-15 years were enrolled during 2014-2015. The Vanderbilt-ADHD-Diagnostic-Parent-Rating Scale (VADPRS) was used to evaluate the children's ADHD symptoms and comorbidities. Children's blood and bone lead concentrations were assessed, the latter using a non-invasive K-X-ray-fluorescence technique. According to blood-lead levels, children were classified into high (blood-lead ≥ 10.0 μg/dL) and low (blood-lead < 10.0 μg/dL) blood-lead groups. According to bone-lead levels, children were classified into high (bone-lead ≥ 2.66 μg/g) and low (bone-lead < 2.66 μg/g) bone-lead groups. We associated blood/bone lead with VADPRS data using multi-variable binary logistic regression models.

RESULTS

Children in the high blood-lead group had higher hyperactivity/impulsivity (P = 0.02) scores than the corresponding low blood-lead group. Children in the high bone-lead group had higher hyperactivity/impulsivity (P = 0.02) and oppositional-defiant-disorder (ODD) (P = 0.03) scores than the corresponding low bone-lead group. After adjusting for relevant confounders, children in the high bone-lead group were more likely to have ODD-behavior than the low group (OR = 6.7, 95%CI: 1.2-36.5). However, no adjusted association was observed between blood-lead and any ADHD-domain score.

CONCLUSION

High levels of cumulative lead exposure in children may be an independent risk factor of ODD-behavior.

Using Pb isotope ratios of particulate matter and epiphytic lichens from the Athabasca Oil Sands Region in Alberta, Canada to quantify local, regional, and global Pb source contributions

Ambient air particulate matter (PM) was collected at the Wood Buffalo Environmental Association Bertha Ganter Fort McKay monitoring station in the Athabasca Oil Sand Region (AOSR) in Alberta, Canada from February 2010 to July 2011 as part of an air quality source assessment study. Daily 24-hour duration fine (PM_2.5) and coarse (PM_10-2.5) PM was collected using a sequential dichotomous sampler. 100 pairs of PM_2.5 and PM_10-2.5 were selected for lead (Pb) concentration and isotope analysis. Pb isotope and concentration results from 250 epiphytic lichen samples collected as far as 160 km from surface mining operations in 2008, 2011, and 2014 were analyzed to examine longer term spatial variations in Pb source contributions. A key finding was recognition of thorogenic ²⁰⁸Pb from eastern Asia in the springtime in the PM_2.5 in 2010 and 2011. ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb isotope ratios were used in a three-component mixing model to quantify local, regional, and global Pb sources in the PM and lichen data sets. 47 ± 3% of the Pb in the PM_2.5 at AMS-1 was attributed to sources from eastern Asia. Combined results from PM_10-2.5 and PM_2.5 indicate PM_2.5 Pb contributions from eastern Asia (34%) exceed local AOSR sources of PM_2.5 Pb (20%), western Canada sources of PM_2.5 Pb (19%), and PM_10-2.5 Pb from fugitive dust including oil sands (14%), tailings (10%), and haul roads (3%). The lichen analysis indicates regional sources contribute 46% of the Pb, local sources 32%, and global sources 22% over the 2008-2014 timeframe. Local sources dominate atmospheric Pb deposition to lichens at near field sites (0-30 km from mining operations) whereas regional Pb sources are prevalent at distal sites (30-160 km). The Pb isotope methodology successfully quantified trans-Pacific transport of Pb to the AOSR superimposed over the aerosol footprint of the world's largest concentration of bitumen mining and upgrading facilities.

Spatial variation of heavy metal contamination in the riparian sediments after two-year flow regulation in the Three Gorges Reservoir, China

Regular impoundment of the Three Gorges Reservoir (TGR) with intensified human activities in the watershed imparts a significant effect on the environmental changes in the riparian zone. In this study, six heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in the riparian sediments of the entire TGR mainstream were investigated in 2014 and 2016 to identify their contamination and risk characteristics and decipher the main factors for the variation of the metal contamination. The results showed that the concentrations of the heavy metals in the sediments did not vary significantly between 2014 and 2016, and their contamination degrees decreased in the order of Cd> > Cu ≈ Zn > Pb > Cr ≈ Ni in 2014 and Cd> > Zn > Cu ≈ Pb > Cr ≈ Ni in 2016. The potential eco-risk of Cd was extremely high in the two years, while the eco-risk of other metals was very low. The sediments showed a moderate to high contamination level, a high potential eco-risk but a low toxic risk to aquatic biota in the two years. Spatially, the contamination and risk levels of heavy metals were relatively higher in the downstream TGR region in 2014 except for the sites close to the urban areas but in the upper-middle TGR region in 2016. Increasing anthropogenic influence contributed to the high contamination and risk levels of Cd, Cu, Pb and Zn in the upper-middle region in 2016. The results indicated that the Cd contamination in the riparian sediments of the TGR was still a vital environmental issue, and the decreased sediment inputs from the upstream major tributaries, the periodic and anti-seasonal flow regulation, local geomorphological characteristics and anthropogenic activities determined the contamination distribution of heavy metals in the riparian sediments.

Responses of magnetic properties to heavy metal pollution recorded by lacustrine sediments from the Lugu Lake, Southwest China

Environmental magnetism, which is rapid, sensitive, economical, and non-destructive, has been used to assess heavy metal pollution in lake sediments based on the relationships between magnetic properties and heavy metal concentrations. We conducted a systematic environmental magnetic and heavy metal study of the sediments of the core LGS from Lugu Lake in Southwest China. The results show that the concentration-related magnetic parameters (χ, χ_ARM, and SIRM) in the core LGS showed an increasing trend from bottom to top. The results of rock magnetism indicated that the dominant magnetic particles were magnetite. Two sources of magnetic minerals can be distinguished by the correlations of χ vs. χ_fd% and χ vs. χ_ARM/χ: the surrounding catchment and anthropogenic activities. In addition, Pearson correlation analysis and principal component analysis showed that the concentration-dependent magnetic parameters have significant correlations with heavy metal (Al, Ti, Fe, Cr, Ni, Cu, Zn, and Cd) concentrations as well as the Tomlinson pollution load index (PLI), indicating that there are essential linkages of sources, deposition, and migration between magnetic particles and heavy metals. Based on previously reported ¹³⁷Cs and ²¹⁰Pb data, the historical trends of heavy metal pollution in Lugu Lake were successfully reconstructed, and the causes of heavy metal pollution were mainly agricultural practices and atmospheric metal depositions from anthropogenic sources. The significant correlations between magnetic parameters, heavy metals, and the PLI indicate that magnetic parameters can potentially be used as an index of heavy metal pollution in lacustrine deposits.

One-century sedimentary record of heavy metal pollution in western Taihu Lake, China

Long-term trends of sediment compositions are important for assessing the impact of human activities on the sediment and protecting the sediment environment. In this study, based on the contents of heavy metals and the Pb isotope ratios in lake sediments, atmospheric dustfall and soil in Yixing, China, the representative heavy metals (Zn, Pb, Cr and Cd) in lake sediments from western Taihu Lake were studied. The evolution history of heavy metals in the local environment was constructed for the past 100 years. From 1892 to the 1990s, the anthropogenic fluxes of the representative heavy metals were negligible, indicating minimal anthropogenic emissions of heavy metals. Since the 1990s, anthropogenic fluxes of the representative heavy metals began to increase, concurrent with the economic growth and development in the western Taihu Lake Basin after the Chinese economic reform. The maximum flux percentage of the heavy metals in the sediments, caused by human activities, is 23.0% for Zn, 31.6% for Pb, 39.5% for Cr and 85.3% for Cd, indicating that most of the Cd comes from human activities. The Cd content in the western Taihu Lake Basin was significantly higher than that in the other areas, and the rapid development of the industry in the western Taihu Lake Basin and ceramics in Yixing led to the enrichment of heavy metals in local sediments. Since the 21st century, measures have been taken to control the pollution of heavy metals, including the increase in local government attention and the deployment of environmental monitoring technology. However, heavy metal content remains high, and the Pb content is still increasing. The ratios of Pb isotopes show that the main sources of heavy metals in the western Taihu Lake sediments, the local soil of Yixing and the atmospheric dustfall are coal combustion, leaded gasoline combustion, industrial wastewater and domestic sewage.

Recent atmospheric metal deposition in peatlands of northeast China: A review

China is one of the fastest-growing economies of the late 20th and early 21st centuries, and heavy metal emissions have increased in parallel with rapid industrialization and urbanization. Over the last decade, several studies of geochemical records from peat have reconstructed changes in atmospheric metal pollution in China. We review the peat records that detail the history of atmospheric metal pollution over the last two centuries in NE China. The ecological risk (ER) of accumulated metals and their potential eco-toxicological effects, through threshold and probable effect concentrations (TEC and PEC), are also evaluated. Peat records of metals show an increase of pollution loads in the environment over the pre-industrial level during the past two centuries, with an unprecedented increase in China over the last 60 years. There is generally good agreement between geochemical peat records from NE China and others records elsewhere in China. However, some discrepancies are observed especially with Hg records from lake sediments. These discrepancies could be explained by several factors, including post-depositional processes or uncertainties arising from dating methods. The ecological risk of heavy metals is found to be relatively weak in the remote and high-altitude environment in NE China. Although, most metals are under the TEC, Pb concentrations usually surpass it and are getting close to the PEC which indicates increasing ecological risks. Some areas of improvement have been highlighted such as the need for more long-term studies on atmospheric metals and a greater number of Pb isotopes records to better capture the long history of human activity and the spatial variability in metal deposition of the region.

Heavy metals and lead isotopes in soils, road dust and leafy vegetables and health risks via vegetable consumption in the industrial areas of Shanghai, China

Vegetable fields have a high risk of heavy metal contamination from pollution sources in suburban and industrial areas of cities. Eighty-seven soil samples, 106 leafy vegetables and 48 road dust samples were collected from industrial areas of Shanghai, China. We studied the levels of heavy metals, health risk through consumption of leafy vegetables, and sources of Pb in soils, road dust and leafy vegetables. Soil Cd, Zn, Pb, Cu, Hg and As concentrations exceeded the soil background values in 73.6%, 97.7%, 52.3%, 37.8%, 95.1% and 20.2% soil samples, respectively, but were below the criteria for agricultural soil in China, with the exception of Hg. The concentrations of Cd, Zn, Pb, Cu and As in road dust were significantly higher than concentrations in soils, while Hg concentration in road dust was lower. Cd, Zn, Pb, Hg and Cu concentrations in soils and Zn, Pb and Cu concentrations in road dust were greatest near the municipal solid waste incineration power plant. Heavy metal concentrations in the edible tissues of vegetables were not correlated with their total values in soils and varied among vegetable species. The trends in transfer factors (TFs) in different vegetables were Cd>Zn>Cu>As>Hg>Pb. There was low health risk from heavy metal exposure by consumption of vegetables based on Hazard Quotients (HQ_M): As was the major contributor to HQ_M, followed by Cd and Pb. Parent material of the Yangtze River Estuary was the major source of Pb in soils, while coal-fired, stationary industrial emissions and municipal waste incineration emissions were the major sources of Pb in dust and vegetables based on use of the lead isotopic tracing method. Accumulation of Pb in leafy vegetables was through foliar uptake and directly related to atmospheric Pb.

Use of multiple tools including lead isotopes to decipher sources of ozone and reactive mercury to urban and rural locations in Nevada, USA

Ambient air particulate matter (<2.5μm in diameter) samples were collected on two different filter types in 2014 and 2015 over 24h periods and analyzed for reactive mercury (gaseous oxidized mercury+particulate bound mercury) concentrations and lead isotopes to determine sources of pollution to three sites in Nevada, USA. Two sites were located on the western edge of Nevada (Reno, urban, 1370m and Peavine Peak, rural, high elevation, 2515m); the third location was ~485km east in rural Great Basin National Park, NV (2061m). Reactive mercury samples were collected on cation exchange membranes simultaneously with lead samples, collected on Teflon membranes. Lead isotopic ratios have previously identified trans-Pacific lead sources based on the 206/207 and 208/207 lead ratios. Influence from trans-Pacific air masses was higher from March to June associated with long-range transport of pollutants. Spring months are well known for increased transport across the Pacific; however, fall months were also influenced by trans-Pacific air masses in this study. Western North American background ozone concentrations have been measured and modeled at 50 to 55ppbv. Median ozone concentrations at both rural sites in Nevada were within this range. Sources leading to enhancements in ozone of 2 to 18ppbv above monthly medians in Nevada included emissions from Eurasia, regional urban centers, and global and regional wildfires, resulting in concentrations close to the USA air quality standard. At the high elevation locations, ozone was derived from pollutants being transported in the free troposphere that originate around the globe; however, Eurasia and Asia were dominant sources to the Western USA. Negative correlations between reactive mercury and percent Asian lead, Northern Eurasia and East Asia trajectories indicated reactive mercury concentrations at the two high elevation sites were produced by oxidants from local, regional, and marine boundary layer sources.

Preliminary assessment on exposure of four typical populations to potentially toxic metals by means of skin wipes under the influence of haze pollution

To investigate the exposure risk of human beings to nine potentially toxic metals (PTMs), namely, Cu, Cr, Zn, As, Cd, Pb, Ni, Mn, and Co, skin wipe samples were collected from four types of populations, namely, children, undergraduates, security guards, and professional drivers, under different haze pollution levels in Xinxiang, China by using Ghost wipes. The Ghost wipes were quantitatively analyzed by inductively coupled plasma mass spectrometry (ICP-MS) after microwave digestion. Generally, Zn (ND-1350μg/m² for undergraduates, ND-2660μg/m² for security guards, ND-2460μg/m² for children, and ND-2530μg/m² for professional drivers) showed the highest concentration among the four populations, followed by Cu (0.02-83.4μg/m² for undergraduates, ND-70.2μg/m² for security guards, 23.2-487μg/m² for children, and ND-116μg/m² for professional drivers). As (ND-5.7μg/m² for undergraduates, ND-2.3μg/m² for security guards, ND-21.1μg/m² for children, and ND-11.0μg/m² for professional drivers) and Co (ND-6.0μg/m² for undergraduates, ND-7.9μg/m² for security guards, ND-13.4μg/m² for children, and ND-2.1μg/m² for professional drivers) showed the lowest concentrations in all populations. Remarkable differences were found among the four populations and PTM levels decreased in the following order: children, professional drivers, security guards, and undergraduates. Gender variation was discovered for undergraduates and children. Generally, PTM contamination in skin wipes collected during a light haze pollution level was generally higher than that during a heavy haze pollution level, but PTM contamination was comparable between the two haze pollution levels for children. Non-carcinogenic exposure risks to As, Cd, and Pb for all populations were higher than those for the other six elements but all of them were within the acceptable safety threshold, indicating no apparent non-carcinogenic risk.