Harry Harmens

Mosses as biomonitors of atmospheric heavy metal deposition: Spatial patterns and temporal trends in Europe

In recent decades, mosses have been used successfully as biomonitors of atmospheric deposition of heavy metals. Since 1990, the European moss survey has been repeated at five-yearly intervals. Although spatial patterns were metal-specific, in 2005 the lowest concentrations of metals in mosses were generally found in Scandinavia, the Baltic States and northern parts of the UK; the highest concentrations were generally found in Belgium and south-eastern Europe. The recent decline in emission and subsequent deposition of heavy metals across Europe has resulted in a decrease in the heavy metal concentration in mosses for the majority of metals. Since 1990, the concentration in mosses has declined the most for arsenic, cadmium, iron, lead and vanadium (52-72%), followed by copper, nickel and zinc (20-30%), with no significant reduction being observed for mercury (12% since 1995) and chromium (2%). However, temporal trends were country-specific with sometimes increases being found.

Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe

In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses (<0.8%) were observed in northern Finland and northern UK. The highest concentrations (≥ 1.6%) were found in parts of Belgium, France, Germany, Slovakia, Slovenia and Bulgaria. The asymptotic relationship between the nitrogen concentrations in mosses and EMEP modelled nitrogen deposition (averaged per 50 km × 50 km grid) across Europe showed less scatter when there were at least five moss sampling sites per grid. Factors potentially contributing to the scatter are discussed. In Switzerland, a strong (r(2) = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured site-specific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution.

Terrestrial mosses as biomonitors of atmospheric POPs pollution: a review

Worldwide there is concern about the continuing release of persistent organic pollutants (POPs) into the environment. In this study we review the application of mosses as biomonitors of atmospheric deposition of POPs. Examples in the literature show that mosses are suitable organisms to monitor spatial patterns and temporal trends of atmospheric concentrations or deposition of POPs. These examples include polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs), dioxins and furans (PCDD/Fs), and polybrominated diphenyl ethers (PBDEs). The majority of studies report on PAHs concentrations in mosses and relative few studies have been conducted on other POPs. So far, many studies have focused on spatial patterns around pollution sources or the concentration in mosses in remote areas such as the polar regions, as an indication of long-range transport of POPs. Very few studies have determined temporal trends or have directly related the concentrations in mosses with measured atmospheric concentrations and/or deposition fluxes.

Country-specific correlations across Europe between modelled atmospheric cadmium and lead deposition and concentrations in mosses

Previous analyses at the European scale have shown that cadmium and lead concentrations in mosses are primarily determined by the total deposition of these metals. Further analyses in the current study show that Spearman rank correlations between the concentration in mosses and the deposition modelled by the European Monitoring and Evaluation Programme (EMEP) are country and metal-specific. Significant positive correlations were found for about two thirds or more of the participating countries in 1990, 1995, 2000 and 2005 (except for Cd in 1990). Correlations were often not significant and sometimes negative in countries where mosses were only sampled in a relatively small number of EMEP grids. Correlations frequently improved when only data for EMEP grids with at least three moss sampling sites per grid were included. It was concluded that spatial patterns and temporal trends agree reasonably well between lead and cadmium concentrations in mosses and modelled atmospheric deposition.

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.

Ozone impacts on vegetation in a nitrogen enriched and changing climate.

This paper provides a process-oriented perspective on the combined effects of ozone (O3), climate change and/or nitrogen (N) on vegetation. Whereas increasing CO2 in controlled environments or open-top chambers often ameliorates effects of O3 on leaf physiology, growth and C allocation, this is less likely in the field. Combined responses to elevated temperature and O3 have rarely been studied even though some critical growth stages such as seed initiation are sensitive to both. Under O3 exposure, many species have smaller roots, thereby enhancing drought sensitivity. Of the 68 species assessed for stomatal responses to ozone, 22.5% were unaffected, 33.5% had sluggish or increased opening and 44% stomatal closure. The beneficial effect of N on root development was lost at higher O3 treatments whilst the effects of increasing O3 on root biomass became more pronounced as N increased. Both responses to gradual changes in pollutants and climate and those under extreme weather events require further study.

Multi-elements atmospheric deposition study in Albania

For the first time, the moss biomonitoring technique and inductively coupled plasma–atomic emission spectrometric (ICP-AES) analytical technique were applied to study multi-element atmospheric deposition in Albania. Moss samples (Hypnum cupressiforme) were collected during the summer of 2011 and September–October 2010 from 62 sites, evenly distributed over the country. Sampling was performed in accordance with the LRTAP Convention–ICP Vegetation protocol and sampling strategy of the European Programme on Biomonitoring of Heavy Metal Atmospheric Deposition. ICP-AES analysis made it possible to determine concentrations of 19 elements including key toxic metals such as Pb, Cd, As, and Cu. Cluster and factor analysis with varimax rotation was applied to distinguish elements mainly of anthropogenic origin from those predominantly originating from natural sources. Geographical distribution maps of the elements over the sampled territory were constructed using GIS technology. The median values of the elements in moss samples of Albania were high for Al, Cr, Ni, Fe, and V and low for Cd, Cu, and Zn compared to other European countries, but generally were of a similar level as some of the neighboring countries such as Bulgaria, Croatia, Kosovo, Macedonia, and Romania. This study was conducted in the framework of ICP Vegetation in order to provide a reliable assessment of air quality throughout Albania and to produce information needed for better identification of contamination sources and improving the potential for assessing environmental and health risks in Albania, associated with toxic metals.

Ozone and plants

The International Conference on Ozone and Plants was held on May 18-21, 2014, in Beijing, China, hosted by the Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (http://english.rcees.cas.cn/), on behalf of the IUFRO Research Group 7.01.00 “Impacts of Air Pollution and Climate Change on Forest Ecosystems” (http://www.iufro.org/science/divisions/ division-7/70000/70100) and the ICP Vegetation (http:// icpvegetation.ceh.ac.uk). A special session was organised by the Task Force on Hemispheric Transport of Air Pollution (http://htap.org) of the UNECE Long-range Transboundary Air Pollution Convention (http://www.unece.org/env/lrtap). The conference gathered more than 110 scientists from 17 countries to share the state of the art of ozone research and discuss scientific gaps in the understanding of the interaction between ozone and plants. The 2nd International Conference on Ozone and Plants is scheduled for 2017.

Mapping background values of atmospheric nitrogen total depositions in Germany based on EMEP deposition modelling and the European Moss Survey 2005

BackgroundIn order to map exceedances of critical atmospheric deposition loads for nitrogen (N) surface data on the atmospheric deposition of N compounds to terrestrial ecosystems are needed. Across Europe such information is provided by the international European Monitoring and Evaluation Programme (EMEP) in a resolution of 50 km by 50 km, relying on both emission data and measurement data on atmospheric depositions. The objective of the article at hand is on the improvement of the spatial resolution of the EMEP maps by combining them with data on the N concentration in mosses provided by the International Cooperative Programme on Effects of Air Pollution on Natural Vegetation and Crops (ICP Vegetation) of the United Nations Economic Commission for Europe (UNECE) Long-range Transboundary Air Pollution (LTRAP) Convention.MethodsThe map on atmospheric depositions of total N as modelled by EMEP was intersected with geostatistical surface estimations on the N concentration in mosses at a resolution of 5 km by 5 km. The medians of the N estimations in mosses were then calculated for each 50 km by 50 km grid cell. Both medians of moss estimations and corresponding modelled deposition values were ln-transformed and their relationship investigated and modelled by linear regression analysis. The regression equations were applied on the moss kriging estimates of the N concentration in mosses. The respective residuals were projected onto the centres of the EMEP grid cells and were mapped using variogram analysis and kriging procedures. Finally, the residual and the regression map were summed up to the map of total N deposition in terrestrial ecosystems throughout Europe.Results and discussionThe regression analysis of the estimated N concentrations in mosses and the modelled EMEP depositions resulted in clear linear regression patterns with coefficients of determination of r2 = 0.62 and Pearson correlations of rp = 0.79 and Spearman correlations of rs = 0.70, respectively. Regarding the German territory a nationwide mean of 18.1 kg/ha/a (standard deviation: 3.49 kg/ha/a) could be derived from the resulting map on total N deposition in a resolution of 5 km by 5 km. Recent updates of the modelled atmospheric deposition of N provided a similar estimate for Germany.ConclusionsThe linking of modelled EMEP data on the atmospheric depositions of total N and the accumulation of N in mosses allows to map the deposition of total N in a high resolution of 5 km by 5 km using empirical moss data. The mapping relies on the strong statistical relationship between both processes that are physically and chemically related to each other. The mapping approach thereby relies on available data that are both based on European wide harmonized methodologies. From an ecotoxicological point of view the linking of data on N depositions and those on N bioaccumulation can be considered a substantial progress.ZusammenfassungHintergrundFür die Kartierung kritischer Eintragsraten (Critical Loads, CL) für Stickstoff (N) werden flächendeckende Depositionsdaten benötigt. Diese werden europaweit im EMEP-Programm und auf nationalstaatlicher Ebene in Forschungsprojekten zur Verfügung gestellt. Es handelt sich um Ergebnisse aus Modellierungen, die u.a. auf Messwerten der N-Emissionen und der atmosphärischen N-Deposition beruhen. Dieser Artikel stellt am Beispiel der Daten zur N-Deposition aus dem European Monitoring and Evaluation Programme (EMEP) dar, wie deren räumliche Auflösung durch Kombination mit Daten der N-Anreicherung in Moosen aus dem International Cooperative Programme on Effects of Air Pollution on Natural Vegetation and Crops (ICP Vegetation) der United Nations Economic Commission for Europe (UNECE) Long-range Transboundary Air Pollution (LTRAP) Convention.erhöht werden kann.MethodenDie in einer Auflösung von 50 km mal 50 km vorliegende EMEP N-Depositionskarte wurde mit geostatistich validen Kriging-Karten über die Anreicherung von N in Moosen in einem Geografischen Informationssystem (GIS) verknüpft. Anschließend wurden die Mediane aller 5 km mal 5 km großen Rasterzellen der N-Anreicherungskarte innerhalb der jeweiligen 50 km mal 50 km abdeckenden EMEP-Rasterzellen berechnet. Die Mediane der geschätzten Elementkonzentrationen im Moos sowie die Depositionswerte wurden ln-transformiert und korrelations- und regressionsanalytisch untersucht. Sodann wurden die Regressionsfunktionen auf die Kriging-Flächenkarten der N-Anreicherungen in Moosen angewendet. Die Residuen der Regressionsfunktion wurden bestimmt, entlogarithmiert, auf die Mittelpunkte der entsprechenden EMEP-Rasterzellen projiziert, variogrammanalytisch auf räumliche Strukturen untersucht und mit Lognormal-Kriging flächenhaft interpoliert. Die Kriging-Karte der Residuen wurde abschließend mit der regressionsanalytisch berechneten N-Depositionsflächenkarte verrechnet.Ergebnisse und DiskussionDie Regressionsanalyse zeigt, dass die N-Anreicherung in den Moosen aus Hintergrundgebieten mit der N-Gesamtdeposition europaweit mit Pearson Korrelationen von rp = 0.79 sowie Spearman Korrelationen von rs = 0.70 korreliert ist. Das Bestimmtheitsmaß des Regressionsmodells beträgt r2 = 0,62. Die statistische Auswertung der auf dieser Grundlage berechneten Karte der N-Gesamtdeposition ergibt einen deutschlandweiten Mittelwert der von 18.1 kg/ ha / a (Standardabweichung 3.49 kg / ha / a). Vergleicht man die Ergebnisse dieser Berechnungen mit Ergebnissen aus anderen Verfahren, so zeigen sich z.T. Unterschiede. Die am Ende des Jahres 2009 anlässlich eines Workshops zur Modellierung von Schadstoffeinträgen und ihren Wirkungen auf Ökosysteme veröffentlichten N-Gesamtdepositionsmodellierungen entsprechen allerdings ungefähr denen, die anhand der Daten aus dem EMEP und ICP Vegetation in dieser Untersuchung berechnet wurden.SchlussfolgerungenDie Verknüpfung der Daten zur N-Gesamtdeposition (EMEP) und der N-Anreicherungen in Moosen (ICP Vegetation) ermöglicht eine empirisch validierte, räumlich differenzierte Kartierung der N-Gesamtdeposition. Die ausgeprägte, statistisch hoch signifikante Korrelation zwischen den beiden physikalisch und chemisch miteinander verbundenen Prozessen der atmosphärischen Deposition und der Bioakkumulation bilden die Grundlage der Kartierung. Die Karten nutzen vorhandenes Datenmaterial, das auf der Grundlage europaweit harmonisierter Methoden in zwei qualitätskontrollierten Messprogrammen erhoben wurde. Aus dem Blickwinkel der Ökotoxikologie ist die Verknüpfung von Daten über Stoffeinträge in terrestrische Ökosysteme und N-Anreicherungen in deren Moosbiomasse ein Fortschritt.

Current and future ozone risks to global terrestrial biodiversity and ecosystem processes

Abstract Risks associated with exposure of individual plant species to ozone (O3) are well documented, but implications for terrestrial biodiversity and ecosystem processes have received insufficient attention. This is an important gap because feedbacks to the atmosphere may change as future O3 levels increase or decrease, depending on air quality and climate policies. Global simulation of O3 using the Community Earth System Model (CESM) revealed that in 2000, about 40% of the Global 200 terrestrial ecoregions (ER) were exposed to O3 above thresholds for ecological risks, with highest exposures in North America and Southern Europe, where there is field evidence of adverse effects of O3, and in central Asia. Experimental studies show that O3 can adversely affect the growth and flowering of plants and alter species composition and richness, although some communities can be resilient. Additional effects include changes in water flux regulation, pollination efficiency, and plant pathogen development. Recent research is unraveling a range of effects belowground, including changes in soil invertebrates, plant litter quantity and quality, decomposition, and nutrient cycling and carbon pools. Changes are likely slow and may take decades to become detectable. CESM simulations for 2050 show that O3 exposure under emission scenario RCP8.5 increases in all major biomes and that policies represented in scenario RCP4.5 do not lead to a general reduction in O3 risks; rather, 50% of ERs still show an increase in exposure. Although a conceptual model is lacking to extrapolate documented effects to ERs with limited or no local information, and there is uncertainty about interactions with nitrogen input and climate change, the analysis suggests that in many ERs, O3 risks will persist for biodiversity at different trophic levels, and for a range of ecosystem processes and feedbacks, which deserves more attention when assessing ecological implications of future atmospheric pollution and climate change.