The potential of different plant species for heavy metals accumulation and distribution

Abstract

Different plant organs (leaves, flowers, stems or roots) from naturally occurring wild plants and trees, and cultivated plants (vegetables and fruits) were evaluated as possible bioindicators of heavy-metal pollution in the Republic of Serbia. Concentrations of Pb, Zn and Cd were determined in plant parts collected from areas with different degrees of metal pollution (Kosovska Mitrovica - industrial area and Leposavić - control area). Accumulation and distribution of heavy metals in the plant depend on the plant species, the levels of the metals in the soil and air, the element species and bioavailiability, pH, cation exchange capacity, climacteric condition, vegetation period and multiple other factors. The highest amounts of heavy metals were found in the root of the sensitive Plantago major (Pb 660, Zn 2300 and Cd 33.25 μg g-1 d.w.) and less in the resistant Rumex acetosella. In over ground organs the highest amounts of heavy metals were found in the leaves (283 μg g-1 d.w. Pb) and then in the fruits (3,5-136 μg g-1) and vegetables (1.5-13 μg g-1). In this study, the bark of Robimia pseudoacacia was a better bioindicator of heavy-metal pollution than other plant parts. Summarizing the results, it can be concluded that R. pseudoacacia, P. major and R. acetosella were better metal accumulators and fruits and vegetables were metal avoiders.

Full text

Journal of Food, Agriculture & Environment, Vol.10 (1), January 2012 959
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Journal of Food, Agriculture & Environment Vol.10 (1): 959-964. 2012
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The potential of different plant species for heavy metals accumulation and distribution
Radmila Filipović-Trajković 1, Zoran S. Ilić 2*, Ljubomir Šunić 2 and Snežana Andjelković 3
1 Faculty of Natural Sciences and Mathematics, Department of Biology, 38220 Kos. Mitrovica
2 Faculty of Agriculture, Priština-Lešak, Kopaonička bb, 38219 Lešak, Serbia.3Institute for Forage Crops, 37251 Globoder,
Kruševac, Serbia. *e-mail: zoran_ilic63@yahoo.com
Received 18 November 2011, accepted 3 January 2012.
Abstract
Different plant organs (leaves, flowers, stems or roots) from naturally occurring wild plants and trees, and cultivated plants (vegetables and fruits)
were evaluated as possible bioindicators of heavy-metal pollution in the Republic of Serbia. Concentrations of Pb, Zn and Cd were determined in
plant parts collected from areas with different degrees of metal pollution (Kosovska Mitrovica - industrial area and Leposavić - control area).
Accumulation and distribution of heavy metals in the plant depend on the plant species, the levels of the metals in the soil and air, the element species
and bioavailiability, pH, cation exchange capacity, climacteric condition, vegetation period and multiple other factors. The highest amounts of heavy
metals were found in the root of the sensitive Plantago major (Pb 660, Zn 2300 and Cd 33.25 µg g-1 d.w.) and less in the resistant Rumex acetosella.
In over ground organs the highest amounts of heavy metals were found in the leaves (283 µg g-1 d.w. Pb) and then in the fruits (3,5-136 µg g-1) and
vegetables (1.5-13 µg g-1). In this study, the bark of Robimia pseudoacacia was a better bioindicator of heavy-metal pollution than other plant parts.
Summarizing the results, it can be concluded that R. pseudoacacia, P. major and R. acetosella were better metal accumulators and fruits and vegetables
were metal avoiders.
Key words: Heavy metals, plant, accumulation, distribution.
Introduction
Pollution of the natural environment by heavy metals is a universal
problem because these metals are indestructible and most of them
have toxic effects on living organisms when permissible
concentration levels are exceeded 1. Heavy metals are important
environmental pollutants and many of them are toxic even at very
low concentrations. Heavy metals make a significant contribution
to environmental pollution as a result of human activities such as
mining, smelting, electroplating, energy and fuel production, power
transmission, intensive agriculture (fertilizers, pesticides and
sewage), municipal wastes, sludge dumping, and military
operations 2, 3. A very important source of heavy metals and other
pollutants of soil and plants is passenger traffic 4. All plants have
the ability to accumulate heavy metals which are essential for
their growth and development. These metals include Mg, Fe, Mn,
Zn, Cu, Mo and Ni 5. Plants absorb heavy metals through the root
from the soil, and through over ground vegetative organs from
the atmosphere 6. Most heavy metals accumulate in the top soil
and in the long term their contaminations increase in the soil as
a result of an increased absorption and accumulation in plants.
The quantity or level of heavy metals absorption in plants, depends
not only on the concentration levels of the metals in the physical
and chemical composition of the soil, but also varies in different
parts of the plant 7. Certain plants also have the ability to
accumulate heavy metals which have no known biological
function 8. However, excessive accumulation of these heavy metals
can be toxic to most plants. The ability to both tolerate elevated
levels of heavy metals and accumulate them in very high
concentrations has evolved both independently and together in
a number of different plant species 9. Some of these species can
accumulate very high concentrations of toxic metals and to levels
that far exceed the soil levels 8. Heavy metal uptake by plants is
performed constantly during their vegetation period and during
the year. The uptake reaches its highest value at the end of the
vegetation period 10. Only 1% or less of the total plant body
accumulates heavy metals. Some of these elements are present in
the protein structure in high amounts and play essential roles in
protein structures, especially in enzymes 11. It is established that
heavy metals cause morphological, physiological and biochemical
changes in plants 12. However, the presence of heavy metals in
the environment of plants is a kind of stress that will lead to
physiological changes and also decrease the physiological abilities
of plants 8.
Keeping in mind the harmful consequences generated by the
accumulation of heavy metals in plants, we felt that studying the
accumulation and distribution of heavy metals on plant organs is
of great importance as plants are an important link in the nutritional
chain. Any negative and toxic impact on plants will therefore
present a danger for other living organisms, especially for animals
and humans. To this end, we undertook research to determine the
content of heavy metals in plants that grow in the region of
Kosovska Mitrovica, which is a zone highly contamined by heavy
metals.
Materials and Methods
Sampling area: The city of Kosovska Mitrovica is located in the
valley of the Ibar River, about 40 km north of the capital Prishtina.
The town is an industrial area in the autonomic province Kosovo
and Metohija, located at 499 m of altitude, with a continental climate

960 Journal of Food, Agriculture & Environment, Vol.10 (1), January 2012
and a mean annual precipitation of about 614 mm. The lead and
smelting plant in Mitrovica was chosen as the study area because
it is the largest complex and the most important source of lead and
zinc pollution in Serbia. There are many medium and large size
industrial facilities, mainly smelting of lead and zinc, metallurgical
and flotation, a factory of nitrogen fertilizer and sulphuric acid, a
factory producing batteries along with many other factories in the
Kosovska Mitrovica area. Samples from the industrialized area
were taken from different places between 100 and 500 m around
the factories.For uncontaminated controls, samples were taken
from Leposavić, about 35 km north of Kosovska Mitrovica.
Sample soil preparation and analysis: All soils were sampled at
the surface (0 to 10 cm in depth) using hand driven stainless steel
augers. Collected soil samples were air-dried to constant weight
and then sieved through a 500 µm stainless steel mesh wire. Soil
sample of 0.5 g was placed in a glass beaker and 10 ml conc. HNO3
solution was added. Then, the sample was heated at 150ºC for
about 3 h, followed by evaporation to near dryness. After that, 2 ml
of conc. HC1O4 was added and digestion was continued by
evaporation to near dryness again. Then, 2 ml of conc. HCl was
added and heated at 150ºC for about 15 min. Finally, the sample
was transferred to a 25 ml volumetric flask and diluted up to the
mark with doubly distilled water. A Cole-Parmer micro-filtration
apparatus with a 0.45 mm pore size membrane (Micro Filtration
Systems) was used for the filtration of the aqueous phase before
metal determination. Detection of the metals was carried out with
flame atomic absorption spectrophotometer (FAAS) (Perkin Elmer
AA Analyst 700 m odel, Flame Atomic Absorption Spectrophotometer)
connected with deuterium background correction, hollow cathode
lamps (HCl) and acetylene burner.
The absorption measurements of the metals were performed
under the conditions recommended by the manufacturer. Unless
otherwise stated, all chemicals used were of analytical reagent
grade. Triply distilled water was used throughout the experiments.
To carry out experiments, the final concentrations of metal standard
solutions were freshly made by diluting the stock standard
solution with water.
Sample collection and preparation: At the end of the cultivation
season, samples were taken from different parts of the plants under
study (roots, stems and leaves) to determine the levels of Pb, Zn
and Cd in each part. The samples were washed and separated
with a plastic knife, and washed again with distilled water and
dried at 70ºC for three days. The dried samples were ground and
powdered completely for each repetition after complete analysis.
Samples (5 g) were burnt to ashes in a muffle furnace by gradually
increasing the temperature from 25ºC to 450ºC over a one and half
hour period, followed by 2 h at 450ºC. The ash samples were
suspended in 20 ml of aqua regia (HCl:HNO3, 3:1 v/v), diluted
(1:20) with deionised water and analyzed by graphite furnace
atomic absorption spectroscopy (GFAA, Perkins-Elmer model
4100ZL, Cupertino, CA, USA).
All data were subjected to analysis of variance and treatment
means were compared by Duncan’s multiple range test at 1% and
5% probability levels.
Results and Discussion
Evaluation of heavy metal accumulation in plants is of
environmental importance due to its toxicity effects in humans
and other biota. The combustion process leads to the generation
of emissions to air, water and soil, of which emissions to the
atmosphere are considered to be one of the main environmental
concerns. The most important emissions to air from the smelting
of lead and zinc, metallurgical and flotation, are heavy metals (Pb,
Zn and Cd), F and H2S (Table 1).
The plants’ responses to air pollution allow to detect the
presence of pollutants and their identification on the base of their
impact on the plant species, to determine the total effect of all
environmental factors, including air pollution and climate, to
measure the concentration of pollutants and to elucidate the use
of plants as a sensitive system for early diagnosis of the
environmental changes.
Table 2 shows that the concentration of heavy metals declines
in the air as well as in the soil with increasing distance from the
source of contamination. In line with this, the growing distance
from the emitter also reduces the content of the heavy metals in
plant organs. The total metal concentrations were high, but only
a small fraction of them were available for the plants. These results
can be explained by taking into consideration the chemical
properties of the soils. Total soil heavy metal concentration is
commonly used to indicate the degree of contamination 13.
Loading and accumulation of heavy metals in the soil depend on
different factors such as the chemical form of elements, pH, organic
matter content, texture and cation exchange capacity (CEC) of the
soil 14. With increasing pH, organic matter content, CEC and clay,
the percentage and availability of the metals are reduced. In
addition, the existence of carbonate, sulphate, phosphate and
I II III IV V VI VII VIII IX
µg/m
3
Kosovska Mitrovica – polluted area
Pb 33.4 30.1 14.2 13.2 17.1 29.1 38.4 6.5 10.1
Zn 13.6 10.3 22.4 24.9 18.4 14.1 23.6 4.0 6.1
Cd 0.01 0.30 0.13 0.20 0.23 0.22 0.26 0.01 0.02
F 60.2 30.9 92.9 85.2 0.11 120.0 135.1 20.9 40.2
H
2
S 10.8 23.4 33.4 33.4 34.1 55.6 133.4 3.1 5.8
Leposaviü – non polluted, control area
Pb 11.1 9.0 11.4 10.1 9.8 11.9 13.8 2.0 3.1
Zn 8.1 5.1 5.8 7.8 5.2 8.6 9.5 2.8 3.2
Cd 0.01 0.03 0.02 0.03 0.01 0.02 0.03 0.01 0.02
F 16.2 41.9 38.1 26.9 47.0 29.0 51.8 10.6 14.4
H
2
S 22.1 18.1 21.2 22.6 21.5 19.5 32.04 8.0 10.1
Table 1. Air pollution with Pb, Zn, Cd, F and H2S of Kosovska Mitrovica, polluted area,
and Leposavić, control area (average monthly value).

Journal of Food, Agriculture & Environment, Vol.10 (1), January 2012 961
sulphide forms of elements in soil cause an increase in the metal
precipitation and consequently decrease their availability to the
plants 15. Kabata-Pendias and Pendias 3 also expressed that uptake
and release of elements depend on plant species, growth stage
and composition of the soil solution, especially Ca.
The results of our research indicate that heavy metals (Pb, Zn
and Cd) mostly accumulate in tree bark (Fig. 1). The maximum Pb
concentration was 1870.52 and 7.0 µg g-1d.w. of Cd in Robinia
pseudoacacia bark, sampled from the Kosovska Mitrovica area,
where lead and zinc metallurgical activities are present. The data
obtained indicate that the distribution of heavy metals in the organs
of plants is not homogeneous; it probably depends on the nature
of plant species and the physicochemical characteristic of the
element.
The results suggest that R. pseudoacacia may be considered a
bioaccumulator species for Pb, Zn and Cd, and can be used as a
bioindicator of pollution with these metals. Therefore, it seems
that R. pseudoacacia can play a substantial role in remediation of
polluted sites. All these elements (Pb, Zn and Cd) were found to
be at high levels in samples collected from an industrial area.
The strong correlation between the degree of contamination
and concentrations in all plant leaves assessed demonstrate that
the leaves of R. pseudoacacia reflect the environmental changes
accurately and that they seem to act as an effective biomonitor of
environmental quality in areas subjected to industrial and traffic
pollutions 16. Although various authors 17, 18 have reported that
the leaves of R. pseudoacacia are good bioindicators, results
obtained for Pb concentrations in leaves and flowers of R.
pseudoacacia, did suggest that the flowers could be used as
better indicators of Pb pollution than leaves 19.
The analysis of the obtained results indicates the existence of
differences in accumulation of heavy metals in different plant
organs, tissues and different plant species. Distribution of heavy
metals is unequal and the largest is in the tree’s bark, which is
explained by the time of its exposure to the environmental
conditions and structure (roughness), enabling a larger absorption
of heavy metals from the air (aerosol).
Next, a high concentration of heavy metals was found in the
plant roots. In the roots of Plantago major Pb was found at 660,
Zn at 2500 and Cd at 33.25 µg g1d.w. (Fig. 2). After the tree bark,
heavy metals are mostly accumulated in the roots and then in the
leaves as well as in the plant fruits. We found similar results to
Buzzynski20, proving that with the surplus of lead in the soil, plant
roots accumulate 2-5 times as much lead than the over ground
parts. The species P. major is a good accumulator, mainly of Pb,
while P. lanceolata accumulates greater amounts of Zn 21.The
average annual levels of Zn recorded in P. lanceolata for the
region of Asarel, within the rage 24.45-42.63 mg kg-1, are
considerably lower than the levels measured in the same species
in the industrial zone of Plovdiv 22, 119-128 mg kg-1, and much
lower than the content of Zn in the leaves of the same species
growing around a former lead and zinc smelter in Austria 23, 580
mg kg-1. Our results can be compared with already published
results in the sense that the intensity of lead contamination as
well as its accumulation in plant organs progressively declines
with the distance from the emitter. We also note a smaller content
of heavy metals in the leaves. The obtained results prove that P.
major can successfully be used as a bioaccumulation indicator,
especially of Pb and Zn, under the conditions of technogenic
pollution in the region of the Kosovska Mitrovica. Parts of the
deposited particles are not removed by rainfall and become
irreversibly adsorbed or incorporated into the hydrophobic wax
layer of the foliage 24. A comparison of washed and unwashed
samples showed that leaf analyses gave a reasonably reliable
measure of the total aerial fallout of heavy metals in the studied
area 25, and further showed that plant washing after sampling
Heavy metals µg g
-1
Target area Pb Zn Cd Cu Co Ni
Kosovska. Mitrovica 22.69 50.14 0.36 1.29 0.83 1.54
Leposaviü - control area 12.47 2.61 0.05 1.06 0.50 0.30
Table 2. Content of heavy metals in soil (depth 0-10 cm) in Kosovska Mitrovica
(polluted area) and Leposavić (non-polluted, control area) at July.
283
29.5
520
69.2 1.5 0.2
0
0
0
0
0
0
0
0
0
0
0
Pb Zn Cd
1870
1205
762
445
75
0
500
1000
1500
2000
2500
Pb Zn Cd
Zn Pb
K.Mitrovica
Leposavić - Control Leaves
K. Mitrovica
29.5
283
0 Cd
500
69.2
2000
1000
2500
1500
0.2
1.5
520
Zn Pb
K.Mitrovica
Leposavić - Control Bark
K. Mitrovica
1205
1870
0 Cd
500 445
2000
1000
2500
1500
5
7
762
Figure 1. Content of Pb, Zn and Cd (µg g-1d.w.) in leaves and bark of Robinia pseudoacacia L. from
Kosovska Mitrovica and Leposavić.

962 Journal of Food, Agriculture & Environment, Vol.10 (1), January 2012
decreased the element contents to about 10 to 30% in comparison
with unwashed plants.
Lead is available to plants from soil and aerosol sources. In the
field, most uptake has been demonstrated to be through the leaves.
Our results are in agreement with results from the literature,
suggesting that leaves from plants in the polluted area investigated
in this study are better indicators of Pb pollution than other plant
organs. Plant contamination in most cases arises from atmospheric
particle accumulation through their foliage and leaves, and the
degree of contamination depends on the smoothness of leaves,
wind speed and the amount of rainfall 26.
It also proved that the accumulation of heavy metals is higher
in fruit trees than in the products of vegetables and cultivated
plants. These results can be linked to the duration of the vegetable
period of fruit; that is, with the longer period of absorption of
heavy metals from the air.
Studies of vegetables grown in locations close to industry have
reported elevated levels of heavy metals. The results in Table 3
also show that the content of heavy metals in the plant organs is
reduced with an increasing distance from the emitter. With
increasing distance from the source of contamination the
concentration of heavy metals declines in the air as well as in the
soil, which results in the reduction of heavy metal content in plant
organs. The results indicate high concentration of heavy metals
in plant tissue, which exceeds the values of MDK. According to
some data, MDK of heavy metals in vegetables amount to 3 mg
kg-1 for Pb, and 0.3 mg kg-1 for Cd in dry substance of fruit and
vegetables.
Our results can be compared with already published results, as
the intensity of lead contamination as well as its accumulation in
plant organs progressively decline with the distance from the
emitter. Commercial and residential vegetable growing areas are
often located in urban areas, which are subjected to anthropogenic
contamination. Fernández–Turiel et al. 27 found elevated levels of
heavy metals in urban soils located in the vicinity of a Pb smelter
in Lastenia, Argentina. The heavy metals found at elevated
concentrations were Pb 31-8714, Cd 0.27-30.68, Cu 21-242 and Zn
44-4637 mg kg-1.
Vousta et al. 28 studied the impact of atmospheric pollution from
industry on heavy metal contamination in vegetables grown in
Greece. The results of the study indicated significantly higher
levels of metal accumulation in leafy vegetables compared to root
vegetables. This partitioning of Cd is well known, with a higher
accumulation in the edible leafy portions of the crops compared
to the storage organs or fruit 29.
Poniedzialek et al. 30 found differences between crops in the
level of heavy metal accumulation in particular organs. They
described that the absorption and transport of metals could be
modified by many factors, i.e. cultivar, timing of production and
locality. Within the red beet, field pumpkin, chicory, common bean,
white cabbage and parsnip the maximum Cd and
Pb contents were found in leaves 31. The red beet
and common parsnip were characterized by the
highest lead concentration ratios (shoots/roots).
Normal concentrations of Pb in plants are 0.1-10
mg kg-1d.w. according to Kabata-Pendias and
Pendias 32, although they consider a value of 3 mg
kg-1 as normal level 33. Generally, toxic
concentrations of Pb are defined as 30-300 mg
kg-1 34. Although various authors 17, 18 have
reported that leaves of R. pseudoacacia are good
bioindicators, our results for Pb from all locations
did suggest that bark could be used as a better
indicator of Pb pollution than leaves (Fig. 1). The
results for Pb in this study corresponded to those
Kosovska Mitrovica Leposaviü
Vegetables Pb Zn Cd Pb Zn Cd
Solanum lycopersicum L. 3.50 19.75 0.25 4.75 39.5 0.25
Capsicum annuum L. 13.00 59.25 0.25 10.25 27.30 0.25
B. oleracea var.capitata L. 49.75 36.75 1.00 28.25 36.00 0.25
Phaseolus vulgaris L. 3.25 65.25 0.25 1.50 72,25 0.00
Solanum tuberosum L. 8.00 38.75 0.25 1.25 34.75 0.25
Fruits
Mallus domestica Borkb 8.75 4.75 0.25 2.75 8.50 0.00
Pirus domestica medicus. 13.25 6.75 0.00 2.50 4.00 0.00
Cydonia oblonga Mill. 3.50 35.50 0.00 0.75 25.75 0.00
Prunus domestica L. 26.75 7.75 0.00 0.25 46.75 0.0
Rubus caesius L. 136.00 36.50 0.25 11.00 31.50 0.25
Rosa canina L. 24,75 47.25 0.00 4.25 16.50 0.25
Table 3. Content of heavy metals (µg g-1d.w.) in vegetables and fruits collected
in the surroundings of Kosovska Mitrovica and Leposavić.
265
46.2
1125
157.5
17.7 1.2
0
0
0
0
0
0
Pb Zn Cd
103.2
41.5
285
92.5 4.7 0.5
0
500
1000
1500
2000
2500
Pb Z Cd
660
124
2300
325
33.2 2.2
0
500
1000
1500
2000
2500
Pb Z Cd
Zn Pb
46.2
265
0 Cd
500 157.5
2000
1000
2500
1500
1.2
17.7
1125
Leposavić
K. Mitrovica Leaves
Zn Pb
124
660
0 Cd
500 325
2000
1000
2500
1500
2.2
33.2
2300
Leposavić
K. Mitrovica Root
Zn Pb
41.5
103.2
0 Cd
500
92.5
2000
1000
2500
1500
0.5
4.7
285
Leposavić
K. Mitrovica Flowers-fruits
Figure 2. Content of Pb, Zn and Cd (µg g-1d.w.) in leaves, flowers-fruits and root of Plantago major L. from Kosovska Mitrovica and Leposavić.

Journal of Food, Agriculture & Environment, Vol.10 (1), January 2012 963
References
1Mmolawa1, K. B., Likuku, A. S. and Gaboutloeloe, G. K. 2011.
Assessment of heavy metal pollution in soils major roadside areas in
Botswana. African Journal of Environmental Science and Technology
5:186-196.
2Nedelkoska, T. V. and Doran, P. M. 2000. Characteristics of heavy
metal uptake by plant species with potential for phytoremediation
and phytomining. Minerals Engineering 13:549-561.
3Kabata-Pendias, A. and Pendias, H. 1989. Trace Elements in the Soil
and Plants. CRC Press, Florida.
4Stankovic, D., Krstic, B. and Nikolic, N. 2008. Effect of traffic on the
obtained in several samples collected from the Veles region in
Macedonia 35. All cultivated plants (fruit and vegetables) showed
lower Pb content (0.5-13 µg g-1d.w.) in comparison with wild plants.
Only Rubus caesius L. fruit obtained relatively high Pb level (136.0
µg g-1d.w.). Also, with the distance from the emitter the content of
Pb in plant organs is reduced; thus in this study, the levels of Pb
in Pyrus domestica medicus went from 0.25 in control fruit to
35.75 µg g-1d.w. in fruit from a polluted area Kosovska Mitrovica.
Zn is not considered to be highly phytotoxic and the toxicity
limit for Zn (300-400 mg kg-1) depends on the plant species as well
as on the growth stage 34. High concentrations of zinc in plants
may cause the loss of leaf production, whereas low concentrations
may cause deformation of leaves. A plant foliar concentration of
100 mg kg-1 Zn has been quoted by various authors 34 as a critical
indicator of whether the environment is polluted with Zn. Values
obtained for Zn, indicated that all investigated species in this
study had Zn accumulation capacity in their organs. Even the
cultivated plants showing the lowest (<50 µg g-1d.w.) heavy metal
content in this study, had a high Zn concentration. The Zn
accumulation capacities of P. major in root (2.300 µg g-1d.w.) and
in leaves (1.125 µg g-1d.w.) and of R. pseudoacacia (bark 762.5 µg
g-1d.w.) indicated that these plants can be used as possible
bioindicators of Zn pollution (Fig. 2) . The high Zn content in all
plant species from the Mitrovica area is in agreement with the top
soils around the smelter plant, the main polluted area, being highly
polluted with zinc.
Depending on their Cd content, plants are considered Cd
accumulators or Cd avoiders. Generally, it is accepted that the
normal Cd concentrations in plants are between 0.2 and 0.8 mg
kg-1 and toxic concentrations of Cd are defined as 5-30 mg kg-1 32-
34. The cadmium concentration in this study was found to be
under the LOD (0.1 µg g-1d.w.) in all control samples, except for R.
pseudoacacia bark (3.0 µg g-1d.w) and P. major roots (2.25 µg
g-1d.w.) and P. major leaves (1.25 µg g-1d.w.) The concentrations
of Cd (µg g-1d.w) in samples from the Kosovska Mitrovica area
around the lead and zinc smelting plant range from 33.25 (P. major
root) to 17.75 (P. major leaves). A concentration of 5.25 µg g-1d.w.
Cd was observed in R. acetosella roots in samples also taken
from an area around the lead smelter plant (Fig. 3). The
concentration of Cd in leaves from the same plant was 2.25 µg g-1d.w.
154
21
495
54
2.2 0.5
0
0
0
0
0
0
Pb Z Cd
99.5
45.7
757
95
5.2 0.7
0
200
400
600
800
1000
Pb Z Cd
Zn Pb
K.Mitrovica
Leposavić Leaves
K. Mitrovica
21
154
0 Cd
200
54
800
400
1000
600
0.5
2.2
495
5
Figure 3. Content of Pb, Zn and Cd (µg g-1d.w.) in leaves and root of Rumex acetosella from Kosovska Mitrovica and Leposavić.
Zn Pb
K.Mitrovica
Leposavić Root
K. Mitrovica
45.7
99.5
0 Cd
200 95
800
400
1000
600
0.7
5.2
757
The cadmium concentration in cultivated species (fruit and
vegetables) in all samples from control and polluted area was
found to be below the LOD (0.1 µg g-1d.w.). It can also be noted
that Cd values obtained for different organs from one plant species
are very similar. This may support the known fact that Cd root-to-
shoot transport is most likely driven by a transpiration stream 36.
We also noted that, in plants where high Cd levels were found,
high Zn and Pb levels were also recorded.
In addition, the experimental data show that the content of heavy
metals is 2-10 times higher in the fruits of wild species plants than
in the fruits of cultivated species plants. Our opinion is that the
differences in the lead content within wild and cultivated species
are connected with genetic features of the concerned species.
Conclusions
The concentration of heavy metals declines in the air as well as in
the soil with the increasing distance from the source of
contamination. Moreover, with the distance from the emitter the
content of the heavy metals in plant organs is also reduced. Our
results indicate the existence of differences in accumulation of
heavy metals in different plant organs, tissues and in different
plant species. The content of heavy metals is 2-10 times higher in
the fruits of wild species plants than in the fruits of cultivated
species plants. R. pseudoacacia may be considered to be the
bioaccumulation species for Pb, Zn and Cd, and as such can be
used as a bioindicator of pollution with these metals. Accumulation
of heavy metals is higher in fruit trees than in the products of
vegetables and cultivated plants.

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