Trace elements in lichen

Lichens are currently monitored to aid the control of air pollution and to follow changes in pollution patterns [20,21], Lichens are found almost everywhere and accumulate trace elements from the atmosphere therefore they are often used as a practical means for biomonitoring pollution [22,23]. The collection and analysis of 

Bottles were kept at, respectively, -20°C, +20°C and +40°C over a period of 12 months and the elements considered for the homogeneity study were determined at regular intervals during the storage period. Besides the slight variations attributed to measurement uncertainties, no instability could be demonstrated. The material was stored at ambient temperature. 

Eleven laboratories from nine countries participated in the certification (see section 6,7.5). Table 6.19 summaries the different techniques of final determination for the different elements as used by these laboratories. The pretreatment techniques were digestion with combination of acids in a pressurised or atmospheric mode, programmed 

SUMMARY OF TECHNIQUES OF FINAL DETERMINATION USED IN THE CERTIFICATION OF TRACE ELEMENTS IN LICHEN CRM 482 

DCP-AES, ETAAS, ICP-AES, ICP-MS, INAA HAAS, ICP-MS, INAA, RNAA DPASV, ETAAS, ICP-AES, ICP-MS, IDMS ETAAS, IDMS, INAA, RNAA 

---

In the certification exercise of trace elements in lichens (BCR-CRM 482) two or more laboratories applied the same technique of final determination for the same element. In such a case it was possible to compare the results per technique. A grand mean of the means of all the three or more laboratories applying the same technique of final determination was calculated. The obtained grand means were then compared to investigate whether a particular bias could be attributed to any method. The bar-graphs present the grand mean per technique of final measurement (for those elements where this was possible) together with the standard deviation of the set. The table presents the results of the evaluation. 

Saiki, M., Chaparro, C.G., Vasconcehos, M.B.A., Marcehi, M.P., 1995. Determination of trace elements in lichens by instrumental neutron activation analysis. In 7th International Conference on Modern Trends in Activation Analysis, Seoul, Korea, September 24-30, 1995. 

Sloof, J.E., Wolterbeek, H.Th., 1991b. Pattern in trace elements in lichens. Water Air Soil Pollut. 57-58, 785-795. 

Lichens accumulate trace elements from the atmosphere and thus are frequently used instead of air filters for pollution monitoring. Certification of nine elements (Al, As, Cd, Cr, Cu, Hg, Mo, Ni, Pb, and Zn) by a group of ii selected laboratories was performed in BCR CRM 482 (Lichen) after an inter-comparison on trace elements in samples of this material (Quevauviller et al. 1996b). 

Loppi, S. Bonini, I. 2000. Lichens and mosses as biomonitors of trace elements in areas with thermal springs and fumarolic activity (Mt. Amiata, Central Italy). Chemosphere, 41, 1333-1336. 

Jenkis da (1987) Trace elements in saxicolous lichens. In Coughtrey PJ, Martin MH and Uns-worth MH, eds. Pollutant Transport and Fate in Ecosystems, pp. 249-253. Blackwell Sci Publ ... 

Apart from the metal rich zones in the neighborhood of ore deposits and other rocks especially rich in particular trace elements such as peridotites and serpentinites, from central Europe, little data exist yet on the dependence of trace element behavior in common rocks. For several elements, such as Ni and As, upper limits of the trace uptake of plants seem to exist. As soil and plant concentrations are concerned, the uptake is normally dependant on the available concentrations determined with extraction methods such as 0.1 N NaN03. Whereas data on higher plants are relatively abundant, more data on naturally Influenced trace elements in mosses and lichens would certainly be useful. 

Both instrumental NAA (INAA) and PIXE are available at the Instituto Tecnol6-gico e Nuclear (ITN), Sacavem, Portugal, and have been applied in a national study on atmospheric trace elements, using lichens as biomonitor materials. In the present paper, this survey is used to illustrate the potential of NATs in environmental studies. 

Loppi, S., Bargagli, R., 1996. Lichen biomonitoring of trace elements in a geothermal area (central Italy). Water Air Soil Pollut. 88, 177-187. 

Loppi S, Riccobono F, Zhang ZH, Savic S, Ivanov D, Pirintsos SA (2003) Lichens as biomonitors of uranium in the Balkan area. Environ Pollution 125 277-280 Di Leila LA, Frati L, Loppi S, Protano G, Riccobono F (2003) Lichens as biomonitors of uranium and other trace elements in an area of Kosovo heavily shelled with depleted uranium rounds. Atmos Environ 37 5445-5449... 

Trace elements are heavy atoms linked to organic compounds by coordination or covalent bonds these are Fe, I, Cu, Mn, Zn, Co, Mo, Se, Cr, Sn, V, F, and Si. Except for F, all these elements can be detected by XRF/PIXE. Trace elements in living matrices are not often coincidental contaminants but fulfill important functions. The presence of heavy metals in lumps, cryptogram, mosses, and lichens has been recognized and they are used as bio-indicators. Many of these elements can be detected by atomic absorption (AA) or by specific electrodes but using XRF/FIXE, no chemical separation is necessary. Using PIXE techniques, it may not be possible to identify light elements like C, N, O, F, Na but it is certainly possible by the other accelerator-based techniques like nuclear reactions. 

Quevauviller Ph, Herzig R. and Muntau H (1996b) Certified reference material of lichen (CRM 482) for the quality control of trace element biomonitoring. Sci Total Environ 187 143-152 Quevauviller Ph, Lachica M., Barahona E, Rauret G, Ure A, Gomez A, and Muntau H (1997) The certification of the EDTA-extractable contents (mass fractions) of Cd, Cr, Ni, Pb, and Zn and of the DTPA-extractable contents (mass fractions) of Cd and Ni in calcareous soil by the extraction procedures given CRM 600. EUR Report 17555 Quevauviller Ph. Maier EA, and Griepink B, eds. (1995) Quality Assurance for Environmental Analysis. Elsevier. Amsterdam. 

Fahselt, D., Wu, T. W. Mott, B. (1995). Trace element patterns in lichens following uranium mine closures. The Bryologist, 98, 228-34. 

Y. Olmez, C. M. Gulovali, G. E. Gordon, Trace element concentrations in lichens near coal fired power plants, Atmos. Environ., 19 (1985), 1663-1669. 

Monaci et al. (1997) performed a lichen-biomonitoring study in Siena by means of two different methods. The pattern of air quality in the study area was examined on the basis of the in situ frequency of different species of epiphytic lichens, i.e. using their species-specific sensitivity to the complex mixture of phytotoxic pollutants in the urban environment. The distribution of trace elements was evaluated quantitatively by an analysis of thalli of a tolerant species, P. caperata, known to be a reliable bioaccumulator of persistent atmospheric pollutants. The values obtained for Al, Ba, Cr, Cu, Fe, Pb and S were significantly higher in Sienese lichens over and above controls. Traffic was found to be the major source of atmospheric pollution. The pattern of trace-elemental deposition did not always coincide with air quality. lAP values were found to reflect essentially the emission of gaseous phytotoxic pollutants in the urban environment. 

Bargagli et al. (1997) performed a study which applied a method of passive biomonitoring of trace element deposition in urban, industrial and reference areas in Italy, especially in Tuscany, Veneto and Friuli, by means of epiphytic lichens, mainly P. caperata, P. sulcata and X. parietina. Despite the fact that the Pb content of gasoline in Italy was lowered from 0.4 to 0.15 g in 1991, samples of P. caperata collected in the urban environment of Siena still contained considerable amounts of Pb. The data presented in this study included average amounts of Al, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn in lichens from five urban areas in northern and central Italy, from the entire region of Veneto, Tuscany and from remote areas in Calabria. It was shown that the pattern of urban pollution was characterized to a great extent by high values of Al, Cd, Cu, Ni and Pb. Traffic appeared to play a prominent role as these metals are known to be released by vehicular activity. 

Bargagli, R., Nimis, P.L., Monaci, F., 1997. Lichen biomonitoring of trace element deposition in urban, industrial and reference areas of Italy. J. Trace Elem. Med. Biol. 11, 173-175. 

Jeran, Z., Jacimovic, R., Smodis, B., Batic, F., 1996b. The use of lichens in atmospheric trace element deposition studies in Slovenia. Phyton 36, 91-94. 

Trace metals, other chemical elements and lichen physiology research in the nineties... 

To evaluate the feasibility of the use of lichens as in situ biomonitors of atmospheric pollution in a semiarid climate, Rope and Pearson (1990) applied two techniques of evaluation in their study area in Idaho trace element analysis and electrolyte leakage from cells. The lichen Lecanora melanophthalma accumulated for the most part higher levels of elemental content than vascular plants such as Artemisia tridentata and either comparable or lower levels than soil. The above-mentioned lichen was the only species to show a significant difference in electrolyte leakage which could be associated with the distance from a chemical processing plant. 

Bergamaschi L, Rizzio E, Valcuvia MGL et al (2002) Determination of trace elements and evaluation of their enrichment factors in Himalayan lichens. Environ Pollut 120 137-144 Bindlera R, Renberga I, Klamindera J et al (2004) Tree rings as Pb pollution archives A comparison of Pb/ Pb isotope ratios in pine and other environmental media. Sci Total... 

---