A stable isotope study of cave seepage waters

An isotope study (δ18O, δ2-H) of 62 samples of waters from both the interior of the Nerja cave (Málaga, Southern Spain) and the exterior sinkholes and springs at the site was carried out. Rainfall water in the study area was also studied. The mean value of seepage waters can be considered as the mean isotopic value of the precipitation waters of the area. The origin and aquifers of these different types of waters has also been studied, obtaining a clear meteoric origin both for the seepage waters and the waters from the wells and springs, but the aquifer of the latter is different, showing more negative isotopic values. This suggests that they could have mixed with waters from other aquifers which are either deeper or originate at other altitudes.