ABSTRACT
The study compares the use of different tracers for sewage treatment plant outlets (STPO) in surface water and groundwater. Boron, EDTA and chloride are used as classic tracers of sewage components among other water sources. The rare earth element (REE) gadolinium as Gd-DTPA complex is a new tracer which is carried into the environment only via STPO. The input of Gd is of anthropogenic origin. The surface waters in our investigation area are significantly influenced by sewage treatment plants but also extensively used for drinking water production by bank filtration. The stable isotope ratios δ18 O and δD as ideal tracers were compared with our results. Monthly sampling campaigns at a transect over nearly one year gave information on the advantage of using a multiple tracer approach. The investigation proved that the tracers we used will reach groundwater observation wells and production wells. For example the Gd complex passes from the surface water to the production wells without reacting considerably underground.
