Improved biomonitoring of airborne contaminants by combined use of holm oak leaves and epiphytic moss

Biogeochemical prospecting of metallic critical raw materials: soil to plant transfer in SW Ciudad Real Province, Spain

The soil-plant transfer of trace elements is a complex system in which many factors are involved such as the availability and bioavailability of elements in the soil, climate, pedological parameters, and the essential or toxic character of the elements. The present study proposes the evaluation of the use of multielement contents in vascular plants for prospecting ore deposits of trace elements of strategic interest for Europe. To accomplish this general goal, a study of the soil-plant transfer of major and trace elements using Quercus ilex as a study plant has been developed in the context of two geological domains with very different characteristics in geological terms and in the presence of ore deposits: the Almadén syncline for Hg and the Guadalmez syncline for Sb. The results have made it possible to differentiate geological domains not only in terms of individual elements, but also as a combination of major and trace elements using Factor Analysis. The bioconcentration factors have demonstrated the uptake of macronutrients and micronutrients in very high concentrations but these were barely dependent, or even independent of the concentrations in the soil, in addition to high values of this factor for Sb. The Factor Analysis allowed for the differentiation of geogenic elements from other linked to stibnite ore deposits (Sb, S, and Cu). This element (Sb) can be uptake by Quercus ilex via the root and from there translocating it to the leaves, showing a direct relation between concentrations in soil and plants. This finding opens the possibility of using Quercus ilex leaves for biogeochemical prospecting of geological domains or lithological types of interest to prospect for Sb deposits.

Metabolite Profiling of Conifer Needles: Tracing Pollution and Climate Effects

In the face of escalating environmental challenges, understanding the intricate relationship between plant metabolites, pollution stress, and climatic conditions is of paramount importance. This study aimed to conduct a comprehensive analysis of metabolic variations generated through 1H and 13C NMR measurements in evergreen needles collected from different regions with varying pollution levels. Multivariate analyses were employed to identify specific metabolites responsive to pollution stress and climatic factors. Air pollution indicators were assessed through ANOVA and Pearson correlation analyses. Our results revealed significant metabolic changes attributed to geographical origin, establishing these conifer species as potential indicators for both air pollution and climatic conditions. High levels of air pollution correlated with increased glucose and decreased levels of formic acid and choline. Principal component analysis (PCA) unveiled a clear species separation, largely influenced by succinic acid and threonine. Discriminant analysis (DA) confirmed these findings, highlighting the positive correlation of glucose with pollution grade. Beyond pollution assessment, these metabolic variations could have ecological implications, impacting interactions and ecological functions. Our study underscores the dynamic interplay between conifer metabolism, environmental stressors, and ecological systems. These findings not only advance environmental monitoring practices but also pave the way for holistic research encompassing ecological and physiological dimensions, shedding light on the multifaceted roles of metabolites in conifer responses to environmental challenges.

Air quality in post-mining towns: tracking potentially toxic elements using tree leaves

In this study, leaves of the evergreen holm oak Quercus ilex were used to assess airborne contamination of potentially toxic elements (PTEs) at five towns located on the slopes of the Mt. Amiata (central Italy), an area with a long history of mining and, more recently, an important district for the industrial exploitation of geothermal energy. PTE composition and covariance of washed and unwashed Q. ilex leaves of three different ages (6, 12 and 24 month-old) were used to identify atmospheric inputs of PTEs at residential areas, evaluate long-term adsorption and retention of PTEs by the leaves, thus providing an indication of potential human exposure. Moreover, the determination of foliar concentrations of major elements (C, N, S and P) allowed an assessment of the nutritional status of the investigated urban tree stands which excluded the existence of stress condition caused by air pollution or other disturbances. Results indicated that overall Pb, Cu, and Cd concentration were low in the investigated urban sites, if compared with similar studies conducted in larger Italian cities, denoting a low contribution of vehicular traffic to the atmospheric pathway. The five urban settlements were characterized by a specific profile of elements (Al, Ba, Hg and Sb) enriched in unwashed leaves, resulting from the distinct geochemical characteristics of the area and from diffuse (i.e., urban activity) and point sources of PTEs emission (i.e., brownfields, geothermal power plants). The latter sources primarily govern the distribution of Hg, whose contamination was found to be very localized close to a major abandoned mining area. Our data provided quantitative evidence of the spectrum of PTEs potentially impacting resident population and may prove useful in support of follow-up instrumental monitoring campaigns of air quality, as well as for human health and ecological risk assessments.

Global ambient air quality monitoring: Can mosses help? A systematic meta-analysis of literature about passive moss biomonitoring

Surging incidents of air quality-related public health hazards, and environmental degradation, have prompted the global authorities to seek newer avenues of air quality monitoring, especially in developing economies, where the situation appears most alarming besides difficulties around 'adequate' deployment of air quality sensors. In the present narrative, we adopt a systematic review methodology (PRISMA, Preferred Reporting Items for Systematic reviews and Meta-Analyses) around recent global literature (2002-2022), around moss-based passive biomonitoring approaches which might offer the regulatory authorities a complementary means to fill 'gaps' in existing air quality records. Following the 4-phased search procedure under PRISMA, total of 123 documents were selected for review. A wealth of research demonstrates how passive biomonitoring, with strategic use of mosses, could become an invaluable regulatory (and research) tool to monitor atmospheric deposition patterns and help identifying the main drivers of air quality changes (e.g., anthropogenic and/or natural). Besides individual studies, we briefly reflect on the European Moss Survey, underway since 1990, which aptly showcases mosses as 'naturally occurring' sensors of ambient air quality for a slew of metals (heavy and trace) and persistent organic pollutants, and help assessing spatio-temporal changes therein. To that end, we urge the global research community to conduct targeted research around various pollutant uptake mechanisms by mosses (e.g., species-specific interactions, environmental conditions, land management practices). Of late, mosses have found various environmental applications as well, such as in epidemiological investigations, identification of pollutant sources and transport mechanisms, assessment of air quality in diverse and complex urban ecosystems, and even detecting short-term changes in ambient air quality (e.g., COVID-19 Lockdown), each being critical for the authorities to develop informed and strategic regulatory measures. To that end, we review current literature and highlight to the regulatory authorities how to extend moss-based observations, by integrating them with a wide range of ecological indicators to assess regional environmental vulnerability/risk due to degrading air quality. Overall, an underlying motive behind this narrative was to broaden the current regulatory outlook and purview, to bolster and diversify existing air quality monitoring initiatives, by coupling the moss-based outputs with the traditional, sensor-based datasets, and attain improved spatial representation. However, we also make a strong case of conducting more targeted research to fill in the 'gaps' in our current understanding of moss-based passive biomonitoring details, with increased case studies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10668-023-03043-0.

Modeling exposure to airborne metals using moss biomonitoring in cemeteries in two urban areas around Paris and Lyon in France

Exposure of the general population to airborne metals remains poorly estimated despite the potential health risks. Passive moss biomonitoring can proxy air quality at fine resolution over large areas, mainly in rural areas. We adapted the technique to urban areas to develop fine concentration maps for several metals for Constances cohort's participants. We sampled Grimmia pulvinata in 77 and 51 cemeteries within ∼50 km of Paris and Lyon city centers, respectively. We developed land-use regression models for 14 metals including cadmium, lead, and antimony; potential predictors included the amount of urban, agricultural, forest, and water around cemeteries, population density, altitude, and distance to major roads. We used both kriging with external drift and land use regression followed by residual kriging when necessary to derive concentration maps (500 × 500 m) for each metal and region. Both approaches led to similar results. The most frequent predictors were the amount of urban, agricultural, or forest areas. Depending on the metal, the models explained part of the spatial variability, from 6% for vanadium in Lyon to 84% for antimony in Paris, but mostly between 20% and 60%, with better results for metals emitted by human activities. Moss biomonitoring in cemeteries proves efficient for obtaining airborne metal exposures in urban areas for the most common metals.

Status and trends of mercury pollution of the atmosphere and terrestrial ecosystems in Poland

The goal of this paper is to assess the current status and trends of total mercury (THg) contamination of the atmosphere and terrestrial ecosystems in Poland. The study shows that the reduced domestic and worldwide atmospheric emission of Hg resulted in decreased THg level in the terrestrial biotope and biosphere. Considering that Poland is one of the main Hg emitters in Europe, the THg concentrations in its abiotic environment are still elevated. However, the THg level in terrestrial organisms is relatively low, which is because a large proportion of Hg deposited on land is accumulated in organic-rich soils. Regarding the THg concentration, consumption of wildlife and livestock from Poland is safe for humans. Nevertheless, the authors indicate the need for effective environmental monitoring, based on selected bioindicators, which is crucial considering the slowing reduction of Hg emission combined with the consequences of the changing climate.

Monitoring of particulate matter (PM2.5 and PM10) in San Juan city, Argentina, using active samplers and the species Tillandsia capillaris

The concentration of particulate matter (PM2.5 and PM10) was studied in San Juan city, Argentina, during winter and spring of 2017. Samplers of particulate matter (PM) and individuals of the plant species Tillandsia capillaris were placed in the centre of the city to be used as a biomonitors of atmospheric particulate matter. The PM filters and PM deposited in T. capillaris leaves were analysed to measure particle concentration and concentrations of elements (K, Ca, Mn, Fe, Cu, Zn, Br, Sr, Ba and Pb) using X-ray fluorescence by synchrotron radiation (SR-XRF). Linear regression analysis showed significant positive correlations between PM concentration in the atmosphere and the particles deposited on T. capillaris leaves. The elements quantified in PM2.5 and PM10 filters were subjected to a principal component analysis, which showed the presence of three emission sources in the study area (soil, vehicular traffic and industry) in both fractions. It was not possible to conduct this analysis with the elements obtained from the extraction of T. capillaris leaves, since most of them are solubilised at the moment of extraction. Biomonitoring with T. capillaris might be used to estimate the concentration of particulate matter in large areas or in remote sites with no electrical power supply to run active samplers. Further studies should be carried out in other regions, and more variables should be incorporated to obtain increasingly deterministic models.

Moss (Hypnum amabile) as biomonitor of genotoxic damage and as bioaccumulator of atmospheric pollutants at five different sites of Mexico City and metropolitan area

Mexico City has been classified as one megacity, its altitude, thermal inversions, and high seasonal radiation are factors that prevent dispersion of pollutants, which effects are detrimental to health. Therefore, it is important to have an organism that allows evaluate the damage caused by such exposure, as is the case of mosses that obtain nutrients from the atmosphere; this property makes them excellent biomonitors to evaluate genotoxic damage caused by exposure to pollutants, in addition to its large accumulation capacity. For these reasons and to relate the effects of atmospheric pollution with a biological response, we propose to use the moss Hypnum amabile as a bioaccumulator of atmospheric pollutants and biomonitor of the genotoxic effect that the air pollution can induce it through the comet assay. Mosses were placed in five localities of Mexico City and the metropolitan area on the first days of each month of the dry (cold and warm) and rainy seasons, with a 30-day exposure, after which they were changed for a new sample (for 8 months). Each month, the moss exposed was collected and nuclei were isolated to perform comet assay. To demonstrate heavy metal bioaccumulation capacity, samples were observed in a transmission electron microscope and qualitative microanalysis by scanning electron microscopy was carried out parallel. The chemical analysis detected 14 heavy metals by mass spectrometry method with inductively coupled plasma source. Additionally, 22 polycyclic aromatic hydrocarbons were also determined by gas chromatography-mass spectrometry. Analysis of variance and Kruskal-Wallis test were performed to compare DNA damage of each station against control, which was maintained in the laboratory in a chamber with filtered air. This is the first study on the genotoxicity of mosses exposed to the atmosphere of Mexico City and metropolitan area that in addition to proving their accumulation capacity shows their ability to respond to atmospheric pollutants.

A critical review on plant biomonitors for determination of polycyclic aromatic hydrocarbons (PAHs) in air through solvent extraction techniques

Polycyclic aromatic hydrocarbons (PAHs) are hydrocarbons having two or more fused aromatic rings, released from natural (like forest fires and volcanic eruption) as well as man-made sources (like burning of fossil fuel & wood, automobile emission). They are persistent priority pollutants and continue to last for a long time in the environment causing severe damage to human health owing to their genotoxicity, mutagenicity and carcinogenicity. The study of PAHs in environment has therefore aroused a global concern. PAHs adsorption to plant cell wall is facilitated by transpiration and plant root lipids which help PAHs transfer from roots to leaves and stalks, causing more accumulation of contaminants with the increase in lipid content. Hence, these bioaccumulators can be utilized as biomonitors for indirect assessment of ambient air pollution. Efficacy of specific plants, lichens and mosses as useful biomonitors of airborne PAHs pollution has been discussed in this review along with prevalent classical and modified extraction techniques coupled with proper analytical procedures in order to gain an insight into the assessment of atmospheric PAHs concentrations. Different modern and modified solvent extraction techniques along with conventional Soxhlet method are identified for extraction of PAHs from accumulative bioindicators and analytical methods are also developed for accurate determination of PAHs. Process parameters like choice of solvent, temperature, time of extraction, pressure and matrix characteristics are usually checked. An approach of biomonitoring of PAHs using plants, lichens and mosses has been discussed here as they usually trap the atmospheric PAHs and mineralize them.

Testing a novel biotechnological passive sampler for monitoring atmospheric PAH pollution

In this study we evaluated a new type of passive air sampler, the "mossphere" device, filled with a Sphagnum palustre clone. For this purpose, we compared the atmospheric levels of polyaromatic hydrocarbons (PAHs) collected using this device and those collected in conventional bulk deposition and particulate matter (PM10) samplers. All three types of samplers were exposed at 10 sites affected by different levels of pollution and located in two different climate zones. The bulk deposition/ mossphere comparison yielded a greater number of significant regressions with higher coefficients of determination than the PM10/ mossphere comparison. No significant regressions were observed for 3-ring PAHs in either comparison. The mosspheres explain ca. 50% of the variability of the concentrations of 4-, 5- and 6-ring PAHs and total PAHs detected in PM10 and ca. 70% of the corresponding concentrations detected in the bulk deposition. The use of the Sphagnum clone enables standardization of the set-up, thus making the mossphere device a good sampling tool for monitoring 4-, 5- and 6-ring and total PAHs, especially those associated with bulk deposition. The findings indicate the potential usefulness of this innovative technology for mapping PAH levels.

National environmental quality assessment and monitoring of atmospheric heavy metal pollution - A moss bag approach

As airborne pollution is recognised as the single largest environmental health hazard in Europe, the necessity to develop effective systems for monitoring and reducing the level of air pollutants, becomes imperative. The paper describes a tested and implemented long-term biomonitoring system for airborne heavy metals at a national scale. Moss bags (Hylocomium splendens) were exposed in 142 monitoring stations designated in Romania, and the content of Pb, Cd, Ni and As was quantified using inductively coupled plasma mass spectrometry. The results revealed that the accumulation of heavy metals exceeded the established thresholds, marking high pollution levels in 8.8% of samples for As, in 5.63% samples for Cd, in 3.17% samples for Pb, and in 0.35% samples for Ni. The maximum heavy metal concentration was 113.77 mg kg^-1 dry weight for Pb, 44.93 mg kg^-1 dry weight for Ni, 14.68 mg kg^-1 dry weight for As, and 3.88 mg kg^-1 dry weight for Cd, with several overlaps for at least two metals, thus marking pollution hotspots. In order to process, summarise and communicate the obtained data, a software named BioMonRo has been developed as the core part of a complex monitoring and warning-informative system. The software is able to generate heavy metal pollution maps and specific reports, depicting the levels and patterns of distribution, which can be automatically sent to a number of interested recipients. The results show that the developed national system is functional, cost-effective, and could be successfully used for long-term monitoring of airborne heavy metals.

Indoor vs. outdoor airborne element array: A novel approach using moss bags to explore possible pollution sources

This study investigated by the moss-bag approach the pattern of air dispersed elements in 12 coupled indoor/outdoor exposure sites, all located in urban and rural residential areas. The aims were to discriminate indoor vs. outdoor element composition in coupled exposure sites and find possible relation between moss elemental profile and specific characteristics of each exposure site. Elements were considered enriched when in 60% of the sites, post-exposure concentration exceeded pre-exposure concentration plus two folds the standard deviation. Of the 53 analyzed elements, 15 (As, B, Ca, Co, Cr, Cu, Mn, Mo, Ni, Sb, Se, Sn, Sr, V, Zn) were enriched in moss exposed outdoor, whereas a subset of 7 elements (As, B, Cr, Mo, Ni, Se, V) were enriched also in indoor moss samples. The cluster analysis of the sites based on all elements, clearly separated samples in two groups corresponding to mosses exposed indoor and outdoor, with the latter generally exceeding the first. Among outdoor sites, urban were most impacted than rural; whereas other factors (e.g., heating and cooking systems, building material, residence time and family life style) could affect element profile of indoor environments. Based on the indoor/outdoor ratio, As derived from outdoor and indoor sources, B, Mo and Se were enriched mostly in outdoor sites; Ni, Cr and V were specifically enriched in most indoor samples, supporting the presence of indoor emitting sources for these elements. A PCA of all indoor sites based on enriched elements and site characteristics showed that traffic affected indoor pollution in urban areas. The moss bag approach provided useful information for a global assessment of human exposure.

Congruence Evaluation of Mercury Pollution Patterns Around a Waste Incinerator over a 16-Year-Long Period Using Different Biomonitors

To date, there has been an ever-increasing interest in complementary air monitoring techniques, which may fill the deficiencies of air quality networks. The present work reports the results concerning five biomonitoring surveys (BSs) performed in the proximity of a waste incinerator (WI) over a 16-year period. Hg emission related to the WI activity was monitored by means of both active and passive BSs based on three photosynthetically-active biomonitors (i.e., two epiphytic lichens: Pseudevernia furfuracea and Xanthoria parietina; one vascular plant: Robinia pseudoacacia) collected or exposed before and/or after the WI installation, and after a four-month period of inactivity. Hg concentration values observed in biomonitor samples varied according to the implemented species and to the status of WI plant (active vs. inactive). Our data demonstrate that, in the same pollution scenario, P. furfuracea accumulates three times more Hg than both X. parietina and R. pseudoacacia. The results are discussed in the context of the actual European Union directives concerning air pollution monitoring and assessment, revealing that both active and passive BSs are efficient tools to provide a reliable estimation of the spatial changes of Hg concentrations in the environment.

Evidence on the effectiveness of mosses for biomonitoring of microplastics in fresh water environment

Mosses are well known as biomonitors of fresh water for metal pollutants, but no studies were reported so far about their ability to intercept plastic particles, although this kind of pollution has become an urgent issue worldwide. In the present work, the interaction between the moss Sphagnum palustre L. cultured in vitro and polystyrene nanoparticles (NPs) was studied for the first time in a laboratory experiment, in the view of using moss transplants for detecting microplastics in fresh water environments. The ability of S. palustre to intercept and retain polystyrene, and the effects of vitality and post-exposure washing on NP retention by moss were tested. Fluorescence microscope observations showed that polystyrene NPs were retained by moss leaves in form of small (the most abundant fraction) and large aggregates. Particle count analysis highlighted that the number of particles increased while increasing the exposure time. Moreover, moss devitalization favored NP accumulation, likely because of cell membrane damages occurred in dead moss material. Post-exposure washing induced a loss of larger aggregates, suggesting that exposure time is a key point to be carefully evaluated in field conditions. These results encourage the use of S. palustre transplants for monitoring microplastics contamination of fresh water environments.

Comparisons of three plant species in accumulating polycyclic aromatic hydrocarbons (PAHs) from the atmosphere: a review

Plant leaves play a key role in the accumulation of PAHs, as they are able to capture PAHs from the air. In this paper, the mechanism, including absorption and adsorption, for plants to scavenge PAHs from the air was reviewed. Moreover, the differences of PAHs accumulating capability are mainly compared among three representative plant species, including pine needles, Holm oak leaves, and moss. On the whole, it is shown that oak leaves present the strongest PAHs accumulating capability for total PAHs among three plants species. Oak leaves and pine needles show higher accumulating tendency for light and medium molecular weight PAHs, whereas moss presents stronger accumulating tendency for heavy molecular weight PAHs. Environmental factors (i.e., temperature, seasonality, and photolysis) also account for the process of PAHs transferred from air to plants. With the temperature climbing, the concentration of PAHs in the air will increase. Due to the meteorological conditions and the human activities changed with seasons, it was shown that the PAHs were greatly accumulated in leaf surface in winter than in summer. Photolysis was also able to influence the PAHs on leaf surface, which are significant to this process. In conclusion, oak, pine, and moss can be used to filter PAHs when considering urban landscaping. Besides combining the traditional analytical methods with in situ determination, there might be able to provide a novel method to further study the specific absorption mechanisms. The accumulation of PAHs in crop leaf surface related to the application of surfactants is also worth studying.

Biomonitoring levels and trends of PAHs and synthetic musks associated with land use in urban environments

Polycyclic aromatic hydrocarbons (PAHs) are some of the most studied organic compounds in urban environments, due to their known adverse effects on human health and persistence in environmental matrices. During the last decade, new groups of organic compounds with an intensive use worldwide such as synthetic musks have been raising the interest of the scientific community given their toxicity and health effects. However, literature is still scarce in studies dealing with their concentration in the environment, especially in developing countries, where they are even more rare or non-existing at all. We employed leaves of Ligustrum lucidum to assess the concentrations of PAHs and synthetic musks in different land use areas in Cordoba city, therefore contributing with environmental information in Argentina. We found higher levels of PAHs in urban and industrial areas than in the peri-urban sampling sites, naphthalene being one of the dominant PAHs in all sampling areas. Regarding synthetic musk fragrances, polycyclic musks were the most contributing compounds and the highest levels found in industrial areas as well. A high environmental risk could be expected due to the frequent occurrence of galaxolide in addition to the high hazardous potential of phantolide, which was present in 50% of the samples. The results of the present study indicate that leaves of an urban ubiquitous tree can be used to assess the spatial behavior of both "classic" and "emerging" organic pollutants, allowing an assessment of urban air quality in areas where common air sampling devices are unavailable.

Comparison of moss and pine needles as bioindicators of transboundary polycyclic aromatic hydrocarbon pollution in central Japan

Atmospheric pollution by polycyclic aromatic hydrocarbons (PAHs) has become a serious problem, especially in Asia, as PAHs can severely affect ecologically important mountainous areas. Using pine needles and mosses as bio-indicators, this study examined PAH pollution in a mountainous study area and evaluated the influence of transboundary PAHs. PAHs in urban areas were also evaluated for comparison. The study sites were alpine areas and urban areas (inland or coastal cities) across central Japan, in the easternmost part of Asia where atmospheric pollutants are transported from mainland Asia. The mean PAH concentrations of pine needles and mosses were 198.9 ± 184.2 ng g^-1 dry weight (dw) and 131.8 ± 60.7 ng g^-1 dw (mean ± SD), respectively. Pine needles preferentially accumulated PAHs with low molecular weights (LMW PAHs) and exhibited large differences in both PAH concentration and isomer ratios between alpine and urban sites. These differences can be explained by the strong influence of LMW PAHs emitted from domestic sources, which decreased and changed during transport from urban to alpine sites due to dry/wet deposition and photodegradation. In contrast, mosses accumulated a higher ratio of PAHs with high molecular weight (HMW PAHs). A comparison of isomer ratios showed that the PAH source for alpine moss was similar to that for northern coastal cities, which are typically influenced by long-transported PAHs from East Asia. Thus, these results indicate that alpine moss can also be strongly affected by the transboundary PAHs. It is likely that the uptake characteristics of moss, alpine climate, and alpine locations far from urban areas can strengthen the influence of transboundary pollution. Based on these results, the limitations and most effective use of bioindicators of PAH pollution for preserving alpine ecosystems are discussed.

Genotoxic effect of Pb and Cd on in vitro cultures of Sphagnum palustre: An evaluation by ISSR markers

In the present work, the genotoxic effect of cadmium and lead supplied in a laboratory trial, was investigated for the first time in the moss Sphagnum palustre, by ISSR molecular markers. A total of 169 reproducible bands were obtained with 12 primers, ten of which gave polymorphisms (i.e., appearance/disappearance of bands), indicating a clear genotoxic effect induced by the metals. Both metals induced a decrease of the genome template stability in a dose dependent manner. At concentration >10^-5 Cd also induced a general toxic effect in S. palustre, leading to chlorophyll degradation and moss death. Moreover, we followed the fate of supplied heavy metals into the moss tissue by SEM-EDX to see if they entered the cells. SEM-EDX observations on moss cultures treated with equimolar concentrations of the two metals showed that most Pb precipitated in form of particles on moss surface, while Cd did not aggregate in particles and was not found on moss surface. In light of these findings, we concluded that probably Pb induced a genotoxic effect at lower intracellular concentrations than Cd.

Influence of soil characteristics on rare earth fingerprints in mosses and mushrooms: Example of a pristine temperate rainforest (Slavonia, Croatia)

The present study aims to investigate levels and distribution of rare earth elements (REE) in soils, mosses and mushrooms of a pristine temperate rainforest, a non-polluted natural system, in order to characterise their environmental availability and mobility. The multielement analysis of digested soil, moss and mushroom samples was performed by High Resolution Inductively Coupled Plasma Mass Spectrometry. The distribution of rare earths in mosses and mushrooms was found primarily affected by local pedological setting. Mosses displayed a consistent lithological signature with an almost insignificant REE fractionation compared to soils. Mushrooms showed differences in REE concentrations in certain parts of the fruiting body with regard to their main physiological function and indicated a significant impact of soil organic content on the overall REEs uptake. Results of our work highlight the importance of substrate characteristics on the initial levels of REEs in mosses and mushrooms. Moreover, this study provides baseline data on the rare earth element levels in mosses and mushrooms growing in a pristine forest area characterised by naturally elevated REE levels in the soil.

Heavy metal and polycyclic aromatic hydrocarbon concentrations in Quercus ilex L. leaves fit an a priori subdivision in site typologies based on human management

Concentrations of four heavy metals (HMs) (Cd, Cr, Fe, Pb) and four polycyclic aromatic hydrocarbons (PAHs) (fluoranthene, phenanthrene, chrysene, benzo[a]pyrene) in Quercus ilex L. leaves collected at the Campania Region (Southern Italy) in previous air biomonitoring studies were employed to (1) test the correspondence with an a priori site subdivision (remote, periurban, and urban) and (2) evaluate long temporal trends of HM (approximately 20 years) and PAH (approximately 10 years) air contaminations. Overall, Q. ilex leaf HM and PAH concentrations resulted along the gradient: remote < periurban < urban sites, reflecting the a priori subdivision based on human management. Over a long time, although a clear decrease of leaf Pb, chrysene, fluoranthene, and phenanthrene concentrations occurred at the urban sites, a high contamination level persists.

Tracking the route of phenanthrene uptake in mosses: An experimental trial

In recent decades, mosses have been used as native species or as transplants in monitoring a wide range of pollutants from inorganic (i.e. metals and metalloids) to organic contaminants (mainly polycyclic aromatic hydrocarbons-PAHs). To implement the use of mosses as biomonitors of PAHs, one important issue is the study of the interactions between these compounds and moss tissues. In this study we investigated the mode of phenanthrene uptake in four moss species (Amblystegium humile, Plagiomnium affine, Hypnum cupressiforme and a clone of Sphagnum palustre) and its movements from air to plant surface and within the biomonitors, using fluorescent and confocal microscopy. The target compound, partitioned between gas and particulate phase depending on air conditions, was selected since it is one of the most abundant PAHs released into the atmosphere. Our findings support the hypothesis that phenanthrene aggregates in particles and in this form it is chiefly intercepted and uptaken onto moss surfaces, albeit with different frequency in the four species, with S. palustre>H. cupressiforme>P. affine=A. humile. Phenanthrene enters the dead, empty hyalocysts of S. palustre. Specific surface area and composition, frequency and distribution of binding groups may also explain the different ability of phenanthrene uptake by the four moss species.

Development of an analytical method to determine oxy-PAHs and PAHs in Taxus baccata leaves

An analytical method was developed and optimized for the quantification of 16 polycyclic aromatic hydrocarbons (PAHs) and 12 oxygenated PAHs in Taxus baccata leaves. Emphasis was given to the development of an in-cell cleanup step using pressurized solvent extraction, a cleanup step using solid-phase extraction, and the instrumental analysis by GC-HRMS. Different extraction temperatures (between 50 and 200 °C) and Florisil quantities were evaluated for the extraction process. Based on the evaluation of both recoveries and matrix effect factors, a temperature of 200 °C and 1 g Florisil was selected as the optimum. However, the in-cell cleanup was not sufficient in the long term due to increasing chromatographic peak broadening, and further cleanup was necessary. Solid-phase extraction (using Florisil) was evaluated, and breakthrough curves were acquired for all target compounds to determine the optimal elution volume and avoiding matrix interference. Recoveries of the target compounds ranged from 58 to 87 % for the PAHs and from 5 to 105 % for the oxy-PAHs. Matrix effects were determined for all individual target compounds. The optimized method was applied to T. baccata samples obtained from ten sampling locations in Ghent, Belgium. This is the first biomonitoring study in Ghent for PAHs and oxy-PAHs. The presence of significant amounts of toxicologically relevant oxygenated PAHs (Oxy-PAHs) (can enhance ROS formation in human lung cells) in T. baccata was confirmed (max ∑Oxy-PAHs: 230 ng/g; max ∑PAHs: 389 ng/g). This means that these oxygenated PAHs are important pollutants and should be included in future monitoring studies.

Biomonitoring heavy metal contaminations by moss visible parameters

Traditional sampling for heavy metal monitoring is a time-consuming and inconvenient method, which also does not indicate contaminants non-invasively and instantaneously. Moss is sensitive to heavy metals and is therefore considered a pollution indicator. However, it is unknown what kind physiological parameters can indicate metal contaminations quickly and non-invasively. Here, we systematically examined the effects of six heavy metals on physiological parameters and photosynthetic activities of two moss species grown in aquatic media or moist soil surface. We suggest that a phenotype with anthocyanin accumulation pattern and chlorosis pattern and two chlorophyll fluorescence parameters with their images can roughly reflect metal species groups, concentrations and differences between the two moss species. In other words, metal contaminations could be roughly estimated visually using the naked eye. Enzymatic and non-enzymatic anti-oxidative abilities and photosynthetic protein contents of Eurhynchium eustegium were higher than those of Taxiphyllum taxirameum, indicating their differential metal tolerance. Neither anti-oxidative abilities nor photosynthetic proteins were found to be ideal indicators. This study provides new ideas to monitor heavy metals rapidly and non-invasively in water or on wetland and moist soil surface.

The bark of holm oak (Quercus ilex, L.) for airborne Cr(VI) monitoring

In this work, the bark of holm oak was used as a bioindicator to study the atmospheric distribution of Cr(VI). The chosen method (alkaline extraction and atomic absorption determination) was found in the literature, adapted for use with the matrix involved, and validated. The method had some limits, but provided an excellent estimation of Cr(VI) concentrations with good sensitivity and a reasonable time of analysis and cost. Thirty-four samples of holm oak collected in three areas characterised by different possible sources of pollution (the area near a former chromate production plant, an urban area, and a rural "reference" area) were analysed, obtaining concentrations ranging from 1.54 to 502 μg g(-1) near the industrial plant, ranging from 0.22 to 1.35 μg g(-1) in the urban area, and mostly below the detection limit (0.04 μg g(-1)) in the rural area. The bark of holm oak proved to be a good bioindicator to detect Cr(VI) in the environment. The extraction procedure followed by atomic absorption analysis is simple, provides good sensitivity, and it is suitable for environmental studies.

Mosses as an integrating tool for monitoring PAH atmospheric deposition: comparison with total deposition and evaluation of bioconcentration factors. A year-long case-study

Polycyclic aromatic hydrocarbon (PAH) atmospheric deposition was evaluated at a remote site in Northern Spain using moss biomonitoring with Hylocomium splendens (Hedw.) Schimp., and by measuring the total deposition fluxes of PAHs. The year-long study allowed seasonal variations of PAH content in mosses to be observed, and these followed a similar trend to those of PAH fluxes in total deposition. Generally, atmospheric deposition of PAHs is greater in winter than in summer, due to more PAH emissions from domestic heating, less photoreactivity of the compounds, and intense leaching of the atmosphere by wet deposition. However, fractionation of these molecules between the environmental compartments occurs: PAH fluxes in total deposition and PAH concentrations in mosses are correlated with their solubility (r=0.852, p<0.01) and lipophilic properties (KOW, r=0.768, p<0.01), respectively. This annual study therefore showed that atmospheric PAH fluxes can be estimated with moss biomonitoring data if the bioconcentration or 'enriching' factors are known.

Persistent pollutants and the patchiness of urban green areas as drivers of genetic richness in the epiphytic moss Leptodon smithii

We determined genetic variation and metal and polycyclic aromatic hydrocarbon concentrations in Leptodon smithii moss collected in holm oak stands at cities, outskirts and remote areas of Campania and Tuscany (Italy) to investigate if anthropogenic pressure (pollutant emissions and land use change) affects moss genetic richness. In both regions, metal and polycyclic aromatic hydrocarbon concentrations reflected the trend urban>outskirts>remote areas, excepting Tuscany remote site. In both regions, the moss gene diversity increased from urban to remote areas. The findings suggest the extent and the fragmentation of urban green areas, as drivers of moss genetic richness.

Concentration profiles and spatial distribution of perfluoroalkyl substances in an industrial center with condensed fluorochemical facilities

Jiangsu Hi-tech Fluorochemical Industry Park, China, is one of the largest fluorochemical industry centers in Asia and could be a point source of polyfluoroalkyl substances (PFASs) to the surrounding environment. Besides water, sediment and soil samples, tree leaves and bark were also collected to monitor airborne PFASs around the facilities. Perfluorooctanoic acid and short-chain perfluorocarboxylates including perfluorohexanoic acid and perfluoropentanoic acid were found predominantly in all the samples. The target ∑PFASs were distributed in the dissolved phase with a proportion of 96.5±2.9%. High concentrations of ∑PFASs (up to 12,700 ng/L in surface water) were found at sites near and within the wastewater treatment plant and the facilities. The ∑PFASs in the sediment/sludge were in the range of 3.33-324 ng/g dw. For the first time, tree samples were used for bio-monitoring airborne PFASs in the environment. The ∑PFASs in the tree leaf and bark samples were in the range of 10.0-276 and 6.76-120 ng/g dw, respectively. The spatial distribution of ∑PFASs in the tree leaves suggested that airborne PFASs could be transported from the center to the surrounding environment by prevailing wind.