Specific Features of the Dynamics of Salts in Salt-Affected Soils Subjected to Long-Term Seasonal Freezing in the South Transbaikal Region

Observations over the dynamics of the freezing-thawing processes and the migration and accumulation of salts in the soils of the Ivolginsk Depression in Buryatia showed the existence of two stages in the annual cycle of salt migration: the short-term desalinization stage alternates with the long-term salinization stage. The latter stage actually combines two phases: the fall and winter phase of the migration of solutions towards the freezing front and the spring phase of the ascending migration of melt water towards the drying soil surface with further concentration of the solutions owing to evapotranspiration. The desalinization stage in the summer is only typical of the upper soil horizons because of the insufficient amount of summer precipitation; moreover, this stage is not observed every year. Thus, the salt regime of the soils of the depression is greatly affected by the seasonal soil freezing; the long-term salinization in the fall, winter, and spring seasons alternates with a short period of the leaching of salts at the end of summer.