## 3 Results  
### Analysis of Petroleum Hydrocarbons in Soil, Root and Shoot  
Chromatographic analyses of the soil for TPH content showed that bioaugmentation with microbial consortia developed on the basis of indigenous micro-organisms significantly affects the efficiency of its treatment process using _Echinacea purpurea_ as a phytoremediator. At the end of the 6-month experiment, in non-inoculated systems, TPH biodegradation efficiency was low, at 18.40% (Soil DW-1) and 21.87% (Soil OS-1). The application of inoculation with bacterial microbial consortium B1 increased the biodegradation rate of TPH to 35.56% (Soil DW-2) and 40.85% (Soil OS-2). In systems inoculated with microbial consortium B2 enriched with fungal species capable of degrading petroleum hydrocarbons, TPH biodegradation rates were 44.16% (Soil DW-3) and 49.78% (Soil OS-3). In addition, it was observed that the use of \(\gamma\)-PGA significantly increases the efficiency of cleaning up soils polluted with petroleum substances. In soil taken from the site of an oil spill pit (Soil DW), the application of inoculation with microbial consortia B1 and B2 with the addition of \(\gamma\)-PGA in the phytoremediation process resulted in a reduction in TPH concentrations by 46.71% in system 4 and 53.98% in system 5. In addition, in the system inoculated with \(\gamma\)-PGA alone, phytoremediation efficiency using _Echinacea purpurea_ was 3.4% higher than in the non-inoculated system. Similarly, in soil taken from an oil spill site (Soil OS), the phytoremediation efficiency was highest in systems inoculated with microbial consortia containing \(\gamma\)-PGA, achieving 51.19% (Soil OS-4) and 60.47% (Soil OS-5). Inoculation with pure \(\gamma\)-PGA compared to the non-inoculated system led to an increase of 5.02%. In addition, based on chromatographic analyses using two types of soil with different ages of contamination, it was found that aged soils (Soil DW) were less amenable to treatment than freshly contaminated soils (Soil OS). The changes in TPH concentrations in DW and OS soils subjected to bioaugmentation-assisted phytoremediation in the systems studied are shown in Figure 2.  
For a complete evaluation of the effectiveness of the bioaugmentation-assisted soil phytoremediation process, the distribution of alkanes in the studied systems before and after the experiment was determined. It was determined that hydrocarbons with a carbon chain length of nC\({}_{10}\)-nC\({}_{21}\) were best removed from the soil matrix. Slightly worse values of biodegradation degrees were obtained for light hydrocarbons with carbon chain lengths of nC\({}_{6}\)-nC\({}_{9}\). Heavy hydrocarbons with carbon chain lengths of nC\({}_{22}\)-nC\({}_{30}\) and nC\({}_{31}\)-nC\({}_{36}\) degraded at a much lower rate, consistent with previous studies. Moreover, it was observed that in soils vaccinated with a microbial consortium enriched with selected fungal species, a greater reduction in the content of heavy hydrocarbons was obtained than in systems inoculated with a bacterial biopreparation. A summary of the concentrations of selected groups of aliphatic hydrocarbons in DW and OS soils before and after phytoremediation studies in different inoculation systems is provided in Table 3.  
Chromatographic analyses of the roots and shoots showed that aliphatic hydrocarbons can be extracted from the soil into _Echinacea purpurea_ in all systems tested. However, it was observed that in systems not inoculated and inoculated with \(\gamma\)-PGA alone, the concentration of TPH in the roots and shoots was very low, which directly affected the efficiency of phytoremediation. In addition, poor growth of _Echinacea purpurea_ was observed in systems 1 and 7, and 6 and 12 due to a poorly developed root system. Low TPH concentrations are also due to the fact that the diffusion of petroleum substances into the plant is greatly impeded due to the hydrophobic nature of hydrocarbons and their large molecular weights.