Bioremediation of heavy metals in soils of industrial zones: the potential of microbial and plant associations in conditions of complex pollution
Keywords:
bioremediation of soils, heavy metals, microbial-plant associations, phytoextractionAbstract
Soil pollution with heavy metals is a serious environmental problem that requires the development of effective and environmentally friendly cleaning methods. Traditional physico-chemical methods of remediation often lead to disruption of the soil structure and a decrease in its biological activity. This study is aimed at evaluating the effectiveness of microbial-plant associations in bioremediation of soils in industrial areas contaminated with a complex of heavy metals (Pb, Cd, Cr, Cu, Zn). An integrated approach was used in the work, including screening and breeding of metal-resistant microorganisms, assessment of the storage capacity of various types of hyperaccumulating plants and analysis of the synergistic effects of their combined use. The experimental base included 78 experimental sites in three industrial zones with different pollution patterns and types of soil cover. Field trials were conducted during two growing seasons (2021-2023). The results showed that a consortium of metal-resistant bacteria, including strains of Pseudomonas putida, Bacillus megaterium and Arthrobacter globiformis, combined with Brassica juncea and Thlaspi caerulescens, reduces the content of mobile forms of heavy metals by 67.3-78.5%, depending on the type of metal and soil conditions. For the first time, a direct correlation (r=0.83) has been established between the activity of microbial exopolysaccharides and the bioavailability of heavy metals for hyperaccumulating plants. The synergy effect between the processes of rhizospheric bacterial immobilization of metals and their phytoextraction has been revealed, increasing the overall efficiency of bioremediation by 23.7%. The proposed technology provides not only a reduction in the content of toxicants, but also the restoration of the biological activity and functional structure of microbial communities of contaminated soils.
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