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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Administrative data

Endpoint:
biodegradation in water: sediment simulation testing
Type of information:
experimental study
Adequacy of study:
other information
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
significant methodological deficiencies
Remarks:
Does not meet important cirteria of today standard methods

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
Total reductive dechlorination of chlorobenzenes to benzene by a methanogenic mixed culture enriched from Saale river sediment
Author:
Nowak J, Kirsch NH, Hegemann W, Stan HJ
Year:
1996
Bibliographic source:
Appl Microbiol Biotechnol, 45: 700-709
Reference Type:
review article or handbook
Title:
SIDS Initial Assessment Report For SIAM 13 (Bern, 6 - 9 November 2001) - 1,2-Dichlorobenzene
Author:
OECD
Year:
2001
Bibliographic source:
UNEP Publications

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Anoxic sediment samples collected from the Salle river near Jena, Germany, were used as inoculum. This sediment was chosen because of its prior exposure to the waste waters of a pulp mill that used chlorine bleaching. Chlorobenzene-metabolizing methanogenic-enrichment cultures were obtained by inoculating phosphate-buffered RAMM medium with black, anoxic mud (50% v/v) collected form the Saale river and subsequent stationary incubation under strictly anaerobic conditions. Whilst being flushed with nitrogen of the highest purity (6.0), the sediment was transferred and mixed with an equal volume of medium into 1-L serum bottles peviously filled with nitrogen. Several individual chlorobenzene isomers and mixtures of them were added for adaptation (MCB, all DCB, all TCB and 1,2,3,4-tetrachlorobenzene). Upon dechlorination of the added chlorobenzenes, the enrichment cultures were repeatedly fed with the substrates.
The sampling procedure commenced with shaking the bottle for 1 min in order to homogenize the sludge within the aqueous phase. 2 mL homogenate was removed and the liquid extraction of the sample was performed by adding 2 mL aqueous surrogate standard and 2 mL ethyl acetate. The sample was thoroughly shaken and subsequently centrifuged. The supernatant was filtered through a small bed of silica gel and sodium sulfate into an autosampler vial ready for GC analysis. In addition, the gas phases of the bottles were analyed for volatile compounds.
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
1,2-dichlorobenzene
EC Number:
202-425-9
EC Name:
1,2-dichlorobenzene
Cas Number:
95-50-1
Molecular formula:
C6H4Cl2
IUPAC Name:
1,2-dichlorobenzene

Study design

Oxygen conditions:
anaerobic
Inoculum or test system:
natural sediment

Results and discussion

Any other information on results incl. tables

In a study using a methanogenic mixed culture enriched from Saale river sediment, all chlorobenzenes present were transformed by reductive dechlorination via monochlorobenzene to unsubstituted benzene. This occurred after a one week lag phase, which could not be explained. It was found that the dechlorination process was dependent on the biological activity. Reductive dechlorination was stimulated when the mixed cultures were supplemented with pyruvate and methanol.

Applicant's summary and conclusion

Conclusions:
In a study using a methanogenic mixed culture enriched from Saale river sediment, all chlorobenzenes present were transformed by reductive dechlorination via monochlorobenzene to unsubstituted benzene.
Executive summary:

In a study using a methanogenic mixed culture enriched from Saale river sediment, all chlorobenzenes present were transformed by reductive dechlorination via monochlorobenzene to unsubstituted benzene. This occurred after a one week lag phase, which could not be explained. It was found that the dechlorination process was dependent on the biological activity. Reductive dechlorination was stimulated when the mixed cultures were supplemented with pyruvate and methanol.