Lichen and moss bags as monitoring devices in urban areas. Part I: influence of exposure on sample vitality

Samples of the lichen Pseudevernia furfuracea (L.) Zopf and the moss Hypnum cupressiforme Hedw. were exposed for 6 weeks in nylon bags in two air pollution monitoring stations in Trieste and Naples (Italy) with different climates and pollution loads to evaluate influence of environmental conditions on sample vitality. This was assessed before and after exposure by transmission electron microscopy observations, K cellular location, and measurements of C, N, S and photosynthetic pigments content, CO2 gas exchange, and chlorophyll fluorescence. Almost all data sets indicate that exposures caused some damage to the species, considerably heavier in the moss, especially in Naples. The two cryptogams differed significantly in accumulation and retention of C, N, and S, the lichen clearly reflecting NO2 availability. The difference in vitality loss was related to the different ecophysiology of the species, because concentrations of phytotoxic pollutants were low during exposure. Critical notes on the analytical techniques are also given.     

Bags with oven-dried moss for the active monitoring of airborne trace elements in urban areas

To define a harmonized methodology for the use of moss and lichen bags as active monitoring devices of airborne trace elements in urban areas, we evaluated the element accumulation in bags exposed in Naples in different spring weather conditions for 6- and 12-weeks. Three different pre-exposure treatments were applied to moss and lichen materials: water-washing, acid-washing and oven-drying. During the different exposure periods in the Naples urban environment the moss accumulated always higher amounts of elements (except Hg) than lichens and the element accumulation increased during wetter weather and higher PM₁₀ conditions. The oven pre-treatment did not substantially modify the morphology and element composition of moss and the exposure in bags of this material for 6-weeks was sufficient to detect the pattern of airborne trace elements.     

Lichens and mosses as biomonitors of trace elements in areas with thermal springs and fumarole activity (Mt. Amiata, central Italy)

The contribution of thermal springs and fumaroles to environmental levels of Al, As, B, Cd, Cu, Fe, Hg, Mo, Pb, S, Sb and Zn was evaluated by means of lichens (Parmelia sulcata) and mosses (Hypnum cupressiforme) used as bioaccumulators. Compared to the data reported for unpolluted areas, accumulation of Hg, S and Al was found, with values of Hg and S in the same range as in the vicinity of geothermal power plants. Furthermore, fumaroles turned out to be a significant source of atmospheric arsenic.     

Mosses and lichens as biomonitors of trace metals. A comparison study on Hypnum cupressiforme and Parmelia caperata in a former mining district in Italy.

Samples of the moss Hypnum cupressiforme and the epiphytic lichen Parmelia, caperata were collected during the summer of 1999 in an area (Colline Metallifere, central Italy) intensively exploited in the past for metals (Cu, Fe, Pb, Zn) and currently for geothermal resources. Lichens were more sensitive than mosses to emissions of S compounds near geothermal fields and abandoned sulphide ore smelting plants. Comparison of elemental compositions of the two cryptogamic species from the same sampling sites showed significantly higher concentrations of lithophile elements (Al, Cr, Fe, Mn, Ni, Ti) in the moss and atmophile elements (Hg, Cd. Pb, Cu, V, Zn) in the lichen. Patterns of bioaccumulation of elements throughout the study area were quite similar for widespread pollutants such as S, B, As, Zn, Cr and Ni, but the lichen and the moss showed different distribution patterns of Hg, Cd and other elements subject to long-range atmospheric transport. These results are due to differences in the morphology and ecophysiology of mosses and lichens and indicate that these organisms cannot be used interchangeably as biomonitors of metals in areas with mineral deposits.     

Impact of river overflowing on trace element contamination of volcanic soils in south Italy: part II. Soil biological and biochemical properties in relation to trace element speciation

The effect of heavy metal contamination on biological and biochemical properties of Italian volcanic soils was evaluated in a multidisciplinary study, involving pedoenvironmental, micromorphological, physical, chemical, biological and biochemical analyses. Soils affected by recurring river overflowing, with Cr(III)-contaminated water and sediments, and a non-flooded control soil were analysed for microbial biomass, total and active fungal mycelium, enzyme activities (i.e., FDA hydrolase, dehydrogenase, beta-glucosidase, urease, arylsulphatase, acid phosphatase) and bacterial diversity (DGGE characterisation). Biological and biochemical data were related with both total and selected fractions of Cr and Cu (the latter deriving from agricultural chemical products) as well as with total and extractable organic C. The growth and activity of soil microbial community were influenced by soil organic C content rather than Cu or Cr contents. In fact, positive correlations between all studied parameters and organic C content were found. On the contrary, negative correlations were observed only between total fungal mycelium, dehydrogenase, arylsulphatase and acid phosphatase activities and only one Cr fraction (the soluble, exchangeable and carbonate bound). However, total Cr content negatively affected the eubacterial diversity but it did not determine changes in soil activity, probably because of the redundancy of functions within species of soil microbial community. On the other hand, expressing biological and biochemical parameters per unit of total organic C, Cu pollution negatively influenced microbial biomass, fungal mycelium and several enzyme activities, confirming soil organic matter is able to mask the negative effects of Cu on microbial community.     

Implementation of airborne trace element monitoring with devitalised transplants of Hypnum cupressiforme Hedw.: assessment of temporal trends and element contribution by vehicular traffic in Naples city

A biomonitoring of airborne trace elements was performed in 2006 in Naples urban area through the exposure of devitalised Hypnum cupressiforme for 10 weeks at 4 m height. In one street, the moss was exposed at different heights to assess vertical gradients of element concentrations. Results were compared with those of a 1999 biosurvey. Correlations among Al, Fe and Ti suggested a soil particles contribution to element uptake. Cu, Mo and Fe were related with traffic flows. Long-range transport contributed to Cd, Cu and Mo accumulation in moss at higher heights. As in 1999, the airborne element load was higher in coastal sites, more affected by marine aerosols and traffic. In all sites, contents of Cd, Fe, Pb, Ni and V in moss were remarkably lower than in 1999, indicating a positive effect of actions set up in recent years to reduce the traffic and to improve the city air quality.     

A comparison of mussels (Perna viridis) and semi-permeable membrane devices (SPMDs) for monitoring chlorinated trace organic contaminants in Hong Kong coastal waters.

A comparison of mussels (Perna viridis) and semi-permeable membrane devices (SPMDs) was carried out at five sites, representing a gradient of contaminant concentrations, in Hong Kong coastal waters. Mussels, originally collected from a “clean” location, were deployed along with SPMDs at each site for 30 days. Analyses for chlorinated pesticides and polychlorinated biphenyls (PCBs) indicated that SPMDs have potential as monitoring tools, and to some extent can overcome the problems associated with mussels, such as natural variability, differing age, sex, and physical condition. However, in most cases, SPMDs failed to rank the sites in the same order as mussels in terms of contaminant concentrations. Nonetheless, in localities where mussels cannot survive – as shown at Kwun Tong in the present experiment – SPMDs may be valuable in providing an indication of potentially bio-available lipophilic pollutants.     

Heavy metals in urban soils of East St. Louis, IL. Part II: Leaching characteristics and modeling

The city of East St. Louis, IL, has a history of abundant industrial activities including smelters of ferrous and non-ferrous metals, a coal-fired power plant, companies that produced organic and inorganic chemicals, and petroleum refineries. Following a gross assessment of heavy metals in the community soils (see Part I of this two-part series), leaching tests were performed on specific soils to elucidate heavy metal-associated mineral fractions and general leachability. Leaching experiments, including the Toxicity Characteristic Leaching Procedure (TLCP) and column tests, and sequential extractions, illustrated the low leachability of metals in East St. Louis soils. The column leachate results were modeled using a formulation developed for fly ash leaching. The importance of instantaneous dissolution was evident from the model. By incorporating desorption/adsorption terms into the source term, the model was adapted very well to the time-dependent heavy metal leachate concentrations. The results demonstrate the utility of a simple model to describe heavy metal leaching from contaminated soils.     

Environmental risks of chemicals and genetically modified organisms: a comparison. Part II: Sustainability and precaution in risk assessment and risk management

The principles of precaution and sustainability require more consideration in the assessment of environmental risks posed by chemicals and genetically modified organisms. Instead of applying risk reduction measures when there are serious indications for damage, full scientific certainty is often waited for before taking action. The precautionary principle particularly should be applied in those cases in which the extent and probability of damage are uncertain, e.g. in the case of persistent chemicals which are additionally bioaccumulative or highly mobile. Based on these principles, environmental action targets for risks associated with GMOs and chemicals can be developed. Risk management not only includes statutory measures but also instruments designed to influence behaviour indirectly are important to achieve the goals. Particularly for risks of GMOs which provoke fear, risk communication is important. Some rules to which attention should be paid in communication with the public are presented.     

Chemical and biological profiles of sediments as indicators of sources of contamination in Hamilton Harbour. Part II: bioassay-directed fractionation using the Ames Salmonella/microsome assay

Bottom sediment and suspended sediment samples from Hamilton Harbour (western Lake Ontario) and from a major tributary were profiled using a bioassay-directed fractionation approach. Sample extracts were fractionated using an alumina/Sephadex gel clean-up procedure to afford non-polar aromatic fractions which were characterized using chemical analyses and the Ames/microsome bacterial assay in Salmonella typhimurium strains YG1025 with the addition of oxidative metabolism (S9), and YG1024 without S9. Non-polar aromatic fractions of selected samples were separated by normal phase HPLC into 1-min fractions which were subjected to bioassay analyses. The bioassays using strain YG1025+S9, a TA100-type strain, were performed to assess genotoxicity arising from the presence of polycyclic aromatic hydrocarbons (PAH). Fractions which exhibited mutagenic activity contained PAH with molecular masses of 252, 276 and 278 amu; these fractions contained over 80% of the genotoxicity attributable to PAH. Individual compounds identified using Gas Chromatography-Mass Spectrometry analyses in these active fractions included benzo[a]pyrene, indeno[cd]pyrene and dibenz[a,h]anthracene. The YG1025+S9 mutagenic activity profiles were similar for all samples. Mutagenic activity profiles generated using strain YG1024-S9, a TA98-type strain sensitive to compounds characteristic of mobile source emissions, were very different. The mutagenic activities in strain YG1024-S9 were greatest for harbour-suspended sediment samples collected from sites impacted by a major tributary. Suspended sediments collected near areas known to contain high levels of coal tar-contamination in the bottom sediments contained higher levels of genotoxic PAH than suspended sediments collected from other areas of the harbour.