Registration Dossier

Diss Factsheets

Environmental fate & pathways

Biodegradation in soil

Currently viewing:

Administrative data

Endpoint:
biodegradation in soil
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Study period:
Not available
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Published literature data.

Data source

Reference
Reference Type:
publication
Title:
Further Research into the Aerobic degradation of n-Alkanes in a Heavy Oil by a pure culture of A Pseudomonas SP.
Author:
Setti L., Lanzarini G., Pifferi P. G., and Spagna G.
Year:
1993
Bibliographic source:
Chemosphere, Vol 26 No. 6, pp 1151 - 1157, 1993

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Please see details on method in the section 'Any other information on material and methods'.
GLP compliance:
not specified
Test type:
laboratory

Test material

Constituent 1
Reference substance name:
n-alkanes C13 - C35
IUPAC Name:
n-alkanes C13 - C35
Details on test material:
All chemicals used were reagent grade and purchased froim Carlo Erba (Milan). Heavy oil (a residue of an industrial treatment in which the inorganic sulfur was removed_ was obtained from AGIP-Petroli (Rome)
Radiolabelling:
not specified

Study design

Oxygen conditions:
aerobic
Soil classification:
not specified
Duration of test (contact time)open allclose all

Results and discussion

% Degradationopen allclose all
% Degr.:
>= 50 - <= 100
Parameter:
other: C13 degradation
Sampling time:
15 d
% Degr.:
100
Parameter:
other: C13 degradation
Sampling time:
31 d
% Degr.:
0
Parameter:
other: C24 degradation
Sampling time:
15 d
% Degr.:
67 - 84.7
Parameter:
other: C24 degradation
Sampling time:
31 d
% Degr.:
>= 40 - <= 65.1
Parameter:
other: C35 degradation
Sampling time:
31 d
Transformation products:
not specified
Evaporation of parent compound:
not specified
Volatile metabolites:
not specified
Residues:
not specified

Any other information on results incl. tables

The degradation of n-alkanes follows a well-known sequence characterised by the fact that dropping decreases as the molecular weight of the aliphatic compounds increases (Table 1). After one month of fermentation, degradation is over 60% for all n-alkanes, whereas after 15 days only C13 and C14 are degraded over 50%.

Gas chromatographic analyses clearly highlight this phenomenon (please see Fig. 2 attached) and they show that the iso-alkanes, phytane and pristane, are more resistant to degradation.

The degradation of the n-alkanes (Table 1) leads to a heavy oil residue richer in high molecular weight n-alkanes (please see Fig 3 attached). The percentage of n-alkanes above C28 increases between the 15th and 31st day of fermentation, as consequence of degradation of the n-alkane from C13 to C28. The percentage of n-alkanes from C17 to C28 reached its peak at 15 days.

Another finding emerges from examining n-alkane degradation as a function of the incerse of hydrocarbon chain lenght (please see Fig 4 attached). All fermentation trials exhibited the same degradation pattern. After 15 days, two difference linear behaviour patterns were observed one for n-alkanes from C13 to C16 and another for those over C17. By extrapolating the two lines, a changing degradation point (α) is obtained; it corresponds to an average value, n of 16.0 +/-0.6.

After 31 days the value of (α) is still constant, whereas the soilid n-alkane group breaks down into two sub-groups with a changing degradation point (β), whose average value, n, is 27.0 +/-1.0. These two sub-groups include the low solid alkanes, C17 -C28 and the high ones above C28. The first sub-group shows a constant degradation pattern for entire range of compounds while, in the second, degradation depends on the hydrocarbon chain length.

Table 1 n-Alkane degradation percentages in five different trials at two fermentation times

Carbon number (n) 15 days 31 days
I II III IV V
13 50 76 100 100 100
14 22.4 43.8 70.1 82.1 100
15 8.8 21.5 36.3 71.4 93.8
16 5.0 9.1 20.0 64.4 86.4
17 0 3.9 10.7 64.3 86.1
18 - 1.4 8.0 66.8 86.4
19 - 0 8.2 63.6 86.1
20 - - 6.2 62.5 85.4
21 - - 5.6 66.3 85.6
22 - - 6.9 67.6 84.7
23 - - 6.4 66.7 85.5
24 - - 0 67.0 85.0
25 - - - 65.8 84.3
26 - - - 66.1 84.7
27 - - - 63.3 83.6
28 - - - 67.2 69.2
29 - - - 65.1 70.0
30 - - - 64.0 78.4
31 - - - 55.9 73.8
32 - - - 58.6 70.0
33 - - - 56.5 72.0
34 - - - 47.4 70.5
35 - - - 40.0 65.1

Applicant's summary and conclusion

Conclusions:
Setti et al (1993) measured the concentration of n-alkanes up to C35 in a heavy oil, using a Pseudomonas culture. Degradation was faster for lower C number, and three distinct groups were identified. Around C34 the extent of degradation was approx. 65% at 31 days.
Executive summary:

The microbal degradation of the saturated fraction of a heavy oil was examined in aerobic conditions employing a pure culture of a Pseudomonas sp. isolated from soil. A new model of n-alkane degradation is proposed. The n-alkanes were divided into three degradation groups i) liquid n-alkanes, C12 -16; 11) low solid n-alkanes C17 -28; iii) high solid n-alkanes, above C28. Our results show that n-alkane degradation depends on chemical and physical factors such as solubility and surface tension

Categories Display