Microbial communities of urban and industrial polluted soils in the Russian Arctic

The Russian Arctic presents a unique environment for studying the effects of anthropogenic pressure on soil microbial communities under severe climatic conditions. This study investigated the impact of chemical pollution on soil microbial properties by comparing urban and industrially polluted soils in Murmansk region with natural Podzols. Urban soils exhibited significant alterations, including shifts in pH and increased carbon and nutrient contents compared to natural soils. Industrially polluted soils near the copper‑nickel smelter were characterized by elevated heavy metal concentration, while those near the aluminum smelter showed high fluorine and aluminum content. In both cases, carbon content and pH remained similar to natural soils. Industrial emissions significantly changed the soil microbiome, with effects varying depending on the pollution source and chemical composition of the emissions. Soils near the copper‑nickel smelter showed a decline in bacterial gene copies and actinomycete mycelium length, with a predominance of Chloroflexii and Ascomycota. Conversely, soils near the aluminum smelter exhibited less pronounced changes, with Proteobacteria and Basidiomycota being prevalent. Despite these differences, both industrially impacted sites displayed reduced microbial diversity, regardless of the composition of the emissions. In contrast, urban soils demonstrated increased microbial diversity, likely attributed to the emergence of new, favorable ecological niches. Microbial communities in both cities were similar, dominated by Proteobacteria and Ascomycota, and displayed an increase in bacterial gene copies compared to natural soils. These findings highlight the contrasting influences of urban and industrial development on soil microbial communities. While industrial activities suppress microbial life, urbanization fosters the creation of new niches, promoting microbial diversity. This underscores the potential of urban soils to support diverse microbial communities, which is crucial for sustainable development and ecological strategies in Arctic cities.