ECOLOGICAL AND GEOCHEMICAL ASSESSMENT OF SOIL COVER IN THE URBAN AREAS

anglais. Introduction. Urban soil landscape is the most stable indicator of a long-term man-made impact. In the scientific literature, there is practically no data about rare and rare earth metals in the urban soil of Russia and other countries. Thus, the goal of the research was to obtain the data about the content of a number of chemical elements (Na, K, Ca, Sc, Cr, Fe, Co, Zn, As, Br, Rb, Sr, Ag, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Tb, Yb, Lu, Hf, Та, Au, Ra, Th, U) to assess the nature of distribution and the level of man-made impact on the soils in the industrial area of Yoshkar-Ola city. The method was intended to elaborate the geoinformation basis for the study area, bulk rock geochemical sampling and the measurement by means of instrumental neutron activation and gamma-spectrometric analyses, statistical processing and calculation of geochemical and radioecological indices (the backgrounds of natural and industrial areas, concentration ration of the elements in the industrial area relative to the natural background (Кс), indices of polyelemental pollution (Zc)). Results. In the natural area, concentration of the most elements satisfies the background matter content in the soil, determined by other researchers

russe. nevertheless, there was low content of Sr, Br, Nd, Sm and Eu

and high content of Au and Hf in the area. It is important to take into account this fact to assess the industrial area. In the industrial area, there was low content (Кс1,1) of Са, Cs, Sb, Br, Au, Zn, Eu, Сr and Fe

content of the 137Cs man-caused radioactive nuclides was significantly lower in the industrial area than in the natural area, distribution of the natural radioactive nuclides ( 40К, 226Ra, 232Th) depended on the mineral composition of the soil and the location in the landscape. Content of Zc was low in the most part of the studied area (mean value Zc 8,5). High level of polyelement pollution was found to be in the two zones (a zone with Zc 16 - 17 and the zone with Zc 16 - 37)

it is explained by Br, Zn, Ca, As, Sb and Fe content. Conclusion: a summary assessment of the soil pollution in the industrial area of Yoshkar-Ola and a comparison with the data, obtained in some other cities, showed relatively safe environment in the studied city. Concentration of the most elements is explained by the natural factors (they are close to concentration, which is typical for the sandy soil) and soil transformation during the building works.

Приведены результаты геохимических исследований почв промышленной зоны г. Йошкар-Олы. Впервые получены данные о содержании и распределении в поверхностном слое почвы (0 - 10 см) таких элементов, как: As, Cr, Co, Sb, Br, Ba, Rb, Cs, Sr, Hf, Та, Sc, Tb, Sm, Eu, La, Ce, Yb, Lu, U, Th, Au, Ag. Проведено сравнение содержания элементов промышленных городских ландшафтов с природными территориями и данными других исследователей. Повышенные среднегородские концентрации (Kc>1,1) выявлены у Са, Cs, Sb, Br, Au, Zn, Eu, Сr и Fe, при этом техногенные аномалии установлены для Са, Sb, Br, Au, Zn, Сr и Fe. Оценка суммарного загрязнения изученными элементами почв промышленной зоны г. Йошкар-Олы показала относительно благополучную обстановку.