Lichens as sentinels for air pollution at remote alpine areas (Italy)

The present study was undertaken with the aim of using epiphytic lichens as sentinels for air pollution at two remote alpine sites (1,400 and 1,800 m above sea level (asl)) of NW Italy. The results indicated that the site at 1,800 m prompted for early warning indications of biological changes. Although levels of the many elements assayed in samples of the lichen Pseudevernia furfuracea (L.) Zopf, ranging from minor elements (e.g., Al) to ultra-trace (e.g., Pt), were at normal levels, indications of a slowly worsening environment were given by the lichen biodiversity and by damage to cell membranes. The analysis of Pb isotopic ratios suggested that the origin of Pb accumulated in lichens is not local, but linked to the long-range transport by air masses. It was concluded that the origin of pollutants is from air mass coming from the Po plain of Italy and from densely populated areas of Switzerland and France.     

Epiphytic lichens as biomonitors of atmospheric pollution in Slovenian forests

Two country-wide surveys using epiphytic lichens as biomonitors of atmospheric pollution carried out during 2000 and 2001 in Slovenia were compared with surveys in 1991 and 1992. In the first survey, epiphytic lichen cover was studied in more than 500 plots of the 4 x 4 km national grid carried out within the framework of forest decline inventories. In the second survey, the epiphytic lichen Hypogymnia physodes (L.) Nyl., was collected on a 16 x 16 km bioindication grid and analysed for S, N, As, Br, Ce, Cd, Cr, K, La, Mo, Rb, Sb, Th, U and Zn contents. Only 'forested area' sampling points were included in the present study. Lichen cover was low, with about 70% of plots with less than 10% foliose lichen cover. No relationship was found between Hypogymnia trace element, N and S concentrations and foliose epiphytic lichen cover.     

Biodiversity of epiphytic lichens and air pollution in the town of Siena (central Italy).

The results of a biomonitoring survey carried out in the town of Siena (central Italy) using the biodiversity of epiphytic lichens as indicator of air pollution are reported. The general picture was rather good, with more than 60% of the study area being in the categories "semi-natural" or "natural" according to a calibrated scale of environmental naturality/alteration. Compared with the situation of 1995, ameliorating conditions were found as a result of an improvement in air quality over time.     

Predatory insects as bioindicators of heavy metal pollution

Heavy metal concentrations of different predatory insects were studied near by a steel factory and from control sites. Waterstriders (Gerridae), dragon fly larvae (Odonata), antlion larvae (Myrmeleontidae) and ants (Formicidae) were analyzed by AAS. In most cases the metal concentrations were higher near the factory, but e.g. waterstriders had higher cadmium concentrations in control area. Discriminant analysis clearly reveals that all these insect groups can be used as heavy metal indicators. However, the commonly used ants were the least effective in indicating the differences between the factory and control sites. Waterstriders are good in detecting differences in iron and manganese, but seem to be poor in accumulating nickel and lead. Antlions are efficient in detecting differences in iron. Antlions and ants are effective in accumulating manganese; as well antlions are efficient in accumulating cadmium. Waterstriders are poor in accumulating lead, but antlions and ants are effective.     

Oribatid mite communities and metal bioaccumulation in oribatid species (Acari, Oribatida) along the heavy metal gradient in forest ecosystems

The responses of oribatid communities to heavy metal contamination were studied. Concentration of cadmium, copper and zinc in nine oribatid species along a gradient of heavy metal pollution was measured. Oribatid mites were sampled seasonally during two years in five forests located at different distances from the zinc smelter in the Olkusz District, southern Poland. The most numerous and diverse oribatid communities were found in the forest with moderate concentrations of heavy metals. Analysis by atomic absorption spectrophotometry revealed large differences in metal body burdens among species. All studied oribatid species appeared to be accumulators of copper with Oppiella nova, Nothrus silvestris and Adoristes ovatus characterized by the highest bioaccumulation factors. Most species poorly accumulate cadmium and zinc. The accumulation of heavy metals in the body of oribatids was not strictly determined by their body size or the trophic level at which they operate.     

Atmospheric deposition and canopy exchange processes in alpine forest ecosystems (northern Italy)

Throughfall and bulk precipitation chemistry were studied for five years (June 1994–May 1999) at two high elevation forest sites (Val Gerola and Val Masino) which were known to differ in terms of tree health, as assessed by live crown condition. The ion concentration of bulk precipitation samples did not differ significantly between sites, except for Mg²⁺, while the throughfall concentrations differed in the measured values of H⁺, N-NO₃⁻, Cl⁻, Na⁺, K⁺, DOC and weak organic acids. The results of the application of the canopy exchange model indicated a higher contribution from the dry deposition of N-NO₃⁻, N-NH₄⁺ and H⁺ at Val Gerola, where the damage symptoms were more evident. In addition, the canopy leaching of Ca²⁺, K⁺ and weak organic acids were 47%, 21% and 27% higher at Val Gerola than at Val Masino. Annual SO₄²⁻ deposition fluxes (21.3 kg ha⁻¹ yr⁻¹ at Val Masino and 23.6 kg ha⁻¹ yr⁻¹ at Val Gerola) were similar to those reported for moderately polluted European and U.S. sites. Annual N loads were 13.6 and 13.1 kg ha⁻¹ yr⁻¹ in the bulk input, and 15.0 and 18.0 kg ha⁻¹ yr⁻¹ in throughfall inputs, at Val Masino and Val Gerola, respectively. The contribution of the organic fraction to the total N atmospheric deposition load is significant, constituting 17% of the bulk flux and 40% of the throughfall flux. Measured nitrogen loads exceed the critical nutrient loads by several kg N ha⁻¹ at both stations. In particular the nitrogen throughfall load at Val Gerola was about 3 times higher than the critical values.     

Water striders (family Gerridae): mercury sentinels in small freshwater ecosystems

To circumvent some of the previous limitations associated with contaminant-monitoring programs, we tested the suitability of the water strider (Hemiptera: Gerridae) as a mercury sentinel by comparing total mercury concentrations in water striders and brook trout (Salvelinus fontinalis) from a variety of stream sites in New Brunswick, Canada. There was a strong association between the two variables across sites (r(2)=0.81, P<0.001) in systems where both atmospheric deposition and a point source (an abandoned gold mine) were likely contributing to ambient mercury levels. In a small stream draining the gold mine tailings pile, water striders had mercury concentrations an order of magnitude higher than those from reference locations. Temporal variation at three southern New Brunswick stream sites was non-significant. These results suggest that water strider mercury levels accurately quantify food chain entry of the element. The use of sentinel species holds great potential for expanding contaminant-monitoring programs.     

Decomposition of coniferous forest litter along a heavy metal pollution gradient, south-west Finland

The decomposition of Scots pine (Pinus sylvestris) fine root and needle litter was examined along a heavy metal pollution gradient in the vicinity of Harjavalta Metals Smelter complex at Harjavalta, south-west Finland. The study area was found to exhibit a defined gradient of copper and nickel soil contamination along a 8 km long transect starting at 0.5 km from the point emission source with the highest levels found at this site. The background site is located 200 km from the point source. The majority of the heavy metals are confined to the soil organic layer. Litter decomposition and litter quality were compared between litter types after 12, 18, and 30 months incubation at each of four sites. The analyses clearly showed differences in accumulated mass loss, C:N ratio, and nutrient composition that were related to the site of incubation. Needle and fine root litter that was incubated at 0.5 km had a lower accumulated mass loss, 28.1 and 40.9%, respectively, over time when compared to litter incubated at the background site (37.9 and 50.9%, respectively). Concentrations of exchangeable cations in the litter incubated at 0.5 km were considerably less. The heavy metal contamination may provide an explanation for the amount of mass lost and the litter quality through impacts on the soil microbiota.     

Trees as bioindicator of heavy metal pollution in three European cities

Concentrations of four heavy metals were determined in tree leaves and bark collected from polluted and non-polluted areas of three European cities (Salzburg, Belgrade and Thessaloniki) for a comparative study. Platanus orientalis L. and Pinus nigra Arn., widespread in urban northern and southern Europe, were tested for their suitability for air quality biomonitoring. Leaves and barks were collected uniformly of an initial quantity of about 30 g of each sample. Analysis was accomplished by electrothermal atomic absorption spectrometry after total digestion. Site-dependent variations were found with the highest concentration level measured in Belgrade, followed by Thessaloniki and Salzburg. A higher accumulation of heavy metals was found in bark compared to leaves. Pine tree bark, accumulating higher concentrations of trace metals compared to plane tree bark, shows a higher efficiency as bioindicator for urban pollution. Both indicator species are suitable for comparative studies on bioindication of urban air pollution.     

Marine sponges with contrasting life histories can be complementary biomonitors of heavy metal pollution in coastal ecosystems

In this study, we compared the usefulness of a long-living sponge (Hymeniacidon heliophila, Class Demospongiae) and a short-living one (Paraleucilla magna, Class Calcarea) as biomonitors of metallic pollution. The concentrations of 16 heavy metals were analyzed in both species along a gradient of decreasing pollution from the heavily polluted Guanabara Bay to the less impacted coastal islands in Rio de Janeiro, SE Brazil (SW Atlantic). The levels of most elements analyzed were higher in H. heliophila (Al, Co, Cr, Cu, Fe, Mn, Ni, Hg, Ni, and Sn) and P. magna (Ni, Cu, Mn, Al, Ti, Fe, Pb, Co, Cr, Zn, and V) collected from the heavily polluted bay when compared with the cleanest sites. Hymeniacidon heliophila accumulates 11 elements more efficiently than P. magna. This difference may be related to their skeleton composition, histological organization, symbiont bacteria and especially to their life cycle. Both species can be used as a biomonitors of metallic pollution, but while Hymeniacidon heliophila was more effective in concentrating most metals, Paraleucilla magna is more indicated to detect recent pollutant discharges due to its shorter life cycle. We suggest that the complementary use of species with contrasting life histories can be an effective monitoring strategy of heavy metals in coastal environments.     

Evaluation of pollution-related stress factors for forest ecosystems in central Europe

Since the early eighties air pollution by SO2 and Pb and, to a lesser degree by NOx and NH3, have been significantly reduced in Europe. This was done in part for the protection of forest ecosystems. The reductions are reflected in the pollutant impacts and inputs and have been verified through the bioindicator Norway spruce. In contrast, ozone concentrations increased at most of the evaluated measuring locations and trends were calculated based on the results of about 100 stations in Austria and Germany. Despite reduced emissions, large parts of the forest ecosystems are still affected by air-pollution impacts. Negative effects can be assessed using different legal standards and Critical Levels and Critical Loads, respectively: The legal standard for the evaluation of SO2 impact, as used in Austria, is well suited. The provisional European Critical Level for ozone, the AOT40 must, in order to be a meaningful criterion for field applications, be further refined. Continuing the Critical Load concept, the spatial risk of acid depositions in areas of high geomorphic variability were evaluated using the new parameter of 'critical soil depth'. With the help of the newly defined 'lead accumulation index', the accumulation of Pb from air pollution could be evaluated. Air-pollution inputs and the spatial acidification risk is directly related to altitude. Up to altitudes of 1000 m and 1100 m, SO2 impact and acid depositions, respectively were indicated and elevated ozone doses and Pb inputs were observed in the sensitive sub-alpine areas. These results underline the necessity for increased protection of mountain forest ecosystems, among others through a further reduction of emissions or forest-related strategies.     

Evaluation of approaches to calculate critical metal loads for forest ecosystems

This paper evaluates approaches to calculate acceptable loads for metal deposition to forest ecosystems, distinguishing between critical loads, stand-still loads and target loads. We also evaluated the influence of including the biochemical metal cycle on the calculated loads. Differences are illustrated by examples of Cd, Cu, Pb and Zn for a deciduous forest on five major soil types in the Netherlands. Stand-still loads are generally lower than critical loads, which in turn are lower than the target loads indicating that present levels are below critical levels. Uncertainties in the calculated critical loads are mainly determined by the uncertainty in the critical limits and the chemical speciation model. Including the metal cycle has a small effect on the calculated critical loads. Results are discussed in view of the applicability of the critical load concept for metals in future protocols on the reduction in metal emissions.     

Combination of beehive matrices analysis and ant biodiversity to study heavy metal pollution impact in a post-mining area (Sardinia, Italy)

Mining activities represent a major source of environment contamination. The aim of this study was to evaluate the use of bees and ants as bioindicators to detect the heavy metal impact in post-mining areas. A biomonitoring programme involving a combination of honeybee hive matrices analysis and ant biodiversity survey was conducted over a 3-year period. The experimental design involved three monitoring stations where repeated sampling activities focused on chemical detection of cadmium (Cd), chrome (Cr) and lead (Pb) from different matrices, both from hosted beehives (foraging bees, honey and pollen) and from the surrounding environment (stream water and soil). At the same time, ant biodiversity (number and abundance of species) was determined through a monitoring programme based on the use of pitfall traps placed in different habitats inside each mining site. The heavy metal content detected in stream water from the control station was always below the analytical limit of quantification. In the case of soil, the content of Cd and Pb from the control was lower than that of mining sites. The mean heavy metal concentrations in beehive matrices from mining sites were mainly higher than the control, and as a result of regression and discriminant analysis, forager bee sampling was an efficient environmental pollution bioindicator. Ant collection and identification highlighted a wide species variety with differences among habitats mostly associated with vegetation features. A lower variability was observed in the polluted landfill characterised by lack of vegetation. Combined biomonitoring with forager bees and ants represents a reliable tool for heavy metal environmental impact studies.     

Volcanic and anthropogenic contribution to heavy metal content in lichens from Mt. Etna and Vulcano island (Sicily)

Major and trace element concentrations were determined in two lichen species (Parmelia conspersa and Xanthoria calcicola) from the island of Vulcano and all around Mt. Etna. In both areas, the average concentrations of Al, Ca, Mg, Fe, Na, K, P and Ti are substantially greater than those of other elements. Several elements (Br, Pb, Sb, Au, Zn, Cu) resulted enriched with respect to the local substrates. The Br and Pb enrichment factors turned out to be the highest among those calculated in both areas. Data indicate that mixing between volcanic and automotive-produced particles clearly explains the range of Pb/Br shown by lichen samples. Sb is also enriched, revealing a geogenic origin at Vulcano and a prevailing anthropic origin at Mt. Etna. Distribution maps of the enrichment factors show a generalized enrichment of Au and Zn near Mt. Etna, whereas Cu appears to be enriched prevalently in the NE-SE area. The highest levels of Au and Cu at Vulcano occur E-SE from the craters, following the prevailing wind direction.     

PIXE trace element analysis of an aquatic plant as indicator of heavy metal pollution

A new way of detecting trace elements in water is developed by using charged $\text{P}$article $\text{I}$nduced $\text{X}$-ray $\text{E}$mission (PIXE) analysis of cell walls of $\text{Chara corallina}$, a fresh water alga.     

Decomposition of heavy metal contaminated nettles (Urtica dioica L.) in soils subjected to heavy metal pollution by river sediments

Two incubation experiments were conducted to evaluate differences in the microbial use of non-contaminated and heavy metal contaminated nettle (Urtica dioica L.) shoot residues in three soils subjected to heavy metal pollution (Zn, Pb, Cu, and Cd) by river sediments. The microbial use of shoot residues was monitored by changes in microbial biomass C, biomass N, biomass P, ergosterol, N mineralisation, CO(2) production and O(2) consumption rates. Microbial biomass C, N, and P were estimated by fumigation extraction. In the non-amended soils, the mean microbial biomass C to soil organic C ratio decreased from 2.3% in the low metal soil to 1.1% in the high metal soils. In the 42-d incubation experiment, the addition of 2% nettle residues resulted in markedly increased contents of microbial biomass P (+240%), biomass C (+270%), biomass N (+310%), and ergosterol (+360%). The relative increase in the four microbial properties was similar for the three soils and did not show any clear heavy metal effect. The contents of microbial biomass C, N and P and ergosterol contents declined approximately by 30% during the incubation as in the non-amended soils. The ratios microbial biomass C to N, microbial biomass C to P, and ergosterol to microbial biomass C remained constant at 5.2, 26, and 0.5%, respectively. In the 6-d incubation experiment, the respiratory quotient CO(2)/O(2) increased from 0.74 in the low metal soil to 1.58 in the high metal soil in the non-amended soils. In the treatments amended with 4% nettle residues, the respiratory quotient was constant at 1.13, without any effects of the three soils or the two nettle treatments. Contaminated nettle residues led generally to significantly lower N mineralisation, CO(2) production and O(2) consumption rates than non-contaminated nettle residues. However, the absolute differences were small.     

Limited effects of heavy metal pollution on foraging and breeding success in the curlew (Numenius arquata)

We examined the effect of heavy metal pollution on the foraging success and breeding performance of the curlew (Numenius arquata) along a documented pollution gradient from a point source, and also by comparing foraging and breeding parameters between the polluted site and two non-polluted areas. Prey biomass and abundance, and foraging success did not vary along the pollution gradient, and were no less at the polluted site than in the non-polluted areas. Furthermore, there was no difference in adult weight during incubation between the polluted and non-polluted areas. There were also no differences in measures of breeding success along the pollution gradient, or between areas, which could be attributed to pollution per se. Egg shells from the polluted area had higher concentrations of heavy metals than in the non-polluted areas, and egg shells close to the pollution source were contaminated more than those further from it. However, there was no difference in calcium concentrations of egg shells or egg-shell thickness between areas. We conclude that in this study there were minimal immediate effects of heavy metal pollution on foraging and breeding success in the curlew.     

The reproductive success and quality of blue tits (Parus caeruleus) in a heavy metal pollution gradient

Studying the effects of pollution on the reproductive performance of birds in the natural environment is of increasing importance due to the need to monitor environmental quality biologically. In this study we investigated the reproductive success and the quality of blue tits in four study sites (at 0.1, 1, 2.5 and 4 km from a metallurgic smelter) located within a heavy metal pollution gradient during three consecutive years. At the two sites closest to the pollution source, a significantly higher proportion of females had egg laying interruptions, and the interruptions also lasted longer (although not significantly). Although the hatching success differed significantly among sites, these differences could not be related to differences in pollution levels. Other important breeding parameters such as the start of egg laying, the clutch size and the breeding success did not differ significantly among sites. Our results suggest that exposure to heavy metal pollution did not influence blue tit reproduction in an important way.     

The heavy metal content of the teeth of the bank vole (Clethrionomys glareolus) as an exposure marker of environmental pollution in Poland

This investigation is based on the premise that heavy metals are sequestered by the mineral phase of teeth, hydroxyapatite, during their formation. Once formed these tissues are not subject to significant turnover and it is suggested, therefore, that they provide a permanent and cumulative record of heavy metal exposure during the development of the teeth. The teeth of the bank vole (Clethrionomys glareolus) were analysed by inductively coupled plasma mass spectrometry to monitor the animals' exposure to lead, cadmium, zinc, copper and strontium. Animals were trapped in clean and polluted areas in Poland in and around Krakow in 1996 and in Olkusz and Legnica in 1996 and 1997. The control area in 1996 was Bieszcady National Park and in 1997 Borecka Forest. The results showed that there were statistically different concentrations of heavy metals in the teeth of animals from different sites. The high levels of pollution from industrial emissions were related to higher concentrations of heavy metals in the teeth. Unexpectedly high levels of heavy metals in the teeth of animals from Bieszczady National Park, thought to be environmentally clean, suggested cross-border pollution from Slovakia and the Ukraine. It was concluded that the teeth of small mammals, such as the bank vole, are a sensitive and reliable marker of environmental pollution by heavy metals.     

Speciation as a screening tool for the determination of heavy metal surface water pollution in the Guadiamar river basin

The Guadiamar river basin has traditionally received pollutants from two main sources: in its northern section of mining origin, and in its southern section (next to Do?ana National Park) from urban-industrial and agricultural sources. In April 1998, the spill of 6 million m3 of mining wastes (acidic waters and sludge) severely polluted the Guadiamar river basin with heavy metals, which caused serious damage to the local ecosystem. There is a direct association between the physicochemical speciation of an element and its toxicity, biological activity, bioavailability, solubility, etc. This work describes a distribution study of the metals Zn, Cd, Pb and Cu by speciation analysis of surface waters in eleven sampling points of the Guadiamar river basin. Four metal fractions were determined using anodic stripping voltammetry: labile metal forms, H+ exchangeable metal forms, strongly inert forms (associated with organic and inorganic matter in solution), and forms associated with suspended matter. Total concentrations in surface waters followed the trend Zn > Cu > Pb > Cd. The speciation study showed that Zn and Cd were present to a large extent in available forms (labile and H+ exchangeable), while Pb and Cu were found mostly in the less available forms (strongly inert). Moreover, the available forms were found in the northern section (mining pollution) and the strongly inert forms in the southern section (urban, industrial and agricultural pollution). These results can illustrate the potential value of speciation to discern between different sources of pollution.