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Although soil is known to contribute to the concentrations of elements in moss, protocols for atmospheric biomonitoring with terrestrial moss do not include recommendations on how to address this factor. As a result, researchers indiscriminately use a wide range of detection/correction methods without considering whether the results are equivalent. In this study, three of these methods were compared: i) use of the enrichment factor (EF) index; ii) calculation of the ratios of different elements in soil and moss, and subtraction of the contribution of soil concentrations from the raw concentrations of elements in mosses (SCS); and iii) positive matrix factorization (PMF), a receptor modelling method for source apportioning based on multivariate analysis techniques. The aim of the comparison was to determine whether the methods produce equivalent results and, if not, which method is the most appropriate for use in moss biomonitoring surveys. The data used corresponded to 146 samples of Pseudoscleropodium purum collected from a regular sampling grid of 15 × 15 km in Galicia (NW Spain). Comparison of the methods revealed that, although they yield relatively similar results, the corresponding interpretations are not equivalent and none of the methods provides a reliable estimate of the soil contribution to the concentrations of elements in moss samples. Independently of the technique applied, use of Ti as a reference element is not recommended, because, at least in this study, it was present at unusually high levels in moss. Given the absence of a reliable correction method and the fact that most elements are present in fairly high amounts in the soil, we recommend using atmospheric biomonitoring with moss only for Cu, Zn and Cd, i.e. for those elements in moss for which the soil contributes very low amounts and corrections are not therefore necessary The authors belong to the Galician Competitive Research Group GRC/GPC2016-002 and to the CRETUS Strategic Partnership (AGRUP2015/02) which are co-funded by FEDER (EU). Authors would like to thank RIAIDT-USC for the use of analytical facilities. P. Giráldez is grateful to the Spanish Ministerio de Ciencia, Innovación y Universidades for a grant awarded within the Programa de Formacion de Profesorado Universitario (FPU 2018 [grant number FPU18/04134]). Z. Varela was supported by a postdoctoral research grant awarded by the Autonomous Government of Galicia (Spain) SI

We measured the concentrations of Cd, Cu, Hg, Pb and Zn in samples of the terrestrial moss Pseudoscleropodium purum reciprocally transplanted between an unpolluted and two polluted sampling sites. At the beginning of the experiment, the concentrations of all these elements differed significantly between mosses from the unpolluted site and mosses from the polluted sites. In general, the concentrations of the heavy metals in mosses from both polluted sites transplanted to the unpolluted site decreased until they reached the same levels as in autotransplants at this site (after 480-840 days). However, the concentrations of all heavy metals in mosses transplanted from the unpolluted site to both polluted sites increased to higher levels than in the autotransplants (except for Cu, Hg and Pb at one of the sampling sites). These results led us to conclude that mosses that have been continuously exposed to high atmospheric deposition of heavy metals undergo an adaptive response (probably genotypic) to such conditions. We therefore recommend active rather than passive biomonitoring of air quality in industrial environments because atmospheric deposition could be underestimated, and also recommend further investigation into the mechanisms involved in this response.

The concentration of Pb was determined in feathers (contour feathers: mantle, pectoral, ventral, and primary- and secondary-coverts) of two sedentary species of raptors in Galicia (NW Spain): the tawny owl (Strix aluco) and the Northern goshawk (Accipiter gentilis). A high degree of intraindividual variability was observed in all types of feathers, with coefficients of variation exceeding 100 percent. The correlations between feather types were too low to enable use of a single type of body feather to predict the concentration of Pb in the other feathers. The number of body feathers required to differentiate individuals on the basis of the concentration of Pb was extremely high, in some cases higher than the number of the particular type of feather in the bird. All of this provides clear evidence that the contour and covert feathers of the raptor species considered cannot be used to biomonitor contamination by Pb, at least in this sample where the overall feather concentration were fairly uniform.

The concentrations of Hg were determined in all primary flight feathers from 20 specimens of Buteo buteo and 49 specimens of Accipiter gentilis, which had died in various Wildlife Recovery Centres in Galicia (NW Spain) between 2001 and 2009. The aim of the study was to standardize the feather or feathers that should be analyzed in each species to enable inter-individual comparison of the levels of contamination, taking into consideration any variability in the concentrations of Hg caused by the birds' molting patterns. For both species the results show a high degree of both inter (e.g. an individual of A. gentilis showed 426 ng g(-1) of Hg as median and 568 ng g(-1) as median absolute deviation, MAD) and intra-individual variability (e.g. primary feather number seven - P7 - of all the A. gentilis individuals showed 537 ng g(-1) of Hg as median and 1129 ng g(-1) as MAD). Although molting did not have a clear effect on the concentrations of Hg in the flight feathers, it was possible to identify the most representative feather in each individual, taking into account the amount of metal excreted in each feather and the intra-individual variability. For B. buteo use of flight feather P6 is recommended for Hg biomonitoring studies; the amount of Hg excreted to this feather was 509 ng as median, which represents the 14% (from 10 to 20%) of the total Hg present in all the primary feathers. For A. gentilis the recommended feather is P7, which has a median of 86 ng of Hg (corresponding to 12%, and varying between 5 and 22%).

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.

A new simple method is proposed for identifying sources of small scale pollution, by determining the tissue concentrations of pollutants in terrestrial mosses. The method is based on spatial characterization of the processes that generate accumulation of pollutants in these organisms. The steps involved in implementing and applying the method are: (i) obtaining data on pollutants in moss samples collected at least at 35 pairs of sampling sites (SS) separated by 1 km distance; (ii) study of the distribution of the differences in concentration between the pairs of SS, eliminating pairs affected by foci that generate small scale processes; (iii) characterization of the resulting normal distributions and calculation, for different levels of significance, of the probability of a value lying within these distributions, and (iv) application of the calculated quantiles to data corresponding to the differences in concentrations between pairs of SS in the vicinities of foci of small scale pollution, to determine which elements can be considered as pollutants. Given the small number of data required once the distribution of the differences has been established, the method is an inexpensive, efficient way of establishing the probability that a pollutant is being emitted from a particular source. The method is very useful for verifying the results of pollution inventories, evaluating new technologies and improving the design of regional networks for biomonitoring of air quality with terrestrial mosses.

Plants are used as target organisms in most biomonitoring studies of atmospheric deposition of dioxins and furans (PCDD/F) because the most common route of entry of these pollutants into ecosystems is through soils and plants. However, comparison of the results of such studies is difficult because different plant species are used. In the present study we propose the use of mosses as biomonitors of PCDD/F deposition because of their suitable characteristics (absorption of substances from the atmosphere only, large absorbing surface, wide distribution of some species, etc.). We measured the PCDD/F concentrations in tissues of Pseudoscleropodium purum collected in areas far from known sources of pollution and in the surroundings of potential sources of these pollutants (several types of industries, incinerators and burning rubbish dumps). Part of the samples were collected with the aim of monitoring changes in the pollution intensity around some selected sources over time, others were collected to study the spatial gradient of pollution around other sources. Our results indicate that the measurements of the concentration of PCDD/F in the moss tissue allow the detection of strong and weak pollution sources and that these measurements are sensible enough to monitorize changes in the pollution intensity along time, as well as to describe the spatial gradients of pollution created around point sources, and the differences in the relative abundance of isomers (homologue profiles) among different sources. We concluded that mosses are as good biomonitors for PCDD/F as they are for other types of pollutants.

As builders and major components of peatlands, Sphagnopsida (peat mosses) are very important organisms for ecosystems and world’s climate. Nowadays many Sphagnum species as well as their habitats are largely protected, while their scientific and economic relevance remains considerable. Advanced methods of in vitro cultivation provide the potential to work in a sustainable way with peat mosses and address aspects of basic research as well as biotechnological and economical topics like biomonitoring or the production of renewable substrates for horticulture (Sphagnum farming). Here, we describe the establishment of axenic in vitro cultures of the five peat moss species Sphagnum fimbriatum Wils. and Hook., Sphagnum magellanicum Brid., Sphagnum palustre L., Sphagnum rubellum Wils. and Sphagnum subnitens Russ. and Warnst. with specific focus on large-scale cultivation of S. palustre in bioreactors. Axenic, clonal cultures were established to produce high quantities of biomass under standardized laboratory conditions. For advanced production of S.palustre we tested different cultivation techniques, growth media and inocula, and analyzed the effects of tissue disruption. While cultivation on solid medium is suitable for long term storage, submerse cultivation in liquid medium yielded highest amounts of biomass. By addition of sucrose and ammonium nitrate we were able to increase the biomass by around 10- to 30-fold within 4 weeks. The morphology of in vitro-cultivated gametophores showed similar phenotypic characteristics compared to material from the field. Thus the tested culture techniques are suitable to produce S. palustre material for basic and applied research. Electronic supplementary material The online version of this article (doi:10.1007/s11240-014-0658-2) contains supplementary material, which is available to authorized users.