Best options for the exposure of traditional and innovative moss bags: A systematic evaluation in three European countries

Fine-tuning the use of moss transplants to map pollution by Potentially Toxic Elements (PTEs) in urban areas

Mosspheres are a kind of moss transplants which offer a novel approach for detecting atmospheric pollution using devitalized mosses, as they reflect the atmospheric deposition of certain elements and polycyclic hydrocarbons. However, due to the unique features of the mosspheres such as the low elemental concentrations in the cultured material, the data treatment needs to be different from that of conventional biomonitoring studies. In this article, our objectives are to identify the best parameter for expressing the levels of chemical elements accumulated by mosspheres, and to apply a recently developed method to assess the probability of pollution of each sample and of the study area. To do this, we used data from a study in which 81 mosspheres were exposed in a medium-sized city in southwestern Europe. Comparing different pollution indices, we selected the enrichment rate (ER) as the most useful, as it is resilient to fluctuations in the initial concentrations and takes into account the time factor, allowing for greater comparability among studies. Then, we determined that the statistical distribution of the ERs of most elements fitted a normal distribution, showing that most samples did not differ significantly from the background concentrations for these elements. On the other hand, for Ni, Pb and Zn there was a subpopulation of samples above background values. In these cases, we determined the probability of pollution of each sample. Finally, we used indicator kriging to calculate the probability of pollution across the study area, identifying the polluted areas, which for some elements match the distribution of the main industries and highways, indicating that this is a suitable protocol to map elemental pollution in urban areas.

Significance of moss pretreatments in active biomonitoring surveys

The present study examines the impact of pretreatment procedures on the metal concentrations in bags that are to be exposed. We examine Mn, Fe, Cu, Zn, Cd, and Pb amounts in Sphagnum fallax and Dicranum polysetum mosses using atomic absorption spectrometry. The concentration of Hg was also determined using a mercury analyzer. Two sample preparation ways were tested (with and without rinsing) and their influence was evaluated by determining the coefficient of variation (CV). Chlorophyll content was also determined in mosses collected from three habitats (deep woodland, forest road, and wood lot). The results indicate, that the concentration of elements deposited in mosses depends on the species and the habitat where they were collected (ANOVA, p < 0.001). Rinsing of mosses reduces the CV for Mn, Fe, Cu, and Zn and uniform the material prior to exposure (CV for the majority of metals <10%). Selected correlations were found for element concentrations with chlorophyll content. Photosynthetic activity of mosses decreased by about 80% during their one-month storage in the laboratory. Due to the varying concentration of metals in the collected samples, proper, and standardized preparation of mosses before exposure, they can be effectively used in active biomonitoring.

Moss-bag technique as an approach to monitor elemental concentration indoors

The moss-bag technique has been used for many decades to monitor outdoor pollution. More recently, however, the method has been used to monitor indoor air pollution (IAP), as humans spend the majority of their time indoors. The purpose of the research conducted was to evaluate indoor air pollution using active moss biomonitoring. Pleurozium schreberi moss bags were exposed for two seasons (summer and winter), hanging over tile stoves and coal stoves. The selected elements: Al, Cu, Cd, Co, Pb, Zn, V, Ba, Cr, Fe, Mn, Sr, P, Ni, and S were determined by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and, for Hg, by a direct mercury analyzer. The study found the exposure season affected the concentrations of selected elements in 62.5% of cases, and their source was identified. The average concentrations of Co, Ba, Cr, and Sr were higher, and statistically significant, in winter, after a 12-week exposure period of the mosses, regardless of the type of heating or cooking stove owned. The higher phosphorus concentrations obtained in summer indicate physiological stress caused by unfavorable winter exposure conditions. In the future, the number of species used to assess indoor air pollution should be increased and the range of pollutants expanded, along with the identification of their sources, taking residents' lifestyles into account.

Optimizing Moss and Lichen Transplants as Biomonitors of Airborne Anthropogenic Microfibers

Anthropogenic microfibers (mfs) are synthetic particles composed of cellulose (cotton, rayon, acetate, etc.) or petrochemical-based polymers (i.e., microplastics-MPs) that are less than 5 mm in length. The accumulation of mfs, including MPs, in the moss Hypnum cupressiforme and the lichen Pseudevernia furfuracea was compared in a transplant experiment lasting 6 weeks. We also tested the effects of the bag used for transplants on the accumulation of mfs. Anthropogenic particles trapped by both biomonitors were mostly filamentous (99% mfs), and their number was overall higher in the moss (mean ± s.d. 102 ± 24) than in the lichen (mean ± s.d. 87 ± 17), at parity of sample weight. On average, mfs found in lichen were significantly longer than those found in moss bags, suggesting that lichens are less efficient at retaining smaller mfs. Exposure without the net yielded a higher mfs number accumulation in both species, indicating that "naked" transplants provide greater sensitivity. The calculation of daily fluxes evidenced a loss of mfs in the lichen, suggesting the presence of more stable bonds between moss and mfs. Raman microspectroscopy carried out on about 100 debris confirms the anthropogenic nature of mfs, of which 20% were MPs. Overall results indicate that moss is preferable to lichen in the biomonitoring of airborne mfs especially when exposed naked.

Lichens and Mosses as Biomonitors of Indoor Pollution

Biomonitoring in indoor environments is a recent application, and so far, indoor air quality (IAQ) has been investigated only in a few cases using photosynthesising biomonitors. On the whole, 22 studies have been selected and reviewed, being specifically focused on the assessment of IAQ using biomonitors, such as lichens (9 papers), mosses (10), or their combination (3). In general, indoor samples face an altered light regime, ventilation, and a reduced hydration, which should be taken into consideration during the design and implementation of indoor monitoring. This review highlights critical issues (and some solutions) related to sample devitalisation (moss), hydration during exposure, preparation of the exposure device (mostly lichen and moss bags), duration of the exposure, post-exposure treatments, assessment of the vitality of the samples, as well as data elaboration and interpretation. This review evidences the feasibility and usefulness of lichen/moss monitoring in indoor environments and the need to develop standardised protocols.

Unravelling the metal uptake process in mosses: Comparison of aquatic and terrestrial species as air pollution biomonitors

Transplanted mosses have been widely shown to be excellent tools for biomonitoring air pollution; however, it is not clear how the functional groups present on their surfaces affect the uptake of metal cations. In the present study, we examined differences in trace metal accumulation in two terrestrial and one aquatic moss species, and investigated whether the differences depended on their physico-chemical characteristics. In the laboratory, we determined C, N and H contents in their tissues and obtained the ATR-FTIR spectra (to identify the presence of functional groups). We also conducted surface acid-base titrations and metal adsorption assays with Cd, Cu and Pb. In the field, we exposed transplants of each species near different air-polluting industries, and determined the mosses enrichment of Al, Cd, Co, Cr, Cu, Fe, Ni, Pb and V. Laboratory results demonstrated higher metal uptake capacity in the terrestrial mosses Sphagnum palustre and Pseudoscleropodium purum, compared to that in the aquatic moss Fontinalis antipyretica, which can be attributed to a greater abundance of acidic functional groups (i.e. negatively charged binding sites) on the surface of the terrestrial mosses. The affinity of moss for certain elements depends on the abundance and nature of surface functional groups. Accordingly, the metal concentrations generally reached higher levels in S. palustre transplants compared to the other species, except for the uptake of Hg, which was higher in F. antipyretica. However, the findings also suggest an interaction between the type of environment (terrestrial or aquatic) and the moss characteristics that may influence the abovementioned trend. Thus, irrespective of the physico-chemical characteristics, metal uptake varied depending on the environment of origin of the mosses "i.e. atmospheric or aquatic". In other words, the findings suggest that species that accumulate more metals in terrestrial environments will accumulate lower amounts of metals in aquatic environments and vice versa.

Biomonitoring of polycyclic aromatic hydrocarbons (PAHs) by Murraya paniculata (L.) Jack in South Kolkata, West Bengal, India: spatial and temporal variations

Attempts have been made in the present study for ascertaining the concentrations of atmospheric polycyclic aromatic hydrocarbons (PAHs) using passive biosamplers in preference to conventional air sampling methods. Mechanical stirring, sonication, Soxhlet technique and microwave-assisted Soxhlet extraction (MASE) were employed to extract PAHs from an evergreen plant (Murraya paniculata) leaves (having long life-span) sampled from polluted places of South Kolkata, India, with dense population and heavy traffic. Effects of extraction methods and operational parameters (solvent and time) on the recovery levels of PAHs were also investigated. Purified extracts, acquired through adsorption chromatography, were subjected to GC-MS and HPLC-UV analyses for qualitative and quantitative assessment of PAHs. Spatio-temporal distribution of accumulated PAHs across the sampling sites was monitored over premonsoon, postmonsoon and winter supported by pollutant source characterization. The results displayed that the extraction yields of Soxhlet (272.07 ± 26.15 μg g-1) and MASE (280.17 ± 15.46 μg g-1) were the highest among the four techniques. Conditions of extraction with toluene for 6 h were found to be most favorable for PAHs. In spatio-temporal analysis, total concentrations of PAHs in the foliar samples varied from 200.98 ± 2.72 to 550.79 ± 10.11 μg g-1 dry weight, and the highest values being recorded in the samples of Exide More because of daylong inexorable traffic flow/crowding increasing the burden of ambient PAHs. Widespread changes in meteorology exerted influence on seasonal concentrations of PAHs in plant leaves, and extent of leaf contamination by PAHs was observed extreme in winter followed by postmonsoon and then, premonsoon. Foliar accretion of PAHs differed in the study sites with diverse sources of emission from motor vehicles, fossil fuel and biomass burning along with other human interferences.

Polycyclic aromatic hydrocarbons (PAHs) levels in PM10 and bulk deposition using Mosspheres: A pilot study in an urban environment

Study air polycyclic aromatic hydrocarbons (PAHs) capturing the spatial variability of their concentrations is not economically feasible with conventional methods. In the present work we tested, for the first time and under real conditions, the suitability for intensive monitoring and mapping these contaminants of innovative, cost-effective passive air samplers known as "Mosspheres". The Mosspheres, filled with a devitalised Sphagnum palustre L. moss clone, were placed in a 575 m. grid in a medium-sized European city for three months. Concentrations in the moss tissues of 15 priority PAHs, including benzo(a)pyrene, were determined and converted into PM₁₀ and bulk deposition with the equations proposed in a recent study. Low concentrations of PAHs were detected, with only a few enriched points never exceeding the legal thresholds, near industrial areas and busy roads. Despite these low PAH concentrations, Mosspheres were able to detect spatial structure for several PAHs and high-resolution pollution maps were constructed for these compounds. The results prove the high sensitivity and suitability of Mosspheres for mapping PAH levels and for quantitative (i.e. PAHs with 4 or more rings) and qualitative (3-ring PAHs) monitoring. Thus, this study supports their widespread application and its potential inclusion in European Directives on air quality control.

Biomonitoring of Airborne Microplastic Deposition in Semi-Natural and Rural Sites Using the Moss Hypnum cupressiforme

We show that the native moss Hypnum cupressiforme can be used as a biomonitor of atmospheric microplastics (MPs). The moss was collected in seven semi-natural and rural sites in Campania (southern Italy) and was analyzed for the presence of MPs, according to standard protocols. Moss samples from all sites accumulated MPs, with fibers representing the largest fraction of plastic debris. Higher numbers of MPs and longer fibers were recorded in moss samples from sites closer to urbanized areas, likely as the results of a continuous flux from sources. The MP size class distribution showed that small size classes characterized sites having a lower level of MP deposition and a high altitude above sea level.

Moss Bags as Biomonitors of Atmospheric Microplastic Deposition in Urban Environments

Microplastics (plastic particles <5 mm) were first identified in the environment during the 1970s and have since become ubiquitous across every environmental compartment. However, few studies have focused on atmospheric microplastics, and even fewer have used biological monitoring to assess their atmospheric deposition. Here, we assess the efficacy of moss bags as an active biomonitoring technique for atmospheric microplastic deposition. Moss (Pleurozium schreberi) bags were exposed in duplicate at nine deployment sites across a gradient of urban intensity in southern Ontario, Canada. A total of 186 microplastics (mp) were detected in the moss bags, resulting in a mean accumulation of 7.9 mp g^-1 dry weight moss across all sites during the exposure period (45 days). The median microplastic length was 0.56 mm (range 0.03-4.51 mm), and the dominant microplastic type was fibres (47%), followed by fragments (39%). Microplastic accumulation significantly increased with urban intensity, ranging from 3.7 mp g^-1 in low-density suburban areas to 10.7 mp g^-1 in densely populated and trafficked urban areas. In contrast, microfibres by proportion dominated in suburban (62%) compared with urban areas (33%). Microplastic deposition was estimated to range from 21 to 60 mp m^-2 day^-1 across the nine deployment sites. The results suggest that moss bags may be a suitable technique for the active biomonitoring of atmospheric microplastic deposition in urban environments.

Testing mosses exposed in bags as biointerceptors of airborne radiocaesium after the Fukushima Dai-ichi Nuclear Power Station accident

Eight years after the Fukushima nuclear accident, mosses exposed in bags were used to investigate their ability to accumulate radiocaesium and therefore to act as biointerceptors of ¹³⁴Cs and ¹³⁷Cs in the evacuated area of the Fukushima territory. Bags were filled with 3 widely studied moss species (Sphagnum palustre, Hypnum cupressiforme, and Hypnum plumaeforme) and exposed for 3, 6 or 9 weeks at 5 former residential sites within the Fukushima area and, for comparison, at three background sites located 700 km away. The radiocaesium activity concentrations found in moss bags were evaluated as function of exposure time, site conditions and moss species. In the Fukushima area, the moss bags accumulated ¹³⁷Cs at all exposure sites and in all exposure periods, with S. palustre having the highest ¹³⁷Cs accumulation ability. The ¹³⁷Cs activity concentrations (from 28 to 4700 Bq kg^-1) measured in moss bags increased with the exposure time and were consistent with the decontamination status of each exposure site, highlighting the big potential of moss bags to discriminate among exposure sites. Time dependency of ¹³⁷Cs activity concentrations measured in mosses allowed the calculation of location-specific and species-specific factors, which can be used to predict radiocaesium accumulation trends in future biomonitoring surveys performed in the same area with the same experimental design. Autoradiography and electron microscopy analyses of the moss surfaces revealed a prevalence of soil-derived particulate form of radiocaesium, suggesting the use of moss bags as warning sensors of resuspended particles potentially harmful for local residents.

Temporal and spatial biomonitoring of atmospheric heavy metal pollution using moss bags in Xichang

Heavy metal air pollution poses a serious threat to human health and the environment in Chinese tourist cities. In this study, we investigated the temporal and spatial variations of atmospheric heavy metal pollution using moss bags in Xichang, a tourist destination in Southwest China. The biomonitoring investigation used an indigenous moss (Taxiphyllum taxirameum) transplanted into bags. Moss bags were exposed to 22 sites including industrial, agricultural, urban/residential, tourist, and high-traffic sites, across four different seasons in 2019-2020. The results showed that T. taxirameum was a good biomonitor of air pollution in Xichang. Among the 22 sample points, air pollution was the worst along the G102 motorway. Heavy metal emissions varied in different regions and directions. Temporal changes significantly influenced the heavy metals accumulated in moss bags, with low deposition of most elements observed at nearly all sampling sites in summer. Different seasons and regions were important factors affecting atmospheric heavy metal pollution. Based on the correlation analysis and the positive matric factorization model, the results revealed that heavy metals in moss bags in Xichang were mainly derived from anthropogenic sources and atmospheric deposition. Overall, this research provides an important reference for air pollution monitoring in urban areas.

Comparison of Exposure Techniques and Vitality Assessment of Mosses in Active Biomonitoring for Their Suitability in Assessing Heavy Metal Pollution in Atmospheric Aerosol

The most widespread and used technique is the moss-bag method in active biomonitoring of air pollution using mosses. In the literature, we can find various studies on the standardization of this method, including attempts to standardize treatments and preparation procedures for their universal application. Few works comprehensively focus on other methods or compare other techniques used in active biomonitoring with mosses, especially including measurements of their vital parameters. Our experiment aimed to assess air pollution by selected heavy metals (Cu, Zn, Cd, Pb, Mn, Fe, and Hg) using three moss species (Pleurozium schreberi, Sphagnum fallax, and Dicranum polysetum) during a 12-week exposure in an urban area. Mosses were exposed simultaneously using four techniques: moss bag in three variants (exposed to air for total deposition of heavy metals, exposed to air for only dry deposition, and sheltered from the wind) and transplants in boxes. Increases in heavy metal concentrations in mosses were determined using the relative accumulation factor (RAF). The actual quantum yield of photosystem II photochemical was also analyzed as the main vitality parameter. The results indicate that all moss species during the changing environmental conditions survived and retained their vitality, although it decreased by >50% during the exposure. The best biomonitor was the moss P. schreberi, whose RAF increments were the highest throughout the study period for the majority of elements. The moss-bag technique had a statistically significant effect (almost 40%) on the concentration value of a given metal for a certain species, and thus it is the most recommended technique that can be applied in air quality monitoring in urban areas. Environ Toxicol Chem 2022;41:1429-1438. © 2022 SETAC.

Radionuclide and trace metal accumulation in a variety of mosses used as bioindicators for atmospheric deposition

Mosses can be used as biological monitors to study metal pollution and the depositional fluxes of radionuclides. In this study, we analysed the concentrations of radionuclides (²¹⁰Pb (²¹⁰Pb_ex), ⁷Be, ¹³⁷Cs, ⁴⁰K, ²³⁸U, ²²⁶Ra, ²²⁸Ra and ²²⁸Th) and metals (Fe, Zn, Cu, Al, Pb, Cd, Cr, Ni, V and Mn) in moss and soil samples from two different regions. The metal concentrations were higher in mainland China than in the Arctic region, and this is likely associated with the comparatively lower rates of industrial production and human activity in the Arctic region. Principal component analysis and correlation results revealed two radionuclides sources types in mosses, i.e., soil (⁴⁰K, ²³⁸U, ²²⁶Ra, ²²⁸Ra and ²²⁸Ra) and atmospheric (²¹⁰Pb (²¹⁰Pb_ex), ⁷Be ¹³⁷Cs). Clustering and correlation analyses showed that different sources such as traffic (suspended dust), fossil fuels, dry and wet deposition (atmosphere and rainfall), and soil contributed to metal accumulation in mosses. The correlation between radionuclides and metals supported these observations, confirmed the accuracy of our results, and suggests that radionuclides are useful for identifying the source of metals in moss samples. The concentration ratios (CR) values of the radionuclides and the bioaccumulation factor (BCF) and enrichment factor (EF) values of metals in mosses helped identify the most environmentally sensitive moss, i.e., BS (Bryum paradoxum), which can be used for screening and monitoring radionuclides and metal pollution in urban atmospheres. These results support the use of analysing radionuclides in mosses to identify metal sources, and the potential use of mosses can to determine the atmospheric deposition fluxes of radionuclides.

Multi-elemental profile and enviromagnetic analysis of moss transplants exposed indoors and outdoors in Italy and Belgium

Air pollution represents one of the major concerns worldwide, fueled by the increasing urbanization and related PM production worsening air quality in open air as well as in confined environments. In the present work, exposure to atmospheric metal pollution was investigated in 20 paired indoor (I)-outdoor (O) sites located in two urban areas of Italy and Belgium, by chemical (ICP-MS) and magnetic (saturation isothermal remanent magnetization, SIRM) analyses of Hypnum cupressiforme moss exposed in bags. After 12 weeks, the elemental profiles of the moss material exposed in the two countries largely overlapped, except for some elements which specifically accumulated in Belgium (Ag, As, Cd, Mo, Pb and Sb) and in Italy (Ca, Mg, Co, Cr, Sr, Ti and U). Element concentrations were higher in moss exposed outdoors, with the Italian sites mostly showing a terrigenous footprint, and the Belgian sites mostly affected by elements of environmental concern (e.g., As, Pb, Sb). The Indoor/Outdoor ratios (mostly lower than 0.75) indicated indoor pollution as strongly affected by outdoor pollution, although specific elements could be of indoor origin or magnified in indoor environments (e.g., Al, Ag, Cd and Co). In line with the chemical analysis, the SIRM signal was significantly higher in outdoor than indoor moss material. A positive, significant correlation was observed between SIRM and several accumulated elements indicating SIRM analysis as a powerful tool to predict the level of metal pollution. Moss bags were confirmed as a useful and versatile tool to highlight metal contamination even in confined environments, an essential prerogative in the perspective of the evaluation of the total exposure risk for humans to these pollutants.

Mobile Biomonitoring of Atmospheric Pollution: A New Perspective for the Moss-Bag Approach

In this work the potential of moving moss-bags, fixed to bicycles, to intercept particulate matter (PM) and linked metal(loid)s was tested for the first time. Seven volunteers carried three moss-bags for fifty days while commuting by bicycle in the urban area of Antwerp, Belgium. Moreover, one bike, equipped with mobile PM samplers, travelled along four routes: urban, industrial, green route and the total path, carrying three moss-bags at each route. The saturation isothermal remanent magnetization (SIRM) signal and chemical composition (assessed by HR-ICP-MS) of the moss samples indicated that the industrial route was the most polluted. Element fluxes (i.e., the ratio between element daily uptake and the specific leaf area) could discriminate among land uses; particularly, they were significantly higher in the industrial route for Ag, As, Cd and Pb; significantly lowest in the green route for As and Pb; and comparable for all accumulated elements along most urban routes. A comparison with a previous experiment carried out in the same study area using similar moss-bags at static exposure points, showed that the element fluxes were significantly higher in the mobile system. Finally, PM2.5 and PM10 masses measured along the four routes were consistent with element fluxes.

Spider web biomonitoring: A cost-effective source apportionment approach for urban particulate matter

Elevated levels of particulate matter (PM) in urban atmospheres are one of the major environmental challenges of the Anthropocene. To effectively lower those levels, identification and quantification of sources of PM is required. Biomonitoring methods are helpful tools to tackle this problem but have not been fully established yet. An example is the sampling and subsequent analysis of spider webs to whose adhesive surface dust particles can attach. For a methodical inspection, webs of orb-weaving spiders were sampled repeatedly from 2016 to 2018 at 22 locations in the city of Jena, Germany. Contents of Ag, Al, As, B, Ba, Ca, Cd, Co, Cr, Cs, Cu, Fe, K, La, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sb, Si, Sn, Sr, Th, Ti, V, Y, Zn and Zr were determined in the samples using inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-optical emission spectroscopy (ICP-OES) after aqua regia digestion. Multivariate statistical methods were applied for a detailed evaluation. A combination of cluster analysis and principal component analysis allows for the clear identification of three main sources in the study area: brake wear from car traffic, abrasion of tram/train tracks and particles of geogenic origin. Quantitative source contributions reveal that high amounts of most of the metals are derived from a combination of brake wear and geogenic particles, the latter of which are likely resuspended by moving vehicles. This emphasizes the importance of non-exhaust particles connected to road traffic. Once a source identification has been performed for an area of interest, classification models can be applied to assess air quality for further samples from within the whole study area, offering a tool for air quality assessment. The general validity of this approach is demonstrated using samples from other locations.

Studying the influence of seasonal conditions and period of exposure on trace element concentrations in the moss-transplant Pylaisia polyantha

This study evaluates the effects of seasonal conditions and exposure periods on trace element concentrations in samples of the epiphytic moss Pylaisia ​​polyantha when transplanted into urban areas. This assessment was carried out in summer and winter at four sites differing in their level of technogenic trace element load. The contents of 25 trace elements (As, Ba, Br, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Lu, Mo, Nd, Rb, Sb, Sc, Sm, Sr, Tb, Th, U, Yb, and Zn) were determined using neutron-activation analysis, and it was shown that seasonal conditions do not affect vital activity in P. ​​polyantha graft moss. For most elements, the greatest increase in trace element concentration in P. ​​polyantha transplant moss was observed within one month. The high sensitivity of this epiphytic moss-transplant to the level of technogenic load has thus been demonstrated, and it may find utility in future research with similar objectives.

The influence of preparation methodology on the concentrations of heavy metals in Pleurozium schreberi moss samples prior to use in active biomonitoring studies

Active biomonitoring is used to assess environmental pollution of elements such as heavy metals by indicator species such as mosses. They are used, among others, in urbanized areas where no indicator species are found. In such study areas, mosses collected from sites considered to be ecologically clean shall be exposed. In this context, it is very important to prepare the mosses properly before the exposure, so that the information received about the condition of the environment is reliable. In 2018, studies were conducted in the forested areas of southern Poland-in Opolskie Province. Pleurozium schreberi mosses were used in these studies. Atomic absorption spectrometry with flame atomiser (F-AAS) was used to determine the concentrations of Mn, Fe, Ni, Cu, Zn and Pb present. The aim was to study the influence of preparation methodology on Pleurozium schreberi moss samples prior to use in active biomonitoring studies. Four different methodologies were tested across four different sample locations (with varying levels of pollution). The results of the research were analysed and the coefficient of variation (CV) was determined. The value of the CV is influenced, among other things, by the location of the particular sample and the level of pollution by, for example heavy metals, in the moss. The research conducted proves that of the four methods used to prepare mosses for later exposure in active biomonitoring, the best method is averaging with simultaneous conditioning of mosses in demineralised water. This treatment causes the CV coefficient to fall below 10% for most of the metals determined in the moss samples. It has also been shown that maintaining moss collection methodology in accordance with ICP Vegetation standards (open/wooded area-tree canopy) also has a significant impact on the result obtained. Statistical analysis confirmed (Wilcoxon test) that the method of processing the mosses significantly influenced the results obtained. Thanks to the appropriate preparation of the mosses before exposition, they can be used in active biomonitoring of, for example, urban areas.

Environmental pollution influence to soil-plant-air system in organic vineyard: bioavailability, environmental, and health risk assessment

This study was performed in organic vineyard to assess integrated pollution in soil-plant-air system by potentially toxic elements (PTE). Concentrations of 26 PTE were determined in soil, grapevine, and air biomonitors (moss bags) using ICP-OES and ICP-MS. Environmental implication assessment of soil did not show pollution by PTE, except for B in samples collected in the middle of grapevine season (July). Despite low total Cd concentrations in soil, it has the highest influence on increase of environmental risk. Based on biological accumulation concentration (BAC), grapevine is not hyperaccumulator of PTE from soil. Advanced classification algorithm, Kohonen self-organizing map (SOM), was applied to compare environmental implications in organic with conventional vineyards. PTE concentrations were significantly lower in organic than conventional grapevine. PTE concentrations were higher in the outer (leaf and petiole) than in the inner grapevine parts (skin, pulp, and seed). Some airborne elements have an influence on outer grapevine parts, especially on leaves (ratio factor-RF > 1). Moss bag technique testified about lower enrichment of airborne elements compared with the conventional vineyard and urban microenvironments. Environmental and health risk assessments confirmed that organic production is harmless for field workers and grape consumers.

Axenic in vitro cultivation of 19 peat moss (Sphagnum L.) species as a resource for basic biology, biotechnology, and paludiculture

Sphagnum farming can substitute peat with renewable biomass and thus help mitigate climate change. Large volumes of the required founder material can only be supplied sustainably by axenic cultivation in bioreactors. We established axenic in vitro cultures from sporophytes of 19 Sphagnum species collected in Austria, Germany, Latvia, the Netherlands, Russia, and Sweden: S. angustifolium, S. balticum, S. capillifolium, S. centrale, S. compactum, S. cuspidatum, S. fallax, S. fimbriatum, S. fuscum, S. lindbergii, S. medium/divinum, S. palustre, S. papillosum, S. rubellum, S. russowii, S. squarrosum, S. subnitens, S. subfulvum and S. warnstorfii. These species cover five of the six European Sphagnum subgenera; namely, Acutifolia, Cuspidata, Rigida, Sphagnum and Squarrosa. Their growth was measured in suspension cultures, whereas their ploidy was determined by flow cytometry and compared with the genome size of Physcomitrella patens. We identified haploid and diploid Sphagnum species, found that their cells are predominantly arrested in the G1 phase of the cell cycle, and did not find a correlation between plant productivity and ploidy. DNA barcoding was achieved by sequencing introns of the BRK1 genes. With this collection, high-quality founder material for diverse large-scale applications, but also for basic Sphagnum research, is available from the International Moss Stock Center.

Indirect establishment increases the chances of in vitro propagation of mosses occurring in the Cerrado - a new method

Abstract The use of micropropagation techniques is crucial for the conservation of endangered moss species and their reestablishment in nature. This study aimed to establish in vitro cultures of gametophyte fragments of ten species of Cerrado mosses. After disinfestation with alcohol and commercial bleach, moss explants were grown in Petri dishes containing Knop medium. The species Bryum argenteum, B. coronatum, Isopterygium tenerifolium, Leucobryum crispum, Pogonatum pensilvanicum, and Vitalia cuspidifera were successively established with efficiency rate ranging from 1 to 31.2%. However, no aseptic cultures were obtained for the species Barbula indica, Bryum densifolium, Fissidens flaccidus, and Sphagnum platyphylloides. Even though, a few contaminated explants of these species were able to develop and grow. Thus, all ten species were submitted to rescue techniques to establish cultures in aseptic conditions, from partially contaminated explants (indirect establishment). Consequently, the indirect establishment resulted in higher percentages of explant development, which enhanced the establishment of in vitro cultures for most of the species tested. This fact is especially important for conservation purposes, mainly for species whose material is sensitive or scarce. Therefore, indirect establishment as a new in vitro culture methodology was a viable form of propagating the bryophyte species listed in this research. This fact is essential for conservation purpose, especially for species whose material is sensitive or scarcer.

Monitoring of Air Pollution by Moss Bags around an Oil Refinery: A Critical Evaluation over 16 Years

The present study analyzes the results of a biomonitoring campaign, carried out by means of Hypnum cupressiforme Hedw. moss bags around an oil refinery, located in the southwestern part of Sardinia island (Italy). This work focuses mainly on the effects of rainfall and distance from the source of contamination on the content of 14 trace elements measured over 16 years. In addition, to point out any increasing or decreasing trends, as well as any peak in presence of airborne pollutants in the area, annual elements’ concentration values are plotted and discussed. Coefficients of variation were also calculated on accumulation values in order to evaluate stability of measurements across the years and to evaluate if similar exposure conditions, i.e., humidity and distance from contamination source, resulted in more uniform accumulation values. In conclusion, (i) the vicinity of the source of contamination as well as rainfall influenced element content in the biomonitor in the case study differently, depending on the considered element and on the exposure condition, (ii) H. cupressiforme moss bags provided relatively stable measurements during the 16-year time frame (observed variations in elements content can be attributed to environmental inputs in the area), (iii) similar conditions of exposure determined less variable accumulation values.

Methodological advances to biomonitor water quality with transplanted aquatic mosses

The active biomonitoring technique has been demonstrated to be an excellent tool for monitoring water quality; however, further improvement of the protocol is urgently needed. The present study was carried out to determine the best options for various methodological aspects of monitoring some metals and metalloids (i.e. Al, As, Cd, Co, Cu, Fe, Hg, Ni, Zn and Pb): i) the type of transplant, ii) pre-exposure washing (with or without cellular extractants), iii) the ratio between moss weight and bag surface area, and iv) the depth at which the bags are exposed. The importance of the different methodological aspects in the outcome of biomonitoring studies was also assessed by considering the results of the present and other previously published studies. Regarding the type of transplant, the traditionally used net bags were the best option for enclosing the moss; in addition, washing the moss with extracellular extractants (i.e. EDTA) prior to exposure increased the sensitivity of the technique and reduced the required exposure time (i.e. one week). For the amount of moss packed in each bag, a ratio of 12.5 mg cm^-2 was the best choice. Finally, the depth at which the transplants were exposed did not affect pollutant accumulation (in shallow rivers, reservoirs or dams). Pollutant concentrations were also not affected by the existence of thermocline in deep waters during warmer months. Different methodological aspects involved in applying this technique determine the final concentrations of metals in moss. Although the influence of those was variable, for most elements (i.e. As, Cd, Co, Cu, Hg, Pb, Zn) 80% of the total variance was explained by 3-4 aspects, being species selection, devitalization treatment, duration of exposure, and number of transplants exposed the most important.

Morphological Traits Influence the Uptake Ability of Priority Pollutant Elements by Hypnum cupressiforme and Robinia pseudoacacia Leaves

In this paper, a biomonitoring survey of airborne priority pollutant elements was carried out using leaves of native black locust and moss bags filled with Hypnum cupressiforme. The aims of the work were (i) to evaluate if mosses and leaves provide similar information regarding the accumulation of the elements of environmental concern (As, Be, Cd, Cr, Cu, Hg, Mo, Ni, Pb, Sb, Se, V, Zn, Tl); (ii) to evaluate if leaf traits are significantly involved in the uptake mechanisms. Hypnum transplants showed elemental contents generally higher than R. pseudoacacia leaves, despite the shorter exposure time. Moss accumulated larger amounts of elements linked to PM and the resuspension of soil dust. Based on the calculation of deposition flux for each element, R. pseudoacacia showed lower values for most elements—except Cr, Mo and Zn—indicating that uptake takes place both by deposition on the leaf surface and absorption via the root. Leaf traits (micromorphology of surface) play an important role in the interception and retention of PM-linked elements. Hypnum transplanted in bags was confirmed to be a powerful bio-accumulator of airborne elements; by contrast, R. pseudoacacia, with a smooth surface and scarce trichomes, showed a limited ability in airborne element retention. Therefore, widely diffused species, well-adapted to anthropized environments, such as black locust, not always can be considered as good biomonitors. The results are discussed in comparison to other vascular plant species used in biomonitoring studies.

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.

Biosurface properties and lead adsorption in a clone of Sphagnum palustre (Mosses): Towards a unified protocol of biomonitoring of airborne heavy metal pollution

Although mosses are widely used for active biomonitoring of air pollution, a unified protocol for their treatment before exposure in bags is still lacking. Here we used field- and laboratory-grown Sphagnum palustre L. moss, respectively, treated by EDTA and devitalized by oven drying at 100 °C, to elaborate a consistent procedure of metal and proton adsorption on moss surfaces. Acid-base titrations and Pb²⁺ adsorption experiments at different pH values and Pb²⁺ concentrations in solution were performed with both field-collected and laboratory cloned mosses. Devitalization and EDTA treatments did not produce any measurable difference in terms of H⁺ and Pb²⁺ adsorption capacities of moss surfaces. The stability constants for Pb²⁺ adsorption onto moss surfaces as a function of pH (pH-dependent adsorption edge) and at constant pH (5.5 and 6.5) as a function of Pb²⁺ concentration ("langmuirian" adsorption isotherm) were rather similar between different treatments. A Linear Program Modeling (LPM) of adsorption reactions revealed high similarity of adsorption constants regardless of treatments for both field-grown and cloned mosses. Therefore, in view of the use of S. palustre clone for biomonitoring lead in the environment, we recommend devitalization at 100 °C as unique treatment to perform with the aim to preserve the biomonitor before and after its exposure in bags.

Assessment of the possibility of using deciduous tree bark as a biomonitor of heavy metal pollution of atmospheric aerosol

The aim of the research was to assess the possibility to use deciduous tree bark in the biomonitoring of urban areas. The tree bark taken from various deciduous tree species growing in the Opole Province (south-western Poland) was used for the research. The bark was collected from tree trunks in the period of June 2-26, 2017. Concentrations of the heavy metals were determined in the barks by flame atomic absorption spectrometry (FAAS). On the basis of the research, it was determined that type of tree, distance from pollution source, elevation off the ground and the side of trunk from which bark was sampled all influence the research results. A comparison of the values of coefficient of variation CV demonstrated that the bark Quercus robur and Betula pendula is more heterogeneous, e.g. for Fe CV_{Quercus robur} is 48.0 % and CV_{Betula pendula} = 42.3 %, compared to Fagus sylvatica (CV_Fe = 22.6%). In order to limit the influence of environmental factors (e.g. air movement caused by vehicles and pedestrians) on the samples pollution level with analytes, it seems that the optimum level for collecting the samples is 1.5-2.0 m. It was demonstrated that deciduous tree bark can be used as bioindicator in assessing the pollution of atmospheric aerosol by heavy metals, due to its occurrence in urban areas. However, it is important to validate all stages of the analysis procedure that uses deciduous tree bark.

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.

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

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

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.

New Interpretative Scales for Lichen Bioaccumulation Data: The Italian Proposal

The interpretation of lichen bioaccumulation data is of paramount importance in environmental forensics and decision-making processes. By implementing basic ideas underlying previous interpretative scales, new dimensionless, species-independent “bioaccumulation scales” for native and transplanted lichens are proposed. Methodologically consistent element concentration datasets were populated with data from biomonitoring studies relying on native and transplanted lichens. The scale for native lichens was built up by analyzing the distribution of ratios between element concentration data and species-specific background concentration references (B ratios), herein provided for Flavoparmelia caperata and Xanthoria parietina (foliose lichens). The scale for transplants was built up by analyzing the distribution of ratios between element concentration in exposed and unexposed samples (EU ratio) of Evernia prunastri and Pseudevernia furfuracea (fruticose lichens). Both scales consist of five percentile-based classes; namely, “Absence of”, “Low”, “Moderate”, “High”, and “Severe” bioaccumulation. A comparative analysis of extant interpretative tools showed that previous ones for native lichens suffered from the obsolescence of source data, whereas the previous expert-assessed scale for transplants failed in describing noticeable element concentration variations. The new scales, based on the concept that pollution can be quantified by dimensionless ratios between experimental and benchmark values, overcome most critical points affecting the previous scales.

Ti and Zn Content in Moss Shoots After Exposure to TiO2 and ZnO Nanoparticles: Biomonitoring Possibilities

To assess the uptake of nanoparticles by moss shoots and the possibility of biomonitoring the moss of nanoparticle pollution, two moss species frequently used in biomonitoring surveys [Hylocomium splendens (Hedw.) Schimp. and Pleurozium schreberi (Brid.) Mitt.] were repeatedly exposed to known concentrations of either nano-TiO₂ or nano-ZnO suspensions. The interspecies differences were assessed by exposing both the species to 1 g L^-1 nano-ZnO suspension, H. splendens samples were also exposed to either 0.1 g L^-1 or 1 g L^-1 suspension of nano TiO₂. The exposed samples were analysed for Zn or Ti content using Inductively Coupled Plasma-Atomic Emission Spectroscopy. Both species showed a similar accumulation pattern, H. splendens being a slightly better accumulator. The washing suggests that Ti successfully penetrated the interior of the gametophyte. Since the relationship between the exposure and accumulation is linear, moss biomonitoring is, hereby, considered to be a viable, novel technique in nanoparticle pollution assessment.

Developing a Biotechnological Tool for Monitoring Water Quality: In vitro Clone Culture of the Aquatic Moss Fontinalis Antipyretica

One of the main factors limiting active biomonitoring with aquatic mosses is the lack of sufficient material. A laboratory culture of the moss would solve this problem and thus convert the technique into a valuable biotechnological tool for monitoring water quality. With this aim, we first established small and large scale axenic in vitro culture systems for the aquatic moss Fontinalis Antipyretica. We then attempted to enhance the growth rate of the cultures by modifying temperature, photoperiod and medium composition (N:P ratio, P concentration, CO2 supply, NH4NO3 supply and sucrose supply). None of these modifications greatly increased the in vitro growth rate. However, the growth rates were sufficiently high (relative to the initial weight of the cultures) in both systems (45 and 6 mg·day−1·g−1· for flasks and bioreactors respectively) to enable the production of large amounts of material. The ability to culture the material will substantially improve the applicability of the moss bag technique.

Effect of placement conditions for active monitoring of trace element with the epiphytic moss

In this work, problems arising by use of active biomonitoring are discussed. Biomonitoring technique using positioned vertically frameworks and epiphytic moss Pylaisia polyantha is proposed. The influence of tree species on which the bark of the frameworks is fixed, altitude, and orientation is researched. For this purpose, frameworks were placed at two sampling sites of Tomsk on different trees (poplar, birch), at altitudes of 0.5 and 1.5 and with different orientations in May; the exposure time was 20 weeks. The concentrations of As, Ba, Br, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Mo, Rb, Sb, Sc, Sm, Tb, Th, U, Yb, and Zn were determined by neutron activation analysis at the research reactor of Tomsk Polytechnic University. Increasing concentrations of half of the chemical elements was revealed during the exposure. The high-capacity frameworks used to accumulate certain elements-Cs, Eu, Hf, K, Lu, Sb, Yb-were revealed.

Sphagnum palustre clone vs native Pseudoscleropodium purum: A first trial in the field to validate the future of the moss bag technique

Although a large body of literature exists on the use of transplanted mosses for biomonitoring of air pollution, no article has addressed so far the use and the accumulation performance of a cloned moss for this purpose. In this work, a direct comparison of metal accumulation between bags filled with a Sphagnum palustre L. clone or with native Pseudoscleropodium purum Hedw., one of the most used moss species in biomonitoring surveys, was investigated. The test was performed in sites with different atmospheric contamination levels selected in urban, industrial, agricultural and background areas of Italy and Spain. Among the eighteen elements investigated, S. palustre was significantly enriched in 10 elements (Al, Ba, Cr, Cu, Fe, Hg, Pb, Sr, V and Zn), while P. purum was enriched only in 6 elements (Al, Ba, Cu, Hg, Pb and Sr), and had a consistently lower uptake capacity than S. palustre. The clone proved to be more sensitive in terms of metal uptake and showed a better performance as a bioaccumulator, providing a higher accumulation signal and allowing a finer distinction among the different land uses and levels of pollution. The excellent uptake performance of the S. palustre clone compared to the native P. purum and its low and stable baseline elemental content, evidenced in this work, are key features for the improvement of the moss bag approach and its large scale application.

Atmospheric particulate matter intercepted by moss-bags: Relations to moss trace element uptake and land use

Particulate matter has to be constantly monitored because it is an important atmospheric transport form of potentially harmful contaminants. The cost-effective method of the moss-bags can be employed to evaluate both loads and chemical composition of PM. PM entrapped by the moss Pseudoscleropodium purum exposed in bags in 9 European sites was characterized for number, size and chemical composition by SEM/EDX. Moreover, moss elemental uptake of 53 elements including rare earth elements was estimated by ICP-MS analysis. All above was aimed to find possible relations between PM profile and moss uptake and to find out eventual element markers of the different land use (i.e. agricultural, urban, industrial) of the selected sites. After exposure, about 12,000 particles, mostly within the inhalable fraction, were counted on P. purum leaves; their number generally increased from the agricultural sites to the urban and industrial ones. ICP analysis indicated that twenty-three elements were significantly accumulated by mosses with different element profile according to the various land uses. The PM from agricultural sites were mainly made of natural/crustal elements or derived from rural activities. Industrial-related PM covered a wider range of sources, from those linked to specific industrial activities, to those related to manufacturing processes or use of heavy-duty vehicles. This study indicates a close association between PM amount and moss element-uptake, which increases in parallel with PM amount. Precious metals and REEs may constitute novel markers of air pollution in urban and agricultural sites, respectively.

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.