Atmospheric pollution in an urban environment by tree bark biomonitoring--part I: trace element analysis

The cellular consequences of particulate matter pollutants in plants: Safeguarding the harmonious integration of structure and function

Particulate matter (PM) pollution is one of the pressing environmental concerns confronting human civilization in the face of the Anthropocene era. Plants are continuously exposed to an accelerating PM, threatening their growth and productivity. Although plants and plant-based infrastructures can potentially reduce ambient air pollutants, PM still affects them morphologically, anatomically, and physiologically. This review comprehensively summarizes an up-to-date review of plant-PM interaction among different functional plant groups, PM deposition and penetration through aboveground and belowground plant parts, and plants' cellular strategies. Upon exposure, PM represses lipid desaturases, eventually leading to modification of cell wall and membrane and altering cell fluidity; consequently, plants can sense the pollutants and, thus, adapt different cellular strategies. The PM also causes a reduction in the photosynthetically active radiation. The study demonstrated that plants reduce stomatal density to avoid PM uptake and increase stomatal index to compensate for decreased gaseous exchange efficiency and transpiration rates. Furthermore, genes and gene sets associated with photosynthesis, glycolysis, gluconeogenesis, and the TCA cycle were dramatically lowered by PM stress. Several transcription factors, including MYB, C2H2, C3H, G2-like, and WRKY were induced, and metabolites such as proline and soluble sugar were accumulated to increase resistance against stressors. In addition, enzymatic and non-enzymatic antioxidants were also accumulated to scavenge the PM-induced reactive oxygen species (ROS). Taken together, this review provides an insight into plants' underlying cellular mechanisms and gene regulatory networks in response to the PM to determine strategies to preserve their structural and functional blend in the face of particulate pollution. The study concludes by recommending that future research should precisely focus on plants' response to short- and long-term PM exposure.

Comparison of trace elements in tissue of beaver (Castor canadensis) and local vegetation from a rural region of southern Ontario, Canada

Beavers have been analyzed in several studies examining trace elements (TEs) in wildlife; however, most of these studies were undertaken in areas with known environmental pollutants. To understand and quantify natural enrichments of TEs in beaver tissue, samples of kidney, liver, muscle from 28 animals were compared with bark from 40 species of trees and shrubs, from the same, uncontaminated watershed. Pearson correlation and factor analysis show that conservative, lithophile elements such as Al, Ga, Th, and Y, all surrogates for mineral dust particles, explain 61% of the variation in the bark data. In contrast, Cd, Co, Cu, Mn, Mo, Ni, Rb, Se, Sr, and Tl in bark are independent of Al, and therefore most likely occur in non-mineral forms. Comparing tissue concentrations of beaver and bark, the organs are enriched in micronutrients such as Cu, Fe, Mo, Se, and Zn, but also non-essential, benign elements such as Cs and Rb, and potentially toxic elements such as Cd and Tl. Thus, the elements most enriched in beaver organs are those that apparently occur in biological form in the plant tissue. The elements enriched in these animals, relative to bark, appear to offer the most promise for monitoring environmental contamination by TEs using beavers. The majority of TEs of environmental relevance are most abundant in beaver kidney. However, monitoring studies must consider the variation in TE concentrations in beaver tissue, including those due to sex and age. Also, due consideration must be given to background concentrations of TEs in the vegetation composing the diet of the animals. The natural enrichment in the case of elements such as Cd, in beaver tissue relative to bark, is profound. These data establish critical baseline values for TEs in beavers in an unpolluted environment, thereby allowing for their use as model organisms in tracking how heavy metal pollutants may affect wildlife.

Low-dose antimony exposure promotes prostate cancer proliferation by inhibiting ferroptosis via activation of the Nrf2-SLC7A11-GPX4 pathway

Antimony (Sb) is a typical environmental pollutant. With the development of industrialization, antimony is widely used in daily life and enters the human body through the food chain, water source, air pollution, and other channels. The risk of antimony exposure has emerged as one of the public's major health concerns. Current research on antimony shows that antimony has certain biological toxicity, and antimony exposure may be one of the carcinogenic risk factors for bladder cancer, prostate cancer (PCa), and other cancers. But the molecular mechanism of antimony exposure in PCa is still unclear. Our results showed that serum antimony levels were significantly higher in PCa patients than in benign prostatic hyperplasia (BPH), and high levels of serum antimony were associated with poorer prognosis in PCa. We demonstrate that antimony exposure promotes PCa progression in vivo and in vitro. In addition, our results also showed that low-dose antimony exposure resulted in increased GSH, increased GPX4 expression, and decreased Fe2+. Since GPX4 and Fe2+ are important molecular features in the mechanism of ferroptosis, we further found that low-dose antimony exposure can inhibit RSL3-induced ferroptosis and promote PCa proliferation. Finally, our study demonstrates that low-dose antimony exposure promotes Nrf2 expression, increases the expression level of SLC7A11, and then increases the expression of GPX4, inhibits ferroptosis, and promotes PCa progression. Taken together, our experimental results suggest that low-dose antimony exposure promotes PCa cell proliferation by inhibiting ferroptosis through activation of the Nrf2-SLC7A11-GPX4 pathway. These findings highlight the link between low-dose antimony exposure and the Nrf2-SLC7A11-GPX4 ferroptosis pathway, providing a new potential direction for the prevention and treatment of PCa.

Do Antimonite and Silicon Share the Same Root Uptake Pathway by Lsi1 in Sorghum bicolor L. Moench?

A study was conducted to further develop our understanding of antimony (Sb) uptake in plants. Unlike other metal(loid)s, such as silicon (Si), the mechanisms of Sb uptake are not well understood. However, SbIII is thought to enter the cell via aquaglyceroporins. We investigated if the channel protein Lsi1, which aids in Si uptake, also plays a role in Sb uptake. Seedlings of WT sorghum, with normal silicon accumulation, and its mutant (sblsi1), with low silicon accumulation, were grown in Hoagland solution for 22 days in the growth chamber under controlled conditions. Control, Sb (10 mg Sb L^-1), Si (1mM) and Sb + Si (10 mg Sb L^-1 + 1 mM Si) were the treatments. After 22 days, root and shoot biomass, the concentration of elements in root and shoot tissues, lipid peroxidation and ascorbate levels, and relative expression of Lsi1 were determined. When mutant plants were exposed to Sb, they showed almost no toxicity symptoms compared to WT plants, indicating that Sb was not toxic to mutant plants. On the other hand, WT plants had decreased root and shoot biomass, increased MDA content and increased Sb uptake compared to mutant plants. In the presence of Sb, we also found that SbLsi1 was downregulated in the roots of WT plants. The results of this experiment support the role of Lsi1 in Sb uptake in sorghum plants.

Evaluation of urban tree barks as bioindicators of environmental pollution using the X-ray fluorescence technique

Some chemical elements released in nature due to anthropogenic actions are harmful to living beings, and finding efficient and low-cost ways to measure their presence is a challenge. The major goal of this work was to use the barks of urban trees as bioindicators of the presence of these elements. For this purpose, tree barks of sixteen individual trees were collected, including Ipê (Bignoniaceae Family); Sibipiruna (Fabaceae Family); Pine (Pinaceae Family), in the city of Sorocaba, SP, Brazil, in three different districts. Two samples, one of Ipê and another of Sibipiruna, collected in the Mata Atlântica forest in Juquitiba, SP, Brazil, were used as control samples. They were also analyzed; six soil samples were collected in the same places as the tree barks in Sorocaba. The samples were analyzed using the Energy Dispersion X-Ray Fluorescence Spectroscopy technique. The elements studied ranged from Al to Bi. The results were submitted to univariate and multivariate statistical analysis showing that Sibipiruna presented a high concentration of the element Ca. At the same time, Ipê and Pine showed high concentrations of K. In the identified elements, the probable sources of contamination were pointed out, such as elements from the dust of braking automobiles (Al, Si, S, Ti, Fe, Cu, and Ba), elements from the paint used to paint the asphalt (Si, Ca, Cr and Pb) and elements from the tire tread wear (Al, S, Ca and Zn). From the analysis of soil samples and trees, it was found that there was high pollution by the element Pb in the specimens collected in front of the old Saturnia battery factory, located in the district of Éden in the city of Sorocaba, SP, Brazil (Coordinates: Lat 23K253141 m E; Long 23K7405583 m S).

Atmospheric Hg Levels in Tree Barks Due to Artisanal Small-Scale Gold Mining Activity in Bunut Seberang Village in Indonesia

Mercury (Hg) is a useful heavy metal; however, it is toxic to both humans and the environment. Tree bark is an excellent bioindicator, which has been proven to be effective in studying the level of atmospheric Hg contamination. This study aimed to determine the distribution of evaporated Hg using the total weight of Hg (THg) in tree barks in Indonesia at the artisanal and small-scale gold mining (ASGM) area of Bunut Seberang Village and Lampung University, respectively. Samples were taken using purposive sampling, based on the criteria of forestry trees at a height level of 1.3 m above ground as wide as 100 cm2. The samples were analyzed by atomic absorption spectrometry and Scanning electron microscopy to determine the levels of THg and to investigate the bark structures. Results showed that the highest THg values were found in a Magnolia champaca sample (56.5 µg), followed by Swietenia mahagoni (45.8 µg) and Swietenia mahagoni (33.5 µg). All species studied showed THg levels in the tree barks at an elevation from 30 to 320 m above sea level. The Hg amounts found in the sampled barks indicated the dispersion of Hg throughout the ASGM area, which signified hazardous atmospheric conditions in the area.

Availability, Toxicology and Medical Significance of Antimony

Antimony has been known and used since ancient times, but its applications have increased significantly during the last two centuries. Aside from its few medical applications, it also has industrial applications, acting as a flame retardant and a catalyst. Geologically, native antimony is rare, and it is mostly found in sulfide ores. The main ore minerals of antimony are antimonite and jamesonite. The extensive mining and use of antimony have led to its introduction into the biosphere, where it can be hazardous, depending on its bioavailability and absorption. Detailed studies exist both from active and abandoned mining sites, and from urban settings, which document the environmental impact of antimony pollution and its impact on human physiology. Despite its evident and pronounced toxicity, it has also been used in some drugs, initially tartar emetics and subsequently antimonials. The latter are used to treat tropical diseases and their therapeutic potential for leishmaniasis means that they will not be soon phased out, despite the fact the antimonial resistance is beginning to be documented. The mechanisms by which antimony is introduced into human cells and subsequently excreted are still the subject of research; their elucidation will enable us to better understand antimony toxicity and, hopefully, to improve the nature and delivery method of antimonial drugs.

Biomonitoring of metallic air pollutants in unique habitations of the Brahmaputra Valley using moss species-Atrichum angustatum: spatiotemporal deposition patterns and sources

In this paper, we have evaluated the bioaccumulation of metals by Atrichum angustatum, which is a readily available moss species in the Brahmaputra valley, India. A systematic investigation of metallic pollutants in the atmosphere was carried out using A. angustatum as a biomonitor collected from representative locations during three seasons viz. winter, pre-monsoon, and monsoon (n = 99) during the year 2018. The study was done in four unique habitations of the Brahmaputra Valley, which were further divided into three landuse areas: residential, roadside, and industrial. The highest accumulations were seen against Ca, Mg, Zn, and Fe. The calculated contaminant factors and ecological risk indices suggest that the Brahmaputra Valley is mostly contaminated by Cr, Zn, Cu, Ni, and Pb, and these metals pose a maximum ecological risk. The accumulation trend of metallic pollutants was site-specific, but most metals showed positive seasonal accumulation. A significant difference in spatial and seasonal accumulation patterns was specific to metal species. Principal component analysis (PCA) and inter-species correlations revealed that the air quality of Brahmaputra valley was greatly affected by coal burning, vehicular emission, biomass burning, road dust, and crustal dust. Finally, the study led us to the conclusion that A. angustatum can serve as a potential biomonitor for metallic pollutants.

Geo-environmental approach to assess heavy metals around auto-body refinishing shops using bio-monitors

The vehicular industry is looking for continuous challenges to develop the sustainability of its manufacturing, maintenance processes, and vehicle emissions due to marketability, environmental, economic, and policy concerns. The present study focuses on the impact of these processes on the environment. In Pakistan, most of the auto-body refinishing processes are carried out in an open atmosphere. The shades of Azadirachta indica (Neem Tree) are generally used for the outdoor practice of scrapping, grinding, and painting in auto-body refinishing shops of Pakistan. Azadirachta indica leaves were selected as bio-indicator. For the present work, 26 affected sites and 10 control sites were selected from Karachi city, which is the financial hub and biggest city of Pakistan. Concentrations of different metals (Fe, Co, Cd, Cr, Cu, Mn, Mo, Ni, Pb, and Zn) were determined by atomic absorption spectrophotometer. A geographic information system (GIS) is used to present the variation in concentrations within Karachi city. The only positive correlation was observed in Pb and Mn (0.750). Principal component analysis (PCA) is applied to identify the anthropogenic effect between auto-body refinishing areas and control areas. Almost all analyzed metals show higher concentration at affected sites but Pb (87.14 mg/kg), Mn (46.47 mg/kg) and Fe (146.95 mg/kg) were leading the values, as compared to their concentration at control sites, Pb (48.83 mg/kg), Mn (15.23 mg/kg) and Fe (43.07 mg/kg). All analyzed metals are frequently present in different color pigments, whereas Pb, Mn, and Fe may also come from other sources, like the anti-knocking agent, vehicular exhaust, and scraping of car surface.

Geogenic and anthropogenic sources identification and ecological risk assessment of heavy metals in the urban soil of Yazd, central Iran

Urban soil pollution with heavy metals is one of the environmental problems in recent years, especially in industrial cities. The aim of this study is to evaluate the role of geogenic and anthropogenic sources in the urban soil pollution in Yazd, Iran. For this purpose, 30 top-soil (0-10 cm) samples from Yazd within an area of 136.37 Km2 and population of nearly 656 thousand are collected, and the concentration of heavy elements is measured. To evaluate factors affecting the concentration of heavy elements in urban soils and determine their possible sources, Multivariate statistical analysis, including correlation coefficient, principal components analysis (PCA) and cluster analysis (CA) are performed. Enrichment Factor (EF), Geo-accumulation index (Igeo), and Modified potential ecological Risk Index (MRI) are used to assess the level and extension of contamination. Results of this study suggest that As, Cd, Pb and Zn are affected by anthropogenic source, while the concentrations of Fe, Mn, Ni, Cr, Co, Cu and Cs have come from mostly natural geologic sources. As, Cd and Pb are considerably enriched in the area, provided moderately enriched for the elements Mn, Zn and Cu. However, the other heavy elements show minimal enrichment. Igeo reveal that Co, Cr, Cs, Cu, Fe, Mn, Zn and Ni with negative values are unpolluted, Pb posed unpolluted to moderately polluted, and As and Cd represent high polluted. Based on the results of the ecological risk factor, the heavy metals of Mn, Ni, Cr, Zn and Cu have a low ecological risk level. More specifically, we find that Pb shows a moderated ecological risk in 39% of the urban soil in the studied area. As and Cd with respectively 100 and 72% contribution have considerable and very high ecological risk. According to the results of MRI, the area is in a very high ecological risk level, and appropriate management practice is essential to reduce the pollution of heavy elements in this area.

Silicon alleviates antimony phytotoxicity in giant reed (Arundo donax L.)

Silicon enhances photosynthetic efficiency, biomass, and lignification of root structures possibly limiting antimony translocation and mitigating phytotoxicity in giant reed plants. Antimony (Sb) is a non-essential metalloid causing toxic effects in plants. Silicon has been reported to impart tolerance against biotic and abiotic stress in plants. Fast-growing plant, giant reed (Arundo donax L.) is a promising energy crop, can be a suitable plant for phytoremediation. However, information regarding the tolerance capacity with respect to Sb toxicity and potential of Si to mitigate the Sb phytotoxicity in giant reed are very scarce. Rhizomes of giant reed were grown for ten weeks in hydroponics exposed to Sb, Si, and their combination wherein treatment without Sb/Si served as control. Effect of these treatments on rate of net photosynthesis and photosynthetic pigments, phytoextraction ability of Sb, Si and Sb uptake, plant biomass, and lignification and suberization of roots along with localization of Sb and Si were analysed. We found that Si considerably improved the growth and biomass of giant reed under Sb toxicity. Antimony reduced the photosynthesis and decreased the content of photosynthetic pigments, which was completely alleviated by Si. Silicon amendment to Sb treated plants enhanced root lignification. Silicon enhanced lignification of root structures probably restricted the Sb translocation. However, co-localization of Sb with Si has not been observed neither at the shoot nor at the root levels. Similarly, Sb was also not detected in leaf phytoliths. These findings suggest that Si treatment promotes overall plant growth by improving photosynthetic parameters and decreasing Sb translocation from root to shoot in giant reed by improving root lignification.

Pollution, human health risk assessment and spatial distribution of toxic metals in urban soil of Yazd City, Iran

Heavy metal pollution significantly reduces the quality of the environment and threatens human health, especially in industrial cities. This study investigated toxic metals concentrations, pollution levels and human health risks assessment of urban soils in Yazd City, as an industrial city in center of Iran. Soil surface samples (0-10 cm) were collected from 30 points in the area for geochemical analysis. The concentrations of heavy metals were determined using an inductively coupled plasma mass spectrometry (ICP-MS). The values of the mean concentrations of toxic metals (mg kg^-1) in the urban soils decrease in the order of Zn (83.9) > Pb (34.5) > Cr (32.6) > Cu (23.5) > Ni (23.4) > As (5.86) > Co (4.86) > Cd (0.27). The mean concentration of Zn, Pb, As and Cd elements was higher than the background and the crust values. A pollution assessment by Geo-accumulation Index (I_geo), Pollution Index (PI), Contamination Degree (C_D), the Integrated Pollution Index (IPI), the Pollution Load Index (PLI) and Integrated Nemerow Pollution Index (INPI) showed that As, Cd and Pb were moderately enriched and the study area polluted considerably by these toxic metals. Based on PI results, 88.9% of the urban soil samples highly polluted by As. Overall, the quality of the urban soil in Yazd City is clearly affected by toxic metals. Due to the prevailing wind direction, the route of the north-south highway of Iran and the population density and traffic of the northwestern and southern areas of the study area were found the highest level of pollution indicators (IPI > 1.8; LPI > 1.3; C_D > 15 and INPI > 4.3). The results of Pearson correlation analysis indicated that all pollution evaluation indicators were influenced by As and Cu, and showed high significant correlation with these two elements, while neither of them had a significant relationship with Pb and was found also a weak link statistically with Cd. Health risk assessment of toxic metals has been performed in both carcinogenic and non-carcinogenic sectors. The results indicate that oral intake is the main pathway that toxic metals can harm human health for both the child and adults. The carcinogenic risks (RI) of adults and child by toxic metals were as follows: Ni > Pb > Cr > As > Cd. Hazard quotients (HQ) and hazard index (HI) values for child also were higher than these for adults. Generally, the results demonstrated that the potential carcinogenic health risks for adults of toxic metals were in an acceptable range in study area, whereas for Cr, Ni and Pb with RI > 10^-4, the risk of cancer in child probably increases.

Concentrations, sizes distributions, and seasonal variations of ambient air pollutants (particulates, trace metals) in Daya/Xitun District, Taichung, Central Taiwan: a case study at Taichung Science Park

Taichung Science Park in central Taiwan releases ambient air pollutants to the atmosphere. This issue has attracted much attention over the past few years. This study concerns seasonal concentrations of atmospheric particles and metallic elements and particle size distributions. A M.O.U.D.I sampler is used at a Taichung Science Park sampling site to obtain relevant data. Fe, followed by Al, had the highest average metallic element concentrations in particles of various sizes (PM₁₈, PM₁₀, PM_2.5, PM₁ and PM_<1(0.3)); Cd had the lowest. The average concentrations of metallic elements in particles of various sizes were lowest in the summer. Fe, Al and Cr had the three highest concentrations among all metallic elements for all particles sizes in all seasons. Ambient air particulate pollutants (crustal and anthropogenic metallic elements) were released from a single emission source at Taichung Science Park site.

Accumulation of airborne potentially toxic elements in Pinus sylvestris L. bark collected in three Central European medium-sized cities

This study attempts to identify the influence of various aspects of human activities in three medium-sized Central European cities (Cottbus, Germany; Nitra, Slovakia and Słupsk, Poland) on air contamination. For comparison purposes, bark of Pinus sylvestris L. was collected from polluted and non-polluted urban areas. Nine elements: Fe, Mn, Cu, Zn, Ni, Cd, Cr, Pb and S were determined using microwave plasma atomic emission spectrometry, flame atomic absorption spectrometry and elementary analyzer. Results of the study showed significant differences between the cities in term of elements content in pine bark. The differences reflected well specific character of the cities and various effects of human activity. Study revealed that elements spatial variability among the cities is driven by the factor loadings character and reflects various emission sources and their impact range.

Biomagnetic monitoring of atmospheric heavy metal pollution using pine needles: the case study of Isfahan, Iran

Atmospheric deposition particles are fine-sized having a high adsorption capacity. Therefore, they can easily transfer the contamination to other areas. Plants can absorb certain pollutants using their leaves and then accumulate them in their biomass. In this study, the spatial and temporal variability of air pollution was assessed using pine needles as the bioindicators of atmospheric pollution. The magnetic susceptibility (MS) at low and high frequencies (χlf, χhf) and the concentration of selected heavy metals of pine needles (Pinus mugo) were estimated in order to address the possible relationships between needles' MS and the heavy metal concentration in the city of Isfahan, central Iran. In addition, the relationship between the heavy metal concentration of pine needles and that of the atmospheric dust was examined using the published data. Tree pine needles were monthly sampled, from April to December 2015 (T1-T9), during 9 months, from 30 different sites in the Isfahan city. There were two treatments including washed + unwashed (WU) and washed + washed (WW). The heavy metal total concentrations including Zn, Fe, Cu, Co, Pb, and Ni were measured. The mean concentrations of Fe, Zn, Pb, Cu, Ni, and Co were 80.4, 3.9, 1.8, 1.4, 0.6, and 0.3 mg kg-1, respectively. The results revealed that the concentration of heavy metals and MS in the pine needles followed the order Fe > Zn > Pb > Cu > Ni > Co. Also, the heavy metal concentration in the pine needles with different treatments had the following trend: WU > WW. It was shown that there was a significant correlation (p < 0.01) between the heavy metal concentrations and the leaf MS values of the pine needles and the concentration of heavy metals in atmospheric dust. Besides, similar trends were detected for the spatial variability of heavy metals and the pine needles' MS. In general, it could be concluded that the biomagnetic approach could serve as a comparatively fast and low-cost method to detect highly polluted urban areas with selected heavy metals, particularly the areas which are under the influence of anthropogenic and other traffic-related sources.

Spatial-temporal variability of metal pollution across an industrial district, evidencing the environmental inequality in São Paulo

Although air pollution decreased in some cities that shifted from an industrial to a service-based economy, and vehicular emission regulation became more restrictive, it is still a major risk factor for mortality worldwide. In central São Paulo, Brazil, air quality monitoring stations and tree-ring analyses revealed a decreasing trend in the concentrations of particulate matter and metals. Such trends, however, may not be observed in industrial districts located in the urban periphery, where the usual mobile sources may be combined with local stationary sources. To evaluate environmental pollution in an industrial district in southeastern São Paulo, we assessed its spatial variability, by measuring magnetic properties and concentrations of Al, Ba, Ca, Cl, Cu, Fe, K, Mg, Mn, P, S, Sr, Zn in the bark of 62 trees, and its temporal trends, by measuring Cd, Cu, Ni, Pb, V, Zn in tree rings of three trees. Source apportionment analysis based on tree barks revealed two clusters with high concentrations of metals, one related to vehicular and industrial emissions (Al, Ba, Cu, Fe, Zn) in the east side of the industrial cluster, and the other related to soil resuspension (Cu, Zn, Mn) in its west side. These patterns are also supported by the magnetic properties of bark associated with iron oxides and titanium-iron alloy concentrations. Dendrochemical analyses revealed that only the concentrations of Pb consistently decreased over the last four decades. The concentrations of Cd, Cu, Ni, V, and Zn did not significantly decrease over time, in contrast with their negative trends previously reported in central São Paulo. This combined biomonitoring approach revealed spatial clusters of metal concentration in the vicinity of this industrial cluster and showed that the local population has not benefited from the decreasing polluting metal concentrations in the last decades.

Estimating the frequency of hormesis and other non-monotonic responses in plants experiencing road traffic pollution in urban areas and experimental pollutant exposure

Various plant traits are widely utilised to assess environment health. However, non-monotonic responses in plants (hormesis and non-hormetic ones) can induce an incorrect assessment of contamination level because they have maximums and/or minimums. Hence, an increase in the pollution level will not always be accompanied by plant index deteriorations. The frequencies of non-monotonic responses, especially non-hormetic responses, have been insufficiently studied for plant traits. This study analysed the frequencies of non-monotonic changes in plants experiencing urban chemical pollution (B. pendula, T. cordata and T. officinale) and with different pollutant exposures (heavy metals, herbicide glyphosate, formaldehyde and sodium chloride) in experiments (T. aestivum and P. sativum). In the city, we evaluated the traits in plants with the same ontogenetic stages on plots near roads with various traffic and similar abiotic conditions. In urban areas, non-monotonic responses were found in both woody (B. pendula and T. cordata) and herbaceous (T. officinale) species for most traits. Their frequencies corresponded to the proportion of monotonic responses (B. pendula) or were even higher (T. cordata and T. officinale). In studied trees, non-monotonic responses were more common in biochemical traits compared with non-biochemical ones. With experimental pollutant exposure, non-monotonic responses were obtained for most traits of both dicotyledonous (P. sativum) and monocotyledonous (T. aestivum) plants, and their frequency was significantly higher than for monotonic ones. Non-hormetic responses significantly prevailed among non-monotonic changes of plant indexes in the city and experiments. Thus, it is necessary to consider both hormesis and non-hormetic responses to assess correctly environmental quality using plant indexes.

Ecological and health risk assessment of exposure to atmospheric heavy metals

In the present study, we assessed the concentration of airborne HMs (Zn, Cu, Pb, and Cd) and their probable sources using the bark of Pinus eldarica as a bio-indicator. Hence, 47 tree bark samples were harvested according to the land uses and biomonitoring techniques in the city of Yazd, Iran. The potential health risks in 13 age groups, ecological risk, as well as the possible relationship between HM concentrations and traffic indicators, were evaluated. The order of average HM concentrations in the P. eldarica bark samples was as Zn > Pb > Cu > Cd. The mean values of non-carcinogenic risks of all HMs in entire age groups were within secure range (HQ < 1); however, the carcinogenic risk of Cd was higher than the allowed level (TCR > 1 × 10^-6). About Pb, it was in the safe level. The main element causing potential ecological risks was Cd, indicating moderate to very high ecological risk in most of the study areas. There was an inverse significant association between distance from major roads and Pb concentration (β = -0.011 95% confidence interval (CI): 0.022, -0.0001). All HMs in bark samples render the negative Moran's index, representing a random spatial distribution pattern. Besides, according to principal component analysis (PCA), the first component accounted for 36.55% of the total variance, dominated by Cd, Pb, Cu, and Zn, respectively, and characterized by vehicle and industrial emissions. Our results infer that industrial activities and traffic are the main sources of HMs pollution in urban environments that should be considered by decision-makers.

Evaluation of historical atmospheric pollution in an industrial area by dendrochemical approaches

We conducted a dendrochemical study in order to evaluate the exposure of territories and populations to different types of pollutants and to characterise the history of pollution in one of the most intensely industrialised areas of Europe: the industrial port zone of Fos, also heavily urbanised. To perform the study, two tree species have been selected, Pinus halepensis and Populus nigra, on a rural plot located roughly 20 km away from the industrial harbour, an urban plot located in the city of Fos-sur-Mer and an industrial plot. Our study indicated that poplar was a more relevant model for the dendrochemical studies, exhibiting a higher bioaccumulation capacity than pine except for Hg, Sb and Mn. Moreover, thanks to this work, we observed significant exposure of the trees in the urban and industrial areas to As, Cd, Co, Cu, Mo, Sb, Zn, Al, Ca, and Mg, highlighting the exposure of the territory and populations living in the vicinity of the industrial harbour. The temporal variability of the concentrations measured in the tree rings corresponds to the increasing industrialisation of the territory as well as to the evolution of the industrial processes. Thus, this project highlighted the exposure of the Gulf of Fos to atmospheric emissions (industrial, road and urban) of the industrial harbour as well as the changes over time. It also pointed out the relevance of using dendrochemistry to measure atmospheric exposure of metals and metalloids and its temporal variability.

Influence of the residence time of street trees and their soils on trace element contamination in Paris (France)

With the actual increasing interest for urban soils, the evaluation of soil contamination by trace elements and the dynamics of this contamination appear mandatory to preserve plant and thereby human health. Street trees and the associated soil placed in pits located nearby roads could represent convenient indicators of urban and vehicle traffic influences on soils and plants. However, data on these soils remain scarce, many studies investigating park soils rather than street tree soils. Furthermore, trace elements could be one of the main factors causing the observed urban tree decline, while practitioners more and more question the possible reuse of these soils after the death of trees as well as tree litter collected in the streets. We evaluated the contamination in anthropogenic trace elements (TE), namely Zn, Pb, and Cd, of street trees (Tilia tomentosa) and their soils distributed all over Paris (France). Street tree soils are imported from rural areas at the plantation of each new tree so that tree age corresponds to the time of residence of the soil within an urban environment allowing the evaluation of temporal trends on TE concentration in soils and trees. The TE concentration revealed an important soil pollution, especially for the older soils (mean age of 80 years old). The consideration of the residence time of trees and soils in an urban environment evidenced an accumulation of Zn and Pb (ca. 4.5 mg kg^-1 year^-1 and 4 mg kg^-1 year^-1 for Zn and Pb, respectively). However, leaf concentrations in TE were low and indicate that soil-root transfer was not significant compared to the contamination by atmospheric deposition. These results underlined the necessity to deepen the evaluation of the recycling of urban soils or plants submitted to urban contamination.

Urban Allotment Gardens for the Biomonitoring of Atmospheric Trace Element Pollution

This study evaluates the results of the characterization of air pollution in urban green areas using edible plants. To this purpose, we examined the effect of location (i.e., three different levels of pollution), substrate (peat moss and vermiculite), and plant species (oilseed rape [ L.] and kale [ L.]) on the accumulation of trace elements on leaves. A total of 36 samples of unwashed leaves were digested with HNO-HO and analyzed for 27 elements by inductively coupled plasma mass spectrometry. Considering the location, plants exposed next to the road showed higher contents of traffic-related elements, and additionally, outdoors samples were enriched in marine aerosol ions. Cadmium and Pb concentrations did not exceed the European legal maximum levels for vegetables, so their consumption would be safe for human health. Results support the hypothesis that edible plants such as kale and rapeseed could be used as bioindicators of atmospheric pollution.

Trace element biomonitoring in the Peruvian andes metropolitan region using Flavoparmelia caperata lichen

In the present study, in situ lichens (Flavoparmelia caperata) were used to assess the deposition of atmospheric trace elements in the metropolitan area of Huancayo (Junín, Peru). In total, ten sampling sites were chosen and categorized as urban, peri-urban (rural-urban) and rural areas according to land use. In addition, samples were also collected from a non-contaminated area categorized as a control site. The concentrations of 16 trace elements were measured using an inductively coupled plasma mass spectrometer (ICP-MS) and examined by enrichment factor (EF), hierarchical cluster analysis (HCA), and principal component analysis (PCA). Twelve of the 16 trace elements in urban and peri-urban sites present concentration higher than those at the rural and control sites (p < 0.05). The EF results revealed significant enrichment (at least twice that of the control site) of Ba, Cr, Cd, Pb, Sb, V, and Zn at most sites. PCA and HCA showed that more elements were derived from vehicular sources and fewer from agricultural and natural sources.

Ambient air particulates-bound metallic elements sources identifications during winter and summer at a Science Park

The ambient air particulates pollutants of total suspended particulates (TSP) and PM_2.5 were collected by using PS-1 and Wilbur PM_2.5 sampler, simultaneously during the year of 2015-2017 at a photoelectric factory in Science Park of central Taiwan. And those of the ambient air atmospheric metallic elements (Cr, Mn, Ni, Cu, Zn, Pb) concentrations which attached on the TSP and PM_2.5 were analyzed by using inductively coupled plasma optical emission spectrometer. In addition, identifying anthropogenic and natural pollutants sources were conducted by using the enrichment factor (EF) and principal component analysis (PCA) methods. The results indicated that the average TSP and PM_2.5 concentrations were ranked highest in winter season, while summer season was ranked lowest during the year of 2015-2016. In addition, the average highest metallic element concentrations were occurred in winter season for both TSP and PM_2.5 during the year of 2015-2016, while the average lowest metallic elements concentrations in TSP and PM_2.5 were also occurred in winter season during the year of 2016-2017. Moreover, the EF analysis results showed that the metallic element Zn came from anthropogenic emission source. As for metallic element Mn, the results showed that metallic element Mn was mainly attributed to natural emission in this study. Finally, the PCA results showed that metallic elements Cr, Zn and Pb were the dominant emissions metallic elements in this study. As for PM_2.5, the results showed that the metallic elements Cr, Cu and Pb were the dominant emissions metallic elements at this HPB sampling site.

Concentrations and content of mercury in bark, wood, and leaves in hardwoods and conifers in four forested sites in the northeastern USA

Mercury (Hg) is deposited from the atmosphere to remote areas such as forests, but the amount of Hg in trees is not well known. To determine the importance of Hg in trees, we analyzed foliage, bark and bole wood of eight tree species at four sites in the northeastern USA (Huntington Forest, NY; Sleepers River, VT; Hubbard Brook, NH; Bear Brook, ME). Foliar concentrations of Hg averaged 16.3 ng g-1 among the hardwood species, which was significantly lower than values in conifers, which averaged 28.6 ng g-1 (p < 0.001). Similarly, bark concentrations of Hg were lower (p < 0.001) in hardwoods (7.7 ng g-1) than conifers (22.5 ng g-1). For wood, concentrations of Hg were higher in yellow birch (2.1-2.8 ng g-1) and white pine (2.3 ng g-1) than in the other species, which averaged 1.4 ng g-1 (p < 0.0001). Sites differed significantly in Hg concentrations of foliage and bark (p = 0.02), which are directly exposed to the atmosphere, but the concentration of Hg in wood depended more on species (p < 0.001) than site (p = 0.60). The Hg contents of tree tissues in hardwood stands, estimated from modeled biomass and measured concentrations at each site, were higher in bark (mean of 0.10 g ha-1) and wood (0.16 g ha-1) than in foliage (0.06 g ha-1). In conifer stands, because foliar concentrations were higher, the foliar pool tended to be more important. Quantifying Hg in tree tissues is essential to understanding the pools and fluxes of Hg in forest ecosystems.

Characterisation and source identification of the total airborne particulate matter collected in an urban area of Aracaju, Northeast, Brazil

In this work, studies using samples collected in an urban area of Aracaju city, Sergipe State, Northeast, Brazil revealed that soil dust in suspension was the main source of total airborne particulate matter (TAPM), followed by vehicular pollution. The concentration profiles for Cu, Fe, Mn, Ni, V and Ti were established for the collected TAPM samples. The concentrations of SO₂ and smoke were also measured all along the 42 sampling days. Through multivariate data analysis of the results a correlation between Fe, Mn, Ni and Ti in the mineral composition of the particles was established, indicating soil dust in suspension as the main source of TAPM. The concentrations of Cu and smoke were found to be related to vehicular traffic, and the second largest source of TAPM. Enrichment factors (EF) were calculated for the studied elements, and only Cu was found to be enriched. The concentrations of the elements in TAPM were evaluated using the geoaccumulation index (I_geo), and Fe, Mn, Ni, V and Ti were found to derive from natural sources, in TAPM. However, approximately 55% of the samples did not presented Cu contamination (I_geo≤0), and the remaining 45% presented Cu concentrations levels that indicated between low to moderate (0<I_geo≤1) and moderate to heavy contamination (2<I_geo≤3) in the urban area of Aracaju city, Sergipe State, Northeast, Brazil.

Current content of selected pollutants in moss, humus, soil and bark and long-term radial growth of pine trees in the Mezaparks forest in Riga

The aim of this study was to evaluate the use of various indicators in the assessment of environmental pollution and to determine the response of pine to changes of pollution levels. Mezaparks is a part of Riga that has been subject to various long-term effects of atmospheric pollution and, in particular, historically from a large superphosphate factory. To determine the spatial distribution of pollution, moss, pine bark and soil O and B horizons were used as sorbents in this study, as well as the additional annual increment of pine trees. The current spatial distribution of pollution is best shown by heavy metal accumulation in mosses and the long-term accumulation of P₂O₅ pollution by the soil O horizon. The methodological problems of using these sorbents were explored in the study. Environmental pollution and its changes could be associated with the tree growth ring annual additional increment of Mezaparks pine forest stands. The additional increment increased after the closing of the Riga superphosphate factory.

Branch bark of holm oak (Quercus ilex L.) for reconstructing the temporal variations of atmospheric deposition of hexavalent chromium

The bark from the annual segments of the branches of holm oak (Quercus ilex L.) is exposed to trace element deposition for a known period of time and thus it is a possible candidate as a bioindicator for reconstructing historical changes in pollution. A series of samples were analysed for Cr(VI) concentration by electrothermal atomic absorption spectrometry (ET-AAS) after selective extraction in a sodium carbonate solution. In this way the atmospheric deposition of Cr(VI) was reconstructed from 2001 to 2010 in an area where an industrial plant produced Cr(VI) compounds until 2003. The present study shows the potential of this type of sample as a natural archive for persistent pollutants, useful for monitoring changes that occur before a monitoring programme is established, with the advantage of being easy to collect almost everywhere.

Effectiveness of traffic-related elements in tree bark and pollen abortion rates for assessing air pollution exposure on respiratory mortality rates

The majority of epidemiological studies correlate the cardiorespiratory effects of air pollution exposure by considering the concentrations of pollutants measured from conventional monitoring networks. The conventional air quality monitoring methods are expensive, and their data are insufficient for providing good spatial resolution. We hypothesized that bioassays using plants could effectively determine pollutant gradients, thus helping to assess the risks associated with air pollution exposure. The study regions were determined from different prevalent respiratory death distributions in the Sao Paulo municipality. Samples of tree flower buds were collected from twelve sites in four regional districts. The genotoxic effects caused by air pollution were tested through a pollen abortion bioassay. Elements derived from vehicular traffic that accumulated in tree barks were determined using energy-dispersive X-ray fluorescence spectrometry (EDXRF). Mortality data were collected from the mortality information program of Sao Paulo City. Principal component analysis (PCA) was applied to the concentrations of elements accumulated in tree barks. Pearson correlation and exponential regression were performed considering the elements, pollen abortion rates and mortality data. PCA identified five factors, of which four represented elements related to vehicular traffic. The elements Al, S, Fe, Mn, Cu, and Zn showed a strong correlation with mortality rates (R²>0.87) and pollen abortion rates (R²>0.82). These results demonstrate that tree barks and pollen abortion rates allow for correlations between vehicular traffic emissions and associated outcomes such as genotoxic effects and mortality data.

Biomonitoring of genotoxic effects and elemental accumulation derived from air pollution in community urban gardens

Urban gardening is a growing global phenomenon with a positive impact on society. Despite several associated benefits, growing vegetables in urban gardens that are localized in highly polluted areas poses questions about the safety of the produced food. Therefore, the identification of risk factors that result in possible deleterious effects to human health is important for realizing all of the benefits to society. We evaluated the use of two biomonitoring methods in ten urban gardens of Sao Paulo city and one control site: the micronuclei frequencies for early tetrads of Tradescantia pallida (Rose) Hunt. cv. "Purpurea" Boom (hereafter, Trad-MCN) as a short-term indicator of genotoxic response and tree barks to quantify the accumulation of traffic-related chemical elements as a long-term biomarker of air pollution in urban gardens. Mature plants of Tradescantia pallida were exposed in each garden, and their inflorescences were sampled over three months. A random set of 300 early tetrads in 13 to 21 slides per garden were evaluated for micronuclei frequencies. Elemental concentrations in 428 tree barks samples from 107 different trees in the areas surrounding urban gardens were quantified using an energy dispersive X-ray fluorescence spectrometer. The frequency of Trad-MCN has a significant correlation with traffic variables and chemical elements related to road dust and tailpipe emissions deposited in tree barks. Negative associations between Trad-MCN and both the distance through traffic and the presence of vertical obstacles were observed in the community gardens. The Mn/Zn concentrations in tree barks were associated with increased Trad-MCN.

Biomonitoring trace metal contamination by seven sympatric alpine species in Eastern Tibetan Plateau

Biomonitoring permits determinations of trace metal contamination in remote areas like the high mountain ecosystems. In this study, six trace metals (Cd, Cr, Cu, Ni, Pb, and Zn) in seven sympatric alpine species (five tree species: Salix rehderiana, Populus purdomii, Betula albosinensis, Abies fabri, Picea brachytyla, and two dominant mosses: Pleurozium schreberi, Papillaria crocea) at the Hailuogou Glacier foreland, Eastern Tibetan Plateau, were investigated to monitor their contamination. The concentrations of trace metals and Pb isotopic ratios (²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁶Pb) in leaves/needles, twigs, bark, roots, and mosses were determined, and the biological factors and enrichment factors were calculated. The concentrations of Cd, Cr, Pb, and Zn in mosses were significantly higher than those in tree tissues and normal plants indicating the exogenous sources. The accumulation of trace metals (except Cd and Zn) was relatively higher in the tree roots, whereas their enrichments were significant in the leaves/needles and bark. According to biological factors, enrichment factors, and factor analysis, Cd, Pb, and Zn in trees and mosses were markedly impacted by anthropogenic emissions, whereas Cr, Cu, and Ni in trees were mainly from root adsorption from soils. The Pb isotopic compositions identified the anthropogenic Pb mainly from mining and smelting, coal combustion, and vehicle exhausts. The results indicated that mosses were still priority indicator of trace metal contamination from atmospheric deposition, and the leaves and bark of S. rehderiana, P. purdomii, and B. albosinensis were the better alternatives to monitor the atmospheric contamination of trace metals in the alpine ecosystem.

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

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

Investigation of spatial and historical variations of air pollution around an industrial region using trace and macro elements in tree components

Several trace and macro elements (n=48) were measured in pine needle, branch, bark, tree ring, litter, and soil samples collected at 27 sites (21 industrial, 6 background) to investigate their spatial and historical variation in Aliaga industrial region in Turkey. Concentrations generally decreased with distance from the sources and the lowest ones were measured at background sites far from major sources. Spatial distribution of anthropogenic trace elements indicated that their major sources in the region are the iron-steel plants, ship-breaking activities and the petroleum refinery. Patterns of 40 elements that were detected in most of the samples were also evaluated to assess their suitability for investigation of historical variations. Observed increasing trends of several trace and macro elements (As, Cr, Fe, Mo, Ni, V, Cu, Pb, Sb, Sn, and Hg) in the tree-ring samples were representative for the variations in anthropogenic emissions and resulting atmospheric concentrations in Aliaga region. It was shown that lanthanides (La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb) could also be used for the investigation of historical variations due to specific industrial emissions (i.e., petroleum refining). Results of the present study showed that tree components, litter, and soil could be used to determine the spatial variations of atmospheric pollution in a region while tree rings could be used to assess the historical variations.

Impact of mechanical mowing and chemical treatment on phytosociological, pedochemical and biological parameters in roadside soils and vegetation

Many chemical and non-chemical strategies have been applied to control weeds in agricultural and industrial areas. Knowledge regarding the effects of these methods on roadside vegetation is still poor. A 2-year field experiment was performed along a road located near Livorno (Tuscany, central Italy). Eight plots/strips were identified, of which four were subjected to periodical mechanical mowing and the remaining four were treated with a chemical herbicide based on glyphosate (the producer's recommended rates were used for the selective control of broad-leaved weeds). Our results clearly showed that roadside soil and vegetation are a significant reservoir of anthropogenic activities which have a strong negative effect on several phytosociological, pedochemical and biological parameters. Compared with conventional mechanical mowing, chemical treatment induced (i) a significant increase in organic matter in the upper plot layers (+18%), and (ii) a marked reduction in weed height throughout the entire period of the experiment. Irrespectively of the kind of treatment, no significance differences were detected in terms of (i) biological quality of soil (the abundance and diversity of arthropod communities did not change), and (ii) plant elemental content (bulk concentrations of analysed trace elements had a good fit within ranges of occurrence in the "reference plant"). The glyphosate partially controlled broad-leaved weeds and this moderate efficacy is dependent upon the season/time of application. In conclusion, the rational and sustainable use of chemical herbicides may be a useful tool for the management of roadside vegetation.

Biomonitoring of metals for air pollution assessment using a hemiepiphyte herb (Struthanthus flexicaulis)

This work presents first results on elemental characterization of a parasite plant, Struthanthus flexicaulis, collected in urban, industrial and rural areas of Rio de Janeiro state, Brazil, in order to evaluate this plant as a biomonitor of metals pollution. The results were also compared to those obtained for fine particulate matter (PM2.5) collected from filters in nearby locales. The concentrations of PM2.5 measured in the filters were between 8.0 and 18.0 μg m(-3); in some places, these measurements were higher than the 10 μg m(-3), concentration recommended by the World Health Organization (WHO). Samples of the leaves and filters with PM were submitted to acid extraction, and the extracts were employed to determine major elements (Ba, Ca, Fe, K, Mg, P and S) by ICP OES and minor elements (Cr, Cu, La, Mn, Pb, Sr, Ti and Zn) by ICP-MS. Elements' extraction efficiency was evaluated by applying the method to the certified reference materials (CMR) of tomato leaves (NIST 1573(rd)) and urban dust (NIST 1648a). The concentrations of Ca, K and Mg were higher in leaves, while Ba, Ca, K and Zn showed higher concentrations in the PM. As expected, rural sites presented lower metal content. Enrichment factor (EF) and principal component analysis with multiple linear regression analysis (PCA-MLRA) were applied to the concentrations of elements in PM2.5 and in the leaves. Anthropogenic sources could be identified with both tools, which supports the use of S. flexicaulis as a biomonitor.

Traffic-related air pollution biomonitoring with Tradescantia pallida (Rose) Hunt. cv. purpurea Boom in Brazil

This study aimed to verify the capacity of Tradescantia pallida in the biomonitoring of air pollution in urban areas with different traffic intensities and under varying environmental conditions. Experiments were carried out in Ribeirão Preto, in the Southeastern Brazil, with more than 660,000 inhabitants and a fleet of more than 485,000 motor vehicles. Ten seedlings of T. pallida were exposed in three areas in the city, differing in traffic vehicle flow, in two seasons (wet and dry). At the end of each sampling period, which lasted 4 months, samples of leaves were collected, and the content of As, Ba, Ca, Cd, Cr, Cu, Fe, Hg, Mg, Mn, P, Pb, S, and Zn was determined by inductively coupled plasma mass spectroscopy (ICP-MS). The same elements were determined in soil samples for a seasonal characterization in conjunction with secondary data of environmental parameters. Additionally, micronucleus assay with early pollen tetrad cells of Tradescantia (Trad-MN) was conducted by collecting flower buds and analyzing the micronuclei frequencies in pollen mother cells. Although pollutant levels in air were below the Brazilian legal limits, plants exposed in the high-traffic flow area presented higher concentrations of elements related to vehicle emissions, especially under dry conditions, and higher micronuclei frequency in pollen mother cells. These results show the sensitivity of T. pallida to low-level urban air pollution and its suitability as bioindicator for trace elements. This alternative tool for biomonitoring can serve as a support methodology for the adoption of more restrictive public environmental policies in Brazil and extendible to other developing countries.

Necrotic bark of common pine (Pinus sylvestris L.) as a bioindicator of environmental quality

The aim of this study was to determine the pH and the concentration of lead, cadmium, nickel, copper and zinc in aqueous extracts of necrotic bark Pinus sylvestris L. and in adjacent soil, located in two types of forest habitat in different parts in the Niepołomice Forest in southern Poland. The Niepołomice Forest is located about 35 km east of an urban-industrial agglomeration Kraków. Despite the lack of significant differences in pine bark reaction studied, there was a clear difference in contamination of both bark and soil with heavy metals. There was a correlation between the distribution of pollutants in the forest, and the direction of the prevailing winds. More heavy metals were accumulated in the pine bark and soil from the west than the east. The high content of lead, zinc, cadmium and copper in the soils most likely results from the inflow of gas and dust pollutants from the urban-industrial agglomeration of Kraków.

Antimony in the soil-water-plant system at the Su Suergiu abandoned mine (Sardinia, Italy): strategies to mitigate contamination

This study was aimed to implement the understanding of the Sb behavior in near-surface environments, as a contribution to address appropriate mitigation actions at contaminated sites. For this purpose, geochemical data of soil (8 sites), water (29 sites), and plant (12 sites) samples were collected. The study area is located at Su Suergiu and surroundings in Sardinia (Italy), an abandoned mine area heavily contaminated with Sb, with relevant impact on water bodies that supply water for agriculture and domestic uses. Antimony in the soil horizons ranged from 19 to 4400 mg kg(-1), with highest concentrations in soils located close to the mining-related wastes, and concentrations in the topsoil much higher than in the bedrock. The Sb readily available fraction was about 2% of the total Sb in the soil. Antimony in the pore water ranged from 23 to 1700 μg L(-1), with highest values in the Sb-rich soils. The waters showed neutral to slightly alkaline pH, redox potential values indicating oxidizing conditions, electrical conductivity in the range of 0.2 to 3.7 mS cm(-1), and dissolved organic carbon ≤2 mg L(-1). The waters collected upstream of the mine have Ca-bicarbonate dominant composition, and median concentration of Sb(tot) of 1.7 μg L(-1) (that is total antimony determined in waters filtered through 0.45 μm), a value relatively high as compared with the background value (≤0.5 μg L(-1) Sb) estimated for Sardinian waters, but below the limits established by the European Union and the World Health Organization for drinking water (5 μg L(-1) Sb and 20 μg L(-1) Sb, respectively). The waters flowing in the mine area are characterized by Ca-sulfate dominant composition, and median concentrations of 7000 μg L(-1) Sb(tot). Extreme concentrations, up to 30,000 μg L(-1) Sb(tot), were observed in waters flowing out of the slag materials derived from the processing of Sb-ore. The Sb(III) was in the range of 0.8 to 760 μg L(-1) and represented up to 6% of Sb(tot). In the waters collected downstream of the mine, median Sb(tot) concentrations decreased as distance from the mine area increases: 1300 μg L(-1) Sb(tot) in the stream Rio Ciurixeda at 3 km distance, and 25 μg L(-1) Sb(tot) in the main River Flumendosa 15 km further downstream. Attenuation of Sb contamination was mainly due to dilution. Results of modeling, carried out by both EQ3 and Visual MINTEQ computer programs, suggest that sorption of dissolved Sb onto solid phases, and/or precipitation of Sb-bearing minerals, likely give a minor contribution to attenuation of Sb contamination. The slightly alkaline pH and oxidizing conditions might favor the persistence of inorganic Sb(V)-bearing species at long distance in the studied waters. Concentrations of Sb in the plants Pistacia lentiscus and Asparagus ranged from 0.1 to 22 mg kg(-1), with maximum values in plants growing very close to the mining-related wastes. The P. lentiscus grows well on the soils highly contaminated with Sb at Su Suergiu and might be used for revegetation of the Sb-rich heaps, thus contributing to reduce the dispersion of contaminated materials. Major effects of contamination were observed on the water bodies located downstream of the Su Suergiu abandoned mine. The maximum load (16.6 kg Sb per day) to the Flumendosa, the main aquatic recipient, was observed after heavy rain events. Therefore, priorities of mitigation actions should be focused on minimizing the contact of rain and runoff waters on the heaps of mining wastes.

Heavy metal concentrations in timberline trees of eastern Tibetan Plateau

Concentrations of 14 heavy metals (Ag, As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Sb, Tl, V, and Zn) in needles, twigs, bark and xylem of spruce and fir collected at the timberline of eight sites along the Hengduan Mountains, eastern Tibetan Plateau, are reported. Twigs had the highest concentration for most of elements, while xylem had the lowest concentration. The connections between elements in twigs were much richer than other organ/tissues. Pb, Ni, As, Sb, Co, Cd, Hg, Cr and Tl which are partly through anthropogenic sources and brought in by monsoon, have been accumulated in twigs and needles by wet or dry deposition in south and east sites where are within or near pollutant sources. Under moderate pollution situation, vegetation are able to adjust the nutrient element (Cu and Zn) cycle rate, thus maintain a stable concentration level. Seldom V, Ag, and Mo are from external anthropogenic sources. Needles and twigs can be used as biomonitors for ecosystem environment when needles can simply distinguish the origin of elements and twigs are more sensitive to extra heavy metal input.

Accumulation of particulate matter and trace elements on vegetation as affected by pollution level, rainfall and the passage of time

Particulate matter is harmful to human health. To reduce its concentration in air, plants could be used as biological filters, accumulating particulate matter on their foliage. In a study carried out at three sites with differing pollution levels and exposure to precipitation, the capacity of evergreen species (Taxus baccata L., Hedera helix L. and Pinus sylvestris L.) to accumulate particulate matter and trace elements from ambient air in urban areas was investigated. The effects of rainfall and the passage of time on particulate matter deposition on foliage were also determined. The results showed that foliage accumulated an increasing quantity of particulate matter in successive months, but the actual amount of particulate matter and trace elements accumulated differed considerably between sites and plant species. The greatest accumulation of air pollutants occurred on the foliage of plants protected from the rain at a site exposed to traffic related pollution and the smallest accumulation at a rural site. Among the species analysed, the deposited mass of particulate matter and trace elements was the greatest on P. sylvestris. In all species, precipitation removed a considerable proportion of particles accumulated on foliage. Most of the removed particulate matter was large size fraction, but little belong to the smallest size fraction. These results showed that both, the dynamics of deposition and leaf washing by rain during the season need to be considered when evaluating the total effect of vegetation in pollutant remediation.

Integrated evaluation of aerogenic pollution by air-transported heavy metals (Pb, Cd, Ni, Zn, Mn and Cu) in the analysis of the main deposit media

The composition of the ambient air is constantly changing; therefore, the monitoring of ambient air quality to detect the changes caused by aerogenic pollutants makes the essential part of general environmental monitoring. To achieve more effective improvement of the ambient air quality, the Directive 2008/50/EC on 'Ambient Air Quality and Cleaner Air for Europe' was adopted by the European Parliament and the European Council. It informed the public and enterprises about a negative effect of pollution on humans, animals and plants, as well as about the need for monitoring aerogenic pollutants not only at the continuous monitoring stations but also by using indicator methods, i.e. by analysing natural deposit media. The problem of determining the relationship between the accumulation level of pollutants by a deposit medium and the level of air pollution and its risks is constantly growing in importance. The paper presents a comprehensive analysis of the response of the main four deposit media, i.e. snow cover, soil, pine bark and epigeic mosses, to the long-term pollution by aerogenic pollutants which can be observed in the area of oil refinery influence. Based on the quantitative expressions of the amounts of the accumulated pollutants in the deposit media, the territory of the oil refinery investigated in this paper has been referred to the areas of mild or moderate pollution.