OREANDA-NEWS The first scale in Russia for assessing soils of different climatic zones with lead pollution was developed by scientists of the Southern Federal University. The scale is based on data obtained by university researchers that lead, when released into the soil, blocks the work of enzymes that play a key role in plant nutrition and maintaining biodiversity. The results are published in Soil Systems.

Lead is considered one of the most common environmental pollutants, scientists from the Southern Federal University (SFU) said. This heavy metal enters the soil with emissions from metallurgical and mining enterprises, as well as as a result of burning coal at thermal power plants and the use of leaded fuel ("lead gasoline").
According to scientists, due to soil pollution, lead accumulates in plants, and then enters animal and human organisms through "poisoned" food.

Scientists from the Southern Federal University and the Azov-Black Sea branch of the All-Russian Scientific Research Institute of Fisheries and Oceanography analyzed the effect of lead on a wide range of soil enzymes – catalyst proteins that participate in the circulation of oxygen, carbon, nitrogen, sulfur and phosphorus. This allowed us to get a more complete picture of the changes occurring in the soil under the influence of pollutants.

"The enzymes responsible for hydrolysis (the process of decomposition of a chemical substance under the influence of water) and redox reactions turned out to be the most sensitive to lead contamination in sulfur, phosphorus and oxygen cycles," said Tatyana Minnikova, a leading researcher at the Soil Health Laboratory of the Southern Federal University.

Sulfur, phosphorus and oxygen play a key role in plant nutrition and maintaining soil biodiversity. A decrease in the rate of their circulation (due to a violation at one of the stages) restricts the access of nutrients to plants and worsens the general condition of the soil, the university explained.

Based on the data obtained, scientists for the first time ranked the enzymatic activity (the ability of enzymes to accelerate chemical reactions) of soils in different climatic zones from very high to very low.

The researchers also found that the soils of the steppes of the Rostov region, the Moscow region and the Kashirsky district of the Voronezh region are the most resistant to lead, and the soils of the dry steppes and semi–deserts of Kalmykia and the Astrakhan region, the soils of the steppes of the Venevsky district of the Tula region, as well as the soils of broad-leaved forests and forest-steppes of the Domodedovo urban district of the Moscow region are the least stable.

At this stage, scientists plan to expand the range of studied enzymes involved in the circulation of carbon, nitrogen, phosphorus, oxygen and sulfur.