Understanding mercury accumulation in mosses of two subalpine forests in China

The role of forest ecosystems in the global mercury (Hg) biogeochemical cycle is widely recognized; however, using litterfall as a surrogate to assess the Hg sink function of forests encounters limitations. We investigated the accumulation characteristics and influencing factors of Hg in mosses from two remote subalpine forests in southwestern China. The results indicated that there was high Hg accumulation in subalpine forest mosses, with average concentrations of 82 ± 49 ng g-1 for total mercury (THg) and 1.3 ± 0.8 ng g-1 for methylmercury (MeHg). We demonstrated that the accumulation capacity of Hg in mosses was significantly dependent on species and substrates (micro-habitats), the mosses on tree trunks exhibited significantly elevated Hg accumulation levels (THg 132 ± 56 ng g-1, MeHg 1.6 ± 0.2 ng g-1) compared to mosses in other substrates. The surface morphologies and biochemical components of leaf (phyllidia), such as cation exchange capacity (CEC), pectin, uronic acid, and metallothionein, play a crucial role in the accumulation of Hg by mosses. These findings provide valuable insights into Hg accumulation in forest mosses. Suggesting that the contribution of mosses Hg accumulation should be considered when assessing atmospheric Hg sinks of forests.

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.

Assessing heavy metal contamination in a Brazilian metropolis: a case study with a focus on (bio)indicators

The continuous expansion of the global vehicle fleet poses a growing threat to environmental quality through heavy metal contamination. In this scenario, monitoring to safeguard public health in urban areas is necessary. Our study involved the collection of 36 street dust and 29 moss samples from roads of a Brazilian metropolis (Recife) with varying traffic intensities as follows: natural reserve (0 vehicles per day), low (< 15,000 vehicles per day), medium (15,000-30,000 vehicles per day), and high (> 30,000 vehicles per day). ICP-AES analysis was performed to determine the concentrations of nine potentially toxic metals (Ba, Cd, Cr, Cu, Mn, Ni, Pb, V, and Zn) to assess the influence of vehicular flow on urban contamination. In the street dust samples, the mean metal concentrations (mg kg-1) exhibited the following order: Ba (503.7) > Mn (303.0) > Zn (144.4) > Cu (95.3) > Cr (56.1) > Pb (34.2) > V (28.7) > Ni (11.3) > Cd (1.5). Conversely, in the moss samples, the metal concentration order was as follows (mg kg-1): Mn (63.8) > Zn (62.5) > Ba (61.0) > Cu (17.7) > Cr (8.0) > V (7.3) > Pb (7.0) > Ni (2.9) > Cd (0.3). Roads with higher traffic volumes exhibited the highest metal enrichments in moss samples for all metals and in dust samples for Cd, Cr, Mn, Ni, and V. However, dust from low-flow roads had higher enrichments for Ba, Cu, and Zn, indicating the influential role of other traffic-related factors in metal deposition. Our findings highlight traffic flow as the predominant source of pollution in urban centers, with both street dust and moss serving as sensitive indicators of metal input attributable to vehicular traffic. These indicators offer valuable insights for urban quality monitoring and pollution control efforts.

Photo-protection and photo-inhibition during light induction in Barbula indica and Conocephalum conicum under different light gradients

The objectives of this study were to measure the chlorophyll fluorescence (ChlF) parameters of Barbula indica (Hook.) Spreng and Conocephalum conicum (L.) Dumort subjected to various light intensities (LI) as a reflection of their adaptability to their habitats. The electron transport rate (ETR) of all plants under 500 μmol m-2 s-1 photosynthetic photon flux density (PPFD) was significantly higher than other LI treatments, implying that these plants could be grown under a specific and optimal light intensity adapted to 500 PPFD conditions. As LI increased from 50 to 2,000 PPFD, we observed in all plants increased non-photochemical quenching (NPQ) and photo-inhibitory quenching (qI) and decreased photosystem II efficiency (ΦPSII), potential quantum efficiency of PSII (Fv/Fm), actual PSII efficiency (ΔF/Fm'%), and Fv/Fm%. In addition, energy-dependent quenching (qE), the light protection system (qE + qZ + qT), and qI increased as ΦPSII decreased and photo-inhibition% increased under 1000, 1500, and 2000 PPFD conditions, suggesting that these plants had higher photo-protective ability under high LI treatments to maintain higher photosynthetic system performance. B. indica plants remained photochemically active and maintained higher qE under 300, 500, and 1000 PPFD, whereas C. conicum qZ + qT exhibited higher photo-protection under 500, 1000, and 1500 PPFD conditions. These ChlF indices can be used for predicting photosynthetic responses to light induction in different bryophytes and provide a theoretical basis for ecological monitoring.

Hormonal and genetic control of pluripotency in bryophyte model systems

Land plant meristems are reservoirs of pluripotent stem cells where new tissues emerge, grow and eventually differentiate into specific cell identities. Compared to algae, where cells are produced in two-dimensional tissues via tip or marginal growth, land plants have meristems that allow three-dimensional growth for successful exploration of the terrestrial environment. In land plants, meristem maintenance leads to indeterminate growth and the production of new meristems leads to branching or regeneration via reprogramming of wounded somatic cells. Emerging model systems in the haploid dominant and monophyletic bryophytes are allowing comparative analyses of meristem gene regulatory networks to address whether all plants use common or diverse programs to organise, maintain, and regenerate meristems. In this piece we aim to discuss recent advances in genetic and hormonal control of bryophyte meristems and possible convergence or discrepancies in an exciting and emerging field in plant biology.

Implementation of simple and effective fine droplet formation-based spray-assisted liquid phase microextraction for the simultaneous determination of twenty-nine endocrine disruptor compounds and pesticides in rock, soil, water, moss, and feces samples from antarctica using gas chromatography-mass spectrometry

This study established the simultaneous determination of the selected endocrine-disrupting compounds (EDCs) and pesticides in rock, soil, water, moss, and feces samples collected from the Antarctic region. The spray-assisted droplet formation-based liquid phase microextraction (SADF-LPME) coupled to GC-MS system was developed and validated for the screening and monitoring of 29 selected EDCs and pesticides. Binary solvent system, 1:1 (v/v) dichlormethane: 1,2-dichloroethane mixture was employed as an extraction solvent and sprayed onto sample or standard solutions using a straightforward and practical spray apparatus. The factors affecting the extraction process such as extraction solvent type and ratio, extraction solvent volume (spray repetition), vortexing period, and sample pH were properly optimized. Analytical figures of the merit of the method were recorded under the optimal extraction/chromatographic conditions. The LOD, LOQ, and enhancement factor were in the range of 1.0 to 6.6 ng/g, 3.2 to 22.1 ng/g, and 3.7 to 158.9, respectively. The method demonstrated a good linear working range for all the selected analytes with proper coefficients of determination. The usability and reliability of the microextraction strategy was confirmed using seawater, moss, and soil samples, and the %recoveries were within an acceptable range (> 70%) for all examined samples. The environmental samples collected from the Horseshoe and Faure Islands of the Antarctica region were analyzed to assess the potential pollution of EDCs and pesticides. This method has the potential to be employed for the analysis of EDCs in routine analytical laboratories and for controlling and screening the organic pollutant content of different environmental samples.

Multifactorial analysis of terminator performance on heterologous gene expression in Physcomitrella

KEY MESSAGE

Characterization of Physcomitrella 3'UTRs across different promoters yields endogenous single and double terminators for usage in molecular pharming. The production of recombinant proteins for health applications accounts for a large share of the biopharmaceutical market. While many drugs are produced in microbial and mammalian systems, plants gain more attention as expression hosts to produce eukaryotic proteins. In particular, the good manufacturing practice (GMP)-compliant moss Physcomitrella (Physcomitrium patens) has outstanding features, such as excellent genetic amenability, reproducible bioreactor cultivation, and humanized protein glycosylation patterns. In this study, we selected and characterized novel terminators for their effects on heterologous gene expression. The Physcomitrella genome contains 53,346 unique 3'UTRs (untranslated regions) of which 7964 transcripts contain at least one intron. Over 91% of 3'UTRs exhibit more than one polyadenylation site, indicating the prevalence of alternative polyadenylation in Physcomitrella. Out of all 3'UTRs, 14 terminator candidates were selected and characterized via transient Dual-Luciferase assays, yielding a collection of endogenous terminators performing equally high as established heterologous terminators CaMV35S, AtHSP90, and NOS. High performing candidates were selected for testing as double terminators which impact reporter levels, dependent on terminator identity and positioning. Testing of 3'UTRs among the different promoters NOS, CaMV35S, and PpActin5 showed an increase of more than 1000-fold between promoters PpActin5 and NOS, whereas terminators increased reporter levels by less than tenfold, demonstrating the stronger effect promoters play as compared to terminators. Among selected terminator attributes, the number of polyadenylation sites as well as polyadenylation signals were found to influence terminator performance the most. Our results improve the biotechnology platform Physcomitrella and further our understanding of how terminators influence gene expression in plants in general.

How the xerophytic moss Pogonatum inflexum tolerates desiccation

KEY MESSAGE

Desiccation-tolerant process of xerophytic moss Pogonatum inflexum were identified through de novo transcriptome assembly , morphological structure and physiology analysis. Pogonatum inflexum (Lindb.) Lac. is a typical xerophytic moss and have been widely used in gardening and micro-landscape. However, the mechanisms underlying desiccation tolerance are still unclear. In this study, morphological,  physiological and trancriptomic analyses of P. inflexum to tolerate desiccation were carried out. Our results indicate that P. inflexum increase osmoregulation substances, shut down photosynthesis, and alter the content of membrane lipid fatty acids in response to desiccation, and the genes involved in these biological processes were changes in expression after desiccation. 12 h is the threshold for P. inflexum to tolerate desiccation and its photosynthesis has not been damaged within 12 h of desiccation and can still recover after rewater. We also proved that the gametocyte of P. inflexum has the ability to absorb and transport water, and contains lignin-synthesis genes in response to tolerant desiccation. Our findings not only explain the mechanisms of P. inflexum during desiccation, but also provide some attractive candidate genes for genetic breeding.

Evaluating the effect of moss functional traits and sampling on elemental concentrations in Pleurozium schreberi and Ptilium crista-castrensis in Eastern Canada (Québec) black spruce forest

Characterizing atmospheric depositions allows evaluating the impact of air pollution on ecosystems, human health, and the economy. It also informs decision-makers about the implementation of regulations improving environmental quality. Biomonitoring uses organisms, such as mosses, as proxies to assess the presence of atmospheric contaminants (e.g., metals). This approach is cost-efficient and does not require complicated infrastructure or scientific skills, making it suitable for large-scale monitoring initiatives and citizen-based campaigns. Therefore, precise sampling protocols are needed to limit bias. Biomonitoring data remains scarce in North America, compared to e.g., Europe, and there is a need to develop large-scale and long-term biomonitoring initiatives to record current and future atmospheric depositions. As there is no standardized international sampling protocol, this study assessed the impact of parameters known to affect the elemental concentration of mosses, using samples collected along a 1000-km transect in Eastern Canada (Quebec) from 2016 to 2022. We specifically examined the effects of species, stem color, canopy opening, time of sampling, and stem length on 18 elements. Non-parametric statistical tests indicate that these factors have significant effects on some metals, but differences are generally low (<30 %), except for stem length. These results suggest that sampling protocols can be flexible in terms of species, canopy opening, time of sampling, and stem color. However, normalizing the length of the stems analyzed is required to account for differences in growth rates between sites. Moreover, since no large-scale biomonitoring campaign using mosses has been conducted in Eastern Canada, this paper also provides the first elemental baseline for moss in the region.

Evaluation of metal pollution characteristics using water and moss in the Luanchuan molybdenum mining area, China

Luanchuan is rich in molybdenum resources, and mining activities are frequent, but over-mining can cause serious metal pollution to the local environment. To explore the degree of metal pollution caused by mining activities, the content characteristics and spatial distribution of metals in mining areas were studied by measuring the concentrations of Fe, Mn, Zn, Ba, Mo, Cu, Cr, Co, V, and W in surface water and mosses of mining areas. In addition, the metal pollution index (HPI), contamination factor (CF), and pollution load index (PLI) were used to evaluate metal pollution, and factor analysis was used to analyze the sources of metals. The results of the analysis of surface water at the mine site indicate the most abundant element in surface water, with a maximum concentration of 3713.8 μg/L, and its content far exceeds the water quality standard of Class III of the Environmental Quality Standard for Surface Water. The results of the HPI analysis showed that nearly 90% of the surface water was moderately contaminated (HPI ≥ 15). The results of the analysis of atmospheric deposition at the mine site confirm that the metal elements with a high threat to the atmospheric environment are Mo and W. The results of PLI indicate that the level of atmospheric deposition pollution in the study area is severe (PLI > 4). Factor analysis indicated that rock weathering and mining activities were the main sources of metals. This study provides a theoretical basis for the investigation and control of metal pollution in similar metal mining areas.

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.

Regularities of 137Cs distribution in the soil and vegetation cover of elementary landscape-geochemistry system within the forest test plot in the Chernobyl NPP exclusion zone

The main goal of the investigation was to reveal the lateral and vertical regularities of element distribution in the elementary landscape-geochemical system (ELGS) type: summit-slope-closing depression. We used an isotope 137Cs as a tracer of migration of chemical elements in soil and vegetation cover. The study was performed in a test site characterizing undisturbed forest landscapes in the Russian zone of the Chernobyl accident. Investigated ELGS was 16-m long with a relative height difference of 1.5 m. Field measurements of 137Cs activity was performed with a 1-meter step by the modified portable gamma-spectrometer Violinist-III (USA). Cs-137 content in moss and soil cores sampled with the same lateral step was determined in the laboratory using Canberra (USA, HPGe detector). The upper soil layer 8-cm thick contained from 70 to 96% of 137Cs, and 89-99% of the total inventory was fixed in the top 20-cm layer. Cs-137 activity in both the soil and moss cover demonstrated a cyclic type of variability, which was described and modeled using Fourier analysis. Correlation between the actual and modeled activity values (r0.01 = 0.868) showed that three main harmonics are sufficient for representative modeling of the observed cycles. We infer that the revealed patterns are characteristic for most of the chemical elements and may be useful for practical purposes.

Basking in the sun: how mosses photosynthesise and survive in Antarctica

The Antarctic environment is extremely cold, windy and dry. Ozone depletion has resulted in increasing ultraviolet-B radiation, and increasing greenhouse gases and decreasing stratospheric ozone have altered Antarctica's climate. How do mosses thrive photosynthetically in this harsh environment? Antarctic mosses take advantage of microclimates where the combination of protection from wind, sufficient melt water, nutrients from seabirds and optimal sunlight provides both photosynthetic energy and sufficient warmth for efficient metabolism. The amount of sunlight presents a challenge: more light creates warmer canopies which are optimal for photosynthetic enzymes but can contain excess light energy that could damage the photochemical apparatus. Antarctic mosses thus exhibit strong photoprotective potential in the form of xanthophyll cycle pigments. Conversion to zeaxanthin is high when conditions are most extreme, especially when water content is low. Antarctic mosses also produce UV screening compounds which are maintained in cell walls in some species and appear to protect from DNA damage under elevated UV-B radiation. These plants thus survive in one of the harshest places on Earth by taking advantage of the best real estate to optimise their metabolism. But survival is precarious and it remains to be seen if these strategies will still work as the Antarctic climate changes.

Looking at moss through the bioeconomy lens: biomonitoring, bioaccumulation, and bioenergy potential

The field of bioeconomy has been experiencing a surge in interest in recent years as society increasingly recognizes the potential of utilizing renewable biological resources to create sustainable solutions for economic growth, resource management, and environmental protection. Despite its potential, there is a notable lack of studies exploring the utilization of moss as a viable resource within the bioeconomy framework. Aligned with this objective, this paper conducts a keyword analysis using the VOSviewer application to explore the applicability of mosses as a bioeconomy resource. While biomonitoring using mosses has been studied extensively, this paper shifts its focus to discuss advancements in this area. Moreover, it evaluates the viability of moss utilization for bioenergy production and concisely summarizes their application in microbial fuel cells. The review also highlights challenges pertinent to moss utilization and presents future prospects. The overarching goal of this review paper is to assess the potential and utilization prospects of mosses within the realms of bioaccumulation, air purification, and bioenergy. By offering a comprehensive summary of moss applications, performance, and viability across diverse sectors, this paper endeavors to promote the versatile application of mosses in various contexts. It repositions the discussion on mosses, accentuating their utilization potential prior to exploring conclusions and future prospects.

Assessment of atmospheric heavy metal pollution in Qinghai-Tibet Plateau: Using mosses as biomonitor

Atmospheric heavy metal (HM) pollution may pose a significant threat to the fragile ecosystem of Qinghai-Tibet Plateau (QTP). To investigate potential atmospheric HM pollution within the QTP region of China, mosses, along with other higher plants and soil, were collected from 33 sites for heavy metal measurement. The concentration ranges of Zn, Pb, Cd, and Cu in mosses were 6.07-69.9, 5.36-23.9, 0.60-1.05, and 14.4-50.5 mg·kg-1 (dry weight), respectively, significantly higher than those in other higher plants, except for Zn. The spatial distribution of relative concentrations (RCs; moss to top soil) of HMs varied considerably, indicating distinct differences in atmospheric Zn and Cu pollution levels between the northern and southern QTP. This study first reported that moderate regional atmospheric Cu pollution, primarily due to large-scale mining in recent years, had occurred, particularly in southern QTP. Pb also presented slight pollution due to anthropogenic activities. However, Cd showed almost no atmospheric pollution, while Zn concentrations were relatively high in southern QTP. Although less severe than atmospheric pollution levels in Chinese inland or coastal cities, the atmospheric pollution of Pb and Cu in QTP indicated by mosses were far more severe than global background areas, or even worse than most European cities.

Decreased atmospheric deposition of heavy metals in Latvia shown by long-term monitoring using the moss Pleurozium schreberi

In Europe, economic restructuring and technological progress has been aimed at reducing pollution emissions at local, regional and global scales, which has been monitored using standard methods. Among the many methods used to determine deposition of heavy metals, in Europe moss has been used to monitor atmospheric pollution for more than 30 years on a 5-year cycle. This simple method can be used to assess improvement to the environment after massive economic change. Using PCA analysis, this study examines the long-term trends of heavy metal concentrations (Cr, Cu, Ni, Pb, V, Zn) in Latvia. There has been a decline in heavy metal concentrations in Latvia related to the closure of large industries after the collapse of the Soviet Union and due to change in fossil fuels in the energy sector from petroleum to natural gas, but past effect from some sources is still evident. Increased quality of automobile fuel led to a decrease of lead concentration, and conversion of fuel source in the energy sector from oil to natural gas caused a decline of V and Ni concentration.

Investigation of the spatial distribution of airborne polycyclic aromatic hydrocarbons using Rhytidiadelphus squarrosus in Tórshavn, Faroe Islands

Due to adverse effects of Polycyclic Aromatic Hydrocarbons (PAHs) on human health, it is important to understand how airborne PAHs, are spatially distributed within urban areas. Moss has been shown to be a suitable material for biomonitoring of airborne PAH pollution. In this study, the moss Rhytidiadelphus squarrosus was sampled throughout Tórshavn, Faroe Islands. 53 Rhytidiadelphus squarrosus samples were extracted using a matrix solid-phase dispersive extraction method and analysed for 19 parent PAHs and six groups of alkylated PAHs using gas chromatography mass-spectrometry. All PAHs were quantified in at least one Rhytidiadelphus squarrosus sample, and the sum of the EPA 16 PAHs (ƩPAH_EPA16) ranged from 0.90 to 344 µg kg^-1 dry weight. Higher concentrations were found close to the harbour and the main roads. The spatial correlation was investigated for the ƩPAH_EPA16, pyrene, fluoranthene, chrysene, benzo(e)pyrene, benzo(g,h,i)perylene, C1-phenanthrenes/C1-anthracenes, and C2-phenanthrenes/C2-anthracenes using variograms. The effective range of the spatial correlation was between 500 to 700 m of all PAHs. The evaluation of diagnostic ratios of fluoranthene to pyrene, and benzo(a)anthracene to chrysene suggest that different pollution sources affect urban areas of different types. To the best of our knowledge, this is the first time airborne PAH pollution patterns were mapped in an Arctic town, and the first time, Rhytidiadelphus squarrosus was used for tracing PAH pollution sources. Rhytidiadelphus squarrosus is suitable for biomonitoring and mapping PAH pollution within urban areas since it is widespread, and suitable for mapping PAHs.

Radioactivity research in mosses from typical Karst Regions in Leye Tiankeng, Southern China

Radionuclides in environmental ecosystems have ecotoxicity and health impact on human and environment, so radioactive contamination has always been one of the global concerns. This study mainly focused on the radioactivity of mosses collected from the Leye Tiankeng Group in Guangxi. The activities of ^239+240Pu measured by SF-ICP-MS and ¹³⁷Cs measured by HPGe in moss and soil samples are as follows: 0-2.29 Bq/kg in mosses and 1.5-11.9 Bq/kg in soils for ¹³⁷Cs, and 0.025-0.25Bq/kg in mosses and 0.07-0.51Bq/kg in soils for ^239+240Pu. The range of ²⁴⁰Pu/²³⁹Pu atom ratios (0.201 in mosses and 0.184 in soils) and ^239+240Pu/¹³⁷Cs activity ratios (0.128 in mosses and 0.044 in soils) indicated that the ¹³⁷Cs and ^239+240Pu in study area were mainly contributed by global fallout. ¹³⁷Cs and ^239+240Pu showed similar distribution in soils. However, their behaviors in mosses were quite different due to the differences in the growth environment of mosses. The transfer factors of ¹³⁷Cs and ^239+240Pu from soil to moss varied in different growth stages and specific environments. A weak positive correlation among ¹³⁷Cs, ^239+240Pu in mosses and soil-derived radionuclides suggested that resettlement was predominant here. The negative correlation between ⁷Be, ²¹⁰Pb and soil-derived radionuclides indicated that ⁷Be and ²¹⁰Pb came from atmospheric components, while the weak correlation between them suggested that their specific sources were different. The Cu and Ni were moderately enriched in mosses here due to the use of agricultural fertilizers, At the same time, Zn was at a high level in the Lilang area, where transportation was more developed.

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.

Close coupling of plant functional types with soil microbial community composition drives soil carbon and nutrient cycling in tundra heath

Aims

This study aimed at elucidating divergent effects of two dominant plant functional types (PFTs) in tundra heath, dwarf shrubs and mosses, on soil microbial processes and soil carbon (C) and nutrient availability, and thereby to enhance our understanding of the complex interactions between PFTs, soil microbes and soil functioning.

Methods

Samples of organic soil were collected under three dwarf shrub species (of distinct mycorrhizal association and life form) and three moss species in early and late growing season. We analysed soil C and nutrient pools, extracellular enzyme activities and phospholipid fatty acid profiles, together with a range of plant traits, soil and abiotic site characteristics.

Results

Shrub soils were characterised by high microbial biomass C and phosphorus and phosphatase activity, which was linked with a fungal-dominated microbial community, while moss soils were characterised by high soil nitrogen availability, peptidase and peroxidase activity associated with a bacterial-dominated microbial community. The variation in soil microbial community structure was explained by mycorrhizal association, root morphology, litter and soil organic matter quality and soil pH-value. Furthermore, we found that the seasonal variation in microbial biomass and enzyme activities over the growing season, likely driven by plant belowground C allocation, was most pronounced under the tallest shrub Betula nana.

Conclusion

Our study demonstrates a close coupling of PFTs with soil microbial communities, microbial decomposition processes and soil nutrient availability in tundra heath, which suggests potential strong impacts of global change-induced shifts in plant community composition on carbon and nutrient cycling in high-latitude ecosystems.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11104-023-05993-w.

Cell corner middle lamella in hydroids of dendroid moss Hypnodendron menziesii gametophyte is prominently thickened: a proposed role in the mechanical support function

Significantly thickened corner middle lamella of the hydroid cell wall in the stipe of dendroid moss Hypnodendron menziesii has a mechanical support function. The hydroid cell walls of the erect stipe of Hypnodendron menziesii were investigated using light microscopy (LM), transmission electron microscopy (TEM), and TEM-immunogold labeling in support of the proposed biomechanical function for the highly thickened cell corner middle lamellae. The statistical analyses of dimensions of hydroid cell and wall parameters revealed a strong positive correlation between the area of hydroid cell and (i) the hydroid cell walls adhering to thick corner middle lamella, (ii) the area of the thick cell wall at hydroid corners, and (iii) the maximum thickness of cell wall at hydroid corners. The total area of the thick cell wall at the hydroid corners concomitantly increased with the area of the hydroid cell wall adhering to the middle lamella, and with the increased number of hydroids surrounding a reference hydroid. The results suggest that markedly thickened middle lamellae of the hydroid cell wall in Hypnodendron likely function by preventing hydroid cells from collapsing under the tensile forces generated from the transpirational pull on the water column. The specific localization of (1→4)- β-D-galactan and (1,5)-α-L-arabinan in the interface region of the hydroid cell wall and the thick middle lamella is consistent with these cell wall components being involved in the mechanical strengthening of the interface through firm adhesion as well as elasticity, ensuring the structural stability of this cell wall region, which may be prone to delamination/fracturing from the various internal and external pressures imposed. The copious presence of homogalacturonan in the thick middle lamella may further enhance the strength and flexibility of hydroid cell walls.

Bioaccumulation and retention of Po-210 and Pb-210 in two species of mosses from the zone of influence of the former radium-extracting plants

The presented study was aimed at assessing the ability to accumulate and retain ²¹⁰Po and ²¹⁰Pb in two species of the mosses Sphagnum girgensohnii Russow and Pleurozium schreberi (Willd. ex Brid.) Mitt. Mosses were collected in the zone of influence of the former radium-extracting plants (Komi Republic, Russia). ²¹⁰Po and ²¹⁰Pb activity concentrations in S. girgensohnii varied from 131 ± 15.4 to 221 ± 18.3 Bq kg^-1, and from 164 ± 18.6 to 309 ± 26.1 Bq kg^-1 respectively. In P. schreberi corresponding activity concentrations ranged from 107 ± 18.8 to 328 ± 29.2 Bq kg^-1 and from 117 ± 13.2 to 399 ± 31.1 Bq kg^-1. Activity concentrations of ²¹⁰Po and ²¹⁰Pb in autumn were higher than in summer. In the young parts of the mosses, they were lower than in the old parts. To assess the ability to retain accumulated radionuclides, watersoluble (distilled H₂O), exchangeable (1 M CH₃COONH₄), and acidsoluble (0.1 M H₂SO₄) fractions of ²¹⁰Po and ²¹⁰Pb were isolated from the studied mosses by the method sequential extraction. It was revealed that these fractions in total contained up to 26% of ²¹⁰Po and 39% of ²¹⁰Pb. The results showed that the studied moss species are a good biogeochemical barrier and long-term storage for ²¹⁰Pb and ²¹⁰Po.

Emissions of biogenic volatile organic compounds from adjacent boreal fen and bog as impacted by vegetation composition

Peatland ecosystems emit biogenic volatile organic compounds (BVOC), which have a net cooling impact on the climate. However, the quality and quantity of BVOC emissions, and how they are regulated by vegetation and peatland type remain poorly understood. Here we measured BVOC emissions with dynamic enclosures from two major boreal peatland types, a minerotrophic fen and an ombrotrophic bog situated in Siikaneva, southern Finland and experimentally assessed the role of vegetation by removing vascular vegetation with or without the moss layer. Our measurements from four campaigns during growing seasons in 2017 and 2018 identified emissions of 59 compounds from nine different chemical groups. Isoprene accounted for 81 % of BVOC emissions. Measurements also revealed uptake of dichloromethane. Total BVOC emissions and the emissions of isoprene, monoterpenoids, sesquiterpenes, homoterpenes, and green leaf volatiles were tightly connected to vascular plants. Isoprene and sesquiterpene emissions were associated with sedges, whereas monoterpenoids and homoterpenes were associated with shrubs. Additionally, isoprene and alkane emissions were higher in the fen than in the bog and they significantly contributed to the higher BVOC emissions from intact vegetation in the fen. During an extreme drought event in 2018, emissions of organic halides were absent. Our results indicate that climate change with an increase in shrub cover and increased frequency of extreme weather events may have a negative impact on total BVOC emissions that otherwise are predicted to increase in warmer temperatures. However, these changes also accompanied a change in BVOC emission quality. As different compounds differ in their capacity to form secondary organic aerosols, the ultimate climate impact of peatland BVOC emissions may be altered.

Gas chromatography-mass spectrometry (GC-MS) profiling of aqueous methanol fraction of Plagiochasma appendiculatum Lehm. & Lindenb. and Sphagnum fimbriatum Wilson for probable antiviral potential

The bryophytes consist of liverworts, mosses, and hornworts, among which the liverworts are quite different in having cellular oil bodies and contain numerous terpenoids, acetogenins, quinones, phenylpropanoids, flavonoids, etc. These metabolites exhibit interesting biological activity such as allergenic response, insecticide, cytotoxic, neurotrophic, antimicrobial, and anti-HIV actions, etc. Though several bioactive compounds have been isolated in many liverworts, yet most of the liverworts have been unexplored till date regarding their phytochemistry. The ability of liverworts to generate a wide range of important phytochemicals makes them a hoard of bioactive compounds. In the past, a few species of bryophytes have been evaluated against a few viruses and interesting results were obtained that showed their role as an immunity enhancer against viral infection. The phytoconstituents found in liverworts and mosses can be useful to increase human immunity against a variety of viruses, including SARS-CoV-2. Keeping this in view, one of the most developed and robust metabolomics technologies, Gas chromatography-mass spectroscopy (GC-MS) was used to estimate the various phytoconstituents found in a commonly growing thalloid liverwort, Plagiochasma appendiculatum, and moss Sphagnum fimbriatum. The obtained profiles were appraised for their bioactive potential and probable role as antiviral agents.

Experimental assessment of tundra fire impact on element export and storage in permafrost peatlands

Extensive studies have been performed on wildfire impact on terrestrial and aquatic ecosystems in the taiga biome, however consequences of wildfires in the tundra biome remain poorly understood. In such a biome, permafrost peatlands occupy a sizable territory in the Northern Hemisphere and present an extensive and highly vulnerable storage of organic carbon. Here we used an experimental approach to model the impact of ash produced from burning of main tundra organic constituents (i.e., moss, lichen and peat) on surrounding aquatic ecosystems. We studied the chemical composition of aqueous leachates produced during short-term (1 week) interaction of ash with distilled water and organic-rich lake water at 5 g_solid L^-1 and 20 °C. The addition of ash enriched the fluid phase in major cations (i.e., Na, Ca, Mg), macro- (i.e., P, K, Si) and micronutrients (i.e., Mn, Fe, Co, Ni, Zn, Mo). This enrichment occurred over <2 days of experiment. Among 3 studied substrates, moss ash released the largest amount of macro- and micro-components into the aqueous solution. To place the obtained results in the environmental context of a peatbog watershed, we assume a fire return interval of 56 years and that the entire 0-10 cm of upper peat is subjected to fire impact. These mass balance calculations demonstrated that maximal possible delivery of elements from ash after soil burning to the hydrological network is negligibly small (<1-2 %) compared to the annual riverine export flux and element storage in thermokarst lakes. As such, even a 5-10 fold increase in tundra wildfire frequency may not sizably modify nutrient and metal fluxes and pools in the surrounding aquatic ecosystems. This result requires revisiting the current paradigm on the importance of wildfire impact on permafrost peatlands and calls a need for experimental work on other ecosystem compartments (litter, shrubs, frozen peat) which are subjected to fire events.

Vanadium Contamination in Soil and Atmospheric Deposition in Albania

By examining and evaluating the vanadium content in topsoil and moss samples, this study sought to better understand vanadium contamination in soil and atmospheric deposition. In the research area, Hypnium cupressiforme sps. moss is used. According to different distribution patterns and the lack of a link between vanadium in moss and soil samples studied by correlation analysis, no interactions between substrate soil and moss samples were investigated. Maximum vanadium concentrations (13.2 mg/kg and 250 mg/kg, respectively) were found in both moss and soil samples near the Cu mineral-rich Gjegjan area. Using lithium-normalized data on vanadium, the effect of anthropogenic activity on the vanadium in moss and soil samples is examined. There were no relationships between concentration and normalized data in moss and soil samples, showing the simultaneous effects of natural and anthropogenic sources of vanadium in the research area. Country-specific trends revealed no change for vanadium since 2010 in Albania.

Spatial distribution of multi-elements in moss revealing heavy metal precipitation in London Island, Svalbard, Arctic

The Arctic is a sink for major pollutants in the Northern Hemisphere, and is an ideal place to investigate the migration of concerned metals on the local environment. In this study, 13 elements including Li, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, As, Cd, Hg, and Pb were determined in mosses (Dicranum angustum) from London Island in Ny-Ålesund. The results showed that the concentrations of different elements varied greatly at different altitudes, while their distributions in low (0-200 m) and high (200-300 m) altitudes based on cluster analysis were significantly different. Among them, Li, Ti, V, Cr, Mn, Fe, Co, Cu, and As showed significant positive correlations with elevation. This result may be due to the influence of key environmental factors such as elements transported by the airborne dust carried by winds, and surface runoff from snow meltwater. Multiple receptor models (PCA, PMF, and UNMIX) were employed to discuss the sources of metals in mosses from London Island. Elements that showed positive correlation with altitude were attributed to natural sources, and Zn, Cd, Hg, and Pb, which lacked apparent correlation with elevation, were interpreted as from anthropogenic sources by the models. Among them, Zn, Cd, and Hg were from long-range deposition, while Pb was from mixed industrial sources.

Responses of bryosphere fauna to drought across a boreal forest chronosequence

Projected changes in precipitation regimes can greatly impact soil biota, which in turn alters key ecosystem functions. In moss-dominated ecosystems, the bryosphere (i.e., the ground moss layer including live and senesced moss) plays a key role in carbon and nutrient cycling, and it hosts high abundances of microfauna (i.e., nematodes and tardigrades) and mesofauna (i.e., mites and springtails). However, we know very little about how bryosphere fauna responds to precipitation, and whether this response changes across environmental gradients. Here, we used a mesocosm experiment to study the effect of volume and frequency of precipitation on the abundance and community composition of functional groups of bryosphere fauna. Hylocomium splendens bryospheres were sampled from a long-term post-fire boreal forest chronosequence in northern Sweden which varies greatly in environmental conditions. We found that reduced precipitation promoted the abundance of total microfauna and of total mesofauna, but impaired predaceous/omnivorous nematodes, and springtails. Generally, bryosphere fauna responded more strongly to precipitation volume than to precipitation frequency. For some faunal functional groups, the effects of precipitation frequency were stronger at reduced precipitation volumes. Context-dependency effects were found for microfauna only: microfauna was more sensitive to precipitation in late-successional forests (i.e., those with lower productivity and soil nutrient availability) than in earlier-successional forests. Our results also suggest that drought-induced changes in trophic interactions and food resources in the bryosphere may increase faunal abundance. Consequently, drier bryospheres that may result from climate change could promote carbon and nutrient turnover from fauna activity, especially in older, less productive forests.

The effects of clearcut harvesting on moss chloroplast lipidome and adaptation to light stress during boreal forest regeneration

Moss plays an important role in boreal forest ecosystems as an understory bryophyte species. Clearcut harvesting is a common boreal forest regeneration method that can expose understory vegetation to abiotic stressors impeding their recovery following post-harvest conditions. Very little is known concerning how moss remodel their chloroplast lipidome to enhance photosynthetic performance for successful acclimation to light and water stress during boreal forest regeneration following clearcut harvesting. The chloroplast lipidome and photosynthetic performance of Sphagnum sp. and three feathermoss species (Pleurozium schreberi, Hylocomium splendens, and Ptilium crista-castrensis) from a boreal black spruce (Picea mariana) forest were assessed using liquid chromatography-mass spectrometry (LC-MS), photospectrometry, and light response curves. We observed an overall increase in monogalactosyldiacylglycerol (MGDG) and sulfoquinovosyldiacylglycerol (SQDG) and decrease in digalactosyldiacylglycerol (DGDG) and phosphatidylglycerol (PG). In addition, unsaturation of the chloroplast lipidome occurred concomitant with photoprotection by carotenoid pigments to enhance the efficiency and photosynthetic capacity in moss exposed to light and water stress following clearcut harvesting. This appears to be a successful acclimation strategy used by moss to circumvent light stress during boreal forest regeneration following clearcut harvesting. These findings could be of significance in the development of boreal forest management strategies following resource harvesting.

Spatio-temporal monitoring of mercury and other stable metal(loid)s and radionuclides in a Croatian terrestrial ecosystem around a natural gas treatment plant

The natural gas industry bears a certain contamination risk to human and biota due to, among others, mercury, arsenic, and naturally occurring radioactive material content in gas. We tracked multiple stabile metal(loid)s and radionuclides within the natural gas treatment plant Molve, Croatia, ecosystem during the last decade through a comprehensive monitoring of soil, earthworms, moss, livestock (blood, milk, hair, urine, and feces from cows), and wildlife animals (brain, muscle, liver, and kidney of European hare and pheasant). The level of mercury and other stable metal(loid)s has shown temporal variation, but without an obvious trend. The found spatial differences in soil and earthworms were based on the differing soil characteristics of the sampled locations and exceeded the maximal allowable concentration of arsenic and zinc for agricultural soil. The status of essential copper, selenium, and zinc in cows, hares, and pheasants inclined towards deficiency. The measured stable metal(loid) levels in soil and animal samples were generally in the same range of values reported in earlier decades from the same area or non-polluted areas across Europe. The consumption of local cow and game products (e.g., milk, meat) can be considered safe for human health, although game offal is advised to be avoided as a food item due to the low risk of lead and cadmium's adverse effects. Although the activity concentrations of some radionuclides in moss were higher than reported for pristine areas, transfer from soil to moss was assessed as average (except for lead-210). Radiological risk to human and biota around the gas treatment plant Molve was estimated as negligible.

Separation of anthropogenic radionuclides from aqueous environment using raw and modified biosorbents

In this study, two types of biosorbents were used to remove ¹³⁷Cs and plutonium isotopes from aqueous solutions - moss (Ptilium crista - castrensis) and oak sawdust (Quercus robur), both in the form of natural and modified state. Sorbent modification significantly increases the sorbent surface area (for moss sorbents - from 4.0 to 47.2 m²/g, and for sawdust sorbents - from 1.1 to 26.3 m²/g), pore volume (from 10^-3 to 10^-2), concentration and amount of basic cations and anions, as well as active functional groups on the sorbent surface. The main functional groups on the surface of natural sorbents modified with iron hydroxide interacting with analytes are carboxyl and hydroxyl groups. For carbonized sawdust and its subsequent activation with concentrated HCl, in addition to carboxyl and hydroxyl groups, acetyl groups also become active. Carbonated sawdust treated with HCl showed the highest average removal efficiency and sorption capacity for radiocesium and plutonium isotopes in laboratory column experiments - for ¹³⁷Cs ∼78.6% and ∼196.6 Bq/g and for ^239+240Pu ∼83% and ∼41.5 Bq/g, respectively. The moss and moss modified with iron hydroxide also showed good properties of adsorbing plutonium isotopes in field (in-situ) experiments. The best results on the sorption of ¹³⁷Cs in field experiments were shown by carbonated sawdust activated with HCl, and for isotopes of plutonium - the raw moss and moss modified with iron hydroxide. The results of the study showed that sorbents can be used not only for purification of water from plutonium isotopes but allow the operational sampling and more accurate measurement of radiocesium and plutonium isotopes in the fresh water reservoirs by the dynamic flow method.

Composition, environmental implication and source identification of elements in soil and moss from a pristine spruce forest ecosystem, Northwest China

The environmental quality of remote alpine ecosystem has been drawn increasing attention owing to the increasingly severe atmospheric pollution. This study investigated the composition and sources of elements in the soil and moss collected from a pristine spruce forest in the Qilian Mountains, Northwest China. The order of mean concentrations of elements investigated in soil was Fe > K > Na > Mg > Ca > Mn > Cr > Zn > Pb > Ni > Cu > As > Cd > Hg, and that of moss was Ca > Fe > Mg > K > Na > Mn > Cr > Zn > Pb > Ni > Cu > As > Cd > Hg. The concentrations of trace metals (except for As) in soil were greater than the soil background values, with Pb contamination more serious than the other elements. The Nemerow integrated pollution index (NIPI) values indicated that the soils were heavily polluted by Pb, Cd and Ni. The potential ecological risk index (PERI) suggested that the soils were at moderate risk. In particular, Hg and Cd were the most critically potential factors for ecological risk. According to the bioaccumulation factors (BAF), the accumulated concentrations of Ca, Hg, Cd, Pb, Ni, Mg, Cr and Zn in moss were higher than those in soil. By performing the multivariate analyses, natural sources (airborne soil particles) were identified to be the major contributors for all elements, whereas anthropogenic sources also contributed to the accumulations of Pb and Cd in the soil and moss in this region.

A review on moss nitrogen and isotope signatures evidence for atmospheric nitrogen deposition

Moss nitrogen (N) concentration and isotopic composition (δ¹⁵N) values can reveal a better understanding of atmospheric N deposition patterns. Here, we summarize the moss N content and δ¹⁵N signatures using data compiled from 104 papers. Based on the dataset, we summarize the models for assessing the level and reduced (NH_x): oxidised compounds (NO_x) ratio of atmospheric N deposition. Results showed a historical increase in N concentration and ¹⁵N depletion of specimen mosses close to anthropogenic N sources from intensive animal production and agricultural activities (NH_x emission) since the 1800s. However, an increase of moss N with a less negative ¹⁵N observed in the last three decades could be due to a substantial fossil fuel combustion contributed NO_x emission. Spatially, N deposition in Europe decreased due to successful control actions, but Asia has become a hotspot for NH_x emission from agriculture. The present results highlight the importance of moss N and δ¹⁵N values for estimating atmospheric N deposition patterns at spatio-temporal trends.

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

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

Distribution and dispersion of heavy metals in the rock-soil-moss system of the black shale areas in the southeast of Guizhou Province, China

Black shales are easily exposed due to human activities such as mining, road construction, and shale gas development, which results in several environmental issues including heavy metal (HM) pollution, soil erosion, and the destruction of vegetation. Mosses are widely used to monitor metal pollution in the atmosphere, but few studies on the distribution and dispersion of HMs in the rock-soil-moss system are available. Here, mosses (Pohlia flexuosa Harv. in Hook), growing soils, and corresponding parent rocks were collected from black shale areas. After appropriate pretreatment, samples were analyzed for multiple elemental concentrations by ICP-AES and ICP-MS. The results show that black shale parent rocks have elevated HM concentration and act as a source of multiple metals. The overlying soil significantly inherits and accumulates heavy metals released from black shale. Significant positive correlations between HMs in P. flexuosa and the growing soils indicate that HMs are mainly originating from geological source rather than atmospheric deposition. Differential accumulation of HMs is observed between rhizoids and stems in our study. Moreover, P. flexuosa is able to cope with high concentrations of toxic metals without any visible negative effect on its growth and development. Finally, the bioconcentration factor (BCF) for all the HMs in P. flexuosa is less than 1, indicating that it has a tolerance and exclusion mechanism for these metals, especially for the non-essential elements As and Pb. Therefore, the luxuriant and spontaneous growth of P. flexuosa could be used as a phytostabilization pioneer plant in the black shale outcrop where vascular plants are rare.

Autopolyploidization affects transcript patterns and gene targeting frequencies in Physcomitrella

In Physcomitrella, whole-genome duplications affected the expression of about 3.7% of the protein-encoding genes, some of them relevant for DNA repair, resulting in a massively reduced gene-targeting frequency. Qualitative changes in gene expression after an autopolyploidization event, a pure duplication of the whole genome (WGD), might be relevant for a different regulation of molecular mechanisms between angiosperms growing in a life cycle with a dominant diploid sporophytic stage and the haploid-dominant mosses. Whereas angiosperms repair DNA double-strand breaks (DSB) preferentially via non-homologous end joining (NHEJ), in the moss Physcomitrella homologous recombination (HR) is the main DNA-DSB repair pathway. HR facilitates the precise integration of foreign DNA into the genome via gene targeting (GT). Here, we studied the influence of ploidy on gene expression patterns and GT efficiency in Physcomitrella using haploid plants and autodiploid plants, generated via an artificial WGD. Single cells (protoplasts) were transfected with a GT construct and material from different time-points after transfection was analysed by microarrays and SuperSAGE sequencing. In the SuperSAGE data, we detected 3.7% of the Physcomitrella genes as differentially expressed in response to the WGD event. Among the differentially expressed genes involved in DNA-DSB repair was an upregulated gene encoding the X-ray repair cross-complementing protein 4 (XRCC4), a key player in NHEJ. Analysing the GT efficiency, we observed that autodiploid plants were significantly GT suppressed (p < 0.001) attaining only one third of the expected GT rates. Hence, an alteration of global transcript patterns, including genes related to DNA repair, in autodiploid Physcomitrella plants correlated with a drastic suppression of HR.

Callose Detection and Quantification at Plasmodesmata in Bryophytes

In bryophytes (i.e., mosses, liverworts, and hornworts), extant representatives of early land plants, plasmodesmata have been described in a wide range of tissues. Although their contribution to bryophyte morphogenesis remains largely unexplored, several recent studies have suggested that the deposition of callose around plasmodesmata might regulate developmental and physiological responses in mosses. In this chapter, we provide a protocol to image and quantify callose levels in the filamentous body of the model moss Physcomitrium (Physcomitrella) patens and discuss possible alternatives and pitfalls. More generally, this protocol establishes a framework to explore the distribution of callose in other bryophytes.

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.

Zander is a fully desiccation-tolerant moss that expresses an inducible molecular mechanism in response to severe abiotic stress

KEY MESSAGE

The moss Pseudocrossidium replicatum is a desiccation-tolerant species that uses an inducible system to withstand severe abiotic stress in both protonemal and gametophore tissues. Desiccation tolerance (DT) is the ability of cells to recover from an air-dried state. Here, the moss Pseudocrossidium replicatum was identified as a fully desiccation-tolerant (FDT) species. Its gametophores rapidly lost more than 90% of their water content when exposed to a low-humidity atmosphere [23% relative humidity (RH)], but abscisic acid (ABA) pretreatment diminished the final water loss after equilibrium was reached. P. replicatum gametophores maintained good maximum photosystem II (PSII) efficiency (Fv/Fm) for up to two hours during slow dehydration; however, ABA pretreatment induced a faster decrease in the Fv/Fm. ABA also induced a faster recovery of the Fv/Fm after rehydration. Protein synthesis inhibitor treatment before dehydration hampered the recovery of the Fv/Fm when the gametophores were rehydrated after desiccation, suggesting the presence of an inducible protective mechanism that is activated in response to abiotic stress. This observation was also supported by accumulation of soluble sugars in gametophores exposed to ABA or NaCl. Exogenous ABA treatment delayed the germination of P. replicatum spores and induced morphological changes in protonemal cells that resembled brachycytes. Transcriptome analyses revealed the presence of an inducible molecular mechanism in P. replicatum protonemata that was activated in response to dehydration. This study is the first RNA-Seq study of the protonemal tissues of an FDT moss. Our results suggest that P. replicatum is an FDT moss equipped with an inducible molecular response that prepares this species for severe abiotic stress and that ABA plays an important role in this response.

The complete plastid genome sequence of the enigmatic moss, Takakia lepidozioides (Takakiopsida, Bryophyta): evolutionary perspectives on the largest collection of genes in mosses and the intensive RNA editing

Complete chloroplast genome sequence of a moss, Takakia lepidozioides (Takakiopsida) is reported. The largest collection of genes in mosses and the intensive RNA editing were discussed from evolutionary perspectives. We assembled the entire plastid genome sequence of Takakia lepidozioides (Takakiopsida), emerging from the first phylogenetic split among extant mosses. The genome sequences were assembled into a circular molecule 149,016 bp in length, with a quadripartite structure comprising a large and a small single-copy region separated by inverted repeats. It contained 88 genes coding for proteins, 32 for tRNA, four for rRNA, two open reading frames, and at least one pseudogene (tufA). This is the largest number of genes of all sequenced plastid genomes in mosses and Takakia is the only moss that retains the seven coding genes ccsA, cysA, cysT, petN rpoA, rps16 and trnP^GGG. Parsimonious interpretation of gene loss suggests that the last common ancestor of bryophytes had all seven genes and that mosses lost at least three of them during their diversification. Analyses of the plastid transcriptome identified the extraordinary frequency of RNA editing with more than 1100 sites. We indicated a close correlation between the monoplastidy of vegetative tissue and the intensive RNA editing sites in the plastid genome in land plant lineages. Here, we proposed a hypothesis that the small population size of plastids in each vegetative cell of some early diverging land plants, including Takakia, might cause the frequent fixation of mutations in plastid genome through the intracellular genetic drift and that deleterious mutations might be continuously compensated by RNA editing during or following transcription.

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.

Distribution of 137Cs in lichens, mosses and pine needles along the transect from the north to the south of Western Siberia

The ¹³⁷Cs content in mosses (Hylocomium splendens), lichens (Cladonia stellaris) and the needles of the Siberian pine (Pinus sibirica) and the common pine (Pinus sylvestris) along the transect from the north to the south of Western Siberia from N. 67.5° to N. 55° has been investigated. The appearance of ¹³⁷Cs here is linked to the nuclear weapon tests at Novaya Zemlya. The measurements have shown that at all sampling points south of N. 59.6° there is a very sharp decrease in the ¹³⁷Cs specific activity in all components of the ecosystem (in mosses and lichens by about 20 times, and in the needles of conifers by 100 times) instead of a smooth decrease. This fact can be explained by the existence of the global atmospheric circulation consisting of three circulation cells in the Northern hemisphere. It is just around N. 60° that the boundary between the Polar cell and the circulation cell of midle latitudes is drawn. At this boundary, the counter surface air flows of these cells (in our case, a contaminated flow from the north and a clean one from the south) collide and generate the upward air flows here that take ¹³⁷Cs away. In addition, there is water vapor condensation in the upward flows resulting in snowfalls, rains and thunderstorms. And with these precipitation events, large amounts of ¹³⁷Cs should have fallen out to the north of the Polar cell boundary during the Novaya Zemlya tests. The areas south around of N. 60° have been supposed to remain clean, which is what is being observed.

Impact of freeze-thaw cycles on organic carbon and metals in waters of permafrost peatlands

Despite the importance of soil and surface waters freezing in permafrost landscapes, the behaviour of dissolved organic carbon (DOC), nutrients and metals during periodic freeze-thaw cycles (FTC) remains poorly known. The on-going climate warming is likely to increase the frequency of FTC in continental aquatic settings, which could modify the chemical composition of waters. In this study, we conducted 9 repetitive cycles of overnight freezing (-20 °C) and 5 h thawing (4 °C) in the laboratory using representative 0.22 μm-filtered waters from NE European permafrost peatland: leachates of vegetation and soil, and natural surface waters (depression, thermokarst lake and river). Only minor (<5%-15%) changes of DOC concentrations, SUVA₂₅₄ and molecular weight were observed in all leachates and the depression water. In contrast, several trace elements (Fe, Al, P, Mn, As, and REE) exhibited sizable variations during FTC (>10%). The leachates and the depression water were enriched in trace elements, whereas the thermokarst lake and the river demonstrated a decrease in concentration of Fe (-39 and -94%, respectively), Al (-9 and -85%), and Mn (-10 and -79%) during FTC. Overall, the observations demonstrated an increase in aliphatic low molecular weight organic matter (OM), and the precipitation of Fe, Al hydroxides and organo-mineral particles. Therefore, enhanced of frequency of FTC can favour the release of metals and toxicants from acidic OM-rich surface waters and maintain stable OM-metals-colloids in large lakes and rivers, thus regulating aquatic transport of DOC and metals from soils to the Arctic Ocean.

Biochemical and functional characterization of two microbial type terpene synthases from moss Stereodon subimponens

Terpenes constitute a large class of plant secondary metabolites. Usually, there is only one type of terpene synthase in seed plants, which is called typical plant terpene synthase. Currently, as a new family of plant terpene synthases, microbial terpene synthase-like (MTPSL) is identificated in nonseed plants. However, our knowledge about the biological function of most MTPSLs in nonseed plants is very limited. Here, we investigated the biochemical and functional characterization of the enzymes encoded by two MTPSLs from moss Stereodon subimponens, SsMTPSL1 and SsMTPSL2. A phylogenetic tree analysis showed that SsMTPSL1 and SsMTPSL2 are homologous to AaMTPSL1, AaMTPSL3, ApMTPSL1, and ApMTPSL3 from hornworts. The enzyme activity experiment demonstrated that SsMTPSL1 has monoterpene synthase and sesquiterpene synthase activity, and SsMTPSL2 has monoterpene synthase activity. Next, we selected SsMTPSL1 to study its biochemical functions. Anti-bacterial activity test in vitro showed that the products of SsMTPSL1 have an anti-bacterial effect on Escherichia coli, Pseudomonas syringae pv. Tomato DC3000 (Pst DC3000), and Staphylococcus aureus. To further understand the function of SsMTPSL1, the transgenic Arabidopsis thaliana plant of SsMTPSL1 is inoculated by Pst DC3000, and the result showed that SsMTPSL1 enhances the resistance of A. thaliana to Pst DC3000. All in all, this study provides new information about the functions of moss MTPSLs.

Exposure to atmospheric metals using moss bioindicators and neonatal health outcomes in Portland, Oregon

Studying the impacts of prenatal atmospheric heavy-metal exposure is challenging, because biological exposure monitoring does not distinguish between specific sources, and high-resolution air monitoring data is lacking for heavy metals. Bioindicators - animal or plant species that can capture environmental quality - are a low-cost tool for evaluating exposure to atmospheric heavy-metal pollution that have received little attention in the public-health literature. We obtained birth records for Portland, Oregon live births (2008-2014) and modeled metal concentrations derived from 346 samples of moss bioindicators collected in 2013. Exposure estimates were assigned using mother's residential address at birth for six metals with known toxic and estrogenic effects (arsenic, cadmium, chromium, cobalt, nickel, lead). Associations were evaluated for continuous (cts) and quartile-based (Q) metal estimates and three birth outcomes (preterm birth (PTB; <37 weeks)), very PTB (vPTB; <32 weeks), small for gestational age (SGA; 10th percentile of weight by age and sex)) using logistic regression models with adjustment for demographic characteristics, and stratified by maternal race. Chromium and cobalt were associated with increased odds of vPTB (chromium - odds ratio (OR)_cts = 1.09, 95% CI: 1.00, 1.17; cobalt - OR_Q4vsQ1 = 1.33, 95% CI: 1.03, 1.71). Cobalt, chromium and cadmium were significantly associated with odds of SGA, although the direction of association differed by metal (cobalt - OR_cts = 1.04, 95% CI: 1.01, 1.07; chromium - OR_Q3vsQ1 = 0.91, 95% CI: 0.83, 0.99; cadmium - OR_cts = 0.96, 95% CI: 0.93, 1.00). In stratified analyses, odds of SGA were significantly different among non-white mothers compared to white mothers with exposure to chromium, cobalt, lead and nickel. This novel application of a moss-based exposure metric found that exposure to some atmospheric metals is associated with adverse birth outcomes. These findings are consistent with previous literature and suggest that moss bioindicators are a useful complement to traditional exposure-assessment methods.

Towards rare earth element recovery from wastewaters: biosorption using phototrophic organisms

Abstract

Whilst the biosorption of metal ions by phototrophic (micro)organisms has been demonstrated in earlier and more recent research, the isolation of rare earth elements (REEs) from highly dilute aqueous solutions with this type of biomass remains largely unexplored. Therefore, the selective binding abilities of two microalgae (Calothrix brevissima, Chlorella kessleri) and one moss (Physcomitrella patens) were examined using Neodym and Europium as examples. The biomass of P. patens showed the highest sorption capacities for both REEs (Nd³⁺: 0.74 ± 0.05 mmol*g⁻¹; Eu³⁺: 0.48 ± 0.05 mmol*g⁻¹). A comparison with the sorption of precious metals (Au³⁺, Pt⁴⁺) and typical metal ions contained in wastewaters (Pb²⁺, Fe²⁺, Cu²⁺, Ni²⁺), which might compete for binding sites, revealed that the sorption capacities for Au³⁺ (1.59 ± 0.07 mmol*g⁻¹) and Pb²⁺ (0.83 ± 0.02 mmol*g⁻¹) are even higher. Although different patterns of maximum sorption capacities for the tested metal ions were observed for the microalgae, they too showed the highest affinities for Au³⁺, Pb²⁺, and Nd³⁺. Nd-sorption experiments in the pH range from 1 to 6 and the recorded adsorption isotherms for this element showed that the biomass of P. patens has favourable properties as biosorbent compared to the microalgae investigated here. Whilst the cultivation mode did not influence the sorption capacities for the target elements of the two algal species, it had a great impact on the properties of the moss. Thus, further studies are necessary to develop effective biosorption processes for the recovery of REEs from alternative and so far unexploited sources.

Key points

• The highest binding capacity for selected REEs was registered for P. patens.

• The highest biosorption was found for Au and the biomass of the examined moss.

• Biosorption capacities of P. patens seem to depend on the cultivation mode.

Rotation angle of stem cell division plane controls spiral phyllotaxis in mosses

The spiral arrangement (phyllotaxis) of leaves is a shared morphology in land plants, and exhibits diversity constrained to the Fibonacci sequence. Phyllotaxis in vascular plants is produced at a multicellular meristem, whereas bryophyte phyllotaxis emerges from a single apical stem cell (AC) that is embedded in a growing tip of the gametophyte. An AC is asymmetrically divided into itself and a single 'merophyte', producing a future leaf and a portion of the stem. Although it has been suggested that the arrangement of merophytes is regulated by a rotation of the division plane of an AC, the quantitative description of the merophyte arrangement and its regulatory mechanism remain unclear. To clarify them, we examined three moss species, Tetraphis pellucida, Physcomitrium patens, and Niphotrichum japonicum, which exhibit 1/3, 2/5, and 3/8 spiral phyllotaxis, respectively. We measured the angle between the centroids of adjacent merophytes relative to the AC centroid on cross-transverse sections. At the outer merophytes, this divergence angle converged to nearly 120[Formula: see text] in T. pellucida, 136[Formula: see text] in N. japonicum, and 141[Formula: see text] in P. patens, which was nearly consistent with phyllotaxis, whereas the divergence angle deviated from the converged angle at the inner merophytes near an AC. A mathematical model, which assumes scaling growth of AC and merophytes and a constant angle of division plane rotation, quantitatively reproduced the sequence of the divergence angles. This model showed that successive relocations of the centroid position of an AC upon its division inevitably result in the transient deviation of the divergence angle. As a result, the converged divergence angle was equal to the rotation angle, predicting that the latter is a major regulator of the spiral phyllotaxis diversity in mosses.

Heavy Metal and Mineral Composition of Soil, Atmospheric Deposition, and Mosses with Regard to Integrated Pollution Assessment Approach

The fact that there are no real borders between the biosphere, atmosphere, lithosphere, and hydrosphere means that environmental pollution monitoring studies should not only include one of the environmental spheres. Thus, integrated environmental pollution assessment studies conducted in the biosphere, lithosphere, and atmosphere promote the "whole system" approach. In this study, the aim was to determine the pollution in the atmosphere, soil, and plants by taking advantage of the high pollution accumulation characteristics of the mosses. Prevailing wind has the potential to distribute pollutants emitted into the air throughout its path. With this regard, soil, mosses, and atmospheric deposition samples were collected in Çanakkale, Turkey, in two seasons. Concentrations of selected elements were measured by Inductively Coupled Plasma-Mass Spectrometry. The enrichment factor of the selected elements in the soil, moss, and deposition samples was calculated. The highest enrichments were found for Lead in atmospheric deposition, Arsenic in soil, and Mercury in moss samples. Cobalt and chromium accumulated more in mosses than in soil. Elevated arsenic levels found in the samples can pose a great risk for public health and agriculture. The study result showed that the elemental composition of the samples was influenced by the enhanced air plume dispersion of anthropogenic pollution sources along the Northeast-Southwest directions due to wind characteristics in the province. As expected, strong correlations were found among the moss, soil, and atmospheric deposition samples indicating the vital interactions between the environmental components.

Low-cost biomonitoring and high-resolution, scalable models of urban metal pollution

As the global toll on human lives and ecosystems exacted by urban pollution grows, planning tools still lack the resolution to identify priority sites where toxic pollution can be most efficiently averted at a spatial scale that matches funding and management. Here we tackle this gap by demonstrating novel scalable methods to monitor and predict urban metal pollution at high resolution (<5 m) across large areas (10,000-100,000 km²) to guide pollution reduction and stormwater management. We showcase and calibrate predictive models of Zn, Cu, and a synthetic index of pollution for the Puget Sound region of Washington State, U.S., a densely urbanized yet important ecosystem of conservation interest, and exemplify their transferability across the entire United States. We leveraged widely and freely available datasets of car traffic characteristics and land use as predictor variables and trained the models with biological monitoring data of metal concentrations in epiphytic moss from >100 trees based on new rapid and low-cost protocols introduced in this study. Our model predictions, showing that 50% of the total Cu and Zn pollution across the Puget Sound watershed is deposited over only 3.3% of the land area, will allow cities to effectively and efficiently target toxic hotspots.

Heavy metals in different moss species in alpine ecosystems of Mountain Gongga, China: Geochemical characteristics and controlling factors

Terrestrial mosses are promising tracers for research concerning metal atmospheric deposition and pollution. Concentrations of Cr, Co, Ni, Zn, Sr, Cd, Ba, and Pb in different moss species from Mountain Gongga, China were analyzed to investigate the effects of growth substrates, geographic elevation, and type of moss species on the accumulation characteristics of heavy metals, as well as to identify heavy metal sources. The ability of heavy metals to accumulate in moss varied significantly, with low concentrations of Cd and Co; medium concentrations of Cr, Ni, and Pb; and high concentrations of Zn, Sr, and Ba. Elevation significantly influenced the accumulation characteristics of heavy metals, with high concentrations found at lower elevations due to proximal pollution. Growth substrate and moss species were found to have certain influence on the bioconcentration capacities of heavy metals in moss in this study. Correlation analysis showed similar sources for Sr, Zn, and Ba, as well as for Ni, Co, and Cr. The positive matrix factorization (PMF) model was consistent with atmospheric deposition of Pb and Cd; substrate sources of Cr, Co, and Ni; and anthropogenic sources of Ba, Sr, and Zn. This research characterized the accumulation characteristics of heavy metals and their influence factors in different mosses found in alpine ecosystems and provides a reference for future studies in similar areas.