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.

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.

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.

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.

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.

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.

Physiological responses of bryophytes Thuidium tamariscinum and Hylocomium splendens to increased nitrogen deposition.

BACKGROUND AND AIMS: Increased levels of nitrogen (N) deposition lead to enhanced N contents and reduced productivity of many bryophyte species. This study aimed at elucidating the mechanisms by which enhanced N uptake may cause growth reduction of bryophytes, focusing on the effects of N addition on carbon (C) metabolism of bryophytes. METHODS: Plantlets of Thuidium tamariscinum and Hylocomium splendens were fertilized with NH(4)NO(3) (N load equalling 30 kg ha(-1) year(-1)) for 80 d, including a pulse labelling experiment with (13)CO(2) to dissect the partitioning of carbon in response to N addition. KEY RESULTS: Growth of T. tamariscinum was not affected by N addition, while H. splendens showed a trend towards growth reduction. Total N concentration was significantly increased by N addition in H. splendens, a significant increase in amino acid-N was found in T. tamariscinum only. In both bryophyte species, a reduction in concentration of lipids, the greatest C storage pool, as well as markedly enhanced turnover rates of C storage pools in fertilized plants were observed. CONCLUSIONS: The results suggest that growth reduction of H. splendens under high levels of N deposition may be caused by enhanced synthesis of N-containing organic compounds, most probably of cell wall proteins. Disturbance of cellular C metabolism, as indicated by enhanced C pool turnover, may further contribute to the decline in productivity of H. splendens.

Assessing airborne pollution effects on bryophytes: lessons learned through long-term integrated monitoring in Austria.

The study uses measured and calculated data on airborne pollutants, particularly nitrogen (ranges between 28 to 43kgN*ha(-1)*yr(-1)) and sulphur (10 to 18kgSO(4)-S*ha(-1)*yr(-1)), in order to assess their long-term (1992 to 2005) effects on bryophytes at the UN-ECE Integrated Monitoring site 'Zöbelboden' in Austria. Bryophytes were used as reaction indicators on 20 epiphytic plots using the IM monitoring method and on 14 terrestrial plots using standardised photography. The plots were recorded in the years 1992, 1993, 1998, and 2004/2005. Most species remained stable in terms of their overall population size during the observed period, even though there were rapid turnover rates of a large percentage of species on all investigated plots. Only a few bryophytes (Hypnum cupressiforme, Leucodon sciuroides) responded unambiguously to N and S deposition. Nitrogen deposition had a weak but significant effect on the distribution of bryophyte communities. However, the time shifts in bryophyte communities did not depend on total deposition of N and S.

Estimation of element deposition derived from road traffic sources by using mosses.

Sixty moss samples were taken along transects of nine roads in Austria. The concentrations of 17 elements in four moss species were determined. There was a high correlation between several elements like Cu/Sb (0.906), Ni/Co (0.897) or Cr/V (0.898), indicating a common traffic-related source. Enrichment factors were calculated, showing highest enrichment levels for: Cr, Mo, Sb, Zn, As, Fe, V, Cu, Ni, and Co. For these elements, road traffic has to be assumed as a source, which is confirmed by a significant negative correlation of the concentrations in mosses to the distance from the road for most of these metals. The rate of decrease followed a log-shaped curve at most of the investigated transects, although the decline cannot be explained by a single model. Multiple regression analysis highlighted traffic density, distance from and elevation of the road as the most influencing factors for the deposition of the investigated elements. Heavy duty vehicles (HDVs) and light duty vehicles (LDVs) showed different patterns. A comparison of sites likely to be influenced by traffic emissions with average values for the respective regions showed no significant differences for road distances of more than 250 m. Nevertheless, at heavily frequented roads, raised deposition of some elements was found even at a distance of 1,000 m.

Nitrogen content, 15N natural abundance and biomass of the two pleurocarpous mosses Pleurozium schreberi (Brid.) Mitt. and Scleropodium purum (Hedw.) Limpr. in relation to atmospheric nitrogen deposition.

The suitability of the two pleurocarpous mosses Pleurozium schreberi and Scleropodium purum for assessing spatial variation in nitrogen deposition was investigated. Sampling was carried out at eight sites in the western part of Germany with bulk deposition rates ranging between 6.5 and 18.5 kg N ha(-1) yr(-1). In addition to the effect of deposition on the nitrogen content of the two species, its influence on 15N natural abundance (delta15N values) and on productivity was examined. Annual increases of the mosses were used for all analyses. Significant relationships between bulk N deposition and nitrogen content were obtained for both species; delta15N-values reflected the ratio of NH4-N to NO3-N in deposition. A negative effect of nitrogen input on productivity, i.e. decreasing biomass per area with increasing N deposition due to a reduction of stem density, was particularly evident with P. schreberi. Monitoring of N deposition by means of mosses is considered an important supplement to existing monitoring programs. It makes possible an improved spatial resolution, and thus those areas that receive high loads of nitrogen are more easily discernible.

Variations in heavy metal concentrations in the moss species Abietinella abietina (Hedw.) Fleisch. according to sampling time, within site variability and increase in biomass.

Concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mo, Ni, Pb, V and Zn were analysed in the moss Abietinella abietina (Hedw.) Fleisch. to estimate atmospheric heavy metal depositions. Samples were taken at five comparable sites within a radius of 25 m four times during the year 2000 (July 3rd, August 3rd, September 7th, October 3rd). The samples were taken by means of a PVC-tube (r=10 cm) and could therefore be related to aboveground growth and aerial deposition. The investigation showed significant differences between the various sampling times for concentrations of all heavy metals in total but not between concentrations of a single metal. For Cu, Hg, Mo, Pb and Zn temporal variation (=variation between the four times of sampling) was larger than spatial variation (=variation of concentrations between sub-samples at a single sampling time). Growth rates of the mosses differed significantly between sampling times, which reflects the low precipitation at the beginning of the season. Biomass increase, dust and precipitation influenced the metal concentrations. The calculation of deposition rates, which takes growth rates into account, showed significant differences between the various sampling times for Al, Cd, Cr, Cu and Ni, which is controversial to the results obtained from concentrations of these elements. Additionally, the calculation of atmospheric deposition rates showed a constant increase of metal depositions throughout the investigated period, which can not be seen by considering the concentrations only.