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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

Administrative data

biodegradation in water and sediment: simulation tests
Type of information:
experimental study
Adequacy of study:
supporting study
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Secondary literature

Data source

Reference Type:
secondary source
European Union Risk Assessment Report, Nitrobenzene, CAS No: 98-95-3
European Chemicals Bureau
Bibliographic source:
3rd Priority List, Volume: 77
Report date:

Materials and methods

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:

Results and discussion

Any other information on results incl. tables

During incubation of nitrobenzene in an aquifer system (groundwater plus fine material of sediment) no biodegradation was observed during the exposure period of 150 days. The incubation was performed at 10°C in the dark in a slowly rotating box with aeration taking place (minimum oxygen concentration 9 mg/l). The test substance was monitored by GC-FID and GC-ECD, the initial concentration was 0.15 mg/l (Nielsen et al., 1996).

In an earlier study performed by the same author (Nielsen and Christensen, 1994) sediment and groundwater were incubated with a mixture of organic compounds containing nitrobenzene at a concentration of 0.15 mg/l. After a lag phase of 70 days nitrobenzene was primarily degraded by 100% within 20 days in only 2 out of 16 experiments. No degradation took place in the other experiments. No explanation for this inconsistency is given. These results are considered not valid, however they confirm that nitrobenzene is persistent under environmental conditions.

20% primary degradation of nitrobenzene in an aquifer test system with an initial concentration of 0.1 mg/l were found after 50 days (Albrechtsen et al., 1997). Again a mixture of chemicals was tested. This time a control sample was examined. The decrease of nitrobenzene in this control was 15%. Hence the loss of nitrobenzene was mainly due to abiotic elimination processes such as evaporation.

It is not possible to derive a degradation rate constant for the sediment. All that can be said is that nitrobenzene in sediment is not biodegradable in the tests described above.

Applicant's summary and conclusion