Estimation of modern sedimentation rate in Zun-Torei Lake (East Trans-Baikal Region) by 137Cs

On the basis of bottom sediment core dating performed by the technogenic isotope ¹³⁷Cs, the rate of sedimentation in periodically drying Zun-Torei Lake (water area is up to 300 km²) is estimated at 2.88 mm per year over the last 59 years. This value is in agreement with the data of palinological determinations (3.44 mm per year). High sedimentation rates are attributed to intensive evaporite sedimentation and probable eolian addition of terrigenous material.     

Vegetation of Central Transbaikalia in the Late Glacial period and Holocene

Presented are the latest findings from investigating bottom sediments in Lake Arakhlei, containing continuous records of the vegetation evolution in the Beklemishevskaya depression and its mountain surroundings for the last 13 500 years.     

Structural and geographical analysis of cross-border three-member areas

A specific geographical structure identified at the junction point of the borders of three countries is characterized by a radial symmetry in the distribution of areas with varying degrees of nature management restrictions, which get tougher closer to the junction. The special protection areas are located in the junction point of the borders.     

Neutron-capture elements in halo, thick-disk, and thin-disk stars. Strontium, yttrium, zirconium, cerium

We derived Sr, Y, Zr, and Ce abundances for a sample of 74 cool dwarfs and subgiants with iron abundances, [Fe/H], between 0.25 and ?2.43. These estimates were obtained using synthetic spectra, assuming local thermodynamic equilibrium (LTE) for Y, Zr, and Ce, allowing for non-LTE conditions for Sr. We used high-resolution (λ/Δλ?40 000 and 60 000) spectra with signal-to-noise ratios between 50 and 200. We find that the Zr/Y, Sr/Y, and Sr/Zr ratios for the halo stars are the same in a wide metallicity range (?2.43 ≤ [Fe/H] ≤ ?0.90), within the errors, indicating a common origin for these elements at the epoch of halo formation. The Zr/Y ratios for thick-disk stars quickly decrease with increasing Ba abundance, indicating a lower rate of production of Zr compared to Y during active thick-disk formation. The thick-disk and halo stars display an increase in the [Zr/Ba] ratio with decreasing Ba abundance and a correlation of the Zr and Eu overabundances relative to Ba. The evolutionary behavior of the abundance ratios found for the thick-disk and halo stars does not agree with current models for the Galaxy’s chemical evolution. The abundance ratios of Y and Zr to Fe and Ba for thin-disk stars, as well as the abundance ratios within each group, are, on average, solar, though we note a slight decrease of Zr/Ba and Zr/Y with increasing Ba abundance. These results provide evidence for a dominance of asymptotic-giant-branch stars in the enrichment of the interstellar medium in heavy elements during the thin-disk epoch, in agreement with the predictions of the nucleosynthesis theory for the main s-process component.