Strontium isotopes as environmental tracers for identification of groundwater circulation in multi-layered aquifer systems

The results of the research concerning measures of strontium isotopes and concentrations, were presented in this article. This environmental tracers occuring in groundwater and surface water allowed for the preliminary identification of groundwater circulation in the multi-layered aquifer system. The study area concerned Żarnowiecka Upland and Valley of the Żarnowieckie Lake with the Piaoenica river, where the occurrence of 3 to 5 aquifers in Quaternary, Miocene and Oligocene was confirmed. The valley area is also the Main Groundwater Reservoir (MGR) No. 109. The results clearly indicated on substantial differences in the values of 87Sr/86Sr isotopic signatures and strontium concentrations in each of aquifers. These differences made possible to determine the percentage of the groundwater in the Piaoenica drained from the upland and from the valley. Calculations showed the groundwater component from the upland may constitute up to 80% of river water, and the river is a regional drainage base even for the Oligocene aquifer occurring at a depth of approx. 200 m. The results confirmed no link between the shallowest aquifers occurring in the upland, and the drainage role of the Piaśnica river. The characteristic of shallow groundwater is similar to the rainwater