| Abstract [eng] |
The aim of this work is to investigate the change of 18O/16O isotope ratio of Neris water and water entering Vilnius wells using the method of stable isotope mass spectrometry and to estimate the time period during which Neris water enters specific wells. Prior to the start of the study, it was hypothesized that the wells located near the Neris River may be close enough to the rapid infiltration zone and for this reason, it may be possible to experimentally observe the addition of the wells to the river water. The aim is to find out how fast infiltration into wells takes place and whether the duration of this process can be estimated by monitoring the annual change of stable water isotopes. The findings emphasize that seasonal variation of Neris river water δ18O values was observed after the results were obtained, as well as a significant correlation was found between δ18O values and river water temperature. It was established that the change of stable oxygen isotopes is also observed in the well #2, as well as in the samples of water supplied from well #1. In the wellfield #1 constant oxygen isotope values were recorded which are close to the average annual value of precipitation oxygen isotopes. The experimental average water passage time from the Neris River to the well #2 was also determined, which is close to the theoretical value. Similarly, the period during which surface water enters the wellfield #3 and reaches the end user has been determined. Using the obtained data and available models, a preliminary local surface water meteorological water line was identified. |
