APPLICATIONS OF ATOMIC ABSORPTION SPECTROMETRY
TO THE STUDY OF THE VEGETATIVE PROCESSES
OF THE PLANTS GROWN IN SPECIAL CONDITIONS
I. MÎNDRECI1, C. VASILE2, M. PASCU1, G. CAZACU2
1 ”Gr. T. Popa” University, 16 University Str., 760004 Iaºi
2 ”P. Poni” Institute of Macromolecular Chemistry, 41A Gr. Ghica Voda Alley, 700487 Iaºi
Received December 21, 2004
Atomic absorption spectrometry has been used in order to study the response
of some plants (Vicia X hybrida hort, Pisum Sativum) to the conditions created by
the degradation in their culture soil of different polymer mixtures (blends of synthetic
polymers (polyethylene (PE), polypropylene (PP))/natural polymers (collagen,
different types of lignin)).
Key words: atomic absorption spectrometry, terrestrial plants growth test,
polyolefins, collagen, lignin.
It is well known that polyolefins, such as polypropylene (PP) and
polyethylene (PE) show high resistance against photo- and biodegradation ,
leading to the waste accumulation and the environment pollution. One solution
which can be used in order to overcome this problem is to turn these synthetic
polymers into environmentally friendly materials, by blending them with natural
polymers, such as: lignin, starch, cellulose, or their derivatives . In this way,
the rate of the environment degradation of polyolefins is significantly increased,
leading to the diminution of the generated waste quantity (especially from
packaging and agriculture film).
Due to the slow rate of the environmental degradation process, sensitive
tests are necessary for evidencing the changes occurring in polymer samples or
in their environment. One of the suitable tests for the appreciation of the
biodegradability/environmental degradation of polymer mixtures is the terrestrial
plants growth test, which implies the burial of the materials in the culture soil of
the plants, following their effect on the physiological-vegetative processes.
Atomic absorption spectrophotometry, a sensitive method for the
determination of the micro- and macroelements content from biological and
Paper presented at the 5th International Balkan Workshop on Applied Physics, 5–7 July
2004, Constanþa, Romania.
Rom. Journ. Phys., Vol. 50, Nos. 9– 1 0 , P. 1163–1169, Bucharest, 2005
1164 I. Mîndreci et al. 2
pharmaceutical samples, can be successfully applied for the plants, in order to
study their response to the conditions created by the degradation/disintegration
in their culture soil of different polymer materials.
Vegetative processes have been followed by determining the content of
micro- and macroelements of Vicia X hybrida hort, Pisum Sativum plants,
cultivated in natural or greenhouse conditions when, in the culture soil, mixtures
of synthetic polymers (polyethylene (PE), polypropylene (PP))/natural polymers
(hydrolyzed collagen, cellulose, different types of lignins) have been buried.
2. MATERIALS AND METHODS
Different kinds of polymeric materials have been studied.
1. Binary blends of PE and PP with ammonium lignosulphonate (LA) and
epoxy-modified ammonium lignosulphonate (LER) have been prepared. The
sheets of polymer blends (0.5-1 mm thickness) have uniform brown colour and
smooth surfaces .
2. Maleic anhydride grafted polyolefin rubbers, kindly supplied by Exxon
3. Isotactic polypropylene (MIDIA-Romanian Petrochemical), with a melt
flow index of 2.46g/10 min, an intrinsic viscosity in decaline at 135°C of
2.11 dL/g, and a density of 0.909 g/cm3, has been blended with different
quantities (4–13 wt%) of epoxy-modified lignin (LER), in the presence of
glycidyl methacrylate-grafted polypropylene (PP-g-GMA) .
In order to increase the biodisintegration rate of these blends, they have
been photooxidized by means of a XENOTEST instrument, equipped with an
UV-source with 1.120 kW/m2 intensity. The working temperature was 55 ± 5°C,
and the exposure time varied between 50 and 200 hours .
4. Blends of low density polyethylene (LDPE)/hydrolyzed collagen (HC)
have been prepared, using as compatibilizing agents acrylic acid functionalized
low density polyethylene (LDPE-g-AAc) and bismaleinimide functionalized low
density polyethylene (LDPE-g-BMI) .
Mentioned polymeric materials have been buried in the culture soil of Vicia
X hybrida hort and Pisum Sativum plants. The plants growth test is based on the
assumption that the degradation products evolved from environmentally
degradable polymer materials buried in soil could change the soil conditions and,
consequently, the vegetation growth . The influence of the degradation
products released in the soil (pH = 8–9) on the vegetation (in greenhouse
(35–40°C, high humidity) or natural conditions) was established by monitoring
the dynamics of plants growth during several vegetation cycles, by observations
on germination, plant height, blooming, number of buds, seeds, vegetable crude
and dried mass after cropping, chlorophyll pigments, carotenoidic pigments,
3 Vegetative processes of the plants 1165
minerals including macro- and microelements, according to the standard
methods. All these observations have been reported to the values corresponding
to the reference plant (grown without a polymer sample in its culture soil).
The content in micro- and macroelements has been determined by means of
an atomic absorption spectrophotometer AAS 1N, Carl Zeiss Jena. This device is
provided with different lamps and etalon solutions for each type of element
which has to be determined
Even if the obtained values are sometimes affected by different factors, the
spectrophotometric method can be considered as a reliable one for having an
image on the influence of the polymer samples on the vegetative processes of the
plants, if a great number of determinations are realized for the same plant, grown
in the same conditions.
3. RESULTS AND DISCUSSION
Water absorption after soil burial in the culture soil of Vicia X hybrida hort
significantly increases when in the polyolefin matrix is incorporated a natural
polymer, due to its hydrophilic character (Fig. 1). Water absorption favors the
accumulation of microorganisms at the surface of the buried polymer blends, this
fact leading to the surface cracking of the polymeric materials. The evolved
degradation products change the properties of the culture soil (i.e., pH,
composition, etc.) and, consequently, influence the growth of the respective
plants. This fact is evidenced by the evolution in the plant growth, as well as by
the content in chlorophyll and carotenoidic pigments, and in micro- and
macroelements (Table 1).
Fig. 1. – Water absorption after 6 and, respectively, 12 months of soil burial
of some PO/lignosulfonates blends in the culture soil of Vicia X hybrida hort.
1166 I. Mîndreci et al. 4
The content in micro- and macroelements for Vicia X hybrida hort grown in the presence of some
Sample (mg/100 g dried mass) (mg/100 g dried mass)
Na Ca Mg Fe Mn Cu Zn
Reference plant 632.7 278.6 86.2 0.28 0.38 0.37 1.73
PE/8% LA 927.5 179.8 54.9 0.09 0.45 0.03 0.18
PE/10% LA 909.5 299.9 60.6 0.18 0.85 0.05 0.52
PE/10% LER 606.2 180.6 78.9 0.14 0.37 0.09 0.55
PP/8% LA 686.7 262.8 86.1 0.84 0.78 0.10 0.68
PP/10% LA 735.7 286.8 90.3 0.13 1.32 0.17 0.85
PP/10% LER 601.6 174.4 66.7 0.28 0.73 0.22 1.62
It can be observed that the values obtained for the content in microelements
of the plants grown in the presence of PE/LS blends are, generally, smaller with
respect to the values corresponding to the reference plant. In the meantime, the
quantity of microelements increases with the increase in lignosulfonate content.
This behavior can be explained by the fact that, increasing the quantity of natural
polymer in the polymer blends leads to an increase of the environmentally
degradation rate. This means, a higher quantity of natural polymer released in the
culture soil, which implies a higher accumulation of microelements.
The mineral content (ash) of the plant varies in function of the nature of the
sample buried in soil (Table 2). From macroelements, the magnesium shows an
Mineral content of the Vicia Hybrida hort plant grown in the presence of the ethylene-propylene
copolymers grafted with maleic anhydride buried in its culture soil
Sample Ash (wt% ) Macroelements (wt%) * Microelements (wt %) *
Na K Ca Mg Fe Mn Cu Zn
Reference plant 10.15 5.6 13.4 3.06 2.27 0.5 0.01 0.03 0.8
EP-g-MA 0.3 11.87 4.7 13.9 2.67 2.35 0.45 0.02 0.04 0.22
EP-g-MA 0.3/5 LER 16.3 2.3 4.49 1.69 0.98 0.46 0.01 0.01 0.09
EP-g-MA 0.3/10 LER 17.4 2.3 7.2 1.52 1.05 0.44 0.01 0.05 0.11
EP-g-MA 0.3/15 LER 29.3 2.27 5.34 1.19 0.81 0.25 0.009 0.01 0.07
* reported to the ash content.
5 Vegetative processes of the plants 1167
important decrease in the presence of the polymer blends. In what is concerning
the microelements, the content of iron does not vary while the others decrease in
respect with the content of the reference plant. This could be explained in part by
the capacity of lignin to form complexes with the metals and also by the changes
in the pH of the soil, which becomes more acidic by the release of the degradation
products such as carboxylic acids, ketones, aldehydes, etc. from the degrading
An opposite situation was found in the case of the test performed in
presence of the IPP/LER blends. Mineral content was increased in all plants
grown with respect to the reference plant. This increase is higher for the
unphotooxidized blends, the corresponding values increasing with LER content
(Fig. 2), the micro- and macroelements content being modified (Table 3).
Fig. 2. – Mineral content for Vicia X hybrida hort grown in the
presence of unphotooxidized and photooxidized IPP/LER blends vs.
The ash content for Pisum Sativum grown in the presence of the LDPE/HC
blends is increased with respect to the reference plant (Fig. 3), while the
quantities of calcium and magnesium are decreased (Table 4).
1168 I. Mîndreci et al. 6
The content in micro- and macroelements for Vicia X hybrida hort grown in the presence of
IPP/LER blends, in greenhouse conditions
Sample (mg/100 g dried mass) (mg/100 g dried mass)
Na Ca Mg Fe Mn Cu Zn
Reference plant 632.70 278.63 86.23 0.28 0.38 0.37 1.73
IPP 729.30 1056.64 243.54 2.04 2.71 1.05 2.72
IPP/3.96%LER 762.70 675.54 205.64 0.52 2.30 0.48 2.42
IPP/6.97% LER 731.58 911.02 244.29 0.36 2.09 0.50 2.43
IPP/9.08% LER 897.95 534.48 253.89 0.86 1.75 0.25 1.07
IPP/13.05% LER 1072.08 675.45 299.04 0.46 2.48 0.76 4.52
IPP/13.06% LER 1019.05 527.38 185.62 0.41 1.34 0.59 2.34
IPP 1059.25 299.11 75.18 0.41 1.27 0.78 0.97
IPP/3.96%LER 693.75 376.91 104.48 0.56 1.33 0.38 1.51
IPP/6.97% LER 849.15 276.13 110.32 0.31 1.45 0.56 3.74
IPP/9.08% LER 886.82 318.85 107.89 0.88 1.59 0.66 2.42
IPP/13.05% LER 1068.75 444.68 101.66 1.09 1.54 1.21 2.43
IPP/13.06% LER 725.72 348.76 114.02 2.15 1.40 0.80 2.16
Fig. 3. – Ash content of
Pisum Sativum grown in the
presence of LDPE/HC
blends, vs. HC content.
7 Vegetative processes of the plants 1169
The content in micro- and macroelements for Pisum Sativum grown in the presence of
Sample Macroelements (mg/100 g ash) Microelements (mg/100 g ash)
Na Ca Mg Fe Mn Cu Zn
Reference plant 138.5 1543.6 285.1 34.4 3.8 1.6 4.1
LDPE/5HC 137.4 1018.9 258.2 45.5 3.6 8.45 3.6
LDPE/10HC 171.6 1126.2 241.4 23.3 2.2 22.8 6.2
LDPE/30HC 174.6 1017.9 292.9 63.9 4.6 16.5 3.6
Blending of synthetic polymers with natural polymers represents a way for
obtaining materials with tailored properties, by varying their composition.
The plants growth test should be considered as a reliable experiment for the
assessment of biodegradation, and environmental degradation of polymeric
The physiological vegetative processes of the plants grown in the presence
of the synthetic polymer/natural polymer blends are perturbed due to the release
in their culture soil of the degradation products. The changes reported to the
reference plant (without polymer sample) depend on the natural polymer type
Atomic absorption spectrophotometry has proved to be a sensitive method
which can be successfully applied for the plants, in order to study their response
to the conditions created by the degradation/disintegration in their culture soil of
different polymer mixtures.
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