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

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

Global decrease in heavy metal concentrations in brown algae in the last 90 years

In the current scenario of global change, heavy metal pollution is of major concern because of its associated toxic effects and the persistence of these pollutants in the environment. This study is the first to evaluate the changes in heavy metal concentrations worldwide in brown algae over the last 90 years (>15,700 data across the globe reported from 1933 to 2020). The study findings revealed significant decreases in the concentrations of Cd, Co, Cr, Cu, Fe, Hg, Mn, Pb and Zn of around 60-84% (ca. 2% annual) in brown algae tissues. The decreases were consistent across the different families considered (Dictyotaceae, Fucaceae, Laminariaceae, Sargassaceae and Others), and began between 1970 and 1990. In addition, strong relationships between these trends and pH, SST and heat content were detected. Although the observed metal declines could be partially explained by these strong correlations, or by adaptions in the algae, other evidences suggest an actual reduction in metal concentrations in oceans because of the implementation of environmental policies. In any case, this study shows a reduction in metal concentrations in brown algae over the last 50 years, which is important in itself, as brown algae form the basis of many marine food webs and are therefore potential distributors of pollutants.

Analysis of intra-thallus and temporal variability of trace elements and nitrogen in Fucus vesiculosus: Sampling protocol optimization for biomonitoring

To advance the methodological standardization of the biomonitoring technique using macroalgae, we comprehensively characterized the intra-thallus and temporal patterns of variation in concentrations of a wide set of elements (Al, As, Cd, Co, Cr, Cu, Fe, Hg, Ni, Pb, Zn, N) and δ15N signal in 6 consecutive Fucus vesiculosus apical dichotomous sections collected monthly over a four-year period (2015-2019) at 3 sites on the NW coast of Spain. The concentrations of Al, Co, Fe, Ni, Pb and Zn increased significantly from the youngest to the oldest dichotomies regardless of the sampling time and collection site; As, Cd, N and δ15N showed the opposite trend. Time series analysis revealed a significant and consistent seasonal variation of As, Cd, Co, Cu, Fe, Hg, Ni, Zn, N and δ15N concentrations, with maximum values in winter and minimum values in summer. We discussed the possible mechanisms driving these two sources of variation, and proposed an efficient and effective sampling strategy to minimize their impact in the results of biomonitoring studies, in which the part of the algal thallus selected for chemical analysis and the sampling frequency were carefully considered. This protocol will improve the conclusions and comparability of biomonitoring data from coastal environments.

Characteristics and prognosis of jejunoileal gastrointestinal stromal tumours (GISTs) in the era of imatinib: a comparative study with gastric GISTs

BACKGROUND

Gastrointestinal stromal tumours (GISTs) located in the jejunum or ileum (JI-GIST) are considered worse prognosis compared to those of gastric (G-GIST) location. It has been suggested that this dogma should be revised. The aim of this study was to describe the characteristics of jejunoileal GISTs and its prognosis and to compare them with G-GISTs in the era of imatinib.

METHODS

We retrospectively reviewed the clinical histories of all the patients diagnosed with GISTs between January 2000 and November 2016: Clinical and pathological data, as recurrence, metastatic state, disease-free survival (DFS) as well as overall survival (OS) rates of patients were reviewed.

RESULTS

JI-GIST patients comprise 29 cases (37.7%). Compared to G-GIST, JI-GIST patients had undergone emergency surgery more frequently (37.9% vs. 10.4%, p = 0.007). According to the NIH-Fletcher classification, the low or very-low risk group represents 17.2% of JI-GISTs as opposed to 37.6% of G-GISTs (p < 0.005). When the AFIP-Miettinen system was used the low or very-low group represented 17.2% of JI-GISTs vs. 58.4% in the G-GISTs group (p < 0.001). Both local recurrence (24.1% vs. 12.5%, p < 0.05) and metastatic rate (34.5% vs. 22.9%, p < 0.05) were higher in the JI-GIST group than in G-GIST. 5- and 10-year DFS and 10-year OS rate were lower for JI-GIST (54.5% and 39.6% vs. 77.2% and 60.8%, and 57.9% vs. 65%, respectively, p < 0.05).

CONCLUSIONS

The observed differences between both groups in DFS and OS rates at long term could be attributed to the effect of imatinib.

Can proteomics contribute to biomonitoring of aquatic pollution? A critical review

Aquatic pollution is one of the greatest environmental problems, and therefore its control represents one of the major challenges in this century. In recent years, proteomics has emerged as a powerful tool for searching protein biomarkers in the field of pollution biomonitoring. For biomonitoring marine contamination, there is a consensus that bivalves are preferred organisms to assess organic and inorganic pollutants. Thus, the bivalve proteome was intensively studied, particularly the mussel. It is well documented that heavy metal pollution and organic chemicals altered the structural proteins causing degradation of tissues of molluscs. Also, it is well known that proteins involved in stress oxidative such as glutathione and enzymes as catalase, superoxide dismutase or peroxisomes are overexpressed in response to contaminants. Additionally, using bivalves, other groups of proteins proposed as pollution biomarkers are the metabolic proteins. Even though other marine species are used to monitor the pollution, the presence of proteomic tools in these studies is scarce. Concerning freshwater pollution field, a great variety of animal species (fish and crustaceans) are used as biomonitors in proteomics studies compared to plants that are scarcely analysed. In fish species, proteins involved in stress oxidative such as heat shock family or proteins from lipid and carbohydrate metabolism were proposed as candidate biomarkers. On the contrary, for crustaceans there is a lack of proteomic studies individually assessing the contaminants. Novel scenarios, including emerging contaminants and new threats, will require proteomic technology for a systematic search of protein biomarkers and a greater knowledge at molecular level of those cellular pathways induced by contamination.

Optimization of a MALDI-Imaging protocol for studying adipose tissue-associated disorders

Matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) is increasingly recognized for its potential in the discovery of novel biomarkers directly from tissue sections. However, there are no MALDI IMS studies as yet on the adipose tissue, a lipid-enriched tissue that plays a pivotal role in the development of obesity-associated disorders. Herein, we aimed at developing an optimized method for analyzing adipose tissue lipid composition under both physiological and pathological conditions by MALDI IMS. Our studies showed an exacerbated lipid delocalization from adipose tissue sections when conventional strategies were applied. However, our optimized method using conductive-tape sampling and 2,5-dihydroxybenzoic acid (DHB) as a matrix, preserved the anatomical organization and minimized lipid diffusion from sample sections. This method enabled the identification of a total of 625 down-regulated and 328 up-regulated m/z values in the adipose tissue from a rat model of extreme obesity as compared to lean animals. Combination of MALDI IMS and liquid chromatography (LC)-MS/MS data identified 44 differentially expressed lipid species between lean and obese animals, including phospholipids and sphingomyelins. Among the lipids identified, SM(d18:0_18:2), PE(P-16:0_20:0), and PC(O-16:0_16:1) showed a differential spatial distribution in the adipose tissue of lean vs. obese animals. In sum, our method provides a valuable new tool for research on adipose tissue that may pave the way for the identification of novel biomarkers of obesity and metabolic disease.

Optimal number of Fucus vesiculosus samples to differentiate between sites affected by distinct levels of heavy metal contamination

The presence of trace elements in marine habitats is a serious environmental problem which increasingly affects ecosystem and human health. The use of macroalgae as contamination biomonitors represents a valuable alternative approach to traditional physicochemical methods. The present study was carried out to determine the optimal number of samples of Fucus vesiculosus needed to detect statistically significant differences in the mean concentrations of Al, As, Cd, Co Cr, Cu, Fe, Hg, Ni, Pb, Zn, N and δ15N between two sampling sites affected by different levels of contamination. For this purpose, we plotted the density distributions of the concentrations of the different elements and examined the local variability at three sites. For sites with mean concentrations differing by more than 30 %, 20 samples were sufficient to detect significant differences for all of the elements, except Cr. The proposed methodology could be used in other studies in the absence of specific research on each species and region.

Matching times: Trying to improve the correlation between heavy metal levels in mosses and bulk deposition

The relationship between the concentrations of metals in moss tissues and atmospheric deposition is highly complex, resulting in a general lack of correlations between these two matrices. Here, we tried to improve the significance of the moss-bulk deposition (BD) relationship by eliminating the mismatch between the time that the moss tissue selected for analysis is exposed to atmospheric deposition, and the time during which BD is collected. For this, we analysed the concentrations of Cd, Hg and Pb in new grown tissue of Pseudoscleropodium purum and BD collected monthly, for one year, in 21 sampling sites (SS) under different degrees of pollution. Additionally, we assessed how different moss tissues, including native moss (green parts and new grown tissues of P. purum) and moss transplants of Sphagnum denticulatum, reflect BD to find out which moss tissues provide a better estimate of the atmospheric deposition of heavy metals. First of all, our results showed that eliminating the mismatch between native moss exposure time and BD collection period is not enough to improve their correlation. Environmental variation emerged as the main driver of tissue content variation altering the moss-BD relationship unpredictably. Secondly, native P. purum represents BD values better than devitalized transplants by displaying a greater number of significant correlations with BD. Specifically, green parts of P. purum generally represent better BD than new grown tissues. Overall, we conclude that neither native mosses nor transplants are good estimators of atmospheric heavy metal deposition rates. However, they are good qualitative indicators of the atmospheric deposition, by allowing us to differentiate SS subject to a wide range of pollution levels. Additionally, green parts of P. purum, and likely of other mosses with similar growth forms, should be used in passive biomonitoring studies to make results from different studies comparable.

Methodological advances to biomonitor water quality with transplanted aquatic mosses

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

Testing a novel biotechnological passive sampler for monitoring atmospheric PAH pollution

In this study we evaluated a new type of passive air sampler, the "mossphere" device, filled with a Sphagnum palustre clone. For this purpose, we compared the atmospheric levels of polyaromatic hydrocarbons (PAHs) collected using this device and those collected in conventional bulk deposition and particulate matter (PM10) samplers. All three types of samplers were exposed at 10 sites affected by different levels of pollution and located in two different climate zones. The bulk deposition/ mossphere comparison yielded a greater number of significant regressions with higher coefficients of determination than the PM10/ mossphere comparison. No significant regressions were observed for 3-ring PAHs in either comparison. The mosspheres explain ca. 50% of the variability of the concentrations of 4-, 5- and 6-ring PAHs and total PAHs detected in PM10 and ca. 70% of the corresponding concentrations detected in the bulk deposition. The use of the Sphagnum clone enables standardization of the set-up, thus making the mossphere device a good sampling tool for monitoring 4-, 5- and 6-ring and total PAHs, especially those associated with bulk deposition. The findings indicate the potential usefulness of this innovative technology for mapping PAH levels.

Sampling optimization for biomonitoring metal contamination with marine macroalgae

The aim of the present study was to optimize the protocol for sampling marine macroalgae to be used to biomonitor heavy metal contamination in marine ecosystems. For this purpose, we collected 50 subsamples of the brown seaweed Fucus vesiculosus at random in each of three sampling sites (SS) and determined the concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Hg, N, Ni, Pb, Zn and δ15N. We used semivariograms to explore the possible existence of spatial structure in the concentrations of the elements. Spatial structure was observed in 88% of the semivariograms studied, with element concentrations varying longitudinally and transversally along the SS. Using randomization techniques, we estimated that in each SS, a minimum of 30 evenly distributed subsamples should be collected within three bands parallel to the coastline (and also at different heights on the rocks if necessary), and analyzed in a single composite sample representative of the intra-SS variability.

Evaluation of the aggregation process in a mixture of propofol and benzocaine

We report on a mass-resolved IR spectrosopic study on propofol-benzocaine aggregates. This is a complex system due to the several conformational isomers that both monomers may adopt and to the combination of functional groups they present, which allow the molecules to interact in many possible ways. However, our results demonstrate that a single conformation is favored for each stoichiometry. In the heterodimer, propofol acts as a proton donor to the ester group of benzocaine, while the whole cluster is stabilized by dispersive forces. These dispersive forces account for an important part of the system's stabilization energy as the calculations suggest. Propofol does not show any affinity for the amino group of benzocaine, even when a second molecule of propofol is introduced. These results demonstrate the difficulty in anticipating the aggregation preferences of even small organic molecules.

Application of macroalgae analysis to assess the natural variability in selected pollution concentrations (N and Hg), and to detect sources of it in coastal environments

Here we present a new method in which algae are used to detect sources of heavy metal and organic pollution in coastal areas. The procedure involves characterization of the natural range of concentrations of the elements in areas not affected by local sources of pollution and subsequent comparison of concentrations in the study site to these natural range levels. To develop the method, the concentrations of various elements were determined in specimens of the macroalgae Fucus vesiculosus collected at >150 sampling sites along the shoreline. The natural variability in the element concentrations in these zones was established by determining the differences in the tissue concentrations of the elements between pairs of samples separated by different distances. The method was then tested in the surroundings of possible sources of nitrogen and was found to be a tool for detecting sources of small scale nitrogen contamination and for monitoring and evaluating water quality.

Biomonitoring freshwater FISH farms by measuring nitrogen concentrations and the δ15N signal in living and devitalized moss transplants

The trophic balance of freshwater aquaculture activities has traditionally been monitored by chemical analysis of water; however, the parameters measured are usually characterized by high temporal variability. Aquatic mosses can be used as biomonitors as they integrate both continuous and episodic contamination events. Here we report, for the first time, a method for monitoring N enrichment in the surroundings of fish farms by measuring the N content and isotopic signal (δ¹⁵N) of transplanted living and devitalized specimens of the aquatic moss Fontinalis antipyretica. For this purpose, moss samples ("moss bags") were exposed at increasing distances (10, 100, 300 and 1000 m) up- and downstream of the effluent discharge points of four trout farms, for 10 and 30 days. The low natural (background) variability in δ¹⁵N in upstream samples enabled detection of outlier values, caused by aquaculture discharges, at distances of 10 and 100 m downstream, especially in devitalized moss and after 10 days of exposure. However, the unexpectedly low N contents of moss samples exposed close to the discharge points complicates interpretation of the high levels of N forms detected by conventional physicochemical analysis of water. Although the mechanisms that modify N parameters in moss tissues were not clear, measurement of the isotopic signal δ¹⁵N in devitalized moss exposed for 10 days proved useful for monitoring the N pollution associated with intensive freshwater aquaculture.

Additional malignancies in patients with gastrointestinal stromal tumors (GIST): incidence, pathology and prognosis according to a time of occurrence-based classification

BACKGROUND

The aim of the study is to clarify if a classification based on the time of occurrence of associated malignancies in GIST patients can help in the understanding of the clinical controversies observed in these patients.

METHODS

We retrospectively reviewed all the patients diagnosed with GIST tumors between January 1999 and October 2016. They were divided into GIST patients associated with other tumors (A-GIST) and those not associated (NA-GIST). A-GIST patients were also divided into four types according to the proposed classification.

RESULTS

Of 104 GIST patients, 32 (30.7%) (A-GIST group) had at least one additional primary malignancy. The most frequent location of the associated malignancy was the GI tract (26%). Compared to NA-GIST, A-GIST were more often asymptomatic with a lower risk of recurrence. The main cause of death in NAGIST was GIST itself, being associated tumors the main cause of death in A-GIST group. No differences were found in DFS and OS between A-GIST and NA-GIST.

CONCLUSIONS

The use of the proposed classification classifies GIST patients with associated malignancies in different subtypes that differ substantially in terms of incidence, type of neoplasms associated, cause of the association and prognosis.

Biomonitoring coastal environments with transplanted macroalgae: A methodological review

The use of macroalgae transplants is a recent technique used in pollution biomonitoring studies in marine ecosystems. Only 60 articles published between 1978 and 2017 reported the use of this environmental tool for the active biomonitoring of inorganic pollutants and nutrients worldwide. In this review paper, we evaluated studies on this topic in relation to the development of methodological aspects of the technique and the degree of standardization of the protocols used. On the basis of findings of this review, we conclude that the technique is not yet standardized and that uniformisation of protocols is required to enable comparison of the results of different studies. We propose a new protocol for applying the technique, in which each suggestion has been carefully and rigorously compared with the relevant findings reported in the available literature.

Do mosses exist outside of Europe? A biomonitoring reflection

The passive moss biomonitoring technique has been proved a useful environmental tool for the study of the air quality. However, after more than 40years of its discovery, it has not been used yet in decision making when dealing with atmospheric pollution. Scientific efforts and funding are wasted when these sort of findings do not have a meaningful impact on society. Thus, the aim of this review is to showcase the reasons preventing the worldwide application of the moss technique. The results showed that the possible reasons underlying this problem are the lack of standardization of the technique, transmission of a false idea of robustness, and the lack of a theoretical background. Knowing and accepting these problems is the first step to encourage scientists and funding bodies to invest their efforts in really improving the technique for its application in environmental policies and not only in scientific circles.

Quantification of the overall measurement uncertainty associated with the passive moss biomonitoring technique: Sample collection and processing

In this study we examined 6080 data gathered by our research group during more than 20 years of research on the moss biomonitoring technique, in order to quantify the variability generated by different aspects of the protocol and to calculate the overall measurement uncertainty associated with the technique. The median variance of the concentrations of different pollutants measured in moss tissues attributed to the different methodological aspects was high, reaching values of 2851 (ng·g^-1)² for Cd (sample treatment), 35.1 (μg·g^-1)² for Cu (sample treatment), 861.7 (ng·g^-1)² and for Hg (material selection). These variances correspond to standard deviations that constitute 67, 126 and 59% the regional background levels of these elements in the study region. The overall measurement uncertainty associated with the worst experimental protocol (5 subsamples, refrigerated, washed, 5 × 5 m size of the sampling area and once a year sampling) was between 2 and 6 times higher than that associated with the optimal protocol (30 subsamples, dried, unwashed, 20 × 20 m size of the sampling area and once a week sampling), and between 1.5 and 7 times higher than that associated with the standardized protocol (30 subsamples and once a year sampling). The overall measurement uncertainty associated with the standardized protocol could generate variations of between 14 and 47% in the regional background levels of Cd, Cu, Hg, Pb and Zn in the study area and much higher levels of variation in polluted sampling sites. We demonstrated that although the overall measurement uncertainty of the technique is still high, it can be reduced by using already well defined aspects of the protocol. Further standardization of the protocol together with application of the information on the overall measurement uncertainty would improve the reliability and comparability of the results of different biomonitoring studies, thus extending use of the technique beyond the context of scientific research.

Trace element concentrations in the moss Hypnum cupressiforme growing in a presumably unpolluted area

In this study we determined the concentrations of As, Cd, Hg, Ni and Pb in samples of the moss Hypnum cupressiforme collected during 5 different sampling surveys (2006-2014) in a presumably unpolluted area in northern Spain (25 sampling sites). We then applied factor analysis (FA) to the data to explore the factors underlying the spatial and temporal variability in the concentrations. The percentage of variance explained by the FA ranged between 34 and 98%, and was usually higher than 70%. The FA yielded 5 factors that explained the variance in the concentrations of Cd, As, Hg and Pb in all sampling surveys and also a single factor that explained the variance in Hg and Pb concentrations in 2006. Although the lack of obvious sources of pollution in the study region (at least for the elements considered) suggests that most elements (except perhaps Ni) probably originated from long-range atmospheric transport, this would not explain the results of the FA. We suggest that rather than being due to the origin of the pollutants (as frequently assumed), the spatio-temporal variability in the concentrations of these elements is probably determined by a series of other factors: the physicochemical characteristics of the pollutants and of the moss binding surfaces, physiological processes (e.g. moss growth), and the characteristics of the sampling sites (e.g. vegetation cover, elevation, slope, aspect). We therefore conclude that the assumption that variations in element concentrations in moss tissues are due to the origin of the pollutants is an oversimplification that leads to erroneous interpretation of the results of biomonitoring studies with terrestrial mosses.

Study of temporal trends in mercury concentrations in the primary flight feathers of Strix aluco

Temporal trends in Hg concentrations were determined in the primary flight feathers of 146 specimens of Strix aluco which had died in various Wildlife Recovery Centres in Galicia (NW Spain) between 1997 and 2014. The aim of the study was to determine whether standardization of a primary flight feather (or feathers) in this species is essential for identifying temporal trends in Hg concentrations. For this purpose, we had to first standardize the feather(s) analyzed to enable comparison of the levels of Hg detected in different feathers. The results show a high degree of both inter and intra-individual variability but despite that, it was possible to identify P5 as the most representative feather taking into account the amount of metal excreted in each feather and the intra-individual variability: its median was 133ng, which represents 15% (from 7% to 15%) of the total Hg present in all the primary feathers. However, this "standard feather" did not reveal any temporal trend in Hg concentrations for the study period. This lack of trend was found irrespective of the feather considered and it is expected that detection of any existing trend would also not depend on the feather considered. We conclude that use of any particular feather is not essential for identifying temporal trends in Hg concentrations, because the pattern will be identified regardless of the feather selected.

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

To develop an internationally standardized protocol for the moss bag technique application, the research team participating in the FP7 European project "MOSSclone" focused on the optimization of the moss bags exposure in terms of bag characteristics (shape of the bags, mesh size, weight/surface ratio), duration and height of exposure by comparing traditional moss bags to a new concept bag, "Mossphere". In particular, the effects of each variable on the metal uptake from the air were evaluated by a systematic experimental design carried out in urban, industrial, agricultural and background areas of three European countries with oceanic, Mediterranean and continental climate. The results evidenced that the shape, the mesh size of the bags and the exposure height (in the tested ranges), did not significantly influence the uptake capacity of the transplanted moss. The aspects more affecting the element uptake were represented by the density of the moss inside the bags and the relative ratio between its weight and the surface area of the bag. We found that, the lower the density, the higher the uptake recorded. Moreover, three weeks of exposure were not enough to have a consistent uptake signal in all the environments tested, thus we suggest an exposure period not shorter than 6 weeks, which is appropriate in most situations. The above results were confirmed in all the countries and scenarios tested. The adoption of a shared exposure protocol by the research community is strongly recommended since it is a key aspect to make biomonitoring surveys directly comparable, also in view of its recognition as a monitoring method by the EU legislation.

Evaluation of the use of moss transplants (Pseudoscleropodium purum) for biomonitoring different forms of air pollutant nitrogen compounds

We investigated whether three different types of moss transplants (devitalized moss bags with and without cover and auto-irrigated moss transplants) are suitable for use as biomonitors of the deposition of oxidised and/or reduced forms of N. For this purpose, we determined whether the concentration of atmospheric NO2 was related to the % N, δ(15)N and the activity of the enzyme biomarkers phosphomonoesterase (PME) and nitrate reductase (NR) in the tissues of moss transplants. We exposed the transplants in 5 different environments of Galicia (NW Spain) and Cataluña (NE Spain): industrial environments, urban and periurban environments, the surroundings of a cattle farm and in a monitoring site included in the sampling network of the European Monitoring Programme. The results showed that the moss in the auto-irrigated transplants was able of incorporating the N in its tissues because it was metabolically active, whereas in devitalized moss bags transplants, moss simply intercepts physically the N compounds that reached it in particulate or gaseous form. In addition, this devitalization could limit the capacity of moss to capture gaseous compounds (i.e. reduced N) and to reduce the oxidised compounds that reach the specimens. These findings indicate that devitalized moss transplants cannot be used to monitor either oxidised or reduced N compounds, whereas transplants of metabolically active moss can be used for this purpose. Finally, the NR and PME biomarkers should be used with caution because of the high variability in their activities and the limits of quantification should be evaluated in each case.

Using devitalized moss for active biomonitoring of water pollution

This paper presents the results of an experiment carried out for the first time in situ to select a treatment to devitalize mosses for use in active biomonitoring of water pollution. Three devitalizing treatments for the aquatic moss Fontinalis antipyretica were tested (i.e. oven-drying at 100 °C, oven-drying with a 50-80-100 °C temperature ramp, and boiling in water), and the effects of these on loss of material during exposure of the transplants and on the accumulation of different heavy metals and metalloids were determined. The suitability of using devitalized samples of the terrestrial moss Sphagnum denticulatum to biomonitor aquatic environments was also tested. The structure of mosses was altered in different ways by the devitalizing treatments. Devitalization by boiling water led to significantly less loss of material (p < 0.01) than the oven-drying treatments. However, devitalization by oven-drying with a temperature ramp yielded more stable results in relation to both loss of material and accumulation of elements. With the aim of standardizing the moss bag technique, the use of F. antipyretica devitalized by oven-drying with a temperature ramp is recommended, rather than other devitalization treatments or use of S. denticulatum.

Mass resolved IR spectroscopy of aniline–water aggregates

Aniline is the simplest aromatic amine and therefore it is a prototypical system to study the microhydration and excited state dynamics of aromatic amines.

Active biomonitoring with the moss Pseudoscleropodium purum: Comparison between different types of transplants and bulk deposition

Active biomonitoring with terrestrial mosses can be used to complement traditional air pollution monitoring techniques. Several studies have been carried out to compare the uptake capacity of different types of moss transplants. However, until now the relationship between the uptake of elements in devitalized moss bags and in irrigated transplants has not been explored. In this study, the final concentrations of Cd, Cu, Hg, Pb and Zn were determined in irrigated and devitalized moss transplants in the surroundings of a steelworks. The concentrations were also compared with those of the same elements in the bulk deposition to determine which type of moss transplant yields the closest correlations. Devitalized moss retained higher concentrations of all of the elements (except Hg) than the irrigated moss. Both irrigated and devitalized moss transplants appear to detect the same type of contamination (i.e. particulate matter and dissolved metals rather than gaseous forms) as significant correlations were found for Cu, Hg, Pb and Zn, whereas, neither type of the moss transplant was sensitive enough to detect changes in the soluble fraction load of bulk deposition. Further studies will be needed to a better understanding of the correlation between the concentrations of elements in moss transplants with the particulate fraction of the bulk deposition. This will enable the establishment of a more robust and accurate biomonitoring tool.

Topical and intravenous tranexamic acid reduce blood loss compared to routine hemostasis in total knee arthroplasty: a multicenter, randomized, controlled trial

INTRODUCTION

Tranexamic acid (TXA) is becoming widely used in orthopedic surgery to reduce blood loss and transfusion requirements, but consensus is lacking regarding the optimal route and dose of administration. The aim of this study was to compare the efficacy and safety of topical and intravenous routes of TXA with routine hemostasis in patients undergoing primary total knee arthroplasty (TKA).

MATERIALS AND METHODS

We performed a randomized, multicenter, parallel, open-label clinical trial in adult patients undergoing primary TKA. Patients were divided into three groups of 50 patients each: Group 1 received 1 g topical TXA, Group 2 received 2 g intravenous TXA, and Group 3 (control group) had routine hemostasis. The primary outcome was total blood loss. Secondary outcomes were hidden blood loss, blood collected in drains, transfusion rate, number of blood units transfused, adverse events, and mortality.

RESULTS

One hundred and fifty patients were included. Total blood loss was 1021.57 (481.09) mL in Group 1, 817.54 (324.82) mL in Group 2 and 1415.72 (595.11) mL in Group 3 (control group). Differences in total blood loss between the TXA groups and the control group were clinically and statistically significant (p < 0.001). In an exploratory analysis differences between the two TXA groups were not statistically significant (p = 0.073) Seventeen patients were transfused. Transfusion requirements were significantly higher in Group 3 (p = 0.005). No significant differences were found between groups regarding adverse events.

CONCLUSION

We found that 1 g of topical TXA and 2 g of intravenous TXA were both safe strategies and more effective than routine hemostasis to reduce blood loss and transfusion requirements after primary TKA.

LEVEL OF EVIDENCE

I.

A critical review of protocols for moss biomonitoring of atmospheric deposition: sampling and sample preparation

Currently, the most important guideline for the application of the moss technique to monitor the atmospheric deposition of heavy metals is the "Heavy metals, nitrogen and POPs in European mosses: 2015 survey" published by the UNECE ICP Vegetation. Two main problems have been identified with this guideline: i) some of the recommendations regarding the methodological aspects involved in the application of the moss technique are not based on scientific criteria; and, ii) some recommendations in the manual are very vague and some aspects are even left out (e.g., elevation, distance to the coast). As a result there exists a high variability in the application of the protocol and many scientists adapt it to the specific conditions in the studied areas without evaluating how changes affect the results obtained. Therefore, in this article a total of 369 studies were reviewed including both methodological and application studies of the passive biomonitoring of the atmospheric deposition of heavy metals with terrestrial mosses. The results of this review have shown on the one hand, that none of the articles completely accomplished the ICP-Vegetation protocol suggestions, either because the information regarding some aspects was lacking or simply because the authors did not follow the manual suggestions. On the other hand, it was found that the results of methodological studies sometimes contradicted the ICP Vegetation manual recommendations. Thus, a new protocol in which each suggestion has been carefully and rigorously contrasted with the available literature has been proposed in this paper. In addition, practical and economic issues have also been considered and much more concise suggestions have been proposed which would facilitate its fulfilment in a more objective way.

Relationship between trace metal concentrations in the terrestrial moss Pseudoscleropodium purum and in bulk deposition

The relationship between trace metal concentrations in Pseudoscleropodium purum (Hedw.) M. Fleish. and bulk deposition (BD) was examined at 21 sites (SS) to ascertain whether the lack of correlations reported in previous studies are due to limitations in the experimental design. Thus, we implemented some improvements to it and examined the correlations in depth. We could conclude that this relationship is determined by other variables rather than by the pollutant inputs themselves (BD). Thus, whether or not moss concentrations and bulk deposition are significantly correlated will depend on the combination of the above referred factors in a given area at a given time. Therefore, P. purum in particular, and most likely native terrestrial mosses in general, are less than ideal biomonitors for yielding absolute values of atmospheric trace metal deposition. We recommend their use as qualitative indicators and the use of classical methods to obtain absolute values.

Heavy metal and nitrogen concentrations in mosses are declining across Europe whilst some "hotspots" remain in 2010

In recent decades, naturally growing mosses have been used successfully as biomonitors of atmospheric deposition of heavy metals and nitrogen. Since 1990, the European moss survey has been repeated at five-yearly intervals. In 2010, the lowest concentrations of metals and nitrogen in mosses were generally found in northern Europe, whereas the highest concentrations were observed in (south-)eastern Europe for metals and the central belt for nitrogen. Averaged across Europe, since 1990, the median concentration in mosses has declined the most for lead (77%), followed by vanadium (55%), cadmium (51%), chromium (43%), zinc (34%), nickel (33%), iron (27%), arsenic (21%, since 1995), mercury (14%, since 1995) and copper (11%). Between 2005 and 2010, the decline ranged from 6% for copper to 36% for lead; for nitrogen the decline was 5%. Despite the Europe-wide decline, no changes or increases have been observed between 2005 and 2010 in some (regions of) countries.

On the use of Arion ater to biomonitor environmental pollution by Cd, Cu, Fe, Mn and Zn, with a special insight into the population variability

The suitability of Arion ater as a biomonitor of Cd, Cu, Fe, Mn and Zn was assessed. Individual specimens were collected from 22 sampling sites. Slugs from 3 of the sites were analysed individually, whereas the slugs from the other sites were pooled to make a composite sample for each site. The tissue burdens did not differ between individuals from contaminated and uncontaminated sites, and there was no gradient of bioaccumulation of any of the elements in the surroundings of the smelter. Analysis of the individual specimens from the 3 sites revealed very high coefficients of variation for the metal concentrations. As a result of the high level of variation, large numbers of slugs are required to produce a low error in characterizing the mean concentration at each site. Furthermore, as a consequence of the similar mean concentrations and high variability, large numbers of samples are needed to detect significant differences between pairs of sites.

Primordial germ cell migration in the yellowtail kingfish (Seriola lalandi) and identification of stromal cell-derived factor 1

Primordial germ cells (PGCs) are progenitors of the germ cell lineage, giving rise to either spermatogonia or oogonia after the completion of gonadal differentiation. Currently, there is little information on the mechanism of PGCs migration leading to the formation of the primordial gonad in perciform fish. Yellowtail kingfish (Seriola lalandi) (YTK) (order Perciforms) inhabit tropical and temperate waters in the southern hemisphere. Fundamental details into the molecular basis of larval development in this species can be easily studied in Australia, as they are commercially cultured and readily available. In this study, histological analysis of YTK larvae revealed critical time points for the migration of PGCs to the genital ridge, resulting in the subsequent development of the primordial gonad. In YTK larvae at 3, 5, 7 and 10 days post hatch (DPH), PGCs were not yet enclosed by somatic cells, indicating the primordial gonad had not yet started to form. While at 15, 18 and 20 DPH PGCs had already settled at the genital ridge and started to become enclosed by somatic cells indicating the primordial gonad had started to develop. A higher number of PGCs were observed in the larvae at 15 and 18 DPH indicating PGCs proliferation, which corresponds with them becoming enclosed by the somatic cells. Directional migration of PGCs toward the genital ridge is a critical event in the subsequent development of a gonad. In zebrafish, mouse and chicken, stromal-cell derived factor (SDF1) signalling is one of the key molecules for PGC migration. We subsequently isolated from YTK the SDF1 (Slal-SDF1) gene, which encodes for a 98-residue precursor protein with a signal peptide at the N-terminus. There is spatial conservation between fish species of four cysteine residues at positions C9, C11, C34 and C49, expected to form disulphide bonds and stabilize the SDF structure. In YTK, Slal-SDF1 gene expression analyses shows that this gene is expressed in larvae from 1 to 22 DPH and demonstrates distinct spatial localisation in the larvae at 7 DPH. These results provide a platform for further studies into the molecular machinery of PGC migration in yellowtail kingfish, as well as other perciform fish species.

Use of a moss biomonitoring method to compile emission inventories for small-scale industries

We used a method of detecting small-scale pollution sources (DSSP) that involves measurement of the concentrations of elements in moss tissues, with the following aims: (i) to determine any common qualitative patterns of contaminant emissions for individual industrial sectors, (ii) to compare any such patterns with previously described patterns, and (iii) to compile an inventory of the metals and metalloids emitted by the industries considered. Cluster analysis revealed that there were no common patterns of emission associated with the industrial sectors, probably because of differences in production processes and in the types of fuel and raw materials. However, when these variables were shared by different factories, the concentrations of the elements in moss tissues enabled the factories to be grouped according to their emissions. We compiled a list of the metals and metalloids emitted by the factories under study and found that the DSSP method was satisfactory for this purpose in most cases (53 of 56). The method appears to be a useful tool for compiling contaminant inventories; it may also be useful for determining the efficacy of technical improvements aimed at reducing the industrial emission of contaminants and could be incorporated in environmental monitoring and control programmes.

Efficacy and safety of fibrin glue and tranexamic acid to prevent postoperative blood loss in total knee arthroplasty: a randomized controlled clinical trial

BACKGROUND

Postoperative blood loss in patients after total knee arthroplasty may cause local and systemic complications and influence clinical outcome. The aim of this study was to assess whether fibrin glue or tranexamic acid reduced blood loss compared with routine hemostasis in patients undergoing total knee arthroplasty.

METHODS

A randomized, single-center, parallel, open clinical trial was performed in adult patients undergoing primary total knee arthroplasty. Patients were divided into four groups. Group 1 received fibrin glue manufactured by the Blood and Tissue Bank of Catalonia, Group 2 received Tissucol (fibrinogen and thrombin), Group 3 received intravenous tranexamic acid, and Group 4 (control) had no treatment other than routine hemostasis. The primary outcome was total blood loss collected in drains after surgery. Secondary outcomes were the calculated hidden blood loss, transfusion rate, preoperative and postoperative hemoglobin, number of blood units transfused, adverse events, and mortality.

RESULTS

One hundred and seventy-two patients were included. The mean total blood loss (and standard deviation) collected in drains was 553.9 ± 321.5 mL for Group 1, 567.8 ± 299.3 mL for Group 2, 244.1 ± 223.4 mL for Group 3, and 563.5 ± 269.7 mL for Group 4. In comparison with the control group, Group 3 had significantly lower total blood loss (p < 0.001), but it was not significantly lower in Groups 1 and 2. The overall rate of patients who had a blood transfusion was 21.1% (thirty-five of 166 patients analyzed per protocol). Two patients required transfusion in Group 3 compared with twelve patients in Group 4 (p = 0.015). No significant difference was observed between the two fibrin glue groups and the control group with regard to the need for transfusion. There was no difference between groups with regard to the percentage of adverse events.

CONCLUSIONS

Neither type of fibrin glue was more effective than routine hemostasis in reducing postoperative bleeding and transfusion requirements, and we no longer use them. However, this trial supports findings from previous studies showing that intravenous tranexamic acid can decrease postoperative blood loss.

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

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

Establishing reference values of spectral reflectance indices in transplants of Pseudoscleropodium purum for potential use in atmospheric biomonitoring

We studied the spatiotemporal variation of the photochemical reflectance index (PRI) and the chlorophyll content index (CHL index) in a terrestrial moss, using self-watering transplants distributed in 8 sampling sites that were sampled periodically during up to 4 years. We did not detect any seasonal patterns or difference between the studied sites, and therefore the variation across the sites reflected the influence of environmental variables in the area. We established the reference thresholds associated with physiological stress as -0.212 for PRI and 1.195 for CHL index. Our findings could be applied for biomonitoring atmospheric contamination on the basis of the physiological stress shown by the moss used.

On the use of epigaeic mosses to biomonitor atmospheric deposition of nitrogen

In this study, we investigated whether the terrestrial moss Pseudoscleropodium purum can be used to biomonitor atmospheric deposition of nitrogen (N). For this purpose, we first determined whether there are any interspecific differences in the concentrations of total N and δ(15)N between the two species of terrestrial moss most commonly used in biomonitoring studies, P. purum and Hypnum cupressiforme. Second, we determined the spatial distribution of N and δ(15)N at small and large scales: (1) by analysis of 165 samples from the surroundings of an aluminium smelter and (2) by analysis of 149 samples from sites forming part of a regular 15 × 15-km sampling network in Galicia (northwest Spain). We did not find any interspecific differences in either total N or δ(15)N. Analysis of δ(15)N enabled us to identify large-scale spatial patterns of distribution that were congruent with the location of the main N emission sources (unlike the analysis of total N). However, we did not identify any such patterns for the small-scale source of N emission studied. The results show that analysis of δ(15)N has an advantage compared with the analysis of total N in that it provides information about the source of N rather than about the amount of N received. Furthermore, isotope discrimination appears to occur, with the bryophytes preferentially accumulating the N(14) isotope. Although this amplifies the signal of reduced forms, it is not problematical for determining spatial-distribution patterns.

[The 2013 Seville Consensus Document on alternatives to allogenic blood transfusion. An update on the Seville Document]

Since allogeneic blood transfusion (ABT) is not harmless, multiple alternatives to ABT (AABT) have emerged, though there is great variability in their indications and appropriate use. This variability results from the interaction of a number of factors, including the specialty of the physician, knowledge and preferences, the degree of anemia, transfusion policy, and AABT availability. Since AABTs are not harmless and may not meet cost-effectiveness criteria, such variability is unacceptable. The Spanish Societies of Anesthesiology (SEDAR), Hematology and Hemotherapy (SEHH), Hospital Pharmacy (SEFH), Critical Care Medicine (SEMICYUC), Thrombosis and Hemostasis (SETH) and Blood Transfusion (SETS) have developed a Consensus Document for the proper use of AABTs. A panel of experts convened by these 6 Societies have conducted a systematic review of the medical literature and have developed the 2013 Seville Consensus Document on Alternatives to Allogeneic Blood Transfusion, which only considers those AABT aimed at decreasing the transfusion of packed red cells. AABTs are defined as any pharmacological or non-pharmacological measure aimed at decreasing the transfusion of red blood cell concentrates, while preserving patient safety. For each AABT, the main question formulated, positively or negatively, is: « Does this particular AABT reduce the transfusion rate or not?» All the recommendations on the use of AABTs were formulated according to the Grades of Recommendation Assessment, Development and Evaluation (GRADE) methodology.

[The 2013 Seville Consensus Document on alternatives to allogenic blood transfusion. An update on the Seville Document]

Since allogeneic blood transfusion (ABT) is not harmless, multiple alternatives to ABT (AABT) have emerged, though there is great variability in their indications and appropriate use. This variability results from the interaction of a number of factors, including the specialty of the physician, knowledge and preferences, the degree of anemia, transfusion policy, and AABT availability. Since AABTs are not harmless and may not meet cost-effectiveness criteria, such variability is unacceptable. The Spanish Societies of Anesthesiology (SEDAR), Hematology and Hemotherapy (SEHH), Hospital Pharmacy (SEFH), Critical Care Medicine (SEMICYUC), Thrombosis and Hemostasis (SETH) and Blood Transfusion (SETS) have developed a Consensus Document for the proper use of AABTs. A panel of experts convened by these 6 Societies have conducted a systematic review of the medical literature and have developed the 2013 Seville Consensus Document on Alternatives to Allogeneic Blood Transfusion, which only considers those AABT aimed at decreasing the transfusion of packed red cells. AABTs are defined as any pharmacological or non-pharmacological measure aimed at decreasing the transfusion of red blood cell concentrates, while preserving patient safety. For each AABT, the main question formulated, positively or negatively, is: "Does this particular AABT reduce the transfusion rate or not?" All the recommendations on the use of AABTs were formulated according to the Grades of Recommendation Assessment, Development and Evaluation (GRADE) methodology.

Moss bag biomonitoring: a methodological review

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

Phenolic compounds and sensorial characterization of wines aged with alternative to barrel products made of Spanish oak wood (Quercus pyrenaica Willd.)

Wood of Quercus pyrenaica has suitable properties for the wine ageing process. However, the forest available for the barrel making from this particular type of tree is very limited. Nevertheless, it is highly advisable to use this kind of wood in order to manufacture alternative oak products. This study presents the results of ageing the same red wine using different pieces of wood (chips and staves) of Spanish oak (Q. pyrenaica), American oak (Quercus alba) and French oak (Quercus petraea) in conjunction with small, controlled amounts of oxygen. In addition, the phenolic parameters, colour and sensory analysis point out that wines aged with Q. pyrenaica pieces have similar enological characteristics to those aged with American or French oak pieces of wood (chips and staves). Furthermore, the total oxygen consumed and its relation with sensory properties also has been studied in this article in order to know how the oxygen behaves in these processes. Besides, it is going to put forward the fact that chips and staves from Q. pyrenaica oak are suitable for the ageing of red wines and better considered than American or French ones, showing higher aromatic intensity, complexity, woody, balsamic and cocoa. Finally, the tasters valued highly the wines with staves, pointing out its flavour and roundness in mouth.

Use of raptors for biomonitoring of heavy metals: gender, age and tissue selection

The concentrations of cadmium, mercury and lead were determined in liver, kidney and feathers of Accipiter gentilis, Buteo buteo and Strix aluco. No significant differences in the concentrations of metals were observed in relation to either age or gender. Cadmium levels in feathers and in kidney were significantly correlated (p < 0.01 or p < 0.05) in all species. In B. buteo, cadmium concentrations in feathers and in liver were also correlated (p < 0.01), as were the concentrations of lead in feathers and in liver (p < 0.05). The low correlation coefficients let to reject the possibility of predicting metals concentrations in viscera from the concentrations in feathers.

Cellular location of K, Na, Cd and Zn in the moss Pseudoscleropodium purum in an extensive survey

The aim of the present study was to determine if use of the Sequential Elution Technique (SET) improves interpretation of data on the total concentrations of elements in the moss Pseudoscleropodium purum, obtained in a regional network, by providing information about the cellular location, bioavailability and temporal representativeness of different elements. In total, 147 sites located at the vertices of a 15×15 km network were sampled. The total, extra- and intracellular concentrations of K, Na, Cd and Zn were determined and the spatial structure was analysed by use of robust variograms. The percentage of intracellular K was high (85%) compared with that of the extracellular K (15%), whereas those of the extra and intracellular Na and Cd were similar, both close to 50%. Zinc comprised a higher percentage of extracellular metal (61%). Spatial structure was clearly observed in both the total and intracellular concentrations of Na and in the total and extracellular concentrations of Zn. These results demonstrated that use of the SET improves interpretation of the total concentrations of elements, with differences between the elements that are metabolically regulated and those that possibly are not. Despite problems regarding particles deposited on the moss surface, the extracellular concentration of elements may provide information about the potential risks associated with possible solubilization of these particles and their posterior absorption. However, the intracellular concentration, which is not influenced by the presence of particles on the moss surface, provides more realistic toxicological information, as it may be related to metabolic processes in the moss. We therefore recommend prioritizing the use of the intracellular fraction when using mosses in environmental monitoring networks.

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.