Proceedings SWIM 16,Miedzfzdroje - Wolin lsland 2000 Nicholas Copernicus university Vol. 80 (2000) p. 87-94, 4 figs Preliminary hydrochemical, isotope,and noble gas investigations on the origin of salinity in coastal aquifersof WesternPomerania, Poland A. Krawiecl, A. Riibel', A. Sadurski3, S. M. Weise4, A. Zubers l University of Nicolas Copernicus, Toruh, Sienkiewicza 4, PL-87100 Toruh, Poland, a rekm rv@cc. u ni.toru n. pl ; 'lnstitut fiir Umweftphysik, Univers et Heidelberg, lm Neuen-heimer Feld 229, D-69120 Heidelberg, Germany, a nd re. rue be l@u n. u ni -h e ide I be rg ; 3University of Nialas Copernicus, Toruh, Sienkiewicza 4, PL-87100 Toruh, Poland, h GeologicelInstitute, Warsaw Rakowiecka 4, Poland asad@pgi.waw.pt aGSF-National Research Centerfor Environment and Health, Institute of Hydrology, Ingolste er Landstr. 1, D-85764 Neuherberg,Germany, weise@gsf.de; 5lnstitute of Nuclear Physics, Radzikowskiego 152, PL-31342 Cracow Poland, zu be t@n ovel 1.ftj. ag h. ed u. pl ABSTRACT Preliminary environmental tracer investigations performed in Westen Pomerania .evealed a complex origin ofwaters andthe origin oftheir salinity. Nineteen samples were taken for hydrochemical andstable isotope analyses, andtenofthem alsofornoble gasdeterminations. Samples represent different geological formations withwaters of different salinity. Of nineteen samples, only three represent fresh Holocene water:iour Holocene water withadmixture ofascending pre-Quaternary water, andtwo Holocene water wiihsalinity fo.mindirect intrusion ofthe Baltic Seawater. Two samples represent evidently dominant component of glacial watefwith salinity most probably gained also by a small admixture of ascending saline water. Threesamples represent glacial watermixed with Holocene and pre-Quaternary waters. Fivesamples (four deep wellsand a spring) represent pre-Quatemary saline water as indicated bothby the isotopic composition of waterand noble gas data.ln conclusion, the dominant source of salinity is not caused by Baltic waterintrusions, but by ascending waters from Mesozoic formations, whichin the central and northern Poland contain pre-Quaternary meteoric waters with high salinity gained fromZechstein salt structu.es. The area of investigation extends alongthe Baltic Seashore fromSwinoujscie in the westto Ustronie Morskie in the east (fig. 1). In that re- gionthere arethree health resorts (Swiniouiscie, Kamien Pomorski and Kolobzeg)wheresaline waters are exploited for therapeutical purposes. Withinthe present study 19 samples were col- lected at 18sites for chemical andisotopic analy- ses, in that ten for noblegas determinations (in somecases the technical conditions wereunfa- vourable for noble gas sampling). Samples were takenat different depths from formations of dif- ferentstratigraphy and lithology. Fresh groundwater reservoirs are scarce and of limited extend due to shallow occurrences of brackish andsaline waters. Their exploitation of- ten leadsto the degradation of quality due to brackish water intrusions. Therefore, the origin of brackish and saline waters in Western Pomerania was a subject of a number of stud- ies. Kolago (1964) andDowgia o (1965) showed that their occurrences in Jurassic. Cretaceous and Cenozoic formations are mainly related to anticline structures and dislocation zones., Dowgiallo (1971 , 1988) regarded the saline wa- tersin Mesozoic formations of northern andcen- tral Poland to be mixtures of waters of difierent origin and age(calling them poligenetic waters). Similarly Dowgiallo andTongiorgi (1972) on the basis of some isotopedata regarded them to