The scientists from the Faculty of Geography and the Faculty of Soil Science of Moscow State University compared the Russian and foreign standards for heavy metals content in soils. The experts studied about 1000 soil samples, tested domestic and foreign maximum permissible limits of chemical elements on unpolluted Russian soils.
“The countries where there are no standards for some substances can use someone else’s standards. But you must first check these standards on background soils so as not to make a fool of yourself if it turns out that background soils contain more of a certain pollutant than given in the used standard. And in many Russian works, they simply take the standards of the USA or the Netherlands, without first conducting the analysis that we did," said Ivan Semenkov, head of the expeditionary work, senior researcher at the MSU Faculty of Geography.
The scientists specifically used soils removed from sources of pollution in order to compare obviously clean samples with the existing standards. According to the results of comparing the "pure" samples with the standards from different countries, it turned out that the content of some heavy metals was higher than the permissible limits. For example, the American standard for manganese and the Canadian standard for chromium and vanadium are lower than the concentrations of these metals in all soils studied by the researchers in Western Siberia.
"This happened because in each country the composition of the original rocks is slightly different, and the elemental composition of the soil is inherited from the rocks. Plus, vegetation and soil are different from place to place. And some plants are able to accumulate elements more. After a plant dies, the accumulated substances get on the soil surface and can remain there and accumulate on the so-called biogeochemical barrier. Our task is to monitor the accumulation of heavy metals on the biogeochemical barriers in uncontaminated soils to the levels exceeding the norm. No one has ever done this before," said Ivan Semenkov.
As a result, the researchers found that for sod-podzolic, gray forest soils and chernozems of Western Siberia the following standards are best suited: the Canadian standards for lead and zinc (45 and 200 mg / kg); the German standards for nickel and chromium (140 and 40 mg / kg);the Dutch for copper and barium (96 and 890 mg / kg); and the Russian for manganese (1500 mg / kg).
The study was carried out by the scientists from Moscow State University with the support of the Russian Science Foundation as a part of the work on the domestic system for standardization of the content of chemical elements in soils. The system is important for the production of safe agricultural products and the timely removal from the cities of the surface layer of soil contaminated by transport and the operation of enterprises.