『Abstract
　Kopaida plain is a cultivated region of Eastern Greece, with special characteristic related with the paleogeographic evolution and the changes in land use. The present article examines the contamination that derives from nitrates, in terms of contaminant levels, definition of sources and spatial distribution of contaminant plume. For this purpose, 50 water samples were collected from the karstic aquifer and analyzed for 15 parameters including major ions, trace elements, physicochemical parameters, and stable isotopes. The assessment of the above parameter values along with the notes derived by the statistical process revealed the existence of nitrate contamination which has been spatial defined with the aid of spatial interpolation techniques. The correlation of NO3^- concentrations with the stable isotope values, defined the infiltration conditions and showed contaminant transport. Nitrate values revealed the potential environmental threat for local people, as 10％ of the samples exceeded the parametric value of 50 ppm and 54％ of them are above 25 ppm, indicating no optimal quality conditions. The origin of nitrate contamination seems to derive exclusively from the application of N-fertilizers, since the rest of potential sources were not verified by analytical data and field works.

Keywords: Nitrate contamination; Hydrogeochemistry; Stable isotopes; Lopaida plain』

Introduction
Study area
　Geographical setting
　Geology
　Hydrology-Hydrogeology
Methodology
　Groundwater sampling and analysis
　Statistical processing of data
　Simulation of NO3^- spatial distribution
Results and discussion
　General hydrogeochemical characteristics
　Nitrate contamination
Conclusions
References