Deuterium as indicators of the natural and anthropic stress on the waters of the Danube Delta, Romania

The natural flow of water has been examined in the Danube Delta Biosphere Reserve Romania, the largest deltas in Europe, using deuterium (2H) as a natural tracer. The understanding of the circulation of the water and pollutants into protected zones is essential to protect the maintenance of all ecological functions of delta. The isotopic content variations of water due to the climatic changes and anthropogenic activities are fast, the isotopic signature being indicators for the water flow-paths changes before irreversible environmental transformations occur. Contours maps of the mean deuterium concentrations have been used to reveal the changes of the water flow-paths from the running waters (Danube's distributaries, channels/canals with active, controlled or absent circulation of water) and the standing freshwater (lakes with active, reduced or controlled change of water). The isotopic maps show the changes of pathways due to the climatic changes that have the impact on the water balance, the erosion of coastal areas and the man made pressures on the Danube Delta. (author)