buffer properties of soils are present. Monitoring the content of heavy metals in the
components of the environment is an important component of environmental
conservation, and as a consequence, ensuring the quality of life.
Heavy metals are dangerous pollutants of the environment. They are getting into
the ground with gas emissions from manufacturing companies and vehicles, with
impurities of fertilizers, pesticides, etc., they accumulate in the soil to dangerous
concentrations and adversely influence groundwater, agricultural plants, and can affect
the human body and endanger its health. Accumulating heavy metals leads to a
decrease in pH in the soil, and destroying the soil-absorbing complex. In studies on
sod-podzolic soils, it was found that heavy metal contamination was accompanied by
significant changes in the biota: a decrease in the total number of bacteria, their spore
formation, a sharp decrease in actinomycetes and an increase in the number of fungi,
and decrease in the number of soil insects and earthworms.
Heavy metals are toxic and interfere with the activity of microflora of soil. Their
concentration can be preserved in the soil for decades or even centuries. Special
attention should be made to some heavy metals, in particular to Zn, Cu, Pb, and Cd.
Heavy metals that get into the soil, primarily their mobile form, are subject to
various transformations. One of the main processes affecting soil fraction is the
attachment of humus. The migration opportunities of them are generally reduced. This
explains their high content in the uppermost humus layer of soil. The depth of
penetration of heavy metals in contaminated soils usually does not exceed 20 cm, but
with severe contamination, they can penetrate up to a depth of 160 cm. The greatest
migration capacity is characterized by Hg and Zn, which are usually evenly distributed
in a layer of soil at a depth of 0-20 cm. Pb more often accumulates in the surface layer
(0-2.5 cm), Cd occupies an intermediate position between them.
The degree of environmental pollution by chemical elements, primarily heavy
metals, is determined by the relative to the background content of the elements or the
maximum permissible concentration (MPC).
With an average degree of pollution, the content of heavy metals only affects the
soil fauna. Soil starts the processes of redistribution of different groups of
microorganisms and their adaptation to the conditions of contamination. With a high
degree of soil contamination, it is not only a process of changing and reconstructing
the ratio of microorganisms, which is very different from the unpolluted, but also the
change of some chemical and physical properties of the soil. As long as heavy metals
are firmly bound to the constituent parts of the soil and are difficult to access, their
negative impact on the soil and the environment will be negligible. However, if the soil
conditions allow the heavy metals to pass into the soil solution, there is a direct threat
of soil contamination, there is the possibility of their penetration into plants, as well as
in the organisms of people and animals that consume these plants [7].
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