Search

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.

Transplants of Flavoparmelia caperata (L.) Hale were used to test possible relationships between chlorophyll a fluorescence (CaF) and ambient atmospheric conditions (temperature, precipitation, SO2 and NOx levels). Portions of the same thalli collected in a pristine site (A) of the Trieste Karst were exposed at that site, as the control, and in four other sites (B E) in NE Italy, near to pollution monitoring stations. These sites had been selected in order to provide similar two by two climatic conditions (sites B,C: more humid; D,E: drier) and air pollution load (sites B,D: low; C,E: high). Before exposure and after 43 and 90 days of exposure, CaF measurements were carried out in the laboratory under controlled conditions. A classification of meteorological and pollution parameters recorded during exposure substantially confirmed the differences between site couplets. After 90 days, samples from sites A (control) and B (with very low pollution load) showed only slightly reduced NPQ, qN, Fo, and Fm values. Samples from site D, with medium air pollution load, and sites C,E, with high air pollution loads, showed proportionally greater variation for most of the CaF parameters. A highly significant correlation was found between NPQ, qN, Fm, and NOx pollution but not with SO2 or O3. Effects of NOx on lichens and possible action mechanisms are discussed. The results strongly suggest that CaF measurements of lichen transplants can be a valid tool in biomonitoring studies.

Although small bags containing living or dead moss or lichens are widely used to monitor persistent atmospheric pollutants in urban and industrial environments, uptake mechanisms and the reliability of this approach have been scarcely investigated. Shoots of the moss Hypnum cupressiforme Hedw. and lobes of the lichen Pseudevernia furfuracea (L.) Zopf from unpolluted areas were pre-treated by: 1) water washing (WL, WM); 2), oven drying at 120 °C for 24 h (OL, OM); 3) HNO3 washing (AL, AM); 4) NH4-oxalate extraction at 85 °C for 15 h (OLoxa, OMoxa, ALoxa, AMoxa). Four bags with 500 mg of each material were exposed for six weeks in Trieste and Naples (Italy) on the roof of automatic devices for continuous recording of NOx, SO2, CO, PM10, and climatic data. Two synthetic materials (A: quartz fibre filter Whatman QMA 1851047; B: cation-exchange filter Pall ICE 450) were exposed in the same conditions to compare uptake processes and accumulation capacity with bio-materials. 15 elements were analysed before and after exposure. CO2 gaseous exchange, chlorophyll fluorescence, chlorophyll content, and K, Ca and Mg intra- and extra-cellular distribution assessed in WL and WM. Results demonstrate that WM vitality was drastically reduced after the exposure in both sites, whereas WL vitality was mostly unmodified as shown by increased C and N content at levels reflecting CO and NOx pollution. Average concentrations (µg g-1 dry wt) of trace metals increased significantly in all materials and were scarcely influenced by the vitality or type of pre-treatment, although concentrations were always higher in moss shoots than in lichen lobes. For a reliable comparison between synthetic and biological materials, the specific surface area was estimated and concentrations expressed as ng cm-2. This resulted in similar concentrations in moss shoots and lichen lobes but significantly lower concentrations in synthetic materials. Passive capture of airborne particulate matter accounted for most of the metal uptake.

Blood lead (PbB) levels were determined in children living in Campania (in Naples and in a rural zone in the district of Caserta). Atmospheric lead (PbA) concentration in these considered areas was monitored for 1 yr (1993-1994). The children tested were questioned about common sources of lead, other than atmospheric, relating to their living and dietary habits. The PbB levels in children living in Naples were, at the 50th percentile, 13.8 micrograms/dl in males and 13.7 micrograms/dl in females; in children living in the rural area the median PbB levels were 8.9 micrograms/dl in males and and 8.8 micrograms/dl in females. The annual mean values of atmospheric lead were 1.15 +/- 0.24 micrograms/m3 in Naples and 0.23 +/- 0.07 micrograms/m3 in the rural area. Significant and congruent mean differences between urban and rural sites were found in children's blood and concurrent air lead. Considering the PbB level of 10 micrograms/dl as the maximum level that is not associated any known adverse effect in children, the Neapolitan group can be considered at risk of chronic intoxication by lead.

The intrathalline heterogeneity of chlorophyll a fluorescence (CaF) in thalli of the foliose lichen Flavoparmelia caperata was studied measuring Fo, Fm, Fv/Fm, ΔF/Fm′, NPQ and Ft in two spots of 25 mm2 positioned at ca 0.8 and 3 cm from the thallus margin. Measurements were carried out both in the field and in the laboratory using north-exposed, epiphytic thalli occurring in a deciduous wood of the Karst plateau (Trieste, NE Italy). With the exception of NPQ, all parameters were statistically higher in the marginal spots than in the central ones, suggesting that the level of photochemical activity is higher where the photobiont cells are more dense and younger. Fm and Fv/Fm of marginal spots measured in the field were statistically lower than those measured in the laboratory, probably as a consequence of the different pre-treatment conditions. The importance of selecting a specific measuring spot, particularly for biomonitoring purposes, is discussed.

Recent hypotheses suppose that dry lichens emit a faint chlorophyll a fluorescence because of a “long-wavelength quencher” embedded in the antenna complex that protects photosystem II (PSII) from photodamage. To verify in the field the PSII re-activation promptness induced by water availability, chlorophyll a fluorescence was measured on the epiphytic lichen Flavoparmelia soredians after two months without rainfall events in a Mediterranean cork oak wood (Bosco Santo Pietro, Sicily, Italy). Measurements were carried out at dawn and sunset on north- and south-exposed populations under different regimes of hydration and dark-adaptation. The results show that prolonged hydration increases the photochemical conveying of energy to PSII and decreases the non-photochemical energy dissipation that otherwise might occur in the antenna complex of the lichen photobionts. A slight decrease in PSII efficiency caused by photoinhibition was observed in thalli exposed to ambient light (up to 600 µmol photons m-2 s-1) only when kept fully hydrated. The results are discussed on the basis of our knowledge on the ecology of the species, that is a representative component of Mediterranean epiphytic lichen communities.

A thorough chemical, molecular and morphological study has been carried out on a problematic group in the genus Lepraria characterized by lobed, granular thalli with a raised rim and a preference for mosses, rocks and mineral soils in exposed, xeric habitats. The material examined was collected in seven countries of the Mediterranean-Macaronesian region, from chalk, carbonate rocks and derived soils (A-thalli), and from siliceous rocks and derived soils (B-thalli). The results of a phylogenetic analysis based on 93 ITS sequences (29 of which newly obtained) support the identification and the segregation of two taxa at species level, provisionally identified as Lepraria isidiata s. lat., (most of the A-thalli), and L. santosii s. lat. (B-thalli plus the remaining A-thalli), as the observed genetic variability is quite high. Three chemotypes were detected in L. isidiata s. lat., and seven in L. santosii s. lat. The two taxa are morphologically well characterized: in L. isidiata s. lat. the thallus is thicker and the propagules larger than in L. santosii s. lat. The first stages of thallus development from single propagules are described in both species. Some critical remarks are made about the increasing use of the species rank for taxa of Lepraria, which are morphologically and genetically scarcely characterized.