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Environmental fate & pathways

Biodegradation in soil

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biodegradation in soil, other
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study is not performed according to an internationally recognized guideline, but is well described, giving interesting insights on the catechol biodegradation in soil.

Data source

Reference Type:
Biodegradation, stabilization in humus, and incorporation into soil biomass od 2,4-D and chlorocatechol carbons
Stott D.E., Martin J.P., Focht D.D., Haider K.
Bibliographic source:
Soil Sci. Soc. Am. J., 47, 66-70.

Materials and methods

Principles of method if other than guideline:
Biodegradation in soil
GLP compliance:
not specified
Test type:

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Details on test material:
The ring 14C-labeled catechol was synthesized according to Martin et al. (1979). The purity was tested by gas chromatography after direct silylation with N-methyl-N-trimethylsilyl-trifluoracetamide.

Study design

Oxygen conditions:
Soil classification:
not specified
Details on soil characteristics:
Four soils were used for the tests:
- Steinbeck loam (pH: 5)
- Fallbrook sandy loam (pH: 5.5)
- Greenfield sandy loam (pH: 7)
- Sorrento loam (pH: 7.4)
The four soils used in this study were air-dried, sieved prior to use.
No more information.
Duration of test (contact time)
6 mo
Initial test substance concentrationopen allclose all
Initial conc.:
25 ppm
Based on:
other: test mat. / Concentration used in both testing periods (6 months and 1 year)
Initial conc.:
500 ppm
Based on:
other: test mat. / Concentration used in the 1-year testing period only
Parameter followed for biodegradation estimation:
CO2 evolution
Experimental conditions
23 °C
other: 60% of the water capacity
Details on experimental conditions:
- Soils were incubated in the presence of the organic substrates in a closed system. The moisture content was 60% of the water capacity, the temperature was 23°C. The flasks were aerated with a constant stream of humidified and CO2-free air. The amounts of total CO2 and 14C02 released were analysed.
- Concentrations of 25 and 500 ppm were tested for 1 year. Only the concentration of 25 ppm was tested for 6 months.
- Each treatment was duplicated.

- The biodegradation of ring labelled catechol, free or linked into model humic acid polymers, was followed over 6-month and 1-year incubation periods, and the distribution of the residual activity in biomass, new humus, and 6N HCl hydrolysable substrates was determined.
- The 14C-labelled catechol was incorporated into model humic acid polymers by reacting about 1 g of a phenolic mixture with 14 mg of peroxidase over a 5-d period.
- The 14C activity of the organic substrates, the 14CO2 evolved during incubation, the residual 14C remaining in the soil after incubation or extractions have been described.

Results and discussion

% Degradation
% Degr.:
> 24 - < 50
other: dissipation
Sampling time:
6 mo
Transformation products:
not specified
Evaporation of parent compound:
not specified
Volatile metabolites:
not specified
not specified
Details on results:
- 96% of the 14C-labelled catechol in the reactive mixture was recovered in the polymers.
- 37 to 50% of the catechol was lost over 1 year indicating substantial stabilisation of the compound, probably by enzymatic polymerisation reactions. Catechol incorporated into model polymers was still more stable with 6 to 22% of the 14C evolved as CO2.
- After 1 year, about 3 to 8% of the residual 14C activity from catechol was present in the biomass. The amount of residual C in the biomass from the catechol incorporated into the model polymers varied from 0.2 to 2.1%.

- % 14C evolved as 14CO2 in 6 months (catechol at 25 ppm):
in Steinbeck loam: 24
in Fallbrook sandy loam: 50
in Greenfield sandy loam: 28
in Sorrento loam: 26

- % 14C evolved as 14CO2 in 1 year (catechol at 25 ppm):
in Steinbeck loam: 39
in Fallbrook sandy loam: 39
in Greenfield sandy loam: 40
in Sorrento loam: 43

- % 14C evolved as 14CO2 in 1 year (catechol at 500 ppm):
in Steinbeck loam: 50
in Fallbrook sandy loam: 40
in Greenfield sandy loam: 38
in Sorrento loam: 37

Applicant's summary and conclusion