Terrestrial Mosses Research Articles

Is it possible to estimate atmospheric deposition of heavy metals by analysis of terrestrial mosses?

Here we present a critical review of diverse research studies involving estimation of atmospheric deposition of heavy metals from the concentrations of the contaminants in terrestrial moss. The findings can be summarized as follows: i) significant correlations between the concentrations of contaminants in moss and bulk deposition were observed in only 40.1% of the cases in which the relationship was studied and in only 14.1% of the cases, the coefficient of correlation was > 0.7; ii) some method-related problems were identified (i.e. small sample sizes, elimination of some data from the regression analyses, large distances between the moss sampling sites and the bulk precipitation collectors, differences in times of exposure of the moss samples and collection times for the bulk precipitation), so that the results of the studies may not be completely valid, and iii) evidence was found in the relevant literature that moss does not actually integrate the atmospheric deposition received. We also discuss the reason why, in accordance with the published data, bulk deposition cannot be correctly estimated by determination of the final concentrations of contaminants in the organism, such as the existence of different sources of contamination, the physicochemical characteristics of the sources of deposition, physicochemical processes to which the organism is subjected and the biological processes that take place in the moss. Taking into account the above findings, it was concluded that, except for certain elements and specific cases (i.e. Pb and Cd), atmospheric deposition of elements cannot be accurately estimated from the concentrations of metals and metalloids in moss tissues. However, the analysis of moss does provide information about the presence of contaminants in the atmosphere, their spatial and temporal patterns of distribution and how they are taken up by live organisms. Use of mosses is therefore recommended as a complementary (rather than an alternative) technique in the conventional analysis of bulk deposition of contaminants.

Study of the air quality in industrial areas of Santa Cruz de Tenerife (Spain) by active biomonitoring with Pseudoscleropodium purum

A biomonitoring technique with terrestrial moss transplants (50 sampling sites in a regular grid) was used in an area of the city of Santa Cruz de Tenerife, close to an oil refinery and to an area of dense road traffic for a period of 2 months. The concentration of metals and metalloids (As, Cd, Hg, Ni, Pb and V) and 16 polycyclic aromatic hydrocarbons (PAHs) were determined. The density distribution was represented, the enrichment factors calculated and multifactorial analysis applied. In addition, contamination maps were elaborated on the basis of the bioconcentration obtained, and after confirming the existence of spatial structure, the response surfaces were represented. The results showed very high levels of contamination by Ni and V in the study area, with similar dispersal patterns observed for both. The concentrations of Cd, Hg, Pb and PAHs were lower. Active biomonitoring with terrestrial mosses was found to be a suitable technique for implementing inexpensive environmental monitoring programmes in urban and industrialized areas.

Species–environment relationships of mosses in New Zealand indigenous forest and shrubland ecosystems

Small and challenging to identify, bryophyte species are often under-represented in large-scale studies of vegetation patterns. Bryophyte occurrence is likely to be influenced by multiple processes and little is known about the relative importance of the different factors across diverse landscapes. Species–environment relationships of 15 common terrestrial moss species in native forests of South and Stewart islands, New Zealand, were examined. Models were developed for each species to test relationships between species distribution and 22 environmental predictors, using Generalised Regression Analysis and Spatial Prediction (GRASP). The New Zealand nationwide vegetation survey LUCAS, although showing several limitations, provided data to investigate factors that may influence bryophyte distribution along large gradients. Combined biotic (primarily total vegetation cover) and abiotic (mean annual temperature and rainfall) effects best contributed to distribution models of all but two moss species. Canopy tree species at a site were also important predictors in the spatial distribution of several individual moss species, possibly through altering the physical environment and resource availability, although both bryophytes and vascular plant species may be influenced independently by the same factors. The study highlights the importance of different factors influencing bryophyte distributions and identifies several factors controlling distributions that require further investigation.

Influence of roads and inhabited areas on metal concentrations in terrestrial mosses

The guidelines regarding sampling terrestrial mosses for biomonitoring the atmospheric contamination in a region specifically recommend that sampling close to focal points of contamination (i.e. roads, populated areas, etc.) should be avoided for satisfactory characterization of general patterns of contamination. However, these recommendations cannot always be followed in many parts of the world with dense, highly dispersed populations. The aim of the present study was to determine how the distances between sampling sites (SS) and contamination foci such as roads, isolated houses and urban nuclei affect regular, large-scale sampling networks. Metal concentrations obtained in biennial sampling surveys carried out between 2000 and 2006 in Galicia (NW Spain) were used, and the relative proportions of the concentrations corresponding to small-scale and large-scale processes were calculated. The possible relationship between the mean concentrations corresponding to small-scale processes in the different sampling surveys and the distances from SS to roads, buildings and urban nuclei was established by a GIS. Outliers in the data were identified at many of the SS and frequency statistics revealed the absence of any relationship between the distance to these foci and the concentrations of metals in the moss. The method also revealed many instances of the influence of one or more small-scale contamination foci such as airports and railways (often not considered in the sampling recommendations) on SS. Relocation of such SS would improve the representativeness of the sampling grid.

Evaluation of cations and chelating agents as extracellular extractants for Cu, Pb, V and Zn in the sequential elution technique applied to the terrestrial moss Pseudoscleropodium purum

Three experiments were carried out to select the best extractant for use in the sequential elution technique, to enable extraction of Cu, Pb, V and Zn from the extracellular fraction of the terrestrial moss Pseudoscleropodium purum. The optimal concentrations of the extractants tested (CoCl 2, NiCl 2, Pb(NO 3) 2, SrCl 2, dimercaprol, EDTA, penicillamine) were determined on the basis of the maximum extraction of Zn achieved without any alteration of the plasma membrane. The capacity of these agents (at the optimal concentrations established) to extract the extracellular fractions of Cu, Pb, V and Zn was then evaluated. Extraction with 10 mM EDTA is recommended for all 4 elements considered. As a second option, the use of 50 mM penicillamine is recommended to extract Cu, 30 mM dimercaprol to extract Pb and V and 20 mM NiCl 2 to extract Zn. It was also concluded that these results cannot be extrapolated to other cryptogams, and that separate assays are required.

How lichens and mosses reflect atmospheric deposition of natural and artificial radionuclides

In a national survey in Slovenia, two biomonitors, the epiphytic lichen Hypogymnia physodes and the terrestrial moss Hypnum cupressiforme, were analysed for 210 Pb and 137 Cs. Further, the results for 210 Pb were compared with outdoor 222 Rn and with precipitation data. 210 Pb activity concentrations in moss carpets and lichen thalli ranged between 180-2450 and 200-1990 Bq kg -1 , respectively. 210 Pb showed similar spatial distributions in the two biomonitors with the highest levels in north-western and southern parts of the country, with a strong gradient to the eastern part, reflecting the movement of global air masses and the amount of precipitation. Increased 222 Rn concentrations over carbonate rocks were not reflected in lichen and moss 210 Pb levels. 137 Cs activity concentrations in lichens and mosses in the ranges 73-1400 and 49-600 Bq kg -1 , respectively, were obtained. There was a relatively good agreement between the two biomonitors, with the highest values in the northern part of the country.

Spatial structure of trace elements in extensive biomonitoring surveys with terrestrial mosses

The size of the area affected by contamination processes mainly depends on the type of contaminant and the way it is emitted. In regular sampling, the size of the sampling grid will therefore interact with the scale at which the contamination processes are produced, for each contaminant, so that the grid will only enable characterization of those processes that occur at scales larger than the grid, i.e. large scale processes. The present study analysed the data corresponding to tissue concentrations of Cd, Cu, Fe, Hg, Mn, Pb, Se, V and Zn in the terrestrial moss Pseudoscleropodium purum obtained in regular sampling surveys with grids of different sizes (15 × 15, 7.5 × 7.5 km) plus a series of accessory points located at 1 km from the 15 × 15 km sampling grid; all sampling sites were located in Galicia and were sampled in March 2004. The objective of the study was to characterize the interaction between the scale of the sampling grid and the scale at which the contamination processes are produced, for each contaminant, to enable adjustment of the size of the grids to the scale at which the contamination processes are mainly produced. For this purpose, the spatial structure of the concentration of each element was analysed by use of semivariograms created with a robust estimator of the semivariance. The results of the study verified the existence of a real interaction between the scale of the sampling grid and the scale of the contamination processes. The results also demonstrated how in the study area, the contamination processes associated with Cd, Pb and V are generally small scale processes, whereas those associated with Cu, Hg and Se are generally large scale processes.

Use of the terrestrial moss Pseudoscleropodium purum to detect sources of small scale contamination by PAHs

Here we present a simple, economic method of identifying sources of small scale contamination by polycyclic aromatic hydrocarbons (PAHs). The method involves determining the concentrations of the contaminants in the terrestrial moss Pseudoscleropodium purum and consists of the following steps: i) testing for the existence of gradients of decreasing concentrations of PAHs in the moss in relation to distance from different emission sources; ii) measurement of the concentration of PAHs at 35 pairs of sampling sites, each separated by a distance of 1 km; iii) study of the distribution of the differences in concentration between these pairs of sampling sites and elimination of extreme values (affected by small scale sources of contamination); iv) characterization of normal distributions to determine the probability of the data being thus distributed; and v) testing the method in the surroundings of possible sources of small scale contamination by PAHs. The decrease in concentration of all of the compounds followed a steep gradient with increasing distance from the emission source; after elimination of the outliers, the distribution of the differences in concentration between the 35 pairs of sampling sites was normal for all compounds, except benzo( a)pyrene. Application of the method to 15 different types of industries provided satisfactory results and the method proved to be a very useful tool for monitoring and evaluating air quality.

Eukaryotic Microbial Communities Associated with the Rhizosphere of the Temperate Fern Thelypteris noveboracensis (L.) Nieuwl

Abstract Microbial communities, associated with terrestrial mosses (Bryopsida) and the rhizosphere of agricultural and natural occurring seed plants, have been rather extensively examined; but less is known about associations with seedless vascular plants, including ferns. The New York fern (Thelypteris noveboracensis), typically found within deciduous forests, occurs in locally extensive stands in North America extending from northeastern Canada to southeastern U.S.A. Soil samples were obtained in autumn (2007) and early summer (2008) within a plot of T. noveboracensis in the understory of deciduous trees in the forest reserve at Torrey Cliff, NY to document the rhizosphere (root-associated) density of commonly occurring heterotrophic eukaryotic microbes (protozoa), including microflagellates, naked amoebae and testate amoebae. The ranges in densities (number/g soil dry weight) are as follows: microflagellates (6.5 × 106–1.3 × 108), naked amoebae (1.8 × 103–4.0 × 106) and testate amoebae (ca. 400). Very ...

Effect of growth on active biomonitoring with terrestrial mosses

The effects of growth of autoirrigated, shaded transplants of Pseudoscleropodium purum on the quantification of tissue concentrations of Cd, Cu, Hg, V and Zn, were investigated in 4 exposure periods, each of 56 days, at 7 sampling sites (contaminated and uncontaminated). Concentrations of the elements in the basal portions of the moss shoots were compared with the concentrations in the portions of the shoots that grew during the exposure period. Mercury and V were present at lower concentrations in the new portions of the shoots than in the basal portions, whereas the opposite was true for Cd, Cu and Zn. The magnitude of error introduced by growth was not negligible, and in some cases was higher than 40%, relative to the results obtained by analysis of the whole shoot. Devitalization of moss prior to its use as transplant material is recommended to avoid growth of the plant during the exposure period.

Testing differences in methods of preparing moss samples. Effect of washing on Pseudoscleropodium purum

When terrestrial mosses are used to study the risks associated with the accumulation of airborne pollutants, samples must be washed to remove deposits adhering to the surface. Here, we studied the effects of washing the samples as well as of freezing, drying, and acclimatization treatments. The differences between the concentrations of Al, As, Cd, Cr, Cu, Fe, Hg, K, Ni, Pb, Se, V, and Zn in washed and unwashed samples were significant, and therefore, it would not be valid to combine or compare the data corresponding to samples treated thus. We also investigated whether there were significant differences in the concentrations of various metals and metalloids yielded from samples subjected to different treatments prior to washing (freezing, drying, acclimatization after drying, and acclimatization only), while also considering possible effects of the level and type of contamination and the weather conditions. For many of the elements, we found significant differences that depended on both the levels of contamination at each sampling site and the weather. As these differences may be due to changes in the contents of the different cellular fractions, the sequential elution technique was applied to determine the locations of Cu, K, and Zn. The freezing and drying procedures were rejected because they alter the permeability of the membranes and lead to underestimation of the concentrations of elements. With the acclimatization procedure, particles of some elements adhere to the surface, making this option unsuitable when a description of bioconcentration is required. Taking into account these limitations and the lack of an optimal procedure, acclimatization after drying is proposed as the best option for harmonizing the method.

Temporal trends (1990-2005) in heavy metal accumulation in mosses in Slovakia

Biomonitoring of multielement atmospheric deposition using terrestrial moss is a well-established technique in Europe. The moss samples of Hylocomium splendens, Pleurozium schreberi and Dicranum sp. were collected in Slovakia. Separately we evaluated the atmospheric deposition in the National Parks (Vysoke Tatry, Nizke Tatry, Zapadne Tatry -Jelenec, Slovenský raj) and in a landscape protection area (Velka Fatra). In comparison to the median northern Norway values of heavy metal contents in moss, the Slovak atmospheric deposition loads of elements were found to be higher. The survey has been repeated and in this paper we report on the temporal trends in the concentration of Cd, Cr, Cu, Fe, Hg, Ni, Pb, V and Zn between 1990 and 2005. Metal- and sites-specific temporal trends were observed. In general, the concentration of Cd, Cr, Cu, Fe, Hg, Ni, Pb, V and Zn in mosses decreased between 1990 and 2005; the decline was higher for Pb than for Cd. The observed temporal trends for the concentrations in mosses were similar to the trends reported for the modelled total deposition of cadmium, lead and mercury in Europe. The level of elements, determined in bryophytes reflects the relative atmospheric deposition loads of elements at the investigated sites. Factor analysis was applied to determine possible sources of trace element deposition in the Slovakian mosses.

Bioindication of Trace Metals in Brachythecium rutabulum Around a Copper Smelter in Legnica (Southwest Poland): Use of a New Form of Data Presentation in the Form of a Self-Organizing Feature Map

Concentrations of the elements Al, Be, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn were measured in the terrestrial moss Brachythecium rutabulum and the soil on which it grew. Soil and moss plants were sampled at sites situated 1.5, 3, 6, 9 and 15 km to the north, south, east and west of the Legnica copper smelter (SW Poland). The self-organizing feature map (SOFM) or Kohonen network was used to classify the soil and moss samples according to the concentrations of the elements. The self-organizing map yielded distinct groups of B. rutabulum and soil samples, depending on the distance from and direction to the source of pollution. When the map-identified groups of sites with similar soil metal concentrations were combined with the map-identified groups of sites with similar metal concentrations in B. rutabulum, these maps were found to correspond closely. The SOFMs accurately represented the least polluted, moderately polluted and severely polluted sites, reflecting the distribution of metals that is typical of the smelter area, caused by the prevailing westerly and northerly winds.

Heavy Metal Transfers Between Trophic Compartments in Different Ecosystems in Galicia (Northwest Spain): Essential Elements

In the present study, we determined the concentrations of Cu, Fe, Mn, and Zn in soil and several trophic compartments at a total of 16 sampling stations. The trophic compartments studied were primary producers, represented by two species of terrestrial mosses (Pseudoescleropodium purum and Hypnum cupressiforme) and oak trees (Quercus robur or Q. pyrenaica); primary consumers, represented by the wood mouse (Apodemus sylvaticus) and the yellow necked mouse (A. flavicollis); secondary consumers, represented by the shrew (Sorex granarius); and finally, detritivores, represented by slugs (Arion ater). Thirteen of the sampling stations were located in mature oak woodlands (Quercus sp.); two of the sampling stations were located in the area surrounding a restored lignite mine dump, and the other in an ultrabasic area. The analytical determinations revealed a lack of significant correlations among trophic compartments, possibly caused by effective regulation of metals by organisms and/or spatial variation in availability of metals from soil or food. Furthermore, the only element that showed a clear pattern of biomagnification was Cu; as for the other elements, there was always some divergence from such a pattern. Finally, the patterns of bioaccumulation in contaminated and woodland sampling stations were very similar, although there was enrichment of the concentrations of Cu, Mn, and Zn in the mice viscera, which, except for Mn, were related to higher edaphic concentrations.

Comparison of the accumulation of elements in two terrestrial moss species

The present study involved intercalibration of the concentrations of Al, As, Be, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V, and Zn in two species of terrestrial mosses, Pseudoscleropodium purum and Hypnum cupressiforme, collected in Galicia (NW Spain). The moss samples were collected from highly contaminated areas as well as areas with intermediate levels of contamination. Intercalibration was performed by type II regressions, and differences in the bioconcentration capacity of the two species were analyzed by ANCOVA. The slopes and elevations of the regression lines were well characterized and the lines obtained enabled intercalibration of a wide range of concentrations. The high values of the coefficients of determination for Cd, Cr, Fe, Hg, Mn, Pb, V, and Zn, allowed practical application of intercalibration because noise was reduced in the final data set. The high values of the slopes of the regression lines for some elements suggest that data corresponding to these species should not be used simultaneously without it first being transformed by the corresponding intercalibration line. In general terms, H. cupressiforme has a higher bioconcentration capacity than P. purum; this cannot be explained by differences in the concentration of uronic acids in the cell wall, the level of desesterification of these acids, the cationic exchange capacity of the species. However, the differences between species may be explained by morphological differences or differences in specific surface area.

The biosphere: A homogeniser of Pb-isotope signals

Rock, soil, and plant (terrestrial moss, European mountain ash leaves, mountain birch leaves, bark and wood, and spruce needles and wood) samples, collected at 3 km intervals along a 120 km long transect (40 sites) cutting the city of Oslo, Norway, were analysed for their Pb concentration and Pb-isotope ratios. A general decrease in 206Pb/207Pb, 208Pb/207Pb and 206Pb/208Pb ratios, with a characteristic low variability in all plant materials and the plant-derived O-horizon of soil profiles, compared to rocks and mineral soils, is observed along the transect. It is demonstrated that minerogenic and biogenic sample materials belong to two different spheres, the lithosphere and biosphere, and that geochemical processes determining their chemical and isotopic compositions differ widely. Background variation for both sample materials needs to be established and documented at the continental and global scale before the anthropogenic influence on the geochemistry of the earth’s surface can be reliably estimated.

Systemic RNAi mediated gene silencing in the anhydrobiotic nematode Panagrolaimus superbus.

BackgroundGene silencing by RNA interference (RNAi) is a powerful tool for functional genomics. Although RNAi was first described in Caenorhabditis elegans, several nematode species are unable to mount an RNAi response when exposed to exogenous double stranded RNA (dsRNA). These include the satellite model organisms Pristionchus pacificus and Oscheius tipulae. Available data also suggest that the RNAi pathway targeting exogenous dsRNA may not be fully functional in some animal parasitic nematodes. The genus Panagrolaimus contains bacterial feeding nematodes which occupy a diversity of niches ranging from polar, temperate and semi-arid soils to terrestrial mosses. Thus many Panagrolaimus species are adapted to tolerate freezing and desiccation and are excellent systems to study the molecular basis of environmental stress tolerance. We investigated whether Panagrolaimus is susceptible to RNAi to determine whether this nematode could be used in large scale RNAi studies in functional genomics.ResultsWe studied two species: Panagrolaimus sp. PS1159 and Panagrolaimus superbus. Both nematode species displayed embryonic lethal RNAi phenotypes following ingestion of Escherichia coli expressing dsRNA for the C. elegans embryonic lethal genes Ce-lmn-1 and Ce-ran-4. Embryonic lethal RNAi phenotypes were also obtained in both species upon ingestion of dsRNA for the Panagrolaimus genes ef1b and rps-2. Single nematode RT-PCR showed that a significant reduction in mRNA transcript levels occurred for the target ef1b and rps-2 genes in RNAi treated Panagrolaimus sp. 1159 nematodes. Visible RNAi phenotypes were also observed when P. superbus was exposed to dsRNA for structural genes encoding contractile proteins. All RNAi phenotypes were highly penetrant, particularly in P. superbus.ConclusionThis demonstration that Panagrolaimus is amenable to RNAi by feeding will allow the development of high throughput methods of RNAi screening for P. superbus. This greatly enhances the utility of this nematode as a model system for the study of the molecular biology of anhydrobiosis and cryobiosis and as a possible satellite model nematode for comparative and functional genomics. Our data also identify another nematode infraorder which is amenable to RNAi and provide additional information on the diversity of RNAi phenotypes in nematodes.

Atmospheric deposition of trace element pollutants in Macedonia studied by the moss biomonitoring technique

For the first time the atmospheric deposition of trace metals was studied over the entire territory of the Republic of Macedonia. Samples of the terrestrial mosses Hypnum cupressiforme, Camptothecium lutescens, and Homalothecium sericeum were collected in September-October 2002 at 73 sites evenly distributed over the country, and a total of 43 elements were determined by instrumental neutron activation analysis and atomic absorption spectrometry. Principal component factor analysis was used to identify the most polluted areas and characterize different pollution sources. The most important sources of trace metal deposition are ferrous and non-ferrous smelters, oil refineries, fertilizer production plants, and central heating stations. Four areas appear to be particularly exposed to metal pollution: Veles, Skopje, Tetovo, and Kavadarci-Negotino, whereas the predominantly agricultural regions in the south, southwest, and southeast show levels closer to European median values for most elements of mainly pollution origin.

Comparison of different types of biomasses for copper biosorption

Three biomass, birch wood Betula sp., marine brown alga Fucus vesiculosus, and terrestrial moss Pleurozium schreberi, have been compared as raw materials for preparation of biosorbents for removal of copper ions from diluted water solutions. Small sample doses (0.5 g/100 ml) of the biosorbents prepared from alga and moss enabled more than 90% removal of Cu(II) ions from diluted water solutions (5–20 mg/l). The sample from sawdust was less effective. A pseudo-second-order rate model properly described the experimental kinetic data for the biosorbents. The maximum sorption capacities ( X m) determined from the experimental equilibrium isotherms by applying the Langmuir model showed that the alga had the best copper-binding ability ( X m = 23.4 mg/g), followed by the moss ( X m = 11.1 mg/g), and the sawdust ( X m = 4.9 mg/g). No visible damages or performance losses were detected for the alga and moss after five sorption–desorption cycles using diluted HCl as eluent.

Uptake of137Cs and60Co by bryophytes and lichens

Sustainable ecosystems much depend on bioaccumulation processes. This study was dedicated to the role of bryophytes. Laboratory experiments showed that the 60Co2+ uptake by terrestrial mosses D. scoparium, P. commune and lichen H. physodes from water solution is a fast process, typical for ion exchange reactions. Equilibrium at 20°C was reached within 2 hours, with prevailing proportion of cobalt localized extracellularly. In the case of mosses, higher proportion of 60Co was found in brown tissue than in green tissue. The 137Cs+ uptake by lichen H. physodes is a two-phase process: the rapid phase of ion exchanges, followed by the slow phase, typical for active transport across biological membranes. Obtained data can serve for prediction of sorption processes of 137Cs and 60Co contamination in the case of their escape from nuclear equipment in a water-soluble form into the moss and lichen vegetation.