ABSTRACT
This chapter describes the behaviour of the fluorescent dyes in living organisms. The fluorescent tracers, as the most often used in tracing techniques, are written about the most, whereas, for example geobombs, can be described in few words. An example of a physical method is the opto-electronic measurement of fluorescent materials. In 1982, Martina Zupan reported on the decay of fluorescent tracers in polluted surface water. Detection limits for the water soluble tracers are reached when the measured values for the tracer no longer significantly differ from the background levels. Especially sewage water, landfill drainage water, and polluted rivers have high backgrounds of salts and can cause problems in using salts as a tracer. In the combined tracing test from 1969 in the percolation area of the Upper Danube, the tracers potassium chloride and sodium chloride were injected on the same day in different sites.
