Using stable isotopes to assess river water dynamics and groundwater input in the largest European Arctic river (Severnaya Dvina).

Rivers play a key role in the water cycle on the earth via integrating all hydrological channels to return terrestrial precipitations back to the oceans. In addition, rivers, together with groundwater, are powerful transformers of the surface lithosphere, responsible for chemical weathering of rocks and the removal of solute into the ocean. Tracing the dynamics of surface water and groundwater versus atmospheric feeding of rivers presents important issues in Arctic regions due to the ongoing change of the structure of hydrological runoff.

Transformation of the chemical composition of surface waters in the area of the exploited Lomonosov diamond deposit (NW Russia).

The specific objective of this study was to investigate the changes in the chemical composition of river waters during the exploitation of the Lomonosov diamond deposit and the danger of these changes for the ichthyofauna. It was found that the Ca-HCO composition of river water both upstream and downstream from the quarry was almost identical before discharge of the drainage waters into the river. In subsequent years, the water downstream from the quarry acquired a Na-HCO composition, and then a Na-HCO-Cl composition and TDS increased by 2.

Evolution of groundwater chemistry in coastal aquifers of the south-eastern White Sea area (NW Russia) using C and U-U dating.

The specific objectives of the study are to clarify the sources and characteristics of groundwater in the aquifers along the coast of the White Sea in northwestern Russia, and on this basis to perform a broad C and U/U dating of all their types, taking into account the mixing processes. Investigation of an evolution of the groundwater chemistry revealed that the main evolutionary trends are the following: (1) Mixing Late Pleistocene brackish water end member (brackish1) and Mikulino seawater end member with strongly brackish and salty water in the Vpd aquifer (salty Vpd) formation. Groundwater dating showed the "brackish1" residence time in the aquifer of 32.