Gx value

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GHS pictogram for substances hazardous to the aquatic environment

The G value or Gx value or G x value is a measure used in ecotoxicology for the toxicity of waste water. G x values ​​can be determined in various aquatic organisms: the G A value in algae , the G D value in daphnia and the G L value in luminescent bacteria are determined; the test on fish (G F value) has now been replaced in Germany for animal welfare reasons by the test on fish eggs or fish embryos, which provides the G egg value.

Several dilution stages are made from the wastewater to be examined and the test organism is added. The dilution level with the highest concentration , from which no poisonous (toxic) effect on the organism in question is observed, forms the G x value. A high G x value means high toxicity , a low G x value low toxicity. Due to the process, the lowest possible G x value is 1 (fish) or 1.25 (algae, daphnia) and means that the wastewater in its undiluted form or the lowest possible dilution level does not have any effect on the organism concerned. The execution of the tests is stipulated in various standardized work regulations (e.g. German standard procedure , DEV).

See also

Individual evidence

  1. ↑ Final report no .: 208/03 of the Saxon State Ministry for Environment and Agriculture (PDF file; 254 kB), September 2003
  2. ^ Ulm University of Applied Sciences, Institute for Applied Natural Sciences: Bioluminescence
  3. ↑ German standard methods for the examination of water, wastewater and sludge - test procedure with aquatic organisms (group L) - determination of the effect of substances in water on small crustaceans (daphnia short-term test) (L 11)
  4. ↑ German standard methods for water, waste water and sludge analysis; Test method with aquatic organisms (group L); Determination of the non-acutely toxic effect of wastewater against daphnia via dilution levels (L 30)
  5. ↑ German standard methods for water, waste water and sludge analysis; Test method with aquatic organisms (group L); Determination of the non-toxic effect of wastewater on green algae (Scenedesmus chlorophyll fluorescence test) using dilution levels (L 33)
  6. ↑ Water quality - Determination of the inhibiting effect of water samples on the light emission of Vibrio fischeri (luminous bacteria test)
  7. ↑ Water quality - determination of the acute toxicity of wastewater on zebrafish eggs (Danio rerio)