Registration Dossier

Administrative data

biodegradation in soil
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

Aerobic soil micro-organisms have been tested for their potency to degrade nitrobenzene during incubation in soil columns (Kincannon and Lin, 1985). Nitrobenzene as a component of different types of waste sludge was given to different types of soil. The origin and composition of these different types of sludge were not further specified. A column filled with sandy loam soil was loaded with DAF sludge (an industrial waste not further described). The nitrobenzene concentration dropped from 2,400 mg/kg soil to 800 mg/kg within 97 days (67% elimination). Another sandy loam soil column was loaded with slop oil sludge and the nitrobenzene concentration dropped by 98% within 76 days (from 2,746 mg/kg to 54 mg/kg). In silt loam soil, loaded with wood preserving sludge the nitrobenzene degradation was 87% (from 393 mg/kg to 54 mg/kg) within 78 days and started at day 151. Nitrobenzene was monitored by gas chromatography of extracts of treated soils. In a sterilised control assay a nitrobenzene concentration of 122 mg/kg soil dropped to 19 mg/kg within 21 days (84% removal). It can be assumed that the loss is due to volatilisation.

To simulate a rapid infiltration land treatment system for wastewater microcosms were used (Piwoni et al., 1986). The microcosms consisted of 1.5 metre soil columns filled with a fine sandy soil with sampling ports at various depths. The top of the column was closed in a ‘green house’ and air was replaced every 8 minutes. Nitrobenzene containing wastewater was added to the soil during a 12 week acclimatisation period. After that the columns received wastewater containing nitrobenzene at a concentration of 271 μg/litre each day (every 4 hours at a dosage of 4.4 ± 0.17 cm3/day). The water samples were analysed by extraction and GC- analysis. As a result, only less than 0.1% of the nitrobenzene volatilised from the column and less than 0.1% were found in the final effluent which means that more than 99.9% were degraded. As only primarily biodegradation was determined in adapted soil samples, results cannot be taken for the derivations of kinetic biodegradation rates in soil.

There are contradictory results on the volatilisation behaviour and biodegradability of nitrobenzene in soil. In one study the elimination of nitrobenzene was due to volatilisation and the other study shows that more than 99% of the nitrobenzene was primarily degraded and almost no nitrobenzene evaporated. No explanation for this inconsistency can be given.

Applicant's summary and conclusion