Search

Background: The history of human populations occupying the plains and mountain ridges separating Europe from Asia has been eventful, as these natural obstacles were crossed westward by multiple waves of Turkic and Uralicspeaking migrants as well as eastward by Europeans. Unfortunately, the material records of history of this region are not dense enough to reconstruct details of population history. These considerations stimulate growing interest to obtain a genetic picture of the demographic history of migrations and admixture in Northern Eurasia. Results: We genotyped and analyzed 1076 individuals from 30 populations with geographical coverage spanning from Baltic Sea to Baikal Lake. Our dense sampling allowed us to describe in detail the population structure, provide insight into genomic history of numerous European and Asian populations, and significantly increase quantity of genetic data available for modern populations in region of North Eurasia. Our study doubles the amount of genome-wide profiles available for this region. We detected unusually high amount of shared identical-by-descent (IBD) genomic segments between several Siberian populations, such as Khanty and Ket, providing evidence of genetic relatedness across vast geographic distances and between speakers of different language families. Additionally, we observed excessive IBD sharing between Khanty and Bashkir, a group of Turkic speakers from Southern Urals region. While adding some weight to the "Finno-Ugric" origin of Bashkir, our studies highlighted that the Bashkir genepool lacks the main "core", being a multi-layered amalgamation of Turkic, Ugric, Finnish and Indo-European contributions, which points at intricacy of genetic interface between Turkic and Uralic populations. Comparison of the genetic structure of Siberian ethnicities and the geography of the region they inhabit point at existence of the "Great Siberian Vortex" directing genetic exchanges in populations across the Siberian part of Asia. Slavic speakers of Eastern Europe are, in general, very similar in their genetic composition. Ukrainians, Belarusians and Russians have almost identical proportions of Caucasus and Northern European components and have virtually no Asian influence. We capitalized on wide geographic span of our sampling to address intriguing question about the place of origin of Russian Starovers, an enigmatic Eastern Orthodox Old Believers religious group relocated to Siberia in seventeenth century. A comparative reAdmix analysis, complemented by IBD sharing, placed their roots in the region of the Northern European Plain, occupied by North Russians and Finno-Ugric Komi and Karelian people. Russians from Novosibirsk and Russian Starover exhibit ancestral proportions close to that of European Eastern Slavs, however, they also include between five to 10 % of Central Siberian ancestry, not present at this level in their European counterparts. Conclusions: Our project has patched the hole in the genetic map of Eurasia: we demonstrated complexity of genetic structure of Northern Eurasians, existence of East-West and North-South genetic gradients, and assessed different inputs of ancient populations into modern populations. [ABSTRACT FROM AUTHOR]

Monitoring studies in the area of Kravtsovskoe oil field in the southeastern Baltic Sea have been carried out since 2003. Terrigenous bottom sediments (0-5 cm layer) in the area (23 stations) are represented by all grain size types. Down to the depth of 30-50 m, these are mostly quartz sands; at depths of 60-110 m, these are terrigenous mud with C content of 1-3%. The concentration and distribution of toxic elements (Cu, Co, Cd, Pb, Ba, and Hg) over sediment types and bed area are the same as in the Baltic Sea as a whole: Cu, Co, Cd, Pb, and, partially, Hg are distributed in accordance with the 'fraction rules' (with minimums in sands and coarse aleurites and maximums in mud); Ba distribution is independent of the sediment type. The concentrations of toxic elements tend to increase with time: the concentrations of such elements in samples (at the same stations) somewhat increase compared with their concentrations before the construction of D-6 oil platform, during its construction, and during oil production. This trend in the concentrations of toxic elements in sediments can be due to the steelwork of D-6 platform. The increase in Ba concentration is likely due to drill mud spills during exploration drilling. None of the elements shows sediment pollution in excess of MAC anywhere in the area. [ABSTRACT FROM AUTHOR]