The "Mercury breathing" of the Baikal rift zone according to the study of tree annual rings (on the example of Tunkinskaya depression)

The work evaluates the general distribution of mercury in the rings of trees of the Tunkinskaya depression (the Republic of Buryatia, the national park "Tunkinsky").The used methods of dendrochronology and dendrogeochemistry allow us to estimate the contribution of different factors affecting the quality of the environment and ascertain the history of natural components pollution. In this research, the phenomenon of natural degassing of mercury in the Baikal Rift Zone (BRZ) according to the study of annual tree rings is considered. The BRZ covers 13 large parallel lobes separated from each other by high mountain ridges and bridges. Geodynamic activity of the zone is shown by contrast relief transformation and high seismicity. High tectonic and seismic activity causes the "output" of mercury to the surface. The dynamics of Hg concentration changes in the Tunkinskaya lobe for more then half a century was observed. The average mercury content in the sample was 7 ng/g, the max – 35ng/g. The max concentration is detected in areas of the territory associated with free tectonic faults. The connection between the peaks of high mercury concentration in wood and periods of major earthquakes was detected. (paper)