Analysis Of N(Sr-87)/N(Sr-86),Delta Sr-88/Sr-86(Srm987) And Elemental Pattern To Characterise Groundwater And Recharge Of Saline Ponds In A Clastic Aquifer In East Austria

Elemental and isotopic pattern of n(Sr-87)/n(Sr-86) and delta Sr-88/(86)SrSRM987 were used to characterise groundwater and recharge of saline ponds in a clastic aquifer in East Austria. Therefore, shallow, artesian and thermal groundwaters of the investigated aquifer along with rainfall and rivers were analysed using (MC) ICP-MS. The n(Sr-87)/n(Sr-86) ratio and elemental pattern changed with aquifer depth as a result of progressing bedrock leaching and dissolution with increasing groundwater residence time. The n(Sr-87)/n(Sr-86) ratio of shallow groundwater below saline ponds of 0.71019 +/- 0.00044 was significantly different from thermal groundwater of 0.71205 +/- 0.00035 (U, k = 2). In contrast to previous theories, this result suggested no recharge of saline ponds by upwelling paleo-seawater. Isotope pattern deconvolution revealed that rainfall accounted to about 60% of the n(Sr-87)/n(Sr-86) ratio of shallow groundwater below saline ponds. The delta Sr-88/Sr-86(SRM987) values of groundwater decreased from about 0.25 % in most shallow, to predominantly negative values of about -0.24 % in artesian groundwater. This result indicated leaching and dissolution of weathered minerals. In turn, the delta Sr-88/Sr-86(SRM987) of deep thermal groundwater showed positive values of about 0.12 %, which suggested removal of 86Sr from solution by carbonate precipitation. These results highlight the potential of delta Sr-88/Sr-86(SRM987) signature as an additional geochemical tracer.