Next Article in Journal
Unravelling the Concentrations of Five Rare Earth Elements in Two Vineyard Red Soils
Next Article in Special Issue
Metal Ions, Element Speciation Forms Retained on Wet Chitin: Quantitative Aspects of Adsorption and Implications for Biomonitoring and Environmental Technology
Previous Article in Journal / Special Issue
Accumulation of Atmospheric Metals and Nitrogen Deposition in Mosses: Temporal Development between 1990 and 2020, Comparison with Emission Data and Tree Canopy Drip Effects
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Pollutants
Volume 3
Issue 1
10.3390/pollutants3010009
pollutants-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Influence of Precipitation on the Spatial Distribution of 210Pb, 7Be, 40K and 137Cs in Moss

by
Kayla Wilkins
1,
Hazel Cathcart
1,
Padraig Hickey
2,
Olwyn Hanley
2,
Luis León Vintró
3 and
Julian Aherne
1,*
1
School of Environment, Trent University, Peterborough, ON K9L 0G2, Canada
2
Office of Radiation Protection and Environmental Monitoring, Environmental Protection Agency, D14 YR62 Dublin, Ireland
3
UCD School of Physics, University College Dublin, D04 N2E5 Dublin, Ireland
*
Author to whom correspondence should be addressed.
Pollutants 2023, 3(1), 102-113; https://doi.org/10.3390/pollutants3010009
Submission received: 31 December 2022 / Revised: 1 February 2023 / Accepted: 1 February 2023 / Published: 6 February 2023
(This article belongs to the Special Issue Surveys and Case Studies in Biomonitoring of Atmospheric Pollution)
Browse Figures
Versions Notes

Abstract

:
Mosses have been widely used as biomonitors of a variety of atmospheric pollutants, including radionuclides. Here we determine the radionuclide activity concentration of 210Pb, 137Cs, 7Be, and 40K in moss tissue (Hylocomium splendens) collected from 24 sites across Ireland and assess the influence of precipitation on radionuclide spatial distribution. Lead-210 was the most abundant radionuclide (range: 226–968 Bq kg–1), followed by 7Be (range: <DL—604 Bq kg–1), 40K (range: <DL—155 Bq kg–1), and 137Cs (range: <DL—41 Bq kg–1). Albeit nearly thirty years since the Chernobyl disaster, 137Cs activity concentration was detected at 67% of the study sites; however, the spatial distribution was not fully consistent with the 1986 Chernobyl deposition pattern. Rather, 137Cs was weakly correlated with rainfall, with higher concentrations along the west coast, suggesting that the 2011 Fukushima Dai-ichi nuclear accident was also a potential source. Average annual rainfall was a significant predictor of 210Pb activity (linear regression, R2 = 0.63, p < 0.001). As such, the highest radionuclide activity was observed for 210Pb (average: 541 Bq kg–1), owing to the high levels of precipitation across the study sites (average: 1585 mm). In contrast, 7Be or 40K were not correlated with precipitation; rather, 40K and 7Be were significantly correlated to each other (rs = 0.7), suggesting that both radionuclides were transferred from the substrate or through soil re-suspension. Precipitation is widely reported as an important factor in the spatial distribution of radionuclides; however, only 210Pb activity concentrations in moss were strongly influenced by precipitation in the current study.

1. Introduction

Mosses are widely used as biomonitors of atmospheric deposition because they are broadly distributed (essentially found everywhere), relatively easy to sample, and have a high capacity to trap and accumulate atmospheric particles [1,2,3,4]. Moss biomonitoring has been widely used to assess the atmospheric deposition of nitrogen [5,6,7,8,9], trace elements [10,11,12,13], persistent organic pollutants [14,15,16,17], microplastics [18,19], and radionuclides [20,21,22]. Numerous studies have shown that radionuclides accumulate in mosses [23,24,25], making them effective biomonitors for detecting radionuclides that occur in trace atmospheric concentrations.
Since the first nuclear weapons test in 1945, there has been considerable interest in monitoring radionuclides in the atmosphere and their fallout in the environment [26]. Radionuclides are monitored to assess potential human health risks (e.g., the European Commission’s Radioactivity Environmental Monitoring program (URL: rem.jrc.ec.europa.eu accessed on 1 December 2022); the Irish Environmental Protection Agency’s radiation monitoring program (URL: www.epa.ie/radiation accessed on 1 December 2022)), quantify atmospheric processes [27,28], predict geological processes, such as erosion [29,30] or sedimentation rates [31], and to gain insight into the paths and processes by which they are transported through the environment [32,33,34]. Radionuclide activity in moss has been widely reported; nonetheless, studies would benefit from a biomonitoring program to coordinate these efforts similar to heavy metals (i.e., the International Cooperative Programme (ICP) on Vegetation (URL: icpvegetation.ceh.ac.uk accessed on 1 December 2022)).
Radionuclides predominantly come from natural sources, of either cosmic (e.g., beryllium-7 [7Be]; [35]) or terrestrial (e.g., lead-210 [10Pb]; potassium-40 [40K]) origin. The radionuclide 7Be (half-life 53.3 days) is produced by cosmic rays in the lower stratosphere and upper troposphere, where it is adsorbed by particles and ultimately removed from the atmosphere by wet and dry deposition [36,37]. While 210Pb (half-life 22.3 y) is a progeny of 222Rn in the 238U decay series in soils, a fraction of 222Rn escapes to the atmosphere where it decays to 210Pb, is adsorbed by particles, and is removed by wet and dry deposition [38]. In contrast, the long-living radionuclide 40K is found in soil and is only detectable in the atmosphere if soil particles are suspended. Radionuclides also have anthropogenic sources, including medical testing and treatments, nuclear energy plant waste (e.g., Sellafield nuclear power plant waste discharges into the Irish Sea; [39]), nuclear weapons tests (>2000 since 1945), and nuclear power plant accidents. The 1986 Chernobyl and 2011 Fukushima Dai-ichi nuclear power plant accidents widely released caesium-137 (137Cs, half-life 30.1 y) into the environment (e.g., 0.085 EBq (exabecquerels) of 137Cs were released from Chernobyl). Furthermore, commercial processes that use peat have the potential to reintroduce previously deposited (legacy) radionuclides back into the atmosphere [40,41], as is the case with the burning of biomass [23,42]. In Ireland, most of the radiation exposure comes from natural sources, with 55% in the form of radon accumulation in homes. Only 14% of radiation exposure comes from anthropogenic sources, mainly through radiation in medical diagnostics [43]. Nonetheless, radiocaesium was widely dispersed in the Irish environment following the Chernobyl disaster in May 1986, with a mean 137Cs atmospheric deposition level of 3.2 kBq m–2 [44]. Climate (notably rainfall) has been highlighted as an important factor in the dispersion and atmospheric deposition of radionuclides [37,45,46,47].
The objective of this study was to determine the spatial distribution of 210Pb, 137Cs, 7Be and 40K radionuclide activity concentrations in moss (Hylocomium splendens (Hedw.) B.S.G.) across Ireland and its relationship to precipitation. All the samples for radionuclide analysis (n = 24) were collected under the 2015 ICP Vegetation moss biomonitoring survey [48,49]. We predicted that 210Pb and 7Be would be highly spatially variable and correlated with annual rainfall following the results of previous studies [50,51,52]. In contrast, we predicted that 137Cs and 40K would be less spatially variable and not correlated with annual rainfall, given that potassium and caesium in living moss tissue can be transferred from the substrate on which it grows (e.g., soil) or by lateral transfer between annual growth segments [26]. Radiocesium concentrations have been measured in Sphagnum mosses from Irish blanket bogs [53], but this is the first study to report radionuclide concentrations in H. splendens in Ireland.

2. Materials and Methods

2.1. Study Area and Sampling Procedures

Ireland is situated on the northwest periphery of continental Europe; as such, its climate is greatly influenced by the Atlantic Ocean. The prevailing Atlantic winds provide a constant source of relatively ‘clean’ air, as well as marine inputs (e.g., sea salts). The average annual temperatures are moderate, with typically only one day or less below freezing during the winter, and rarely rising above 20 °C during the summer [54]. The average annual precipitation is high, typically consisting of light, but frequent, rainfall. There is generally more rainfall in the west (1000–1400 mm yr−1) than the east (750–1000 mm yr−1).
During the summer of 2015 (25 May–10 June and 28 July–5 August), H. splendens (Hedw.) B.S.G. (see Supplementary Materials Figure S1) moss was collected across Ireland to assess the deposition of trace elements (at 112 sampling locations; for further details on trace elements, see [48]); where the sample mass permitted (>10 g), moss tissue was also analysed for radionuclides. The subset of samples analysed for radionuclides was predominantly from the west of Ireland, with a few from the central and eastern regions (n = 24, Figure 1). These moss samples were primarily collected from natural grasslands and heathlands, where the dominant land use was rough grazing, and site elevation ranged from 2 to 265 m above sea level (mean = 121 m). The long-term annual average rainfall across the study sites (n = 24) ranged from 979 to 2780 mm (mean = 1585 mm) and the air temperature from 7.9 to 10.5 °C (mean = 9.4 °C [54]). In general, the spatial coverage mirrored that of the wider trace element survey [9,48].
At each sampling location, green moss shoots (representing the last 2 to 3 years of growth; see Supplementary Materials Figure S1) were collected from within an area roughly 50 m × 50 m following the ICP Vegetation survey protocols [55]. All samples were collected by hand (wearing nitrile gloves) and composited into paper bags. Every effort was made to gather samples at least 3 m from any tree canopy, 300 m from main roads, and 100 m from smaller roads and houses.

2.2. Laboratory Analysis

Moss samples were air-dried at room temperature and any debris or dead material was removed by hand. The samples were then oven-dried at 40 °C to a constant weight and packed into a G100 geometry (cylindrical polypropylene tub filled to 100 mL); the moss sample masses ranged from 10 to 25 g. Radionuclide activity in each sample was counted in a GMX-15190 n-type coaxial HPGe detector, shielded by 50 mm of lead. Sufficient counting statistics for moss samples requires relatively long measurement periods when using a HPGe detector [36], which limits the number of study sites. Efficiency of the G100 geometry was determined using NPL’s mixed radionuclide standard (A150897). Radionuclide activity concentration (Bq kg–1) was determined for 210Pb, 7Be, 40K and 137Cs; uncertainty was defined as one standard deviation (see Supplementary Materials Table S1). The measured activity concentrations were corrected for dry weight, and 210Pb was also corrected for self-attenuation following [56]. Radionuclide analysis was completed within one year of fresh sample collection.

2.3. Climate Datasets and Statistical Analysis

Long-term (1981–2010) annual precipitation (Figure 1) and temperature data were obtained from [57]. The distribution of the activity concentration data for each radionuclide was evaluated using the Shapiro–Wilk test for normality. The associations between individual radionuclide activity concentrations in moss, and radionuclide activity concentration and climate (precipitation and temperature) were assessed using Spearman’s (non-parametric) rank-order correlation coefficient (rs). Simple linear regression (with variable transformation where needed) was used to determine whether the observed trends were significant (p < 0.05). The relationship between climate (and geographic location) and activity concentration for each radionuclide was further explored using multiple linear regression. The spatial variability (%) in activity concentration for each radionuclide across the study sites was estimated using normalized median absolute deviation (NMAD, see Supplementary Materials Equation S1). Lastly, to explore the spatial autocorrelation of radionuclide activity concentration, semivariograms were modelled for each element using the ‘gstat’ R package [58].
The radionuclide activity concentrations for 7Be, 40K, and 137Cs contained left-censored data, i.e., multiple data points were below the detection limit (<DL, 0.01 Bq kg–1). Data imputation was carried out using the ‘NADA’ (non-detects and data analysis for environmental data) R package [59], which estimates the distribution of values below the censor limit based on the distribution of values above the censor limit. Boxplots were used to display the data distribution of each radionuclide, with values < DL estimated through the NADA package. Lognormal transformation of the radionuclide activity concentrations provided a more normal distribution. All statistical analyses were carried out in R 3.3.2 [60].
In general, it is difficult to directly compare radionuclide activity concentrations to published studies, as very few have used H. splendens moss. Furthermore, inconsistent methods between surveys can lead to uncertainties [61]; while the ICP Vegetation protocols are widely used and offer consistency, few studies have carried out radionuclide monitoring. In addition, comparison between studies is complicated by confounding factors. It is well established that potassium in moss tissue is either transferred from the substrate (e.g., soil) or by lateral transfer between annual growth segments [26]; therefore, the moss substrate can influence tissue activity concentrations. Furthermore, potassium has an essential physiological function in moss; therefore, 40K activity concentrations vary throughout the growing season [62]. Radiocaesium activity concentrations in moss reflect residual fallout (deposition) from weapons testing and accidental discharges from nuclear facilities, such as the 1986 Chernobyl accident. Therefore, the distribution of 137Cs in moss is related to precipitation (washout), meteorology [63], geographical location (e.g., distance from Chernobyl), and time since accidental release into the environment. Furthermore, caesium enters moss tissue via the potassium transport system; therefore, 137Cs in the environment is expected to follow 40K to a large extent [20]. This soil-to-plant transfer may influence the interpretation (and comparison) of measured 137Cs data in mosses [26]. Given the challenges and limitations of inter-study comparison, we cautiously compare our results to published studies, where possible noting the disparate influences of precipitation on the spatial distribution of radionuclide concentrations in moss.

3. Results and Discussion

The radionuclide activity concentrations in moss tissue ranged from <DL to 968.04 Bq kg–1 (fresh weight), with the highest values observed for 210Pb (Table 1 and Figure 2). Only 210Pb activity was above the detection limit at all sites (see Supplementary Materials Table S1); the average 210Pb activity was 541.5 Bq kg–1 and the median activity was 490.0 Bq kg–1 (Table 1). In contrast, 7Be was not detected at >50% of the study sites, likely owing to its short half-life (53.3 days), and the extended period between sample collection and analysis of moss tissue [36]. The observed activity of 7Be (n = 8) ranged from 283.1 to 604.4 Bq kg–1 (mean = 420.7 Bq kg–1, median = 376.2 Bq kg–1). Potassium-40 was detected at 75% of the study sites (n = 18) and ranged from 57.2 to 155.4 Bq kg–1 (mean = 96.5 Bq kg–1, median = 90.5 Bq kg–1). Both 40K and 7Be activity concentration data were normally distributed with low spatial variation across the study sites (17 and 22%, respectively; Table 1), potentially suggesting a common source. Furthermore, 40K and 7Be were significantly correlated (rs = 0.7; see Supplementary Materials Figure S2), suggesting that both radionuclides were transferred from the substrate or through soil re-suspension. If 7Be in moss was derived from atmospheric particle deposition, then 7Be and 40K would not be correlated [64]. Furthermore, 7Be was negatively correlated to rainfall across the study sites (rs = −0.45).
Few studies have reported 7Be or 40K in moss, and fewer for H. splendens. The observed activity of 7Be (n = 8) was similar to values reported for Serbia (mean = 360 Bq kg–1 [64], mean =314 Bq kg–1 [65], mean = 251 Bq kg–1 [36]) and Thailand (mean = 226 Bq kg–1 [65]). Despite differences in sampling locations, their activity concentrations were similar because 7Be is cosmically sourced; as such, its spatial distribution is less affected by processes and events near the earth’s surface. Nonetheless, 7Be activity concentrations have also been shown to vary by seasons [66]. The observed 40K activities (n = 18) were somewhat lower than the observations reported for Serbia [24,36,67], but direct comparisons are difficult due to differences in the substrate, sampling period, and moss species. As noted, 40K activity levels in vegetation vary throughout the growing season [62], and 40K activity concentration in Irish soil has been associated with granite bedrock [68].
The activity concentrations of 210Pb (225.5−968.0 Bq kg–1) were comparable to those reported for H. splendens (218−913 Bq kg–1) and Pleurozium schreberi (295−1152 Bq kg–1) from five upland lake catchments in the United Kingdom [69]. In concert with the current study, the catchments were in areas of acid-sensitive geology and elevated rainfall [69]. Similar ranges have been reported in other moss species [25,70]. However, it should be noted that 210Pb activity between moss species sampled at the same sites can be quite different, in part due to the different physical characteristics of the species [71]. The spatial variability between study sites was the highest for 210Pb activity concentrations (NMAD = 35%), suggesting high spatial variation in the radionuclide sources; as predicted, the 210Pb activity concentration was strongly correlated with rainfall (rs = 0.8). Furthermore, the comparison of radionuclide activity with rainfall and temperature indicated a significant positive linear relationship (r2 = 0.63, p < 0.001) between rainfall and 210Pb activity concentration only (Figure 3). Nonetheless, rainfall and temperature were the strongest predictors in multiple linear regression (r2= 0.76, see Supplementary Materials Figure S3), but were only marginally stronger compared with rainfall alone. This suggests that the sites with high 210Pb activity were primarily the result of higher rainfall volumes. Several studies have reported a positive correlation between precipitation and the atmospheric deposition of radionuclides [47,72,73]; similarly, a decrease in radionuclides in the air has been associated with precipitation [72,74], attributed to ‘wash out’. In the United Kingdom, ratios of 210Pb to Pb in mosses (226–829 Bq mg–1), soils, and sediments in upland catchments were used to identify sources [69]; the results suggested that the bulk of Pb in moss tissue came from atmospheric deposition, rather than soil re-suspension. Similar ratios of 210Pb to Pb (155–2518 Bq mg–1) were found in moss tissues in this study (Supplementary Materials, Table S2), suggesting that the impact of soil re-suspension was negligible, and the 210Pb activity concentration was dominated by atmospheric deposition.
The observed 137Cs activities (n = 16) ranged from 3.1 to 41.4 Bq kg–1 (mean = 14.0 Bq kg–1, median = 10.4 Bq kg–1; NMAD = 31%). While some studies offer direct species comparison, observed activity concentrations are influenced by location and time, i.e., distance from, and time since, the Chernobyl disaster. The measured 137Cs activities in H. splendens tissue in Italy [75] ranged from 38 to 271 Bq kg−1 (mean 121 Bq kg−1), an order of magnitude higher given the temporal difference (10+ years) with this study. Similarly, the 137Cs activities in this study were comparatively low when compared with earlier studies that used various moss species in regions closer to Chernobyl (Belarus and Slovakia [20]; Syrian coastal mountains [76]; Serbia [24]). Nonetheless, the 137Cs activity observed in moss in this study was still related to the Chernobyl accident, given that 137Cs is prone to lateral transfer [20,26,63]. The 137Cs activity in moss sampled during 2007 in Belarus reflected the geographic distribution from the 1986 Chernobyl accident [20], suggesting that the measured activity concentrations were not from the recent deposition of 137Cs, but rather due to the continuous transfer of 137Cs from soil or from older to younger annual moss segments. However, in the current study, the spatial distribution of 137Cs in moss was not fully consistent with the 1986 deposition pattern [44]. Rather, 137Cs was weakly correlated with rainfall (rs = 0.2) with higher activity concentrations along the west coast (Figure 1), suggesting that the 137Cs activity concentrations in the 2015 moss samples were also influenced by recent deposition, potentially related to the 2011 nuclear accident at the Fukushima Dai-ichi power plant in Japan. While regional differences in 137Cs activity concentrations across Ireland were not observed following Fukushima, owing to the significant diffusion of the radioactive plume [77], simulations suggest that cumulated concentrations exceeding 30 mBq d m–3 could have occurred in western Ireland [78]. This is consistent with the higher 137Cs activities observed in moss tissue along the west coast (three of the highest activity concentrations: 21.2, 26.5, and 41.4 Bq kg–1), which may reflect the resuspension of material originally deposited to the Atlantic Ocean, as 137Cs from Fukushima was deposited mostly in the Pacific and Atlantic Oceans [79].
In Norway, a strong correlation between 137Cs concentration in H. splendens versus deposition rate (correlation coefficient 0.75, p < 0.01) was observed immediately following the 1986 Chernobyl nuclear accident, with a ratio of 1.2 ± 0.5 (s.d.) between deposition rate in kBq m–2 and biomonitor (moss) activity in kBq kg–1 [22]. During 2011 (after the Fukushima incident in March), the cumulative deposition of 137Cs in Ireland was estimated at 10–50 Bq m–2 [79]; applying the ratio from [22], the expected H. splendens tissue concentration after 2011 can be roughly estimated at 8–42 Bq kg–1, which is similar to the observed range in this study (Table 1). While it can be assumed that the majority of the radionuclide deposition from the Fukushima accident to Ireland occurred shortly after the incident (e.g., deposition from the Chernobyl accident occurred in the first 48 h from the time the plume was first detected; [46]), the observed concentration of 137Cs in green moss tissue generally represents an average of 2 to 3 years of deposition, which is further confounded by the lateral transfer between annual growth segments.
In southern Poland [52], a multiple regression model was used to demonstrate that the deposition of 7Be was dependent on the amount of precipitation, but the relationship did not hold true for terrestrial nuclides (210Pb, 137Cs, 40K). In contrast, in Serbia, there was no correlation between the precipitation amount or duration and 7Be sampled over time [66]. When 210Pb and 7Be activity in mosses was considered as a cumulative measure of deposition and decay, then a strong relationship with precipitation became apparent [80]. We did not observe any correlation between rainfall amount and 7Be or 40K. While 137Cs deposition was associated with rainfall immediately following the Chernobyl accident [44,45,46], in the current study, 137Cs activity in moss tissue and long-term rainfall averages were only very weakly (positively) correlated. Nonetheless, 137Cs activity in moss tissue was spatially autocorrelated, as indicated by semivariogram modelling (Figure S4); in contrast, 210Pb and 40K showed weak or no indication of a spatial autocorrelation. The spatial clustering of 137Cs and the general occurrence of higher activity near the southwest coastlines (Figure 1) suggests a relationship with rainfall. The spatial clustering of 137Cs following Chernobyl was previously identified [46], and when clustering was taken into consideration, a much stronger relationship between daily cumulative rainfall and 137Cs deposition (r = 0.9) was observed in some regions.

4. Conclusions

It is well established that mosses (e.g., Hylocomium splendens (Hedw.) B.S.G.) are effective biomonitors of radionuclide activity concentration. Here we found that the 210Pb activity concentrations had the highest spatial variation across all study sites, and that almost 30 years since the Chernobyl nuclear disaster, 137Cs activity was detected at 67% of the study sites. Higher 137Cs activity was associated with higher precipitation regions along the southwestern Atlantic coastline, suggesting that the 2011 Fukushima Dai-ichi nuclear accident was also a potential source. Precipitation volume was a significant predictor of 210Pb activity concentration in moss (with 210Pb observed at all study sites). As such, the highest radionuclide activity was observed for 210Pb, owing to the high levels of precipitation. In contrast, 7Be or 40K were not correlated with precipitation; rather, 40K and 7Be were significantly correlated (rs = 0.7) with each other, suggesting that both radionuclides were transferred from the substrate or through soil re-suspension. Precipitation is widely reported as an important factor in the dispersion and deposition of radionuclides; however, only the 210Pb activity concentrations in moss were strongly influenced by precipitation in the current study.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/pollutants3010009/s1, Table S1: Site ID, 210Pb, 137Cs, 7Be and 40K activity concentration (Bq kg–1 dry weight) in moss (Hylocomium splendens (Hedw.) B.S.G.) tissue (n = 24), Table S2: Site ID, location (easting and northing in Irish Grid (m)), elevation (E), precipitation (P), temperature (T), lead-210 (210Pb) activity concentrations and lead (Pb) concentrations in moss tissue, Equation S1: Normalized median absolute deviation (NMAD), Figure S1: Photograph of Hylocomium splendens (Hedw.) B.S.G. tissue showing a ‘stair-step’ shape, which is indicative of annual biomass growth. The green shoots are sampled and typically represent the last 2 to 3 years of growth. [Photo credit: Phaedra Cowden], Figure S2: The 40K activity concentration (Bq kg–1) versus 7Be activity concentration (Bq kg–1) in Hylocomium splendens (Hedw.) B.S.G. across the study sites in Ireland, Figure S3: Predicted against observed (measured) radionuclide activity concentration (Bq kg–1) for 210Pb and 7Be, Figure S4: Semivariogram for 137Cs activity concentration (Bq kg–1) in Hylocomium splendens (Hedw.) B.S.G. across the study sites.

Author Contributions

Conceptualization, K.W., H.C. and J.A.; methodology, P.H., L.L.V. and O.H.; formal analysis, P.H., L.L.V. and O.H.; investigation, K.W., H.C. and J.A.; writing—original draft preparation, K.W., H.C. and J.A.; writing—review and editing, P.H., L.L.V. and O.H.; funding acquisition, J.A. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Irish Environmental Protection Agency under the Climate Change Research Programme (CCRP), grant numbers 2012-CCRP-MS.7 and 2016-CCRP-MS.43.

Data Availability Statement

The data used in this study are provided in the Supplementary Materials.

Acknowledgments

We gratefully appreciate the support of David Dodd (Irish Environmental Protection Agency) for this study. Moreover, we gratefully acknowledge the contribution of Phaedra Cowden, Emily Olmstead, Tanner Liang, and Kevin Adkinson (Trent University) during the field surveys.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Berg, T.; Royset, O.; Steinnes, E. Moss (Hylocomium splendens) used as biomonitor of atmospheric trace-element deposition—Estimation of uptake efficiencies. Atmos. Environ. 1995, 29, 353–360. [Google Scholar] [CrossRef]
  2. Markert, B.; Wappelhorst, O.; Weckert, V.; Herpin, U.; Siewers, U.; Friese, K.; Breulmann, G. The use of bioindicators for monitoring the heavy-metal status of the environment. J. Radioanal. Nucl. Chem. 1999, 240, 425–429. [Google Scholar] [CrossRef]
  3. Rühling, A. A European survey of atmospheric heavy metal deposition in 2000–2001. Environ. Pollut. 2002, 120, 23–25. [Google Scholar] [CrossRef] [PubMed]
  4. Smodiš, B.; Pignata, M.L.; Saiki, M.; Cortés, E.; Bangfa, N.; Markert, B.; Nyarko, B.; Arunachalam, J.; Garty, J.; Vutchkov, M.; et al. Validation and Application of Plants as Biomonitors of Trace Element Atmospheric Pollution—A Co-Ordinated Effort in 14 Countries. J. Atmos. Chem. 2004, 49, 3–13. [Google Scholar] [CrossRef]
  5. Bassingthwaight, T.; Shaw, P.D. Measuring nitrogen and sulphur deposition in the Georgia Basin, British Columbia, using lichens and moss. J. Limnol. 2010, 69, 22–32. [Google Scholar]
  6. Harmens, H.; Norris, D.A.; Cooper, D.M.; Mills, G.; Steinnes, E.; Kubin, E.; Thöni, L.; Aboal, J.; Alber, R.; Carballeira, A.; et al. Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe. Environ. Pollut. 2011, 159, 2852–2860. [Google Scholar] [CrossRef]
  7. Špirič, Z.; Stafilov, T.; Vuckovic, I.; Glad, M. Study of nitrogen pollution in Croatia by moss biomonitoring and Kjeldahl method. J. Environ. Sci. Health 2014, 49, 1402–1408. [Google Scholar] [CrossRef]
  8. Wilkins, K.; Aherne, J. Isothecium Myosuroides and Thuidium Tamariscinum Mosses as Bioindicators of Nitrogen and Heavy Metal Deposition in Atlantic Oak Woodlands. Ann. Di Bot. 2015, 5, 71–78. [Google Scholar] [CrossRef]
  9. Olmstead, E.; Aherne, J. Are tissue concentrations of Hylocomium splendens a good predictor of nitrogen deposition? Atmos. Pollut. Res. 2019, 10, 80–87. [Google Scholar] [CrossRef]
  10. Berg, T.; Steinnes, E. Recent trends in atmospheric deposition of trace elements in Norway as evident from the 1995 moss survey. Sci. Total Environ. 1997, 208, 197–206. [Google Scholar] [CrossRef]
  11. Harmens, H.; Norris, D.A.; Sharps, K.; Mills, G.; Alber, R.; Aleksiayenak, Y.; Blum, O.; Cucu-Man, S.M.; Dam, M.; De Temmerman, L.; et al. Heavy metal and nitrogen concentrations in mosses are declining across Europe whilst some “hotspots” remain in 2010. Environ. Pollut. 2015, 200, 93–104. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  12. Cowden, P.; Aherne, J. Assessment of atmospheric metal deposition by moss biomonitoring in a region under the influence of a long standing active aluminium smelter. Atmos. Environ. 2019, 201, 84–91. [Google Scholar] [CrossRef]
  13. Kapusta, P.; Szarek-Łukaszewska, G.; Godzik, B. Present and Past Deposition of Heavy Metals in Poland as Determined by Moss Monitoring. Pol. J. Environ. Stud. 2014, 23, 2047–2053. [Google Scholar] [CrossRef] [PubMed]
  14. Cabrerizo, A.; Tejedo, P.; Dachs, J.; Benayas, J. Anthropogenic and biogenic hydrocarbons in soils and vegetation from the South Shetland Islands (Antarctica). Sci. Total Environ. 2016, 569–570, 1500–1509. [Google Scholar] [CrossRef] [PubMed]
  15. DoŁęgowska, S.; Migaszewski, Z.M. PAH concentrations in the moss species Hylocomium splendens (Hedw.) B.S.G. and Pleurozium schreberi (Brid.) Mitt. from the Kielce area (south-central Poland). Ecotoxicol. Environ. Saf. 2011, 74, 1636–1644. [Google Scholar] [CrossRef] [PubMed]
  16. Harmens, H.; Foan, L.; Simon, V.; Mills, G. Terrestrial mosses as biomonitors of atmospheric POPs pollution: A review. Environ. Pollut. 2013, 173, 245–254. [Google Scholar] [CrossRef]
  17. Holoubek, I.; Kořínek, P.; Šeda, Z.; Schneiderová, E.; Holoubková, I.; Pacl, A.; Tříska, J.; Cudlín, P.; Čáslavský, J. The use of mosses and pine needles to detect persistent organic pollutants at local and regional scales. Environ. Pollut. 2000, 109, 283–292. [Google Scholar] [CrossRef]
  18. Roblin, B.; Aherne, J. Moss as a biomonitor for the atmospheric deposition of anthropogenic microfibres. Sci. Total Environ. 2020, 715, 136973. [Google Scholar] [CrossRef]
  19. Bertrim, C.; Aherne, J. Moss Bags as Biomonitors of Atmospheric Microplastic Deposition in Urban Environments. Biology 2023, 12, 149. [Google Scholar] [CrossRef]
  20. Aleksiayenak, Y.V.; Frontasyeva, M.V.; Florek, M.; Sykora, I.; Holy, K.; Masarik, J.; Brestakova, L.; Jeskovsky, M.; Steinnes, E.; Faanhof, A.; et al. Distributions of 137Cs and 210Pb in moss collected from Belarus and Slovakia. J. Environ. Radioact. 2013, 117, 19–24. [Google Scholar] [CrossRef]
  21. Boryło, A.; Romańczyk, G.; Skwarzec, B. Lichens and mosses as polonium and uranium biomonitors on Sobieszewo Island. J. Radioanal. Nucl. Chem. 2017, 311, 859–869. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  22. Steinnes, E.; Njfistad, O. Use of Mosses and Lichens for Regional Mapping of 137Cs Fallout from the Chernobyl Accident. J. Environ. Radioact. 1993, 21, 65–73. [Google Scholar] [CrossRef]
  23. Paliouris, G.; Taylor, H.W.; Wein, R.W.; Svoboda, J.; Mierzynski, B. Fire as an agent in redistributing fallout 137Cs in the Canadian boreal forest. Sci. Total Environ. 1995, 160–161, 153–166. [Google Scholar] [CrossRef]
  24. Mitrović, B.; Ajtić, J.; Lazić, M.; Andrić, V.; Krstić, N.; Vranješ, B.; Vićentijević, M. Natural and anthropogenic radioactivity in the environment of Kopaonik mountain, Serbia. Environ. Pollut. 2016, 215, 273–279. [Google Scholar] [CrossRef]
  25. Belivermiş, M.; Kılıç, Ö.; Çayir, A.; Coşkun, M.; Coşkun, M. Assessment of 210Po and 210Pb in lichen, moss and soil around Çan coal-fired power plant, Turkey. J. Radioanal. Nucl. Chem. 2016, 307, 523–531. [Google Scholar] [CrossRef]
  26. Steinnes, E. Passive moss biomonitoring: Atmospheric deposition of radionuclides—Methodological aspects and practical limitations. In Biomonitoring of Air Pollution Using Mosses and Lichens: A Passive and Active Approach—State of the Art Research and Perspectives; Uroševic, M.A., Vukovic, G., Tomaševic, M., Eds.; Nova Science Publishers, Inc.: New York, NY, USA, 2016; p. 246. [Google Scholar]
  27. Baskaran, M. Po-210 and Pb-210 as atmospheric tracers and global atmospheric Pb-210 fallout: A Review. J. Environ. Radioact. 2011, 102, 500–513. [Google Scholar] [CrossRef]
  28. Sykora, I.; Froehlich, K. Radionuclides as Tracers of Atmospheric Processes. Radioact. Environ. 2009, 16, 51–88. [Google Scholar] [CrossRef]
  29. Du, P.; Walling, D.E. Using 137Cs measurements to investigate the influence of erosion and soil redistribution on soil properties. Appl. Radiat. Isot. 2011, 69, 717–726. [Google Scholar] [CrossRef]
  30. Tiessen, K.H.D.; Li, S.; Lobb, D.A.; Mehuys, G.R.; Rees, H.W.; Chow, T.L. Using repeated measurements of 137Cs and modelling to identify spatial patterns of tillage and water erosion within potato production in Atlantic Canada. Geoderma 2009, 153, 104–118. [Google Scholar] [CrossRef]
  31. Alonso-Hernandez, C.M.; Diaz-Asencio, M.; Munoz-Caravaca, A.; Delfanti, R.; Papucci, C.; Ferretti, O.; Crovato, C. Recent changes in sedimentation regime in Cienfuegos Bay, Cuba, as inferred from 210Pb and 137Cs vertical profiles. Cont. Shelf Res. 2006, 26, 153–167. [Google Scholar] [CrossRef]
  32. Ehlken, S.; Kirchner, G. Seasonal variations in soil-to-grass transfer of fallout strontium and cesium and of potassium in North German soils. J. Environ. Radioact. 1996, 33, 147–181. [Google Scholar] [CrossRef]
  33. Koarashi, J.; Atarashi-Andoh, M.; Amano, H.; Matsunaga, T. Vertical distributions of global fallout 137Cs and 14C in a Japanese forest soil profile and their implications for the fate and migration processes of Fukushima-derived 137Cs. J. Radioanal. Nucl. Chem. 2017, 311, 473–481. [Google Scholar] [CrossRef]
  34. Zhiyanski, M.; Sokolovska, M.; Bech, J.; Clouvas, A.; Penev, I.; Badulin, V. Cesium-137 contamination of oak (Quercus petrae Liebl.) from sub-mediterranean zone in South Bulgaria. J. Environ. Radioact. 2010, 101, 864–868. [Google Scholar] [CrossRef]
  35. Lal, D.; Malhotra, P.K.; Peters, B. On the production of radioisotopes in the atmosphere by cosmic radiation and their application to meteorology. J. Atmos. Terr. Phys. 1958, 12, 306–328. [Google Scholar] [CrossRef]
  36. Krmar, M.; Radnović, D.; Hansman, J.; Mesaroš, M.; Betsou, C.; Jakšić, T.; Vasić, P. Spatial distribution of 7Be and 137Cs measured with the use of biomonitors. J. Radioanal. Nucl. Chem. 2018, 318, 1845–1854. [Google Scholar] [CrossRef]
  37. Pham, M.K.; Povinec, P.P.; Nies, H.; Betti, M. Dry and wet deposition of 7Be, 210Pb and 137Cs in Monaco air during 1998–2010: Seasonal variations of deposition fluxes. J. Environ. Radioact. 2013, 120, 45–57. [Google Scholar] [CrossRef]
  38. Yang, H.; Appleby, P.G. Use of lead-210 as a novel tracer for lead (Pb) sources in plants. Sci. Rep. 2016, 6, 21707. [Google Scholar] [CrossRef]
  39. Sumerling, T.J. The use of mosses as indicators of airborne radionuclides near a major nuclear installation. Sci. Total Environ. 1984, 35, 251–265. [Google Scholar] [CrossRef]
  40. Ehdwall, H.; Holmberg, B.-T.; Farzar, K. Radiological and legal aspects of energy production by burning peat. Sci. Total Environ. 1985, 45, 69–75. [Google Scholar] [CrossRef]
  41. Sheppard, S.C.; Gibb, C.L.; Hawkins, J.L. Fate of Contaminants during Utilization of Peat Materials. J. Environ. Qual. 1989, 18, 503–506. [Google Scholar] [CrossRef]
  42. Amiro, B.D.; Sheppard, S.C.; Johnston, F.L.; Evenden, W.G.; Harris, D.R. Burning radionuclide question: What happens to iodine, cesium and chlorine in biomass fires? Sci. Total Environ. 1996, 187, 93–103. [Google Scholar] [CrossRef] [PubMed]
  43. Environmental Protection Agency, Ireland. Radioactivity Monitoring of the Irish Environment 2012–2013. Wexford, Ireland. 2015. Available online: https://www.epa.ie/publications/compliance--enforcement/radiation/Radioactivity_MonReport_2012_2013.pdf (accessed on 1 February 2023).
  44. McAulay, I.R.; Moran, D. Radiocaesium fallout in Ireland from the Chernobyl accident. J. Radiol. Prot. 1989, 9, 29–32. [Google Scholar] [CrossRef]
  45. Persson, C.; Rodhe, H.; De Greer, L. The Chernobyl Accident: A meteorological analysis of how radionuclides reached and were deposited in Sweden. Ambio 1987, 16, 20–30. [Google Scholar]
  46. McAulay, I.R.; Moran, D. Relationships between deposition of Chernobyl originating caesium and ruthenium radio-nuclides and rainfall in Ireland. Analylst 1992, 117, 455–459. [Google Scholar] [CrossRef] [PubMed]
  47. Caillet, S.; Arpagaus, P.; Monna, F.; Dominik, J. Factors controlling 7Be and 210Pb atmospheric deposition as revealed by sampling individual rain events in the region of Geneva, Switzerland. J. Environ. Radioact. 2001, 53, 241–256. [Google Scholar] [CrossRef] [PubMed]
  48. Aherne, J.; Wilkins, K.; Cathcart, H. Critical Loads and Soil-Vegetation Modelling; CCRP Report No. 323; Environmental Protection Agency: Wexford, Ireland, 2020.
  49. Frontasyeva, M.; Harmens, H.; Uzhinskiy, A.; Chaligava, O.; Participants of the Moss Survey. Mosses as Biomonitors of Air Pollution: 2015/2016 Survey on Heavy Metals, Nitrogen and POPs in Europe and Beyond; Report of the ICP Vegetation; Moss Survey Coordination Centre, Joint Institute for Nuclear Research: Dubna, Russia, 2020; ISBN 978-5-9530-0508-1. [Google Scholar]
  50. Alonso-Hernández, C.M.; Morera-Gómez, Y.; Cartas-Águila, H.; Guillén-Arruebarrena, A. Atmospheric deposition patterns of 210Pb and 7Be in Cienfuegos, Cuba. J. Environ. Radioact. 2014, 138, 149–155. [Google Scholar] [CrossRef]
  51. Dueñas, C.; Fernández, M.C.; Gordo, E.; Cañete, S.; Pérez, M. Gross alpha, gross beta activities and gamma emitting radionuclides composition of rainwater samples and deposition to ground. Atmos. Environ. 2011, 45, 1015–1024. [Google Scholar] [CrossRef]
  52. Mietelski, J.W.; Nalichowska, E.; Tomankiewicz, E.; Brudecki, K.; Janowski, P.; Kierepko, R. Gamma emitters in atmospheric precipitation in Krakow (Southern Poland) during the years 2005–2015. J. Environ. Radioact. 2017, 166, 10–16. [Google Scholar] [CrossRef]
  53. Synnott, H.J.; McGee, E.J.; Rafferty, B.; Dawson, D.E. Long-Term Trends of Radiocesium Activity Concentrations in Vegetation in Irish Semi-Natural Ecosystems. Health Phys. 2000, 79, 154–161. [Google Scholar] [CrossRef]
  54. Met Éireann. Thirty-Year Climate Averages. 2012. Available online: https://www.met.ie/climate/30-year-averages (accessed on 7 February 2019).
  55. ICP Vegetation. Heavy Metals in European Mosses: 2010 Survey; Harmens, H., Ed.; Monitoring Manual; ICP Vegetation Programme Coordination Centre: Wales, UK, 2010; p. 27. [Google Scholar]
  56. Cutshall, N.H.; Larsen, I.L.; Olsen, C.R. Direct analysis of 210Pb in sediment samples: Self-absorption corrections. Nucl. Instrum. Methods Phys. Res. 1983, 206, 309–312. [Google Scholar] [CrossRef]
  57. Walsh, S. A Summary of Climate Averages for Ireland 1981–2010; Climatological Note 14; MET Éireann, Glasnevin Hill: Dublin, Ireland, 2012. [Google Scholar]
  58. Pebesma, E.J. Multivariable geostatistics in S: The gstat package. Comput. Geosci. 2004, 30, 683–691. [Google Scholar] [CrossRef]
  59. Lee, L. NADA: Nondetects and Data Analysis for Environmental Data. R Package Version 1.6-1. 2017. Available online: https://CRAN.R-project.org/package=NADA (accessed on 1 February 2023).
  60. R Core Team. R: A Language and Environment for Statistical Computing; R Foundation for Statistical Computing: Vienna, Austria, 2019; Available online: https://www.R-project.org/ (accessed on 1 February 2023).
  61. Fernández, J.A.; Boquete, M.T.; Carballeira, A.; Aboal, J.R. A critical review of protocols for moss biomonitoring of atmospheric deposition: Sampling and sample preparation. Sci. Total Environ. 2015, 517, 132–150. [Google Scholar] [CrossRef] [PubMed]
  62. Sugihara, S.; Efrizal; Osaki, S.; Momoshima, N.; Maeda, Y. Seasonal variation of natural radionuclides and some elements in plant leaves. J. Radioanal. Nucl. Chem. 2008, 278, 419–422. [Google Scholar] [CrossRef]
  63. Gerdol, R.; Degetto, S.; Mazzotta, D.; Vecchiati, G. The vertical distribution of the Cs-137 derived from Chernobyl fall-out in the uppermost Sphagnum layer of two peatlands in the southern Alps (Italy). Water Air Soil Pollut. 1994, 75, 93–106. [Google Scholar] [CrossRef]
  64. Krmar, M.; Radnović, D.; Rakic, S.; Matavuly, M. Possible use of terrestrial mosses in detection of atmospheric deposition of 7Be over large areas. J. Environ. Radioact. 2007, 95, 53–61. [Google Scholar] [CrossRef] [PubMed]
  65. Krmar, M.; Wattanavatee, K.; Radnović, D.; Slivka, J.; Bhongsuwan, T.; Frontasyeva, M.V.; Pavlov, S.S. Airborne radionuclides in mosses collected at different latitudes. J. Environ. Radioact. 2013, 117, 45–48. [Google Scholar] [CrossRef]
  66. Krmar, M.; Radnović, D.; Mihailović, D.; Lalić, B.; Slivka, J.; Bikit, I. Temporal variations of 7Be, 210Pb and 137Cs in moss samples over 14 month period. Appl. Radiat. Isot. 2009, 67, 1139–1147. [Google Scholar] [CrossRef]
  67. Cuculovic, A.; Popovic, D.; Cuculovic, R.; Ajtic, J. Natural radionuclides and 137Cs in moss and lichen in eastern Serbia. Nucl. Technol. Radiat. Prot. 2012, 27, 44–51. [Google Scholar] [CrossRef]
  68. McAulay, I.R.; Moran, D. Natural radioactivity in the soil in the republic of Ireland. Radiat. Prot. Dosim. 1988, 24, 47–49. [Google Scholar] [CrossRef]
  69. Yang, H.; Shilland, E.; Appleby, P.G.; Rose, N.L.; Battarbee, R.W. Legacy Lead Stored in Catchments Is the Dominant Source for Lakes in the U.K.: Evidence from Atmospherically Derived 210Pb. Environ. Sci. Technol. 2018, 52, 14070–14077. [Google Scholar] [CrossRef]
  70. Sert, E.; Uğur, A.; Özden, B.; Saç, M.M.; Camgöz, B. Biomonitoring of 210Po and 210Pb using lichens and mosses around coal-fired power plants in Western Turkey. J. Environ. Radioact. 2011, 102, 535–542. [Google Scholar] [CrossRef]
  71. Uğur, A.; Özden, B.; Saç, M.M.; Yener, G. Biomonitoring of 210Po and 210Pb using lichens and mosses around a uraniferous coal-fired power plant in western Turkey. Atmos. Environ. 2003, 37, 2237–2245. [Google Scholar] [CrossRef]
  72. Kim, G.; Hussain, N.; Scudlark, J.R.; Church, T.M. Factors influencing atmospheric depositional fluxes of stable Pb, 210Pb, and 7Be into Chesapeake Bay. J. Atmos. Chem. 2000, 36, 65–79. [Google Scholar] [CrossRef]
  73. Winkler, R.; Rosner, G. Seasonal and long-term variation of 210Pb concentration in air, atmospheric deposition rate and total deposition velocity in south Germany. Sci. Total Environ. 2000, 263, 57–68. [Google Scholar] [CrossRef]
  74. Likuku, A.S. Factors influencing ambient concentrations of 210Pb and 7Be over the city of Edinburgh (55.9° N, 03.2° W). J. Environ. Radioact. 2006, 87, 289–304. [Google Scholar] [CrossRef]
  75. Griselli, B.; Magnoni, M.; Bertino, S.; Bari, A.; Isocrono, D.; Piervittori, R. Biomonitoring in the evaluation of human impact: Use of lichen biodiversity, and moss accumulation of radioisotopes in an Alpine valley (Valle Orco, Piedmont, Italy). Plant Biosyst.—Int. J. Deal. All Asp. Plant Biol. 2003, 137, 35–46. [Google Scholar] [CrossRef]
  76. Al-Masri, M.S.; Mamish, S.; Al-Haleem, M.A.; Al-Shamali, K. Lycopodium cernuum and Funaria hygrometrica as deposition indicators for radionuclides and trace metals. J. Radioanal. Nucl. Chem. 2005, 266, 49–55. [Google Scholar] [CrossRef]
  77. McGinnity, P.; Currivan, L.; Duffy, J.; Hanley, O.; Kelleher, K.; McKittrick, L.; Colmain, M.O.; Organo, C.; Smith, K.; Somerville, S.; et al. Assessment of the Impact on Ireland of the 2011 Fukushima Nuclear Accident; RPII 12/01; Radiological Protection Institute of Ireland: Dublin, Ireland, 2012; p. 44. [Google Scholar]
  78. Bossew, P.; Kirchner, G.; De Cort, M.; de Vries, G.; Nishev, A.; de Felice, L. Radioactivity from Fukushima Dai-ichi in air over Europe; part 1: Spatio-temporal analysis. J. Environ. Radioact. 2012, 114, 22–34. [Google Scholar] [CrossRef] [PubMed]
  79. Evangeliou, N.; Balkanski, Y.; Cozic, A.; Møller, A.P. Global Transport and Deposition of 137Cs Following the Fukushima Nuclear Power Plant Accident in Japan: Emphasis on Europe and Asia Using High–Resolution Model Versions and Radiological Impact Assessment of the Human Population and the Environment Using Interactive Tools. Environ. Sci. Technol. 2013, 47, 5803–5812. [Google Scholar] [CrossRef] [PubMed]
  80. Krmar, M.; Mihailović, D.T.; Arsenić, I.; Radnović, D.; Pap, I. Beryllium-7 and 210Pb atmospheric deposition measured in moss and dependence on cumulative precipitation. Sci. Total Environ. 2016, 541, 941–948. [Google Scholar] [CrossRef] [PubMed]
Pollutants 03 00009 g001 550
Figure 1. Location of sites in Ireland (n = 24) where moss (Hylocomium splendens (Hedw.) B.S.G.) was collected for radionuclide analysis. Segments represent 210Pb, 137Cs, 7Be, and 40K activity concentration (Bq kg–1); absent segments represent values below the laboratory detection limits. Shading depicts annual average rainfall (m yr–1).
Figure 1. Location of sites in Ireland (n = 24) where moss (Hylocomium splendens (Hedw.) B.S.G.) was collected for radionuclide analysis. Segments represent 210Pb, 137Cs, 7Be, and 40K activity concentration (Bq kg–1); absent segments represent values below the laboratory detection limits. Shading depicts annual average rainfall (m yr–1).
Pollutants 03 00009 g001
Pollutants 03 00009 g002 550
Figure 2. Boxplots show the log-transformed activity concentration (Bq kg–1) of four radionuclides (210Pb, 7Be, 40K, and 137Cs) in moss tissue (Hylocomium splendens (Hedw.) B.S.G.) from the 24 study sites in Ireland (see Figure 1). The horizontal line within the box represents the median, box ends represent the upper and lower quartiles, and whiskers represent 1.5 × the interquartile distance. Data imputation for values < DL was carried out using the NADA R package [59].
Figure 2. Boxplots show the log-transformed activity concentration (Bq kg–1) of four radionuclides (210Pb, 7Be, 40K, and 137Cs) in moss tissue (Hylocomium splendens (Hedw.) B.S.G.) from the 24 study sites in Ireland (see Figure 1). The horizontal line within the box represents the median, box ends represent the upper and lower quartiles, and whiskers represent 1.5 × the interquartile distance. Data imputation for values < DL was carried out using the NADA R package [59].
Pollutants 03 00009 g002
Pollutants 03 00009 g003 550
Figure 3. Average long-term annual rainfall (mm) versus 210Pb activity concentration (Bq kg–1) in Hylocomium splendens (Hedw.) B.S.G. across the 24 study sites in Ireland (R2 = 0.63, p < 0.001).
Figure 3. Average long-term annual rainfall (mm) versus 210Pb activity concentration (Bq kg–1) in Hylocomium splendens (Hedw.) B.S.G. across the 24 study sites in Ireland (R2 = 0.63, p < 0.001).
Pollutants 03 00009 g003
Table
Table 1. Summary statistics for 210Pb, 137Cs, 7Be and 40K activity concentration (Bq kg–1 fresh weight §) in moss (n = 24). Spatial variability (%) in activity concentration across sites for each radionuclide is represented by NMAD (normalised median absolute deviation).
Table 1. Summary statistics for 210Pb, 137Cs, 7Be and 40K activity concentration (Bq kg–1 fresh weight §) in moss (n = 24). Spatial variability (%) in activity concentration across sites for each radionuclide is represented by NMAD (normalised median absolute deviation).
Statistic210Pb Activity137Cs Activity7Be Activity40K Activity
Non-detect (%)0336725
Number > DL2416818
Mean541.514.0420.796.5
Median490.010.4376.290.5
Range225.5–968.03.1–41.4283.1–604.457.2–155.4
NMAD (%)35312217
§ Measured radionuclide activity concentrations (Bq kg–1) were corrected for dry weight, and 210Pb activity concentration was also corrected for self-attenuation.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Wilkins, K.; Cathcart, H.; Hickey, P.; Hanley, O.; León Vintró, L.; Aherne, J. Influence of Precipitation on the Spatial Distribution of 210Pb, 7Be, 40K and 137Cs in Moss. Pollutants 2023, 3, 102-113. https://doi.org/10.3390/pollutants3010009

AMA Style

Wilkins K, Cathcart H, Hickey P, Hanley O, León Vintró L, Aherne J. Influence of Precipitation on the Spatial Distribution of 210Pb, 7Be, 40K and 137Cs in Moss. Pollutants. 2023; 3(1):102-113. https://doi.org/10.3390/pollutants3010009

Chicago/Turabian Style

Wilkins, Kayla, Hazel Cathcart, Padraig Hickey, Olwyn Hanley, Luis León Vintró, and Julian Aherne. 2023. "Influence of Precipitation on the Spatial Distribution of 210Pb, 7Be, 40K and 137Cs in Moss" Pollutants 3, no. 1: 102-113. https://doi.org/10.3390/pollutants3010009

Article Metrics

Back to TopTop