Similarities and differences in geochemical distribution patterns in epiphytic lichens and topsoils from kindergarten grounds in Vilnius

Topsoil and lichen Phaeophyscia orbicularis were sampled from the grounds of kindergartens (Vilnius, Lithuania) using a side-by-side design and analysed for the total contents of Al, As, Br, Ca, Cl, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Si, Sr, Ti, V and Zn. Only Si, Mn and Zn were found to retain their positions in sequences arranged in descending order of their mean contents (>90mgkg−1) in topsoil (Si>Al>Ca>K>Fe>Mg>Na>Ti>P>S>Mn>Cl>Zn) and in lichens (Si>Ca>K>S>Al>Fe>P>Mg>Na>Cl>Mn>Ti>Zn). In lichen thalli, unlike in topsoil, nutrients and lithogenic elements formed separate clusters. Results proved that by origin, the elements captured by lichens were not only from the immediate environs, but also from more distant city districts with different soil lithology. However, both in topsoil and in lichens, As, Cr, Cu, Mo, Ni, Pb, V and Zn form together with S and Br clusters of closely related elements indicating that Phaeophyscia orbicularis is a good urban indicator of polluting elements using which total contamination indices of topsoil ZT and of lichens ZL can be calculated. Higher ZT values were detected in the former industrial-residential areas, while ZL values were higher in new residential-commercial areas. The ratio ZT/ZL was found to be useful in revealing areas where pollution is on the increase.