An assessment of the seawater effect by geochemical and isotopic data on the brackish karst groundwater from the Karaburun Peninsula (Izmir, Turkey)

The study area is located in the center of the Karaburun Peninsula, Turkey, where several karstic springs discharge near the coast 0-2 m above the sea level. The most important discharge points are the Ildiri and Gerence springs. Groundwater obtained from Ildiri springs and several drill wells provide water to the region during the summer periods. The electrical conductivity values are between 1900 and 3900 mu S/cm. Springs are slightly salty and are not used directly as drinking water. Salinity was observed in the spring waters under natural flow conditions. The salinity values of the drillings and springs were measured in dry and wet seasons. Spring waters have conductivity values between 3000 and 4000 mu S/cm. Preliminary surveys reveal that seawater contribution to Ildiri springs is 6.5 % maximum. Gerence spring waters discharge to the surface from a region very close to the sea. The dominant cation is Na, and the dominant anion is Cl. Conductivity values were between 7000 and 13,000 mu S/cm. Gerence spring waters discharge to the sea with seawater contributions ratios between 8.5 and 20.3 % depending on the seasonal changes. While some spring waters discharge 0.5-1.0 m above sea level, the rest of them discharge directly into the sea. Salinization of Gerence spring water is higher than the other springs