Models applicable for evaluation of contaminated sites – biological system at risk

摘要

The different methods that can be used correspond to three types of approaches, testing, monitoring, and modeling (Chapman, 1989, 1991).ud• Experimental models: these are the conventional assays of the occur¬rence, behaviour, and effects of pollutants (1) at different levels of organization, that is, laboratory assays (monospecific tests) and different integrated assays (from multispecific assays up to mesocosms) and (2) for different types of pollutants, from the pure substance to the polluted medium (bioassays).ud• In situ indicators, relative to the environment and to the living elements that populate it or living elements introduced on the site (measure¬ment of pollutants and eco-epidemiological data).ud• Mathematical models.udFor Covello and Merkhofer (1993), this categorization is not absolutely rigid; for example, some mathematical models may be used to express results of conventional assays. Moreover, the distinction between a laboratory assay and an in situ indicator is fundamentally arbitrary. An ecotoxicity assay is a microcosm, in the first sense of the term, that is, a 'world in miniature' that attempts as far as possible to represent the com¬plexity of nature, while the data collected on the site can be considered the result of a single experiment on a grand scale. The bioassays have been linked to ecotoxicity assays, because they have been conducted according to the same standard protocols, but they can be considered a particular form of in situ indicators, since they use a polluted medium rather than a pure substance.ud