2. Sampling strategies

An appropriate, well-defined strategy must, in all cases, be developed well before sampling is actually carried out. This is essential not only in terms of the logic and logistics of the approach in question, but also for the prior evaluation of the sampling program before it is initiated in the field. In other words, the question is whether the final results will provide sufficiently clear answers to the questions posed by environmental managers, legislators or scientists, and whether they are therefore well suited to their intended use.

A review of the various aspects of importance to the definition of a sampling strategy, whether linked to a surveillance, operational or survey control program, is presented in table 1 . In the light of new developments in emerging techniques, the "problem definition and...