Lake in southern Siberia has become a mirror of the national economy
A good indicator was his organic pollutants.
The Russian, Brazilian and British researchers has determined how changing the concentration of organic pollutants in two lakes of the basin of the Selenga river flowing into Baikal for the last 150 years. They showed that the intake of potentially hazardous substances in these reservoirs depended on the economic situation in the country. In the years when Soviet industry was on the rise, the concentration of pollutants in the water increased, and in the period of economic decline as it fell. A scientific paper published in the journal Environmental Pollution.
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Because Baikal is the largest fresh water reservoir on Earth, for its purity monitored carefully. To do this effectively, we need to understand what is the source of the most intensive pollution of the lake and what determines the number of incoming potentially hazardous substances. The Selenga is one of the largest rivers flowing into the lake. It brings in lake water and suspended particles therein. Therefore, the researchers chose two lakes located in the vast Delta of the Selenga 30 km from the town of Selenginsk of Kabansky district of Buryatia. The land around these lakes was used in agriculture in the nineteenth century, and the city of Rostov-on-don was founded in 1961 for the construction and maintenance of pulp and paperboard mill.
Thus, the studied lakes can contain waste from pulp production, and citywide emissions, and organic matter from the fields and livestock farms.
Samples of bottom sediments of the Selenga lakes received the drilling in March 2014, when the lake was covered with ice. Packed them so that they are not in contact with the plastic can change the results of the composition analysis. The age of the deposits was determined by the content of radioactive lead isotopes 210Pb and checked the concentration of cesium isotopes 137Cs and 241Am americium (rate of accumulation of these atoms in different decades of the XX century are well known).
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First and foremost, researchers interested in the content in lake sediments polycyclic aromatic hydrocarbons (PAHs).
These substances, the molecules of which contain several rings of carbon atoms, possess strong carcinogenic effect. The scientists also checked the presence of DDT and its degradation products: it is dangerous for bird life and other animals (especially carnivorous, as its concentration in the food chain increases), as well as human.