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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

Guanidine chloride is shown to be biodegraded in environmental water. 

Key value for chemical safety assessment

Half-life in freshwater:
5.25 d
at the temperature of:
25 °C

Additional information

The development of the microbial populations capable of enhanced guanidinium mineralization is related to the concentration of the cation. At the three highest concentrations (0.1 - 10 mg/l), a biodegrading population developed that ultimately effected the persistence of the cation. Mineralization occurred also at 3 guanidinium concentrations tested from 0.0005 - 0.01 mg/l but not with a similar extensive mineralization rate as at 0.1 - 10 mg/ Guanidinium /L and mineralization rate developed more slowly as at 0.1 mg/L.

Both from direct observations in surface water samples (other experiments in the publication) and from the evaluation of an enriched laboratory population, the development of such a population as well as its degradation of guanidinium would likely be slow.

Degradation tests with 8 river water samples from different locations showed a mean degradation half life for guanidine of 5.25 d at 25°C after a mean lag phase of 30 d.