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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

All studies available, simulating biodegradation under natural conditions, revealed biodegradation of the cresol isomers. m-Cresol and p-cresol were biodegraded under aerobic and anaerobic conditions in water as well as in different sediment types. o-Cresol was degraded by phenol acclimated activated sludge.   

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Additional information

Although the substances are readily biodegradable and no biodegradation simulation test has to be performed for sediments, there are studies available on biodegradation in sediments.

 

m-cresol and p-cresol

p-Cresol and m-cresol are biodegraded in aquifer sediment under anaerobic conditions (Smolenski and Suflita 1987) and by anoxic river sediment within 3-4 weeks (Kaminski et al., 1990).

p-Cresol was completely biodegraded within 4 weeks in a freshwater sediment (Haeggblom et al., 1990). p-Cresol was rapidly biodegraded (ca. 90% after 70 h) in water, water-sediment-suspensions, and by intact sediment-water cores (eco-cores) of marine, estuarine, and freshwater origin. No lag-phase was observed. Pre-exposure did not accelerate degradation (Van Veld and Spain 1983, Spain and Van Veld 1983).

 

o-cresol

The o-cresol metabolic pathway was examined by Masunaga (1986) using phenol-adapted activated sludge. About 90% of o-cresol is degraded after 24 hours and the metabolites also diminish significantly with time. The primary metabolic step is the ring-hydroxylation yielding isomers of dihydroxytoluene (3-methylcatechol, 4-methylresorcinol, methylhydroquinone). Secondary degradation products are formed either by further hydroxylation yielding trihydroxy and tetrahydroxy-toluenes or by cleavage of the aromatic ring system.