Cytological stress and element uptake in moss and lichen exposed in bags in urban area

Metal toxicity in Bryum coronatum Schwaegrichen: impact on chlorophyll content, lamina cell structure, and metal accumulation

This research examined the impact of heavy metals, including Cd, Pb, and Zn, on chlorophyll content and lamina cell structure in Bryum coronatum. After exposure to varying metal concentrations (0.015, 0.065, 0.250, 1, and 4 mg/L), chlorophyll content, chloroplast numbers, lamina cell change, and metal accumulation were investigated. Chlorophyll content was assessed using spectrophotometry, whereas chloroplast numbers and lamina cell changes were examined under a light microscope. Metal accumulation was quantified through ICP-MS. The findings revealed that Cd notably reduced chlorophyll a content, while Pb and Zn showed minimal influence. Cd and Pb exposure decreased the number of chloroplasts in lamina cells, with no impact from Zn. The moss's capacity to absorb metals increased with higher exposure levels, indicating its potential as a biomonitor for heavy metal pollution. Cell mortality occurred in response to Cd and Pb, primarily in the median and apical lamina regions, while Zn had no effect. This study sheds light on heavy metal toxicity in B. coronatum, underscoring its significance for environmental monitoring. Further research on the mechanisms and consequences of heavy metal toxicity in bryophytes is essential for a comprehensive understanding of this critical issue.

Bioaccumulation of Trace Elements from Aqueous Solutions by Selected Terrestrial Moss Species

The interrelationship between metal concentrations in mosses and their surroundings prompts research toward examining their accumulation properties, as it is particularly important for their usage in biomonitoring studies that use mosses. In this study, the kinetics of elemental sorption in three moss species (Pleurozium schreberi, Dicranum polysetum, and Sphagnum fallax) were investigated under laboratory conditions. Sorption from metal salt solutions was carried out under static conditions with decreasing elemental concentration. Functional groups responsible for binding metal cations to the internal structures of the mosses were also identified. It was shown that the equilibrium state was reached after about 60 min. Under the conditions of the experiment, in the first 10 min of the process, about 70.4-95.3% of metal ions were sorbed from the solution into the moss gametophytes by P. schreberi (57.1-89.0% by D. polysetum and 54.1-84.5% by S. fallax) with respect to the concentration of this analyte accumulated in the mosses at equilibrium. It can be assumed that the exposure of mosses with little contamination by heavy metals in an urbanized area under active biomonitoring will cause an increase in the concentration of these analytes in proportion to their concentration in atmospheric aerosols. In the case of P. schreberi and D. polysetum, the O-H/N-H band was enormously affected by the adsorption process. On the other hand, FTIR (Fourier transform infrared spectroscopy) analysis of S. fallax after adsorption showed slight changes for most of the bands analyzed. Based on this study, it can be concluded that mosses can be used as, for example, a biomonitor in monitoring of urban ecosystems, but also in the phytoremediation of surface waters.

Air Quality Assessment by the Determination of Trace Elements in Lichens (Xanthoria calcicola) in an Industrial Area (Sicily, Italy)

This study provides data on variation in the content of metals and metalloids measured in the lichens (Xanthoria calcicola Oxner) collected in the Syracusan petrochemical complex (Sicily, Italy) which is considered one of the largest in Europe. Concentrations of eighteen trace elements measured in the lichens that were collected from 49 different points were analyzed using an inductively coupled plasma (ICP-MS) device. The concentrations of the typical elements of industrial emissions (As, Cr, Ni, and V) highlight the environmental criticality that exists in the study area. The interpretation of the data in terms of multi-element statistical analysis (FA) and enrichment factor (EFs) proved to be particularly useful in identifying several sources that contribute to the presence of trace elements in the atmospheric particulate between anthropogenic emissions and geogenic emissions. The results of this study reveal the versatility of the lichen species Xanthoria calcicola Oxner in the search for trace elements in highly anthropized environments, so the approach followed in this study can also be applied to other industrial contexts.

Metals Induce Genotoxicity in Three Cardoon Cultivars: Relation to Metal Uptake and Distribution in Extra- and Intracellular Fractions

Heavy metal-polluted soil represents an important stress condition for plants. Several studies demonstrated that growth inhibition under metal stress and metal-induced damages, including genotoxicity, is particularly pronounced at the early stages of seedling growth. Moreover, it is reported that heavy metals enter the cytoplasm to exert their detrimental effect, including DNA damage. In this work, we estimated (i) metal-induced genotoxicity by ISSR molecular markers and (ii) the distribution of the metal fractions between symplast and apoplast by EDTA washing, in three cultivars of Cynara cardunculus var. altilis (L.) DC (Sardo, Siciliano, and Spagnolo), grown in hydroponics for 15 days with Cd or Pb: In line with the literature, in all cultivars, the genotoxic damage induced by Pb was more severe compared to Cd. However, a cultivar-specific response was evidenced since Spagnolo showed, under metal stress, a significantly higher genome template stability compared to the other examined cultivars. The lower genotoxicity observed in Spagnolo could depend on the lower intracellular metal concentration measured in this cultivar by chemical analysis. Accordingly, light microscopy highlighted that Spagnolo developed smaller and more numerous epidermal cells under metal stress; these cells would provide a larger wall surface offering a wider metal sequestration compartment in the apoplast.

Is Your Moss Alive during Active Biomonitoring Study?

Biomonitoring was proposed to assess the condition of living organisms or entire ecosystems with the use of bioindicators-species sensitive to specific pollutants. It is important that the bioindicator species remains alive for as long as possible while retaining the ability to react to the negative effects of pollution (elimination/neutralization of hazardous contaminants). The purpose of the study was to assess the survival of Pleurozium schreberi moss during exposure (moss-bag technique) based on the measurement of the concentration of elements (Ni, Cu, Zn, Cd, and Pb), chlorophyll content, and its fluorescence. The study was carried out using a CCM-300 portable chlorophyll content meter, portable fluorometer, UV-Vis spectrophotometer, and a flame atomic absorption spectrometer. As a result of the laboratory tests, no significant differences were found in the chlorophyll content in the gametophytes of mosses tested immediately after collection from the forest, compared to those drying at room temperature in the laboratory (p = 0.175 for Student's t-test results). Mosses exposed using the moss-bag technique of active biomonitoring were characterized by a drop in the chlorophyll content over 12 weeks (more than 50% and 60% for chlorophyll-a and chlorophyll-b, respectively). Chlorophyll content in mosses during exposure was correlated with actual photochemical efficiency (yield) of photosystem II (calculated value of Pearson's linear correlation coefficient was 0.94-there was a significant correlation between chlorophyll a and yield p = 0.02). The highest metal increases in mosses (RAF values) were observed for zinc, lead, and copper after the second and third month of exposure. The article demonstrates that the moss exposed in an urbanized area for a period of three months maintains the properties of good bioindicator of environmental quality.

Quantitative analysis of fine dust particles on moss surfaces under laboratory conditions using the example of Brachythecium rutabulum

The identification of a model organism for investigations of fine dust deposits on moss leaflets was presented. An optical method with SEM enabled the quantitative detection of fine dust particles in two orders of magnitude. Selection criteria were developed with which further moss species can be identified in order to quantify the number of fine dust particles on moss surfaces using the presented method. Among the five moss species examined, B. rutabulum had proven to be the most suitable model organism for the method presented here. The number of fine dust particles on the moss surface of B. rutabulum was documented during 4 weeks of cultivation in the laboratory using SEM images and a counting method. The fine dust particles were recorded in the order of 10 μm-0.3 μm, divided into two size classes and counted. Under laboratory conditions, the number of particles of the fine fraction 2.4 μm-0.3 μm decreased significantly.

Facing metal stress by multiple strategies: morphophysiological responses of cardoon (Cynara cardunculus L.) grown in hydroponics

The contamination of environments by heavy metals has become an urgent issue causing undesirable accumulations and severe damages to agricultural crops, especially cadmium and lead which are among the most widespread and dangerous metal pollutants worldwide. The selection of proper species is a crucial step in many plant-based restoration approaches; therefore, the aim of the present work was to check for early morphophysiological responsive traits in three cultivars of Cynara cardunculus (Sardo, Siciliano, and Spagnolo), helping to select the best performing cultivar for phytoremediation. For all three tested cultivars, our results indicate that cardoon displays some morphophysiological traits to face Cd and Pb pollution, particularly at the root morphology level, element uptake ability, and photosynthetic pigment content. Other traits show instead a cultivar-specific behavior; in fact, stomata plasticity, photosynthetic pattern, and antioxidant power provide different responses, but only Spagnolo cv. achieves a successful strategy attaining a real resilience to metal stress. The capacity of Spagnolo plants to modify leaf structural and physiological traits under heavy metal contamination to maintain high photosynthetic efficiency should be considered an elective trait for its use in contaminated environments.

A Review on Atmospheric Analysis Focusing on Public Health, Environmental Legislation and Chemical Characterization

Atmospheric pollution has been considered one of the most important topics in environmental science once it can be related to the incidence of respiratory diseases, climate change, and others. Knowing the composition of this complex and variable mixture of gases and particulate matter is crucial to understand the damages it causes, help establish limit levels, reduce emissions, and mitigate risks. In this work, the current scenario of the legislation and guideline values for indoor and outdoor atmospheric parameters will be reviewed, focusing on the inorganic and organic compositions of particulate matter and on biomonitoring. Considering the concentration level of the contaminants in air and the physical aspects (meteorological conditions) involved in the dispersion of these contaminants, different approaches for air sampling and analysis have been developed in recent years. Finally, this review presents the importance of data analysis, whose main objective is to transform analytical results into reliable information about the significance of anthropic activities in air pollution and its possible sources. This information is a useful tool to help the government implement actions against atmospheric air pollution.

Element accumulation performance of living and dead lichens in a large-scale transplant application

In bioaccumulation studies, sample devitalization through acid washing or oven drying is commonly applied to enhance the element accumulation efficiency of moss sample. Such aspect, however, has never been considered in biomonitoring surveys using lichens. In this study, the trace element accumulation performance of living (L) and dead (D) samples of the lichen Pseudevernia furfuracea was compared by a side-by-side transplanting at 40 sites in a large, mixed land use area of NE Italy for 8 weeks. Devitalization was achieved without any physico-chemical treatments, by storing lichen samples in a dark cool room for 18 months. Health status of lichens was assessed before and after the sample exposure by chlorophyll fluorescence emission. Although elemental analysis of the two exposed sample sets revealed a similar trace element pollution scenario, the content of 13 out of the 24 selected elements was higher in D samples. By expressing results as exposed-to-unexposed (EU) ratio, D samples show a higher bioaccumulation signal in 80% of transplant sites for Al, Ca, Fe, Hg, Pb and Ti. Overall, the health status of lichen samples might lead to interpretational discrepancies when EU ratio is classified according to the recently proposed bioaccumulation scale.

Significance of the long-term biomonitoring studies for understanding the impact of pollutants on the environment based on a synthesis of 25-year biomonitoring in the Holy Cross Mountains, Poland

This review presents compiled results of complex biomonitoring studies that have been conducted in the Holy Cross Mountains, south-central part of Poland, since the 1990s. The significance of these studies results from several aspects: (i) a number and a variety of plant organisms used, e.g., mosses, lichens, coniferous and deciduous trees, and their tissues (wood, bark, needles, leaves, the aboveground parts of several vascular plants); (ii) applications of a broad scope of instrumental methods aiming at determining major and trace elements (including rare earth elements), organic compounds (PAHs, PCBs, phenols), and stable sulfur isotopes (δ³⁴S); and (iii) different methodological and environmental issues addressed. The comparison and interpretation of results derived from seventeen sampling campaigns carried out between 1994 and 2017 are a valuable source of information on the following: (i) bioaccumulative properties of organisms used in air quality monitoring, (ii) identification and variations of local and regional pollution sources and geochemical landscape patterns and processes over years, and (iii) establishing environmental factors that variously affected chemical composition of plants growing under physiological stress, including roadside vegetation and plants from acid mine drainage areas.

Influence of washing thalli on element concentrations of the epiphytic and epilithic lichen Parmotrema tinctorum in the tropic

To enhance the reliability of active biomonitoring of air pollution using lichens, we tested how a water-washing procedure influences element concentrations in lichens growing on bark and rock substrates. Thalli of the lichen Parmotrema tinctorum were collected from tree bark and sandstones from a relatively clean air site in Khao Yai National Park, Thailand. After dry cleaning, each thallus was divided equally: the first part was directly used for element analysis, and the second part was washed with deionized water before it was sent for element analysis. The concentrations of 13 elements, including Al, As, Ca, Cu, Fe, K, Mg, Mn, Se, Sr, Ti, V, and Zn, were determined using inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the washing procedure substantially decreased the amounts of most elements in the lichens; after washing, concentrations of the elements in the epiphytic thalli showed decreases ranging from 17 to 81% (54% on average), and those in the epilithic thalli showed decreases ranging from 10 to 27% (18% on average). The coefficient of variation (CV) was also reduced for most elements, especially for those in the epiphytic thalli, indicating that washing could produce more homogeneous samples. All elements from the unwashed samples had higher contents in the epiphytic thalli than in the epilithic thalli, but the element contents were higher in the epilithic thalli after washing. Most elements in the washed epiphytic and epilithic thalli were not comparable, indicating that the washing procedure did not produce the same order of magnitude of element contents in the epiphytic and epilithic thalli. Based on the results of this study, we recommend washing pre-exposed lichen samples for more reliable results in active biomonitoring studies of air pollution.

Influence of secondary metabolites on surface chemistry and metal adsorption of a devitalized lichen biomonitor

Despite the broad use of lichens as biomonitors of airborne trace elements, the surface chemistry and metal adsorption parameters of these organisms are still poorly known. The current investigation is aimed at (i) quantifying the acid-base surface properties and the first-order physical-chemical parameters of Cu2+ and Zn2+ adsorption of devitalized Pseudevernia furfuracea, a lichen commonly used in biomonitoring of airborne trace elements, and (ii) comparing the results with those available for moss biomonitors. Equilibrium constants and metal-binding site concentrations were calculated with a thermodynamic model by taking into account the presence/absence of ancillary extracellular cell wall compounds, namely melanin and acetone-soluble lichen substances. An acid-base titration experiment performed in the pH range of 3-10 showed that melanised and non-melanised P. furfuracea samples have lower pHPZC (3.53-3.99) and higher metal-binding site concentrations (0.96-1.20 mmol g-1) compared to that of the mosses investigated so far at the same experimental conditions. Melanin biosynthesis increased the content of carboxyl and phosphoryl groups and reduces that of amine/polyphenols. Cu2+ and Zn2+ adsorption was unaffected by the degree of melanisation while the removal of extracellular lichen substances slightly decreased Zn2+ adsorption. Although Cu2+ and Zn2+ adsorption parameters related to P. furfuracea surfaces were 3 times lower than in the mosses, lichen samples adsorbed the same amount of Cu2+ and 30% more Zn2+. The present study contributes in understanding the role of ancillary cell wall compounds in Cu2+ and Zn2+ adsorption in a model lichen. It also provides a first comparison between the surface physico-chemical characteristics of lichens and mosses frequently used as biomonitors of trace elements.

Factors inducing bryophyte growth on prehistoric pigments and effect of UV-C treatment

In La Glacière cave (France), the touristic activity has been conducted to an environmental parameter change that has led to photosynthetic organism proliferation (microalgae, diatoms, cyanobacteria, bryophytes). The present study is focused on bryophyte development occurring in the show cave that was responsible of limestone biodeterioration. In order to understand the colonization process of limestone, we have maintained limestone blocks under optimal Lampenflora growth conditions. Moreover, some limestone blocks were painted with several pigments that were used in the prehistory (e.g., red ocher, bone char). Microorganisms and bryophyte growth were monitored during 1 year, and then, the block samples were treated using UV-C light (254 nm). Thus, obtained results were compared with in situ treatment in La Glacière cave. Results have showed dense bryophyte propagation on the several blocks. However, the growth rate was correlated with the chemical composition of the pigment. In fact, the presence of some chemical elements such as As, Cr, Ti, and Co contributed to reduce bryophyte growth. Finally, moss treatment using UV-C light has demonstrated high efficiency under in situ condition, while a fast recolonization has been observed for samples maintained in laboratory. This difference was explained by the high bryophyte density under laboratory conditions that make UV-C light penetration difficult.

Open mining pits and heaps of waste material as the source of undesirable substances: biomonitoring of air and soil pollution in former mining area (Dubnik, Slovakia)

Moss and lichen bag technique (Dicranum sp., Hypnum sp., Polytrichum sp., Hypogymnia physodes) and activity of soil enzymes (urease, acid and alkaline phosphatase, fluorescein diacetate, ß-glucosidase) were used as bioindicators of air and soil pollution in Dubník former mining area (East Slovakia). Ten open mining pits and 8 heaps of waste material were chosen for the research purposes. Contamination factor (C_f), degree of contamination (C_d), and pollution load index (PLI) were used to evaluate the level of soil pollution and relative accumulation factor (RAF) expressed the level of air pollution by risk elements (As, Cd, Cu, Fe, Mn, Ni, Sb, Pb, Zn). Based the degree of contamination results, the study area was polluted by individual elements in the following order: Fe>Cd>As>Pb>Sb>Zn>Cu>Ni>Mn. The highest values of Mn and Ni and lower values of urease were determined in open mining pits comparing heaps of waste material. The results of PLI index confirmed extreme pollution at all sampling sites. Considering the average RAF values showed the decrease of accumulation abilities of evaluated taxa in the following order: Dicranum sp.>Hypnum sp.>Hypogymnia physodes>Polytrichum sp.

Functional characterization of metallothionein-like genes from Physcomitrella patens: expression profiling, yeast heterologous expression, and disruption of PpMT1.2a gene

Physcomitrella patens contains four metallothionein-like genes. Three were shown to confer metal tolerance in yeast. Transcript profiling suggests their roles in senescence and reproductive development or cadmium and oxidative stress. Metallothioneins (MTs) have been suggested to play various roles including metal detoxification, nutrient remobilization, ROS scavenging, stress tolerance, and plant development. However, little is known about the forms and functions of MTs in bryophytes. The moss Physcomitrella patens genome was found to contain four MT-like genes. Amino acid sequence composition showed that the P. patens MTs (PpMTs) were clustered with Type 1 plant MTs, and could be further classified into two sub-types, herein referred to as sub-type 1: PpMT1.1a and PpMT1.1b and sub-type 2: PpMT1.2a and PpMT1.2b. Transcript abundance of PpMT1.1b and PpMT1.2b was upregulated in the gametophore compared to protonema, and all, except PpMT1.2a, were highly induced in senescing gametophytes. PpMT1.1a and PpMT1.1b transcripts were upregulated in protonema treated with cadmium and hydrogen peroxide. Unlike many higher plant MTs, the PpMT transcript abundance was not strongly induced in response to copper and zinc. These results suggest that PpMTs may play a role in protecting P. patens from cadmium and oxidative stress and may be involved in tissues senescence and reproductive development. The PpMTs, except PpMT1.2b, were also able to confer metal tolerance and accumulation when heterologously expressed in the ∆cup1 yeast. A P. patens mutant lacking PpMT1.2a through targeted gene disruption was generated. However, it did not show any alteration in growth phenotypes under senescence-induced conditions or hypersensitivity to cadmium, copper, zinc, H₂O₂, and NaCl stresses. Further characterization of additional P. patens mutants lacking single or multiple PpMTs may provide insight into the physiological roles of bryophytic MTs.

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.

Evernia Goes to School: Bioaccumulation of Heavy Metals and Photosynthetic Performance in Lichen Transplants Exposed Indoors and Outdoors in Public and Private Environments

Recently indoor air quality (IAQ) has become a key issue, especially in schools, where children spend most of the day. Only in a few cases IAQ was investigated using lichens as biomonitors. During autumn 2017, lichens (Evernia prunastri) were exposed for two months indoors and outdoors in public (schools) and private (dwellings) environments, in both rural and urban areas of Slovakia. The bioaccumulation of selected elements and the physiological status of the samples were considered. The content of heavy metals increased in samples exposed outdoors for 11 out of 12 elements (Al, As, Cd, Cr, Cu, Fe, Pb, S, Sb, V and Zn, but not Ca) in the urban area and for 5 (As, Cd, Cu, Pb and Sb) in the rural area. Indoor concentrations were overall similar, both in rural and urban buildings, independently of the outdoor conditions. An indoor accumulation occurred only for Cd, Cu and Pb. An indoor origin was suggested for Cd, while for Cu and Pb, outdoor penetration (car traffic) is the likely cause of indoor values. Indoor exposed lichens maintained their vitality (as reflected by chlorophyll a fluorescence emission). This latter result further supports the use of lichen biomonitoring as a suitable method for assessing IAQ.

Roadside Moss Turfs in South East Australia Capture More Particulate Matter Along an Urban Gradient than a Common Native Tree Species

Urbanisation largely consists of removing native vegetation. Plants that remain interact with air quality in complex ways. Pollutants can be detrimental to plant growth; plants sometimes reduce air quality, yet some species also improve it through phytoremediation. A common pollutant of concern to human health in urban areas is particulate matter (PM), small particles of solid or liquid. Our study compared roadside moss turfs with leaves of a common Australian tree species, Pittosporum undulatum, in their ability to capture PM along an urban gradient. We sampled nine sites, three in each of three levels of urbanisation: low, medium, and high according to road type (freeway, suburban road, quiet peri-urban road). In addition, we deployed a PM monitor over a two-week period in one site of each urban level to provide concentrations of PM2.5. We used chlorophyll fluorescence (Fv/Fm; maximum quantum yield of photosystem II) as a measure of plant stress. We extracted PM in three size fractions using a filtration and washing technique with water and chloroform. Site averages for moss turfs were between 5.60 and 33.00 mg per g dry weight for total PM compared to between 2.15 and 10.24 mg per g dry weight for the tree leaves. We found that moss was more sensitive to increasing urbanisation, both in terms of trapping proportionately more PM than the leaves, and also in terms of photosynthetic stress, with moss Fv/Fm declining by a site average of 40% from low to high urban “class” (0.76 to 0.45). Our study highlights the stressors potentially limiting moss persistence in cities. It also demonstrates its ability to trap PM, a trait that could be useful in urban applications relating to urban greening or air quality.

Railroad derived nitrogen and heavy metal pollution does not affect nitrogen fixation associated with mosses and lichens at a tundra site in Northern Sweden

Traffic derived nitrogen (N) and heavy metal pollution is a well-known phenomenon, but little explored in otherwise pristine ecosystems such as subarctic tundra. Here, the main source of N input to the ecosystem is via N₂ fixation by moss- and lichen-associated bacteria. While inhibitory effects of N deposition on moss-associated N₂ fixation have been reported, we still lack understanding of the effects of traffic derived N and heavy metal deposition on this ecosystem function in an otherwise pristine setting. To test this, we established a distance gradient (0-1280 m) away from a metal pollution source -a railway transporting iron ore that passes through a subarctic birch forest. We assessed the effects of railway-derived pollution on N₂ fixation associated with two moss species Pleurozium schreberi, Hylocomium splendens and with the lichen Peltigera aphthosa. Deposition and availability of N and heavy metals (Fe, Cu, Zn, Pb) as well as the respective contents in moss, lichen and soil was assessed. While we found a steep gradient in metal concentration in moss, lichen and soil with distance away from the pollution source, N deposition did not change, and with that, we could not detect a distance gradient in moss- or lichen-associated N₂ fixation. Hence, our results indicate that N₂ fixing bacteria are either not inhibited by heavy metal deposition, or that they are protected within the moss carpet and lichen tissue.

Activity of the soil enzymes and moss and lichen biomonitoring method used for the evaluation of soil and air pollution from tailing pond in Nižná Slaná (Slovakia)

The surrounding of the poorly maintained tailing ponds is endangered by the toxic substances and represents a serious risk for the health of the local population. The aim of the study was to determine the soil pollution by the hazardous elements (As, Cr, Cd, Cu, Fe, Mn, Ni, Pb, Zn) around the tailing pond using contamination factor (C_f), degree of contamination (C_d) and pollution load index (PLI). The health and the condition of soil were evaluated by soil enzyme activity (urease, acid and alkaline phosphatase, florescein diacetate, and ß-glucosidase). The spreading of the airborne hazardous elements from the body of the tailing pond was evaluated by moss and lichen bag technique and relative accumulation factor was used for the result expression. Cd, Fe, and Mn in soils reached above the limit values at all sampling sites. According to the degree of contamination (C_d), the soils at the sampling area were very high contaminated by As, Cd, Cu, Fe, Mn, Ni, and Pb. The most part of the assessed area was according to the PLI values extremely polluted. The air pollution was the most serious around the tailing pond, but serious levels of some hazardous elements were determined also in the remote distances.

Performance of three cardoon cultivars in an industrial heavy metal-contaminated soil: Effects on morphology, cytology and photosynthesis

In the present work the cytomorphological and physiological effects on three cardoon cultivars - Sardo, Siciliano, Spagnolo - grown in a metal-polluted soil, were investigated, to assess the traits concurring to the high tolerance to metal stress observed in cv. Spagnolo compared to the other two cultivars. The plants were grown for one month on a real polluted soil collected at a dismantling battery plant, highly enriched by heavy metals, especially Cd and Pb, and their leaves were analyzed by a multidisciplinary approach. TEM observations highlighted severe ultrastructural damage in Sardo and Siciliano, and preserved cytological traits in Spagnolo. Both pigment content and photochemistry indicated a decline in photosynthesis in Sardo and Sicilano and a substantial stability of the same parameters in Spagnolo. Protein analysis indicated a decrease in D1 level in all cultivars; in Spagnolo the D1 decrease was more pronounced and associated to a significant increase in Rubisco, a pattern likely preserving photosynthetic efficiency and high biomass production. In conclusion, Spagnolo cardoon was able to face metal stress through a prompt, multiple response balancing structural and functional traits.

The first survey of airborne trace elements at airport using moss bag technique

Air traffic represents an important way of social mobility in the world, and many ongoing discussions are related to the impacts that air transportation has on local air quality. In this study, moss Sphagnum girgensohnii was used for the first time in the assessment of trace element content at the international airport. The moss bags were exposed during the summer of 2013 at four sampling sites at the airport 'Nikola Tesla' (Belgrade, Serbia): runway (two), auxiliary runway and parking lot. According to the relative accumulation factor (RAF) and the limit of quantification of the moss bag technique (LOQ_T), the most abundant elements in the samples were Zn, Na, Cr, V, Cu and Fe. A comparison between the element concentrations at the airport and the corresponding values in different land use classes (urban central, suburban, industrial and green zones) across the city of Belgrade did not point out that the air traffic and associated activities significantly contribute to the trace element air pollution. This study emphasised an easy operational and robust (bio)monitoring, using moss bags as a suitable method for assessment of air quality within various microenvironments with restriction in positioning referent instrumental devices.

Biomonitoring of heavy metals contamination by mosses and lichens around Slovinky tailing pond (Slovakia)

Three moss (Pleurozium spp., Polytrichum spp., and Rhytidiadelphus spp.) and two lichen (Hypogymnia physodes and Pseudevernia furfuracea) taxons covered in the bags were used to monitor air quality. Bags were exposed at the different distances from the tailing pond because of insufficient security and source of heavy metal pollution. Moss/lichen bags were exposed for six weeks at 0-, 50-, 100-, 150- and 200-m distances from Slovinky tailing pond, in the main wind direction (down the valley). Accumulation ability of heavy metals expressed by relative accumulation factor (RAF) increases in the order of Polytrichum spp.<H. physodes <Pleurozium spp.<P. furfuracea <Rhytidiadelphus spp. Moss/lichen species showed different accumulation capacity for individual heavy metals. Rhytidiadelphus spp. was found to possess the significantly highest (P < 0.01) ability to accumulate Cd, Zn, Ni, Mn and Fe. The highest RAF values of Pb, Zn, Ni and Fe were determined in samples exposed at 200-m distance from pollution source.

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.

Genetic structuring of the moss Pseudoscleropodium purum sampled at different distances from a pollution source

In this study, we used amplified fragment length polymorphism analysis to investigate the genetic structure of the terrestrial moss Pseudoscleropodium purum (Hedw.) M. Fleish. naturally exposed to different levels of atmospheric deposition of heavy metals. We also determined the heavy metal concentrations in samples of this moss to evaluate whether there was a relationship between atmospheric pollution and population genetic diversity. A low level of genetic diversity and a limited gene flow among populations were observed which is in accordance to the prevalence of asexual reproduction in this species. In addition, no significant correlation was found between metal content and gene diversity in P. purum, probably because of the common history of the sampled populations and/or to the lack of a drastic reduction of the size of the population; nonetheless, a clear genetic structure was evident in relation to the existing pollution gradient. Thus, based on the results of the principal coordinate analysis and Bayesian analysis of the genotypes, the mixed structure of the second most polluted population would suggest an ongoing differentiation of metal-tolerant genotypes in the most polluted sites of the sampling area.

Chemical, molecular, and proteomic analyses of moss bag biomonitoring in a petrochemical area of Sardinia (Italy)

In this study, Hypnum cupressiforme moss bags were used to examine the atmospheric deposition of trace elements in the oil refinery region of Sardinia (Italy) compared with surrounding natural zones. The concentrations of 13 elements [arsenic (As), calcium (Ca), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), sodium (Na), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn)] were determined using inductively coupled plasma optical emission spectrometry. A significant accumulation of pollutants was detected using active biomonitoring with moss bags compared with a control site. The most relevant contaminants for all of the tested sites were Cr, Cu, Ni, and Zn. Moreover, the accumulation of Cr and Zn in the refinery industrial areas, IA1 and IA2, was more than five times greater than that detected at the control site. Levels of Cd, Mg, and Pb were also higher at all of the monitored sites compared with the control site. Both genomic and proteomic methods were used to study the response of H. cupressiforme to air pollution. No DNA damage or mutations were detected using the amplified fragment length polymorphisms (AFLP) method. At the protein level, 15 gel spots exhibited differential expression profiles between the moss samples collected at the IA1 site and the control site. Furthermore, among the 14 spots that showed a decrease in protein expression, nine were associated with ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and proteins of the light-harvesting complexes of photosystem (PS) II, three were associated with protein synthesis, and three were stress-related proteins. Thus, some of these proteins may represent good moss biosensors which could be used as pre-alert markers of environmental pollution.

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.

Temporal trends of element concentrations and ecophysiological parameters in the lichen Pseudevernia furfuracea transplanted in and around an industrial area of S Italy

This study investigated the temporal trends of element concentrations and ecophysiological parameters (integrity of cell membranes, membrane lipid peroxidation, and sample vitality) in thalli of the lichen Pseudevernia furfuracea transplanted in and around an industrial area of S Italy from May 2010 to May 2011, once every 3 months. Element accumulation at levels indicating that the atmosphere of the study area was polluted by most elements occurred only during the third trimester of exposure, and the ecophysiological parameter best reflecting this trend was sample vitality expressed in terms of activity of the enzyme dehydrogenase. Among the available climatological parameters, the different amount of rainfall during the exposure period may influence the results, especially the number of hours with rainfall >16 mm/day, which is the threshold between light-moderate and moderate-heavy rainfall in the Mediterranean area.

Distinguishing metal bioconcentration from particulate matter in moss tissue: testing methods of removing particles attached to the moss surface

Accurate differentiation of the proportion of bioconcentrated metals (i.e. incorporated into cells) and the proportion that is not bioconcentrated (i.e. adsorbed at the surface) would lead to a better understanding of the uptake processes and would represent an advance in the use of mosses as biomonitors. Traditionally the methods used to remove contaminants that are not bioconcentrated were to wash the plant material with water or to apply the sequential elution technique, but nowadays both options are considered inaccurate for these purposes. The remaining possibilities are to clean the moss samples with a nitrogen jet or by power ultrasound. Samples of terrestrial moss Pseudoscleropodium purum (Hewd.) Fleisch. were collected from five sampling stations. Different nitrogen jet cleaning procedures and ultrasound cleaning procedures were applied to the mosses. To determine whether any of the treatments altered the membrane integrity of the moss samples, the concentrations of K were determined. The shoots were observed under a scanning electron microscope, and the size and number of particles were determined. Nitrogen jet cleaning was determined to be unacceptable because it damaged the phyllids and/or altered the membrane permeability and did not eliminate the particles from the moss surface. Moreover, ultrasound cleaning treatment should also discarded because of the loss of extracellular metals that are transferred to the water in which the moss is cleaned.

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

Concentrations of 12 elements (Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb and Zn) and 16 EPA-listed PAHs were detected in Quercus ilex leaves and the epiphytic moss Leptodon smithii collected at urban, periurban and extraurban holm oak stands, in two Italian Regions (Campania and Tuscany). Levels of environmental contaminants were generally higher in leaves and moss from urban areas than periurban and extraurban ones and samples from Campania had the highest PAH content. The epiphytic moss accumulated higher concentrations of trace elements than leaves and the latter showed a higher accumulation capability for PAHs, especially for those with low molecular weight. The different bioaccumulation in leaves and moss were explained in terms of their distinctive morphological and ecophysiological characteristics. The combined approach seems a promising tool for the monitoring of a wide range of pollutants in Mediterranean urban and extraurban environments.

A multi-approach monitoring of particulate matter, metals and PAHs in an urban street canyon

For the first time until now, the results from a prediction model (Atmospheric Dispersion Modelling System (ADMS)-Road) of pollutant dispersion in a street canyon were compared to the results obtained from biomonitors. In particular, the instrumental monitoring of particulate matter (PM10) and the biomonitoring of 14 polycyclic aromatic hydrocarbons (PAHs) and 11 metals by Quercus ilex leaves and Hypnum cupressiforme moss bags, acting as long- and short-term accumulators, respectively, were carried out. For both PAHs and metals, similar bioaccumulation trends were observed, with higher concentrations in biomonitors exposed at the leeward canyon side, affected by primary air vortex. The major pollutant accumulation at the leeward side was also predicted by the ADMS-Road model, on the basis of the prevailing wind direction that determines different exposure of the street canyon sides to pollutants emitted by vehicular traffic. A clear vertical (3, 6 and 9 m) distribution gradient of pollutants was not observed, so that both the model and biomonitoring results suggested that local air turbulences in the street canyon could contribute to uniform pollutant distribution at different heights.

Moss bag biomonitoring: a methodological review

Although the moss bag technique has been used for active biomonitoring for the past 40years, there is still no standardized protocol that enables application of the technique as a tool to monitor air quality. The aim of this review paper is to evaluate the degree of standardization of each of the variables that must be considered in applying the technique (i.e. the variables associated with preparation of the moss and moss bags, exposure of the bags, and post-exposure treatment). For this purpose, 112 scientific papers that report the methods used in applying the moss bag technique were consulted. Finally, on the basis of the conclusions reached, we propose a protocol that will enable each of these variables to be investigated separately, with the final aim of developing a standardized methodology.

Metal and metalloid foliar uptake by various plant species exposed to atmospheric industrial fallout: mechanisms involved for lead

Fine and ultrafine metallic particulate matters (PMs) are emitted from metallurgic activities in peri-urban zones into the atmosphere and can be deposited in terrestrial ecosystems. The foliar transfer of metals and metalloids and their fate in plant leaves remain unclear, although this way of penetration may be a major contributor to the transfer of metals into plants. This study focused on the foliar uptake of various metals and metalloids from enriched PM (Cu, Zn, Cd, Sn, Sb, As, and especially lead (Pb)) resulting from the emissions of a battery-recycling factory. Metal and metalloid foliar uptake by various vegetable species, exhibiting different morphologies, use (food or fodder) and life-cycle (lettuce, parsley and rye-grass) were studied. The mechanisms involved in foliar metal transfer from atmospheric particulate matter fallout, using lead (Pb) as a model element was also investigated. Several complementary techniques (micro-X-ray fluorescence, scanning electron microscopy coupled with energy dispersive X-ray microanalysis and time-of-flight secondary ion mass spectrometry) were used to investigate the localization and the speciation of lead in their edible parts, i.e. leaves. The results showed lead-enriched PM on the surface of plant leaves. Biogeochemical transformations occurred on the leaf surfaces with the formation of lead secondary species (PbCO(3) and organic Pb). Some compounds were internalized in their primary form (PbSO(4)) underneath an organic layer. Internalization through the cuticle or penetration through stomata openings are proposed as two major mechanisms involved in foliar uptake of particulate matter.