**4. Discussion**

The contents of heavy metals in the tested plants were compared to the natural and toxic contents of metals in plants provided by Kabata-Pendias and Pendias [4], which amount to, respectively: 0.05–0.2 and 5–30 μg Cd/g, 0.1–0.5 and 5–30 μg Cr/ g, 5–30 and 20–100 μg Cu/g, 0.1–5.0 and 10–100 μg Ni/g, 5–10 and 30–300 μg Pb/g, 27–150 and 100–400 μg Zn/g dm. It was found that the contents of copper and zinc in plants are within the natural ranges. However, the contents of cadmium, chromium, nickel, and lead in both plant species for both test areas exceeded the natural values. They were exceeded by several, or several dozen times: more than 3 times for lead and nickel, several times for cadmium, and the highest - several dozen times for chromium. Such high exceedances in the content of heavy metals in the tested plant species in relation to the natural value of these metals in plants indicate the anthropogenic pollution of the selected research areas. Owing to their location (TNP) and great natural value, the research areas should be free from anthropogenic pollutants, however, long-range emission in this case has a large impact on the quality of the natural environment. It should be noted that in mountain areas, the content in plants of heavy metals is influenced by long-range emissions. Communication and industrial pollutants from areas with increased emissions are transported over long distances, even several dozen to several hundred kilometers. The transport of pollutants is related to the prevailing wind directions. For the TNP area, the dominant wind direction is to the south-west. Dusts containing heavy metal are transported from this direction, i.e., from industrial areas in Poland (Silesia) as well as from the Czech Republic and Slovakia. Long-range emissions result in such a high accumulation of metals in plants of the protected area [32–34]. Additionally, the high accumulation of metals in the higher parts of the mountains is also influenced by high wind velocity and a large amount of precipitation [34].

Determining the content of heavy metals in the plants in the tested test areas, an increase in metals was found with increasing altitude. The increase in the metal content concerned all of the tested metals and two plant species. However, this increase was slight and similar for the Kasprowy Wierch and Morskie Oko test areas. Similarly to the author of the present study, an increase in the content of metals in plants along with an increase in altitude was found in their research by Shetekauri et al. [35] in the western Caucasus Mountains for As, Cd, Ti, W in mosses, Sahin et al. [36] in the Kumalar Mountains for Cu, Zn in herbaceous plants, Zechmeister [32] in the Alps for As, Pb, Zn, and V in the *P. schreberi* and *Hylocomium splendens*, Šoltés [37] for the content of Pb in the *Sphagnum girgensohnii* in the Tatra Mountains in Slovakia, Samecka-Cymerman et al. [38] in the Tatra National Park for the content of Cd, Ni, and Zn in the *Athyrium distentifoliu*, Panek [39] in the Poland's Carpathian region for Pb in *P. formosum* and Kuklová et al. [40]. Kuklová et al. [40] found an increase in the content of Cu and Zn in three plant species (the *Dryopteris filix-mas*, *Rubus idaeus*, and *V. myrtillus*) with an increase in altitude. They observed an increase in the Cd content for two plant species: the *D. filix-mas* and the *V. myrtillus*. The re-search was carried out in the Slovak Paradise National Park (Slovenský Raj National Park), Eastern Slovakia, collecting samples

Polytrichum formosum *and* Vaccinium myrtillus *as Phytoindicators of Pollutants… DOI: http://dx.doi.org/10.5772/intechopen.99962*

of plants growing at an altitude of 750, 760, 950, 960, 1,000, and 1,110 m above sea level.

Comparing the accumulation of metals in the two tested plant species, it can be seen that the moss *P. formosum* Hedw. has higher amounts of metals compared to the European blueberry *V. myrtillus* L. The higher accumulation of metals in the moss results from its morphological structure and the ability to accumulate pollutants. In addition, the moss accumulated pollutants for longer than the European blueberry, because in the case of the moss, it was the green parts of the plant (stem and leaves), estimated to be about 3 years old, that were sampled for analysis, while in the case of the European blueberry, it was the leaves (about six months old) that were sampled for analysis. This gives several times longer accumulation time of pollutants.
