25th International Meeting on Organic Geochemistry IMOG 2011

esponce
P-146
Alteration of aromatic hydrocarbons from the oil pollutions by
aerobic biodegradation
Elena Fursenko 1 , Vladimir Kashirtsev 1 , Lyubov Altunina 2 , Varvara Ovsyannikova 2 ,
Ludmila Svarovskaya 2
1 Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk, Russian Federation,
2 Institute of Petroleum Chemistry SB RAS, Tomsk, Russian Federation (corresponding
author:fursenkoea@ipgg.nsc.ru)
At present, in organic geochemistry quite a
considerable interest has been invited by works
addressing compositional changes in oil components
under their biodegradation. Such type of works are
important both when evaluating the biodegradation
intensity of oil pollution and in determining the degree
of natural oil and bitumens microbial oxidation.
This paper offers a comparative analysis for
distribution of aromatic hydrocarbons (HC), identified
by GCMS method in naphthene-aromatic fractions of
chloroform extracts (Echl), obtained prior to and after
modeling the aerobic biodegradation processes in
petroleum drilling mud by aboriginal microflora (two
experiments). Under biodestruction, the mass of
petroleum mud has decreased by 20-30%, on
average, per month. According to the data on the
composition of saturated fraction of Echl, the
biodestruction of petroleum sludge varies from slight
to moderate degree /1, 2/: in the biodegraded
samples the concentration of n-alkanes has
decreased (down to their total disappearance), with
acyclic isoprenanes (mainly, pristine & phytane)
content going higher, in the meantime;
concentration‘s ratios of steranes to terpanes have
not changed.
In chromatograms for total ion current (TIC) in the
biodegraded samples, unlike in the initial ones, there
was observed the escalation of the peaks intensity,
characterizing methylphenanthrenes and
dimethylphenanthrenes (fig. 1).
1 2
initial sample biodegradated sample
retention time (min)
1 2
retention time (min)
Figure 1. Total ion current (TIC) in the naphthenearomatic
fraction of the studied samples
(1 - methylphenanthrenes,
2 - dimethylphenanthrenes)
Alkylbenzenes (fig. 2), methylalkylbenzenes (m/z
105, 106) and dimethylalkylbenzenes (m/z 119, 120),
responce
observed in the initial samples, have disappeared in
the biodegraded samples.
initial sample biodegradated sample
m/z 92
m/z 91
retention time (min)
m/z 92
m/z 91
retention time (min)
Figure 2. The mass chromatograms
for alkylbenzenes
Alkylnaphthalenes (m/z 128) have been hardly
identifiable in the composition of naphthalenes in the
biodegraded samples; whereas the concentrations of
dimethylnaphthalenes (m/z 142, 156) and
trimethylnaphthalenes (m/z 170) have considerably
diminished.
Thus, the comparative analysis performed for the
data on the composition of aromatic HCs in both initial
and biodegraded products has shown that already at
initial stages of biodegradation, alkylbenzenes and,
partly, alkylnaphthalenes undergo a complete
reduction. Whereas dimethylnaphthalenes
trimethylnaphthalenes have been affected by
biodegradation to a lesser extent. At earlier stages of
biodegradation the phenanthrenes and more
condensed structures are known not to be subjected
to alteration. So, apart from the data on the
composition of saturated fractions of oils and
bitumens, it is advisable to use the ratios of aromatic
HCs by their composition for evaluation of the
intensity of their microbial oxidation. We can
recommend to use some specific HC-biomarkers (e.g.
retene) as markers for detection of sources of oil
pollution.
This work was supported by the Interdisciplinary
Integration Project of SB RAS № 31.
References
[1] Kashirtsev, V.A. Organic geochemistry of
naphthides in Siberian Platform. – Yakutsk,
Izdatelstvo SB RAS, YaF, 2003. – p. 160.
[2] Peters, K.E. The biomarker guide/ 2 nd ed./ K.E.
Peters, C.C. Walters, J.M. Moldovan. – USA, New
York: Cambridge University Press, 2007. – P. 1155
287