Heavy metals in lichens and their substrata of roadside phytocenoses in the south of the Tyumen region, Russia

The paper presents an analysis of the peculiarities of the accumulation process for the following heavy metals: Pb, Zn, Sr, and Cu in the bark of Betula pendula Roth (photophyte) and lichens Cladonia coniocraea (Flörke) Spreng., Cladonia fimbriata (L.) Fr., Physconia distorta (With.) J. R. Laundon, Hypogymnia physodes (L.) Nyl. The study sites were located in five administrative zones in the south of the Tyumen region, Russia: Uporovsk region, Zavodoukovsk region, Yalutorovsk region, Yarkovsky region and Tobolsk region. Based on the conducted study, it can be noted that in the bark of Betula pendula Roth of the studied areas, heavy metals varied within the following ranges: Pb 1.18-8.66; Zn 2.58-11.50; Sr 2.15-9.36; Cu 1.30-10.80 mg/kg, statistical significance level p<0.05, 0.01 and 0.001, respectively. In the accumulation of heavy metals by lichens, the location of the sampling point relative to the source of pollution is most important, followed by the species differences. Species differences of lichens are manifested mainly by the difference in the intensity of accumulation of microelements, while the ratio between elements varies little with the species. A high correlation between the content of metals in the thalli of lichens Cladonia coniocraea (Flörke) Spreng., Cladonia fimbriata (L.) Fr., Physconia distorta (With.) J. R. Laundon, Hypogymnia physodes (L.) Nyl. and in the bark of Betula pendula Roth (r=0,95-0.99). Accumulation of heavy metals in the studied components of forest ecosystems can be displayed structurally: the bark of photophytes > lichens. The exception is the accumulation of Sr (Cladonia fimbriata (L.) Fr., Hypogymnia physodes (L.) Nyl.), Cu (Cladonia fimbriata (L.) Fr.), Pb, Zn (Physconia distorta (With.) J. R. Laundon).