Nitrobenzene

Biodegradation in water and sediment: simulation tests

Administrative data

Endpoint:

biodegradation in water and sediment: simulation tests

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Secondary literature

Data source

Reference

Reference Type:

secondary source

Title:

European Union Risk Assessment Report, Nitrobenzene, CAS No: 98-95-3

Author:

European Chemicals Bureau

Year:

2007

Bibliographic source:

3rd Priority List, Volume: 77

Report date:

2007

Materials and methods

Test material

Test material information

Constituent 1

Reference substance name:

Nitrobenzene

EC Number:

202-716-0

EC Name:

Nitrobenzene

Cas Number:

98-95-3

Molecular formula:

C6H5NO2

IUPAC Name:

nitrobenzene

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.