Measurement of toxic potency in fresh waters in the Netherlands; Part A: Methods
De meting van toxische potentie in Nederlandse zoete wateren ; Deel A: Methoden
Roghair CJ, Struijs J, de Zwart D
RIVM Report 607504004
This research is part of the RIVM project 'Kartering Ecotoxische Effecten Stoffen' (KEES ; Geographic Representation of Ecotoxicological Effects of Substances). The report gives a detailed description of a set of methods developed for assessing the toxicity of natural waters by experimental means. The unknown cocktail of organic pollutants present in samples of surface water is concentrated and tested ecotoxicologically. The number of times a given water sample needs to be concentrated before toxic effects are observed is used as a measure of the toxic potency of the water sampled. The results are reported in terms of the fraction of species for which the concentration in the environment exceeds the No Observed Effect Concentration (NOEC). This fraction is defined as the Potentially Affected Fraction of species (PAF). The methods developed have been tested in a pilot study a bimonthly evaluation of toxic potency at 15 stations along the Rivers Rhine, Meuse and Scheldt in the Netherlands during the year 1996.