Objects & methods of researches
Students of Lyceum learned the content of zinc and manganese in the
birch leaves and in mosses that were collected on the areas of Shelekhov
and Arshan by theyself. Other students studied the needles of the pine-trees
as the indicators of the pollution of the environment. Why were these
the objects chosen?
1. We compared to per cents content of zinc and manganese in the clean
birch leaves with per cent of content of zinc and manganese content
in the dirty birch leaves gathered at the suburbs of Shelekhov and at
Arshan (background sample). We find out that the birch leaves growing
in the fields near the Irkutsk Aluminium plant contain zinc in twice
more and manganese almost in ten times than the background leaves contain.
What are the reasons of that fact?
2. Mosses belong to the plants that are the most sensitive for the pollution
of habitat. That’s why they may be chosen for the object of analysis.
3. Xeromorphos needles of pine-tree have low gas resistance for some
a. A needle has a long lifetime. It is constantly
exposed by the influence of gases during its lifetime.
b. A needle has a high sickness rate in comparison with deciduous
Process of needle forming and rise brakes because
of pollutant influence. Because of it needle lifetime decreases to 2-3
years and in individual cases – to one year while it reaches to
6-9 years in young inviolate pine forests. Chlorosis and necrosis of
assimilated plant organs belong to outside changes that are the results
of man-caused pollutant influence. These features are of a big interest
of diagnostic counse.
The plants that have been chosen for research are members of different
departments like Mosses, Gymnospermae and Angiospermae. That gives us
a possibility to learn not only the chemical composition of these plants
but their taxonomy. That’s why our researches have a complex character.
In order to perennial observations for condition of plant components
of biogeocenoses five monitoring areas (or sub territories) were placed.
They had a square of 400 square meters and identical plant dominants
and soils. Three control areas were placed around Shelekhov and two
background areas – around Arshan settlement. On these areas total
geobotanical and soil descriptions were done, samples of plants and
soils were taken for chemical analyses. Common sampless were prepared
by chair of botany and analytical researches were done by chair of physical
methods of analysis of Irkutsk State University.
Method of researches of birch leaves and mosses
Roentgen-spectral fluorescent method of analysis (RSFA) was used for
the determination of the chemical composition of the mosses and content
of the chemical elements in the birch leaves.
Distinguishing feature of a modern RSFA is that it is used for the determination
of elements in the biological objects and for the control of the pollution
of the environment. In comparison with other physical methods of analysis
(such as an atomic absorptive, an emissive spectral, a neutron activation)
when apparatus with the energy spectrum decomposition is used RSFA has
the following advantages:
1. A possibility to determine a big number of elements at the same time:
2. A conservation of the research sample’s materials that gives
us the possibility for its second analysis by different methods:
3. A slight man-hours for analysis, an easy spectrum treatment, a possibility
to use computers for the calculation of the concentration:
4. This method falls for automation easily.
The last two advantages are the most important for the realization of
Preliminary researches have showed that Mn, Fe, Zn, Nb Pb, Sr in the
mosses may be determined by RSFA. So the aim of the present work is
to elaborate the system of the Roentgen-fluorescent determination of
Zn and Mn in the mosses that have a high rate of content of Zn and Mn
rather than the content of other listed elements.
Five samples of mosses and birch leaves were selected for the realization
of the researches in different places. The first two samples were selected
in Arshan settlement. The second sample — at the suburb of Shelekhov
at a distance of 3 km from the industrial zone, the third sample was
selected at a distance of about 6 km from the industrial zone and the
forth sample — at a distance of 0.5 km from Irkutsk Aluminium
Plant. Samples that had been taken in Arshan were named as a background.
The samples that have been selected at the suburb of Shelekhov were
named as control. In other words not only influence of nature facts
were estimated by them but also the influence of environment for the
content of Zn and Mn.
Clean and dirty birch leaves and moss were analyzed independently after
another. It was done for determination of the ways of Zn and Mn penetration
in plant’s organism (from the soil or the atmosphere). Each sample
of the clean and dirty birch leaves was analysed four times.
The researches were led by the roentgen fluorescent spectrometer VRA-30
that is produced by the firm “Carl Zeiss”. This spectrometer
has one scanning channel and is completed by three roentgen pipes with
different anodes (tungsten, rhodium and chrome). X-radiation decomposes
into the spectrum using crystal-analysers LiF(200), LiF(220), PE, ADP,
KAP, Si by Soller method.
Scintillation and flowing proportional counters are used for the registration
of the radiation. The first one is used for K- radiation measuring of
elements that have numbers Z>25 and for the radiation measuring of
L-series of the elements with Z>60. The second one is used for X-radiation
measuring of the elements those are from 9K to 29Cu and for K-radiation
measuring of the elements with Z<60. All process of the regulation,
measuring and inside control of the device are led by inside microcomputer.
During the experiments K-radiation activity was being registered under
the conditions that the tension of the roentgen pipe was 40 kV, current
strength was 40 kA, exposition lasted for 60 seconds and crystal-analyser
LiF(200) and scintillation detector were used. K-lines of Zn and Mn
were the analytical lines.
Method of research of pine-tree needles
The system that had been published in the book “Ecological monitoring”
by F. Snakin (Moscow, 1996) was used for needles research. Observations
had been continued for 3 years (2000, 2001, 2002). 10 branches of pine-tree
that was 2 years old were selected from 10 trees on each area then general
number of needles, numbers of healthy and injured needles were calculated.
There were chosen 3 classes of needles injury (or necrosis):
1. Needles without spots or healthy,
2. Needles with a few small spots,
3. Needles with a lot of black and yellow spots and completely yellow
needles (or dried needles).