25th International Meeting on Organic Geochemistry IMOG 2011

P-381
Permissible concentration of petroleum contaminants as
determined from studying the adaptive reaction of plants in a
model experiment with permafrost soil f yakutia
Sara Lifshits, Olga Chalaya, Yulia Glaznetsova, Iraida Zueva
Institute for Biological Problems of Cryolithozone, Siberian Department, Russian Academy of Sciences,
Yakutsk, Russian Federation (corresponding author:s.h.lifshits@ipng.ysn.ru)
The behavior of plants (Lepidium ruderale L. and
Artemisia vulgaris L.) was studied in a model
experiment with permafrost sod-and-grass soil of
Yakutia contaminated with petroleum. It has been
shown that of all the physiological characteristics of
plants, the most informative in studying the process of
adaptation to petroleum contamination is the survival
coefficient calculated as the ratio of the number of
survived plants to that of germinated seeds. Variation
of the coefficient with the amount of petroleum
introduced into soil is, for both plants, bimodal in
character, with a tendency for a decrease. One can
see two areas of maximum coefficient values in each
of the plots given below, which seem to reflect
different strategies in plant adaptation to the growing
intensity of the stress factor (Fig.1). Addition of
petroleum in quantities of 0.25% for Lepidium
ruderale L. and 0.32% for Artemisia vulgaris L.
resulted in a more intense accumulation of
contaminants in soil (Fig. 1). The proportion of
hydrocarbon fractions in the composition of
contamination and the distribution of individual
alkanes became close to those in reduced crude.
Fig. 1. Plots of the survival coefficient of plants and
the intensity of contaminants accumulation versus the
amount of petroleum added into soil.
Comparison of the results of experiments with and
without growing plants revealed a more profound
transformation of petroleum pollutants in the presence
of plants. The growing plants sped up the destruction
of petroleum hydrocarbons. As a result, the level of
contamination decreased by 60.2% (Artemisia
vulgaris L.) and 66.8% (Lepidium ruderale L.) as
compared with 31.5% observed in cases when
biodegradation of contaminants was only caused by
soil microflora. Studies on the regularities in the
distribution of individual hydrocarbons showed that
not only do the present plants increase the degree of
pollutants transformation but widen the range of
structural isomers of alkanes undergoing
biodegradation too (along with n-alkanes and 2- and
3-methyl alkanes, subjected to transformation were
12- and 13-methyl alkanes and isoprenoids). Thus,
the varying hydrocarbon composition of bitumoids
reflects a tendency toward restoration of the natural
geochemical background (Fig. 2).
Fig. 2. Mass-fragmentograms (m/z 57) of hydrocarbon
fractions in soil samples. Sample A: 0.16% petroleum,
without plants; C: 0.16% petroleum, with growing
Artemisia vulgaris L.; D: 0.16% petroleum, with
growing Lepidium ruderale L.; E: initial soil sample.
The results of studying the adaptive potential of plants
and the efficiency of contaminants transformation
permitted us to estimate the permissible concentration
of contaminants in soil as 1g/kg on average.
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