Reaction product with n-butanol of high-boiling stream resulting from the hydroxylation, oxidative cleavage and hydrolysis of vegetable oil saturated and unsaturated C16-C22 triglycerides.

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Biodegradation in soil is examined. Sound study setup but no guideline followed and no half-life or % degradation determined.

Data source

Reference

Reference Type:

publication

Title:

Triglyceride degradation in soil

Author:

Hita, C. et al.

Year:

1996

Bibliographic source:

Org. Geochem 25(1-2): 19-28

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Test substance was added to 3 different soil types. Soils were incubated at 20°C for 8 weeks. CO2 evolution and formation of metabolites was monitored.

GLP compliance:

not specified

Test type:

laboratory

Test material

Test material information

Constituent 1

Reference substance name:

Glycerol tristearate

EC Number:

209-097-6

EC Name:

Glycerol tristearate

Cas Number:

555-43-1

IUPAC Name:

propane-1,2,3-triyl trioctadecanoate

Test material form:

not specified

Radiolabelling:

no

Study design

Oxygen conditions:

aerobic

Soil classification:

not specified

Soil properties

Soil properties 1

Soil no.:

#1

Soil type:

other: Rendzina

% Clay:

29

% Org. C:

2.7

pH:

8.1

Soil properties 2

Soil no.:

#2

Soil type:

Luvisol

% Clay:

13.5

% Org. C:

7

pH:

4.1

Soil properties 3

Soil no.:

#3

Soil type:

other: Rendollic Eutrochrept

% Clay:

25

% Org. C:

2.2

pH:

7.3

Details on soil characteristics:

Rendzina:
- 31% CaCO3
- CN ratio: 7.3

Glossic Luvisol:
- 7% CaCO3
- C/N ratio: 19

Rendollic eutrochrept:
- 4% CaCO3
- C/N ratio: 7.5

Duration of test (contact time)

Duration of test (contact time) 1

Soil No.:

#1

Duration:

8 wk

Duration of test (contact time) 2

Soil No.:

#2

Duration:

8 wk

Duration of test (contact time) 3

Soil No.:

#3

Duration:

8 wk

Initial test substance concentration

Initial test substance concentration 1

Soil No.:

#1

Initial conc.:

2 000 mg/kg soil d.w.

Based on:

test mat.

Initial test substance concentration 2

Soil No.:

#2

Initial conc.:

2 000 mg/kg soil d.w.

Based on:

test mat.

Initial test substance concentration 3

Soil No.:

#3

Initial conc.:

2 000 mg/kg soil d.w.

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

test mat. analysis

Experimental conditions

Experimental conditions 1

Soil No.:

#1

Temp.:

20

Experimental conditions 2

Soil No.:

#2

Temp.:

20

Experimental conditions 3

Soil No.:

#3

Temp.:

20

Details on experimental conditions:

Three types of soils (rendzina, glossic luvisol and rendollic eutrochrept, see Table 1) were chosen from the Poitou-Charentes region, in the western part of France. Two of these soils (rendzina and glossic luvisol) have already been described by Mouqawi et al. (1981a) , the other soil is a brown calcareous one (rendollic eutrochrept). For each of these soils, the humiferous A horizon topsoil was sampled. The three soil samples were first sieved (<2 ram), adjusted to 2/3 of the water-holding capacity of each respective soil and then weighed into 750 cm 3 flasks in portions calculated to correspond to 100 g o.d. soil. The soils were subsequently supplemented with a pare triglyceride (tristearin) (Fluka Chemicals) at a concentration of 0.2% (wt/ wt). Controls and treatments were carried out similarly in triplicate, incubated for periods of 1 (samples C lw and TRI lw), 4 (samples C 4w and TRI 4w) and 8 weeks at 20°C. Throughout the chosen period the samples were aerated regularly in a closed system with moist, CO2-free air.

Results and discussion

Evaporation of parent compound:

not measured

Volatile metabolites:

no

Residues:

yes

Any other information on results incl. tables

The main result of the monoacid fraction analysis was the rapid formation of stearic acid in considerable amounts. This result showed that an intense hydrolysis reaction with specific lipases of tristearin had occurred after the soil supplementation. The investigation of ester fractions showed that new alkanoic acids (methyl stearate, ethyl stearate and propyl stearate), not determined in the controls, were generated in the supplemented soils.

 

After incubating for 4weeks, the authors observed a decrease in the amount of the components that were generated. It can be concluded that these did not accumulate and were gradually transformed in the biodegradation processes.

 

Results were similar in the three types of soils, showing more or less the general character of these mechanisms (independent in any case of soil pH and soil characteristics, even if the kinetics seem slightly different between acidic and neutral soils). The particular pathway shown here for the elimination of fatty wastes in the soil seems to be all the more important as it is known that fatty acids, mono/diglycerides and glycerol are removed more easily than triglycerides (Eigtved, 1992).

Applicant's summary and conclusion

Executive summary:

The biodegradation of tristearin in soil was examined by adding the test substance to 3 different soil types. The soils were incubated at 20°C for 8 weeks. CO2 evolution and formation of metabolites were monitored.

The test showed a rapid formation of stearic acid and stearic esters in considerable amounts, demonstrating the primary degradation of the test substance under the conditions of the test. After 4 weeks of incubation, these components decreased again. It can therefore be concluded that the primary metabolites do not accumulate, but were further transformed in the biodegradation process.

Ultimate biodegradation as demonstrated by the formation of CO2 was found to be more dependent on te soil type when compared to primary degradation. A detailed study of the soil organic matter is necessary in order to understand the observed differences.