Plants of the genus Thymus L. are traditionally used in medicine and cooking due to the presence of biologically active compounds in them that have fungicidal, antibacterial and other medicinal properties and original taste qualities. Genetic features and growing conditions cause the elemental composition, responsibly of the synthesised medicinal compounds. However, information on the contents and distributions of elements in the organs of Thymus L. is very limited. This study was to set and compare the elements in organs of wild thyme for different soil and climatic conditions. Two species of wild Thymus L. from Mongolian steppe and on the coast of Lake Baikal were collected during flowering. Twenty-four elements, including Si, in soils, roots, stems, leaves and flowers were simultaneously determined by atomic emission spectrometry. Elemental profiles of two species of wild Thymus L. are described. It is assumed that Si is a necessary element of the plant. The predominance of the genetic resistance of plants over the influence of soil and climatic conditions is shown.

This article focuses on the relationships between major (Si, Al, Mg, Fe, Ca, Na, K, S, P and Ti) and potentially toxic trace (Ag, As, B, Ba, Bi, Co, Cd, Cr, Cu, F, Ge, Mo, Mn, Li, Ni, Pb, Sb, Sn, Sr, Tl, V and Zn) elements in Ulaanbaatar surface soils and also sources of the trace elements in the soils distinguished by the methods of multivariate statistical analysis. Results of exploratory data analysis of 325 Ulaanbaatar soil samples show the accumulation of Ca, S, B, Bi, Cu, Mo, Pb, Sb, Sn, Sr and Zn in urban soils. The major elements were grouped by cluster analysis in tree associations characterizing main soil fractions: sandy P-(K-Na-Si), clayey (Mg-Ti-Fe-Al) and silty (S-Ca). The factor analysis shows that silty fraction is enriched in major elements of both natural and anthropogenic origin. The principal component analysis from 32 variables extracted nine principal components with 82.49% of the cumulative explained variance. The results of cluster and factor analyses well agree and reaffirm the enrichment causes of potentially toxic elements are a coal combustion at thermal power stations (B, Bi, Ca, Mo, S and Sr) and traffic emissions (Cu, Pb, Sn and Zn). Spatial distributions of trace elements in the districts of Ulaanbaatar city were obtained by ordinary kriging. It is illustrated that the different principal components define the various origins and patterns of accumulation of trace elements in soils. The supplementation of data set by the concentration of organic carbon and the species of elements could help to identify the sources of such elements as P, Ni, Al, Fe, Ca, Ba, Bi, Cr, Zn, Sr and Sb in urban soils more completely.

The bulletin of Irkutsk State University. Series «Earth Sciences»

This work shows some of the results of investigation into pseudo total content of heavy metals in the surface soil of Ulaanbaatar.The main objectives of this study are to (i) evaluate temporal variability of pseudo-total content of Pb, Cu, Zn, Cd, Cr, Ni, Co and Mn in surface soil of Ulaanbaatar collected from 2003 to 2018, (ii) identify the main discriminates - metals during the years 2003-2018 years and, (iii) investigate the interdependence of main discriminates on the soil reaction (pH) and soil organic matter.Due to urbanization and negative human activities, surface soil in Ulaanbaatar losing their natural features, which are changing, while the spatial and temporal distribution of heavy metals in urban surface soil is becoming irregular. In Ulaanbaatar surface soil, the mean concentration of Cu, Zn and Pb much mois very high and the mean concentration of Co is lower than background soil. In some land use zones, it was found that the mean concentraion of Zn and Cr was considerably higher than the permissible level. The pollution condition of Mn, Zn, Cr, Ni and Cd was the same in 2010-2018 and the pollution conditions of Pb, Cu and Co are different. The main discriminants are Pb, Cu and Co. In Ulaanbaatar soil, a strikingly close correlationhip was established for Cu, Pb with the soil organic matter, and for Cd, Zn, Cr with the pH, respectively.

In the last more than two decades, technogenic environmental pollution of Ulaanbaatar (Mongolia) has become a critical issue due to the rapid growth of the city’s population and environmental objects such as soil, plant and water in Ulaanbaatar territory have been heavily contaminated through air. The objectives of this study were (1) to determine the toxic and biophilic elements in the leaves of laurel poplar (Populus laurifolia) in Ulaanbaatar (Mongolia) and to study the behaviour and interdependence of its distribution, (2) and to assess the ecological state of laurel poplar (Populus laurifolia). In the leaves of laurel poplar (Populus laurifolia) on the territory of Ulaanbaatar, the distribution of most of the studied toxic and biophilic elements is even, but only Mg, Ca, and Mn are not evenly distributed. The biogeochemical feature of laurel poplar (Populus laurifolia) on the territory of Ulaanbaatar was studied by comparing it with the value of the world clarke and with the average content of elements in plant ash according to Alekseenko and with the background value. Our study revealed the accumulation of Zn, Ni, Cd, Pb and the scattering of Fe, Mn, Co, Cu in the leaves of laurel poplar (Populus laurifolia) in Ulaanbaatar In Populus laurifolia leaves in Ulaanbaatar area the median value of Fe/Mn ratio is 4.2-2.7 times, and the median value of Pb/Mn ratio is 6.7 times higher the normal and Cu/Zn ratio is at an equilibrium. The highest Fe/Mn ratios are found along the main highway (10.45) and in the city centre (11.09).

This work summarizes the results of a study into such important urban soil parameters as soil actual (pH) and potential acidity (pH) and soil organic matter content (SOM) in the surface soil of Ulaanbaatar. The soil pH in Ulaanbaatar is slightly alkaline, with a median pH value of 7.36 (actual acidity) and 6.93 (potential acidity), and they were found to be the highest in the industrial zone as compared to other zones in the city. The median value of organic matter content in Ulaanbaatar surface soil was 5.61%, with a high variability in the industrial (C.V.-119%) and transport (C.V.-55.34%) zones. The SOM mean value in urban soil is less than the background value in surface soil from natural area, indicating to increasing compaction and reduction of porosity of soil in urban areas. Also, organic matter content have decreased relatively to previous data, reflecting the urbanization process and such long-term processes as aerial urban fallout.