**4. Indirect effects of industrial emissions – A case study of SMZ JSC Jelšava**

#### **4.1. Results**

Community characteristics and ecological indices (H′, MI2-5, and SI) indicated that the soil conditions at our sites were significantly stressed by the contaminants. Generic richness and H′ were lower under higher loads of heavy metals. The lightly contaminated K4 site had the highest diversity of nematode genera, belonging to the entire c-p scale, including opportunists (e.g. *Rhabditis*, *Acrobeloides*, and *Aphelenchus*) and persisters (e.g. *Dorylaimus*, *Oxydirus*, and *Nygolaimus*). The proportion of persisters with higher c-p values rapidly decreased with increasing pollution, which consequently led to lower nematode diversity and a simplification of the food chain. Diversity was mostly negatively correlated with the degree of pollution, but nematode abundance increased at moderately contaminated K2 and K3, but rapidly decreased under a heavy load at K1. Sánchez-Moreno et al. [39] reported similar findings in southern Spain after the Aznalcollar mining spill. A higher generic diversity reflects a higher resilience of ecosystems and complexity of relationships at all trophic levels [45, 46]. A decrease in generic diversity may cause an ecosystem to regress to an earlier successional stage or even to collapse. On the other hand, an increase in total density under a low or moderate degree of pollution does not necessarily indicate an uncontaminated environment but rather better survival conditions, as in our study (the growth in the population of opportunistic nematodes). Contamination can in some cases act as a direct or indirect stimulus to a particular component of the ecosystem and lead to inaccurate assessments of the actual environmental state [4]. Nevertheless, the generic composition of the nematode communities and several of the ecological indices (EI, SI, and MI2-5) suggest that a certain amount of regression is occurring

Georgieva et al. [42] have studied the combined effect of heavy metals. The maturity of an ecosystem, measured by MI2-5, was negatively affected more under significantly lower polymetallic contamination than if the heavy metals were applied separately. A nematode community was highly insensitive to Cd, showing no significant changes, at soil concentrations up to 160 mg kg-1 [47]. Similar insensitivities in nematode communities were also described for increased levels of As [48]. The toxicity of some elements, though, can increase in combi‐ nation with other heavy metals and may have negative impacts on nematodes [42]. This synergistic effect could thus be responsible for the decrease in MI2-5 and SI towards the pollution source in our study, despite their nonsignificant correlation with the heavy metals.

The analysis of SI and EI at Krompachy indicated significant differences amongst the sites in structural complexity and resource availability of the ecosystem. The graphic representa‐ tion of the SI and EI parameters (Figure 3) mapped K4 in quadrat B (maturing ecosystem with low or moderate disturbance), K1 and K2 in quadrat A (ecosystem under high disturbance and with a disturbed food web), and K3 in quadrat D (stressed ecosystem with a degraded food web). These results indicated differences in the composition of the structural component (c-p groups 3-5) rather than the enrichment component (c-p 1) [49]. The shift in the ecosystem in our study under heavy metal pollution corresponded well

The decomposition of organic matter can also have a large impact on the development of a soil ecosystem and its maturity. The rate of breakdown of organic matter depends on soil condi‐ tions and the participation of a variety of decomposers [11]. We studied decomposition using

in the study area closer to the pollution source.

36 Emerging Pollutants in the Environment - Current and Further Implications

with the conditions reported by [50, 51, 52].

#### *4.1.1. Heavy metals*

The total concentrations of heavy metals in the soil were relatively low and did not exceed the limits for uncontaminated soils (Table 6) set by [26]. Only the concentration of Mg increased, where the total and mobilisable concentrations were more than ten-fold higher at J1 (568.2 and 423.9 mg kg-1, respectively) than at J4 (46.03 and 16.4 mg kg-1, respectively). The increasing Mg gradient, but also for other heavy metals (Cr, Cu, Ni, and Zn) towards the pollution source (J1) is shown in Figure 4.

#### *4.1.2. Composition of the nematode fauna: trophic and c-p groups*

A total of 52 nematode genera were identified (Table 7). The abundance of most genera, e.g. *Helicotylenchus*, *Aphelenchoides*, *Axonchium*, and *Oxydirus,* increased with distance from the pollution source, but some genera, e.g. *Acrobeloides* and *Rhabditis*, dominated only at the most polluted site, J1. The generic richness was approximately two-fold higher at J2-J4 than at J1 (Table 8) and, as with abundance, was significantly (*P*<0.01) limited by pH (Table 9).


*Mobilisable fraction (Na2EDTA extraction)*


abcd Means followed by the same letters on the same rows are not statistically different according to Least Significant Difference Test (P<0.05)

Limit - limits posted by The Decree of the Ministry of Land Management of the Slovak Republic No. 531/1994-540 on the admissible values of harmful substances in uncontaminated soil. n.a. – not available

**Table 6.** Total and mobilisable concentration of trace elements in sampling sites from Jelšava (mg.kg-1) [53].

**Figure 4.** Redundancy analysis (RDA) performed on physicochemical soil properties, trace elements and selected indi‐ ces in relation to sampling sites with data explained 64.0 % of the variation in the first two axes; F=7.1; P=0.002 (Jelšava) [53].

The soil pH and concentrations of Mg, Cr, Cu, Ni, and Zn strongly (*P*<0.01) influenced all trophic groups, predators and omnivores in particular (Tables 8 and 9). Bacterivores, with more than 90% proportion in community at J1, were the only trophic group with a positive corre‐ lation (*P*<0.01) with pH, Cu, Mg, and Zn (Table 9). The proportion of plant feeders, the second most abundant trophic group, was relatively low (8.1%) near the pollution source, while fungivores reached a proportion of only 0.41%, omnivores 0.22%, and predators were absent in community (Table 8).

The distribution of the c-p groups amongst the sites supported their mapping according to r/ K characteristics. The group most tolerant to pollution, c-p 1, dominated under strong contamination (Table 8) and was able to survive even at the higher concentrations of Mg, Zn, and Cu (Table 9). The abundance of c-p 3 was positively correlated only with Cr and Zn (Table 9) and was highest at J1 (Figure 4), mostly due to a high frequency of bacterivores (*Prismato‐ laimus* and *Teratocephalus*) and plant feeders (*Pratylenchus*) (Table 7). In contrast, c-p 4 and 5 were sensitive to Cu, Mg, and Zn contamination and alkaline soil (Table 9), and occurred predominantly at the sites farthest from the pollution source. Representatives of c-p 2 were positively influenced mainly by Corg.

#### *4.1.3. Ecological indices*

**Trace elements Sampling site**

38 Emerging Pollutants in the Environment - Current and Further Implications

admissible values of harmful substances in uncontaminated soil. n.a. – not available

Difference Test (P<0.05)

[53].

**J1 J2 J3 J4 Limit**

*Arsenic (As)* 0.02±0.01a 0.05±0.03a 0.02±0.02a 0.02±0.002a n.a. *Cadmium (Cd)* 0.014±0.005bc 0.023±0.002d 0.008±0.001a 0.013±0.002b n.a. *Chrome (Cr)* 0.10±0.03c 0.02±0.004a 0.01±0.01a 0.02±0.004ab n.a. *Copper (Cu)* 5.13±2.27c 2.32±1.29ab 1.02±0.08a 1.64±0.26a n.a. *Magnesium (Mg)* 423.88±183.43c 60.13±6.12ab 47.75±14.50a 16.43±8.58a n.a. *Nickel (Ni)* 0.52±0.09d 0.30±0.02b 0.20±0.02a 0.34±0.02bc n.a. *Lead (Pb)* 0.48±0.14a 0.91±0.04b 0.75±0.11ab 0.72±0.42ab n.a. *Zinc (Zn)* 0.21±0.04d 0.12±0.03bc 0.06±0.01a 0.09±0.01ab n.a. abcd Means followed by the same letters on the same rows are not statistically different according to Least Significant

Limit - limits posted by The Decree of the Ministry of Land Management of the Slovak Republic No. 531/1994-540 on the

**Figure 4.** Redundancy analysis (RDA) performed on physicochemical soil properties, trace elements and selected indi‐ ces in relation to sampling sites with data explained 64.0 % of the variation in the first two axes; F=7.1; P=0.002 (Jelšava)

The soil pH and concentrations of Mg, Cr, Cu, Ni, and Zn strongly (*P*<0.01) influenced all trophic groups, predators and omnivores in particular (Tables 8 and 9). Bacterivores, with more

**Table 6.** Total and mobilisable concentration of trace elements in sampling sites from Jelšava (mg.kg-1) [53].

The ecological indices indicated degradation of the soil ecosystem at J1, most likely due to the exceptionally high alkalinity and Mg content (Figure 4). J3 had the highest diversity, as shown by H′, which decreased towards J1 (Table 8). MI2-5 and SI supported this trend, with significant changes (*P*<0.01) in values between J1 and J2 (Table 8).

The amount of available food resources in the soil system identified by EI was similar at all sites, but J3 had slightly less favourable conditions (Table 8). A graphic representation of EI and SI suggested a higher level of ecological disruption at J1 relative to the other sites (Figure 5). The trend in CI values reflected the increasing importance of fungi in the decomposition of organic matter with distance from the pollution source. The high concentration of Mg; higher levels of Cu, Zn, and Corg; and soil alkalinity were the most important factors influencing the structure and maturity of the nematode communities (Table 9, Figure 4).




**Table 7.** C-p values and the average abundance (±SD) of nematode genera in individual sampling sites from Jelšava [53].

#### **4.2. Discussion**

**Nematode genera**

**J1 J2 J3 J4**

**c-p Abundance Abundance Abundance Abundance**

*Diplogaster* 1 - 1.25±2.50 2.25±2.87 - *Eucephalobus* 2 8.75±4.11 8.25±5.50 8.25±9.54 1.25±1.89 *Heterocephalobus* 2 3.25±3.77 - - 0.50±1.00 *Chiloplacus* 2 4.00±5.66 - - - *Mesorhabditis* 1 11.50±7.72 4.75±9.50 - - *Monhystera* 2 - 1.00±2.00 1.00±0.82 1.50±1.73 *Panagrolaimus* 1 5.00±5.48 - - - *Plectus* 2 0.50±0.58 5.00±4.08 9.50±5.80 7.25±1.89 *Prismatolaimus* 3 5.25±3.40 6.25±7.59 - - *Rhabditis* 1 176±76.6 286±132.4 69.75±58.01 144.3±114.4 *Teratocephalus* 3 11.75±6.55 - - -

40 Emerging Pollutants in the Environment - Current and Further Implications

*Fungal feeders Aphelenchus* 2 1.25±1.89 9.00±3.56 19±8.04 19.75±9.67 *Diphtherophora* 3 - 1.50±1.73 2±1.83 0.5±0.58 *Dorylaimoides* 4 - 0.5±1 - - *Filenchus* 2 - 2.75±5.5 - 3.75±3.3

*Omnivores*

*Aporcelaimellus* 5 0.5±1 18±5.89 11.25±9.91 7.50±3.11 *Dorylaimus* 4 - 47±36.52 18.5±26.8 37±12.03 *Epidorylaimus* 4 - 11.25±8.06 0.5±0.58 0.5±0.58 *Eudorylaimus* 4 0.25±0.5 2.25±2.63 4±1.83 3.5±1.29 *Mesodorylaimus* 5 - 1.00±0.82 - 11.25±4.92 *Prodorylaimus* 5 - 6.75±6.8 9.75±9.84 12.75±11.67 *Predators*

*Anatonchus* 4 - 0.25±0.50 6.25±2.75 2±1.41 *Clarkus* 4 - 0.5±1 - 15.50±9.61 *Discolaimus* 5 - - 1.25±1.26 - *Miconchus* 4 - 2.00±2.31 2.00±2.16 0.25±0.50 *Mononchus* 4 - 0.50±0.58 0.50±1.00 - *Mylonchulus* 4 - 4.50±2.89 7.25±4.11 3.00±4.24 *Nygolaimus* 5 - 0.25±0.50 - - *Oxydirus* 5 - 16.50±22.22 17.25±9.18 93.75±88.28 In this case study, the long-term industrial emission of magnesite has affected the soil ecosys‐ tem, mostly by changing the basic soil conditions. Such high loads of Mg in the soils as recorded in our study are rare, so the impact of Mg emissions on soil fauna is not often studied and is not yet understood [53]. Similar steep increases in soil alkalinity as a direct consequence of industrial inputs of Mg as was found in our assay described also Machín and Navas [54]. Most studies have investigated the importance of Mg deficiency in higher plants as a trace element important in photosynthesis. Hronec [17] described a decrease in soil fertility and the replace‐ ment of native plant species by tolerant halophytes in an area with high Mg input. Moreover, the long-term fallout of Mg dust (>600 t km-2 y-1) may degrade natural ecosystems and create corrosive crusts that could affect natural interactions in the soil even more [17].

The absence of sensitive nematode groups, likely caused by an ineffective regulation of osmotic pressure by their cuticles due to changes in the concentrations of various ions in the soil pore water, can be a direct effect of altered soil conditions [55]. The concentrations of ions in soil solutions under extreme changes in pH may negatively affect the regulation of water by organisms [56], thereby disrupting homeostasis. A change in the concentrations of soil ions may thus have been an important factor responsible for the decrease in the higher c-p groups (mainly predators and omnivores with highly permeable cuticles) at the sites with high pH and Mg concentration. The indirect influence of contamination was likely a restriction in the availability of resources and the interactions necessary for survival or an effect on the abiotic attributes of the environment [32].


abcd Means followed by the same letters on the same rows are not statistically different according to Least Significant Difference Test (P<0.01).

**Table 8.** Percentage of individual nematode trophic groups and average of ecological indices values calculated for Jelšava sampling sites [53].

In areas with neutral soil pHs (as at J4), strong shifts in soil composition are usually expected after an increase in pH. Alterations in edaphic diversity after pH manipulation have been confirmed experimentally and by field studies. Earthworms, enchytraeids, and nematodes were more abundant after liming [57, 58], but Acari preferred acidic conditions [59, 60]. The altered soil conditions in our study as a consequence of Mg contamination and an extremely high pH have led to direct and indirect effects on the nematode communities and most likely influenced the composition of the entire soil fauna. The plant feeders showed the first signs of the indirect effects of high Mg levels. A fluctuation in plant feeder density is generally considered a sign of changes in primary production [61]. Excessive concentrations of Mg under alkaline conditions induce a deficiency of essential nutrients (e.g. Ca and P) and impede the development of plant root systems [62]. Relatively impoverished phytocoenoses composed mainly of halophytes such as *Puccinellia distans* or *Agrostis stolonifera* are usually found near pollution sources [63]. A shift towards bacterivorous nematodes in the community was another indication of an indirect influence of pollution in our study, because bacteria prosper more than fungi at alkaline pHs [63].

organisms [56], thereby disrupting homeostasis. A change in the concentrations of soil ions may thus have been an important factor responsible for the decrease in the higher c-p groups (mainly predators and omnivores with highly permeable cuticles) at the sites with high pH and Mg concentration. The indirect influence of contamination was likely a restriction in the availability of resources and the interactions necessary for survival or an effect on the abiotic

*Trophic & c-p groups Bacterial feeders* 91.31±6.28a 50.47±12.29bc 38.98±7.86cd 25.20±13.23d *Fungal feeders* 0.41±0.52a 3.02±3.49ab 6.16±2.38b 3.19±0.77ab *Omnivores* 0.22±0.26a 11.32±3.05a 11.24±9.64a 10.09±1.87a *Predators* 0±0a 4.38±3.22ab 12.67±9.17ab 14.94±8.21b *Plant feeders* 8.06±6.18a 30.80±14.86ab 30.95±14.16ab 46.59±5.97b *c-p 1* 67.96±5.10a 58.85±7.00ab 25.66±16.27c 33.42±20.39bc *c-p 2* 25.57±5.57a 15.14±4.42a 38.96±19.95a 15.35±3.55a *c-p 3* 6.11±1.54a 3.81±3.81a 1.04±0.90a 0.94±1.75a *c-p 4* 0.22±0.44a 14.06±4.71b 16.58±7.91b 17.64±3.58b *c-p 5* 0.13±0.25a 8.14±3.10a 17.75±8.25ab 32.65±19.04b *Ecological indices Genera richness* 14.50±0.58a 28.75±2.22b 25.25±3.50b 27.50±1.00b *Abundance* 303.75±104.6a 764±376.06a 358.75±169.6a 742.00±224.8a *Enrichment Index* 91.33±2.30a 93.94±2.01a 68.96±27.63a 87.50±8.31a *Structure Index* 38.12±7.22a 88.25±4.03b 80.73±11.18b 93.24±4.87b *Channel Index* 0.16±0.20a 1.47±1.70a 20.42±32.01a 5.35±3.10a *Maturity Index 2-5* 2.22±0.050a 3.39±0.25b 3.21±0.47b 3.93±0.44b *Shannon-Weaver Index* 1.56±0.08a 2.33±0.24b 2.57±0.13b 2.29±0.11b

abcd Means followed by the same letters on the same rows are not statistically different according to Least Significant

In areas with neutral soil pHs (as at J4), strong shifts in soil composition are usually expected after an increase in pH. Alterations in edaphic diversity after pH manipulation have been confirmed experimentally and by field studies. Earthworms, enchytraeids, and nematodes were more abundant after liming [57, 58], but Acari preferred acidic conditions [59, 60]. The altered soil conditions in our study as a consequence of Mg contamination and an extremely

**Table 8.** Percentage of individual nematode trophic groups and average of ecological indices values calculated for

**Sampling sites J1 J2 J3 J4**

attributes of the environment [32].

42 Emerging Pollutants in the Environment - Current and Further Implications

**Indices, trophic & c-p groups**

Difference Test (P<0.01).

Jelšava sampling sites [53].


**Table 9.** Correlations among heavy metal concentrations, soil characteristics, nematode community structure, and selected ecological indices from Jelšava [53].

An abundance of food for bacteria often increases the proportion of c-p 1 bacterivores, as confirmed experimentally by [58]. Representatives of the genus *Rhabditis* were the most abundant nematodes along the entire transect in our study. The survival and dominance of *Rhabditis* and other bacterivores in this hostile environment could, however, be a complex phenomenon, comprising not only food resources, but also behavioural and physiological adaptations to the hostile conditions [64]. For example, *C. elegans* can withstand high pH and salinity and survive under extreme osmotic pressure [55, 65]. Moreover, c-p 1 nematodes can produce inactive dauer larvae, which increase the chances of withstanding harmful or limited conditions. Other studies [1, 4] have shown that c-p 2 nematodes are also able to withstand severe ecological conditions and comprise the dominant c-p group in highly disturbed ecosystems [66]. Our results only partially supported these findings. More than 25% of the nematodes at J1 belonged to the c-p 2 group, and of these, species of *Cervidellus* and *Chilopla‐ cus* were the most tolerant. The proportion of c-p 2 nematodes within the community, however, was significantly lower than that of c-p 1 nematodes. The discrepancy between the hypothetical dominance of stress-tolerant c-p 2 nematodes and our results was likely due to various physiological and ecological aspects of c-p 1 and 2 nematodes and their population dynamics (e.g. reproduction rate, length of life cycle, and resource availability). The abundance of c-p 1 nematodes in the soil may also be due to, aside from soil fertility reported by [11], the changes in soil pH. Further study is necessary to confirm these possibilities.

**Figure 5.** Structure and Enrichment Index graphic representation (Jelšava) [53]. A - disturbed food web, bacterial de‐ composition; B - maturing food web, balanced decomposition; C - structured food web, fungal decomposition; D - de‐ graded food web, fungal decomposition [11].

This study has demonstrated the negative ecological impact of contamination by quantifying different ecological indices (e.g. SI, MI2-5, and H′) and measuring key parameters of nematode communities (generic richness and abundance). Not all communities traits showed a clear response to stress in the ecosystem, and some responded inconsistently, e.g. abundance similar as in the Krompachy case study did not reflect the stress of the ecosystem. Total abundance should thus not be used as an indicator for either heavy metals, as suggested by [42], or physical or chemical changes in soil properties such as pH. Generic richness and H′, though, indicated substantial differences in species diversity in the ecosystems with diverse contamination and soil salinity, in accordance with diversity shifts observed in other nematode communities [58] and in other edaphic groups after pH manipulation [59, 67]. SI and MI2-5 were the best tools in our study for showing the impact of high Mg concentrations and soil salinity on nematode community structure and the maturity of the ecosystem. SI combined with EI identified J1 as severely disturbed (quadrat A), and the other sites showed only a low degree of stress. A decrease in the intensity of stress and an increase in the complexity of soil community structure with distance from a pollution source have been reported in several other areas of intensive industry [1, 44]. Based on low CI values in our study, indicating predominant bacterial pathway of decomposition, c-p 1 enrichment opportunists were eliminated from maturity assessment (MI2-5), as they respond more to the food availability than pollution [47]. Elimi‐ nating the influence of enriched conditions provided us with clear gradual increase in environment stability and maturity from the site J1 onwards.

## **5. Conclusions**

An abundance of food for bacteria often increases the proportion of c-p 1 bacterivores, as confirmed experimentally by [58]. Representatives of the genus *Rhabditis* were the most abundant nematodes along the entire transect in our study. The survival and dominance of *Rhabditis* and other bacterivores in this hostile environment could, however, be a complex phenomenon, comprising not only food resources, but also behavioural and physiological adaptations to the hostile conditions [64]. For example, *C. elegans* can withstand high pH and salinity and survive under extreme osmotic pressure [55, 65]. Moreover, c-p 1 nematodes can produce inactive dauer larvae, which increase the chances of withstanding harmful or limited conditions. Other studies [1, 4] have shown that c-p 2 nematodes are also able to withstand severe ecological conditions and comprise the dominant c-p group in highly disturbed ecosystems [66]. Our results only partially supported these findings. More than 25% of the nematodes at J1 belonged to the c-p 2 group, and of these, species of *Cervidellus* and *Chilopla‐ cus* were the most tolerant. The proportion of c-p 2 nematodes within the community, however, was significantly lower than that of c-p 1 nematodes. The discrepancy between the hypothetical dominance of stress-tolerant c-p 2 nematodes and our results was likely due to various physiological and ecological aspects of c-p 1 and 2 nematodes and their population dynamics (e.g. reproduction rate, length of life cycle, and resource availability). The abundance of c-p 1 nematodes in the soil may also be due to, aside from soil fertility reported by [11], the changes

**Figure 5.** Structure and Enrichment Index graphic representation (Jelšava) [53]. A - disturbed food web, bacterial de‐ composition; B - maturing food web, balanced decomposition; C - structured food web, fungal decomposition; D - de‐

This study has demonstrated the negative ecological impact of contamination by quantifying different ecological indices (e.g. SI, MI2-5, and H′) and measuring key parameters of nematode communities (generic richness and abundance). Not all communities traits showed a clear response to stress in the ecosystem, and some responded inconsistently, e.g. abundance similar as in the Krompachy case study did not reflect the stress of the ecosystem. Total abundance

in soil pH. Further study is necessary to confirm these possibilities.

44 Emerging Pollutants in the Environment - Current and Further Implications

graded food web, fungal decomposition [11].

Heavy metal contamination of soil is long-term ecological problem. High levels of pollutants may lead to losses in production, breaches in the otherwise strict sanitary limits for agricultural products, and health-related problems for local inhabitants. This study demonstrated that the background geochemical heavy metal content was significantly exceeded, with measurable consequences for the local environments. The sensitive groups of soil nematodes, mainly omnivorous and predacious nematodes of the higher c-p groups, were significantly sup‐ pressed in the ecosystems, and tolerant groups, with better physiological and behavioural adaptations to harsh conditions, survived. Such alterations in community structure may have far-reaching consequences, because some of the ecological regulation or environmental feedbacks provided by nematodes may be suppressed in, or eliminated from, the ecosystem.

Despite the recent decrease in emissions and the application of various treatments to prevent their leakage at both metallurgical plants, the potential threat of further environmental deterioration remains relatively high. The high concentrations of possible toxic elements bound to the soil matrix and temporally unavailable to the soil biota are the main threat in the Krompachy area. The release of the pollutants to the soil solution by sudden shifts in local soil conditions, e.g. an increase in soil acidity by acid rain, could lead to their increased toxicity to soil communities or to groundwater contamination. The threat from pollution to the ecosystem around Jelšava is less imminent, because the levels of toxic elements were not significantly higher. The high Mg concentrations and soil salinity, and consequently the extreme soil alkalinity, however, are the most important problems in this area. Under these conditions, only a few organisms with adaptations for surviving in such an environment are able to prosper, as our results clearly showed. In both case studies, the nematode community structures collapsed near the pollution sources, with the domination of nematodes able to survive inhospitable soil conditions.

## **Acknowledgements**

The authors acknowledge the support of the Slovak Research Development Agency (project LPP-0085-09) (0.6), VEGA (Grant No. 2/0193/14) (0.3), and the project "Application Centre to protect humans, animals and plants against parasites" (Code ITMS: 26220220018) with the support of the Operational Program "Research and Development" funded by the European Regional Development Fund (0.1).
