Roberto Bargagli

Biomonitoring of airborne metals in urban environments: new tracers of vehicle emission, in place of lead

Samples of Quercus ilex leaves and of the inhalable fraction of atmospheric particulate (PM(10)) were collected along a busy road and in a park in Florence (Italy). Quantitative comparisons and correlations of element concentrations in PM(10) collected by air samplers at two sites showed that Ba, Cu, Fe, Mn, Pb and Zn were the main metal pollutants emitted by vehicles in Florence. Very similar results were obtained by the analysis of Q. ilex leaves which were found to accumulate airborne metals as a function of the exposure time (i.e. their age). One-year-old leaves showed the highest rate of metal accumulation. Our results show that the progressive phasing-out of leaded petrol in Italy has resulted in a decrease of about 20% per year in the Pb concentrations in PM(10). Both PM(10) and Q. ilex analysis singled out Ba and Zn as valid tracers of automotive traffic instead of Pb.

Metal biomonitoring with mosses: procedures for correcting for soil contamination

Highly variable total concentrations of 15 elements have been found in five species of epigeic mosses growing in remote areas of Italy and in northern Victoria Land (continental Antarctica). It is very likely that soil particles entrapped in the mosses cause these high element concentration differences, thereby leading to inexact interpretations of baseline concentrations and of element distribution in different parts of mosses. A simple procedure for estimating more plausible background values that consists of subtracting the substratum contribution from raw concentrations of elements in mosses is reported. The normalization of total concentrations to the regional soil composition is also emphasized, in order to point out other possible metal sources.

Elevated cadmium accumulation in marine organisms from Terra Nova Bay (Antarctica)

As a contribution towards identification of the principal environmental factors involved in cadmium accumulation in Antarctic marine organisms and the establishment of a baseline near the Italian Antarctic Station “Baia Terra Nova”, surface sediments, plankton and benthic organisms were studied in coastal waters of Terra Nova Bay (Ross Sea). The cadmium content of sediments was similar to that regarded as background in most marine coastal areas, whereas in surface water, phytoand Zooplankton it was similar to values measured in areas of enhanced upwelling. Algal and animal taxa dominating benthic associations had a higher cadmium content than related species from other seas. Very high concentrations of the metal were found in sponges (10–80 μg/g dw) and in the digestive gland of molluscs (up to 345 μg/g inNeobuccinum eatoni). The rapid regeneration of cadmium and its natural occurrence and bioavailability in highly productive coastal waters seem to be responsible for cadmium accumulation in the tissues of marine organisms near the “Baia Terra Nova” station.

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.

The elemental composition of vegetation and the possible incidence of soil contamination of samples

Samples of olive leaves, the lichen Parmelia perlata (from the same trees) and the moss Scleropodium purum were collected in relatively uncontaminated areas of Calabria and Tuscany (Italy). Total concentrations of Al, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn were determined in unwashed samples. Concentrations of lithophilic elements in mosses collected at the same samplings were higher in dry and barren environments, whereas in lichens they where significantly higher at the end of the dry season. These variations were probably due to the quantities of soil particles trapped in the samples. The normalization of raw concentrations to soil composition is advisable before making comparisons, assessing baseline concentrations and calculating patterns of trace element fallout over large areas.

Barium and Other Trace Metals as Indicators of Vehicle Emissions

In the Siena urban environment, unwashed Q. ilex leaves had a significantly higher Al, Ba, Cr, Fe, Mn, Na, Ni, Pb, Ti, and V content than samples from a neighbouring Mediterranean maquis. Significant relationships between element pairs indicated both the presence of metals emitted by motor vehicles and lithophilic elements, presumably from soil particles, resuspended by wind or turbulence generated by traffic. In order to minimize the effects of soil dust contamination and to seek clues to the metal sources, the estimated substrate contribution was subtracted from the raw concentrations of elements in Q. ilex leaves. Normalization for local soil composition confirmed that automotive emissions are the principal source of pollution in Siena. On the basis of a very significant relationship between normalized concentrations of Pb and Ba and the presence of the latter element in diesel and unleaded gasoline, Ba was recognized as a valuable tracer for vehicle emissions, in the place of Pb.

Passive monitoring of trace elements by means of tree leaves, epiphytic lichens and bark substrate

Total concentrations of Al, Cu, Fe, Hg, Mn, Mo and Zn in theepiphytic lichen Parmelia caperata, substrate bark andleaves of oaks (Quercus cerris and Q. pubescens)from a background area in Tuscany (central Italy) werecompared. The elemental composition of unwashed samples,especially bark, was clearly affected by soil dustcontamination, thereby leading to incorrect interpretations ofbaseline concentrations and relationships between elements.The normalization of total element concentrations to thesurface soil composition (digested and analyzed by the sameprocedures), using Al as reference element, gave more reliablebaseline values and allowed comparison between differentbiomonitors. The suitability of lichens, leaves and barks forstudying the environmental distribution of trace elements interrestrial ecosystems is discussed.

Mercury and methyl mercury in higher fungi and their relation with the substrata in a cinnabar mining area

One-hundred-ninety-five specimens of higher fungi and their substrata collected in the Hg mining area of M. Amiata and around Siena (Central Italy), were analyzed for their total Hg content. Whereas wood decomposers and many species of mycorrhizal fungi accumulated the metal at a very low rate, some mycorrhizal species and all the humus decomposers may accumulate up to 100 ..mu..g.g/sup -1/ d.w. of Hg and in the least contaminated sites, up to 63 times as much Hg as the substratum. Instead in mineralized areas the concentration factor rarely exceeded 1. The methyl mercury content of 35 species (almost all edible), ranged between 0.01 and 3.7 ..mu..g.g/sup -1/ d.w. The possible significance of these findings and the toxicologic implications for local consumers are considered.

Mercury, cadmium and lead accumulation in Antarctic mosses growing along nutrient and moisture gradients

Abstract Accumulation of Hg, Cd and Pb by moss was studied in a coastal ice-free area (Edmonson Point, northern Victoria Land) in relation to the water and nutrient availability and substratum characteristics. Although metal concentrations in surface soils were among the lowest ever reported from remote areas, those of Hg and Cd in mosses were higher, being in the same range as those usually reported in regional surveys in the northern hemisphere. By contrast, Antarctic mosses showed very low Pb concentrations, and no impact from local human activities was detected. Marine aerosols, seabird guano and volcanic emissions appeared to be the more probable sources of Cd and Hg. Besides atmospheric deposition, the main pathway of metals to mosses was probably through evapo-transpiration at their surface which determines an upward migration of ions and their bioaccumulation.

Determination of metal deposition patterns by epiphytic lichens

The use of epiphytic lichens as quantitative monitors of airborne heavy metals needs a standardization of collection, analytical procedures and of data elaboration. Evidence is given of a patterned metal accumulation in lichens and for the foliose species, the analysis of the outermost edge of the thallus is suggested. Moreover, the raw concentrations of metals must be normalized to the earths crustal abundance, as lichens entrap atmospheric particulates which are mostly constituted by soil and rock dust suspended by wind.