Iron and manganese migration in “soil–plant” system in Scots pine stands in conditions of contamination by the steel plant’s emissions

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In the last century, man-made effects and amounts of human-moving chemicals in the biosphere have become comparable to the scale of geological and other natural processes. Counting the number of toxicants entering the environment (including metals) shows that human activity represents currently the significant factor affecting the global and regional cycles of most chemical elements.

The ferrous industry make the globe’s biggest energy-intensive processing industry, as well as one of the largest industrial sectors in terms of discharge to the atmosphere. Emissions from smelters are dominated by carbon dioxide, particulate matter (dust, including heavy metals), and nitrogen oxides. Heavy metals (first of all, iron and manganese) are emitted (in the form of particulate matter) at all stages of the metallurgical producing cycle, from ore processing (iron and manganese ore treatment) to cast iron and steel production.

The study areas were positioned in Lipetsk City (52°37′ N, 39°36′ E), Lipetsk Region, Russia. It is placed into the forest steppe. The low forest cover (the total forest area exists merely of 7.6% of the territory) identifies the Lipetsk region; the part of native forests is 53.8% (other 46.2% are the artificial forest stands). The portion of pine stands (native and artificial) explains 34% of the forested area.

The pine stands of the comparable age (38-45 years old) and similar structure, selected for research, is grown in the sanitary protection zone of the city of Lipetsk in the vicinity of the metallurgical combine (Novlipetsk Steel). Novolipetsk Steel is the largest steel corporation in Russia and is one of the Top 25 World steel-producing companies. The Novolipetsk Steel serves as the most enormous source of air pollution in the Lipetsk region. In 2018, emissions to the atmosphere from the plant amounted to 275970 tons.

Using atomic absorption spectrometry determined iron and manganese content in the soil, fine (< 1mm) roots, annual shoots also needles. To describe the stockpile of elements in the fine roots of pine, we used the biological accumulation coefficient, calculated as a ratio of the metal content in roots to that in soil. To get to know metal relocation in pine, a biological migration coefficient was used, which was calculated as the ratio of element contents in plant organs to that in roots.

The biological accumulation and biological migration coefficients of iron and manganese

Based on the values of the biological accumulation and migration coefficients, what in each case slighter than one, for Scots pine the iron represent not an element that actively accumulates. Nevertheless, for manganese, this stock model is valid only for fine roots, whereas under the contaminated environment, the metal mobility steepen, and the migration pattern shifts towards increased manganese accumulation in the aboveground part of pine trees.

More information about the study and the main results can be found in our article published in Scientific Reports

Gleb Zaitsev

researcher, Ufa Institute of biology, Ufa Federal Research Centre of the Russian Academy of Sciences

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