Heavy Metal (Pb and Ni) Accumulation in the Branch and Bark Tissues of Street Tree Sophora japonica L

Abstract

In this research, the authors present the lead and nickel accumulation and its monthly variation in the branches and barks of the street tree, Sophora japonica L. in Ankara which has a heavy traffic circulation. Of the trees in the street, the ones near the crossroads and the traffic lambs have a heavier accumulation in their branches and barks. The lead and nickel accumulation especially in the branches and barks increases unexpectedly in the rainy seasons. The lead and nickel accumulates slowly in barks but its ratio depends on the age of tree.

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Kastamonu Üni., Orman Fakültesi Dergisi, 2008, 8 (1): 93-96
Kastamonu Univ., Journal of Forestry Faculty
Heavy Metal (Pb and Ni) Accumulation in the Branch and
Bark Tissues of Street Tree Sophora japonica L.
*Ümit BİNGÖL1, Fatmagül GEVEN1, Kerim GÜNEY2
1A.Ü. Fen Fak., Biyoloji Böl., Ankara
2K.Ü. Orman Fak., Orman Müh. Böl., Kastamonu
* Sorumlu yazar: mumit1111@hotmail.com
Geliş Tarihi: 06.05.2008
Abstract
In this research, the authors present the lead and nickel accumulation and its monthly variation in the
branches and barks of the street tree, Sophora japonica L. in Ankara which has a heavy traffic circulation.
Of the trees in the street, the ones near the crossroads and the traffic lambs have a heavier accumulation in
their branches and barks. The lead and nickel accumulation especially in the branches and barks increases
unexpectedly in the rainy seasons. The lead and nickel accumulates slowly in barks but its ratio depends
on the age of tree.
Key words: Ankara, Street trees, Sophora japonica L., Heavy metal, Lead and nickel accumulation.
Cadde Ağacı Sophora japonica’nın Dal ve Kabuklarındaki
Ağır Metal Birikimi
Özet
Bu çalışmada, araştırmacılar trafik akışının yoğn olduğu Ankara’da yetişen cadde ağacı Sophora japonica L.’nın
dal ve kabuklarında biriken kurşun ve nikel miktarının aylık değişimini ortaya koymuşlardır. Trafik ışıkları ve
kavşaklara yakın olan ağaçlarda ağır metal birikiminin daha yoğun olduğu tesbit edilmiştir. Yağmurlu mevsimlerde
beklenmedik bir şekilde dallardaki ve kabuktaki kurşun ve nikel birikiminin arttığı görülmüştür. Kurşun ve nikel
birikimi ağacın yaşına bağlı olarak kabukta dallara göre daha yavaş olmaktadır.
Anahtar kelimeler: Ankara, Cadde ağaçları, Sophora japonica L., Ağır metal, Kurşun ve nikel birikimi.
Introduction
Plants, which produce oxygen through
photosynthesis, enrich and beautify the
environment with their green cover; keep and
protect the soil by their root systems, and
provide shelter for other living beings, are
most valuable beings in nature with a great
importance in the food chain of the nature
and in our ecosystem.
In this research, it is aimed to prove
accumulated lead and nickel which come
from exhaust gas and from the friction of
tires, in the tissues of branches and bark of
the Sophora japonica L., which are planted
on each side of Ankara's streets with heavy
traffic indicating the air pollution.
Today our environment is frequently
polluted by many harmful matters that come
from various sources. Chimney gases,
industrial wastes, the exhaust gas of the
vehicles leave a lot of harmful matters to the
environment. Air pollution gains, besides soil
and water pollution, more and more
importance in environment pollution. The
main causes of air pollution are the rapidly
increasing population and consequently
urbanization and industrialization.
It is claimed that especially in Turkey air
pollution in the cities results from the bad
quality of fuel, the inadequacy of burning
techniques and to a great degree the heating
systems. Additionally, the influence of traffic
is even more important. This is because the
air pollution coming from the traffic is not
seasonal, but continuous throughout the year.
As it is known, large numbers of vehicles
enter traffic every day in Turkey. This
number is about 45.000–50.000 vehicles per
month. The inevitable result of this, is that
the amount of lead and other metals
accumulating in the environment increases.
This situation adds a new problem to the
environmental problems in Turkey, which
are getting more and more popular. It is not
difficult to predict the dimension of pollution
on the plants which will be exposed in such a
polluted environment.
Materials and Methods
For the research carried out in Ankara, we
chose sample plots on both sides of the
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Kastamonu Üni., Orman Fakültesi Dergisi, 2008, 8 (1): 93-96 Bingöl et al.
Kastamonu Univ., Journal of Forestry Faculty
streets with a heavy traffic circulation and
where nearly 4700 vehicles pass per hour.
From the Sophora japonica L. which are
planted on the sidewalks on both sides of the
street, branch and bark samples were
collected in the months October, November,
and December 1996, when the traffic is the
heaviest because of rain and snow fall. Since
the Japanese Sophora is a deciduous tree, and
our work was carried out in the winter
months, we just worked on only branch and
bark samples. Considering that the
accumulation on the side of the tree facing
the street will be different from that on the
back side of the tree, bark samples were only
taken from the front side of each tree
The taking of samples
Trees from six different site were chosen:
5 experimental trees on the streets, and 1
control tree in the Park at Turgut Reis Street
where traffic and pollution is very less. In the
months indicated, branch samples were taken
from each tree at a height of 2 m. from
branches 3–4 years of age (the age was
determined by counting the nodes) by using
pruning scissors. The bark samples were
taken from each tree at a height of 75–100
cm. without harming the wood tissue.
Extraction
The taken samples were put in plastic
bags, labeled, and brought to the laboratory.
They were washed with distilled water in
order to clean the gathered particles on the
surfaces. Then they were dried for 24 hours
in room temperature. After this, they were
given numbers, put in certain amounts (1–5
g) into 35 cc porcelain crosses for which the
tare was allowed, dried for 24 hours in the
hot air stove at 100 oC and weighed on a
sensitive balance, by which its dry weight
was determined. Then it was burned for 4
hours at 600 oC in a burner oven with
thermostat, until it turned to white ash. After
that 10 ml 1,5 N HCl (Merck, pure) was
added to it and it was mineralized 1/2 hour
on a hot plate at 80 oC. Then it was filtered
by means of a glass funnel through a coarse
filter paper into 50 cc seized gauging
balloons and completed to 50 ml with
distilled water. (Devas, 1978; Toker ve ark.,
1990). Later these prepared extracts were
transferred into closed, colored, 100 cc
seized sample bottles. In this way from every
sample to three parallel was prepared and all
this procedure was carried out every month.
Method of measuring
The amount of Pb and Ni in the extracts
has been measured with the A.A.S device
HITACHI Model 180–80, at mode Zeeman
A. A, with double ray ways, by using air-
acetylene flame and by performing
deuterium background correction. The
following parameters were chosen and used
during the study (Table1). 5 time with 5
seconds intervals the figures were read,
average values were taken and amount of Pb
and Ni in the solution was calculated and
indicated as ppm (mg/kg) D.W.
Table 1. The parameters were chosen and
used during the study
Wave length (nm) 283.3
Slit interval (nm) 1.3
Lamp flow (μA) 7.5
Flame Air-Acetylene
Results
In the branch and bark samples taken in
October, November, and December from
trees at the sites on Streets which are exposed
to heavy traffic, quite high accumulation of
Pb and Ni was evident. On the other hand, in
branch and bark samples taken from the
control tree, Pb and Ni accumulation was
quite low in regard to the experimental trees.
Pb and Ni concentrations of the control and
the other experimental trees are presented in
Table 2 to 7.
Table 2. Sample types of the tree in site 1 and proved Pb and Ni concentrations [ppm (mg/kg) D.W.
(dry weight)]
Pb (Lead) Ni (Nickel)
DATE Branches Bark Branches Bark
1994 October 15 54 11 40
1994 November 12 20 9 27
1994 December 26 75 35 66
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Kastamonu Üni., Orman Fakültesi Dergisi, 2008, 8 (1): 93-96 Bingöl et al.
Kastamonu Univ., Journal of Forestry Faculty
Table 3. Sample types of the tree in site 2 and proved Pb and Ni concentrations [ppm (mg/kg) D.W.]
Pb (Lead) Ni (Nickel)
DATE Branches Bark Branches Bark
1994 October 19 70 25 90
1994 November 10 55 19 36
1994 December 37 94 38 71
Table 4. Sample types of the tree in site 3 and proved Pb and Ni concentrations [ppm (mg/kg) D.W.]
Pb (Lead) Ni (Nickel)
DATE Branches Bark Branches Bark
1994 October 66 89 52 62
1994 November 34 51 21 35
1994 December 77 102 49 72
Table 5. Sample types of the tree in site 4 and proved Pb and Ni concentrations [ppm (mg/kg) D.W.]
Pb (Lead) Ni (Nickel)
DATE Branches Bark Branches Bark
1994 October 70 90 38 99
1994 November 33 47 28 71
1994 December 92 127 47 169
Table 6. Sample types of the tree in site 5 and proved Pb and Ni concentrations [ppm (mg/kg) D.W.]
Pb (Lead) Ni (Nickel)
DATE Branches Bark Branches Bark
1994 October 110 121 80 130
1994 November 73 81 60 75
1994 December 139 199 87 154
Table 7. Sample types of the tree in site 6 and proved Pb and Ni concentrations [ppm (mg/kg) D.W.]
Pb (Lead) Ni (Nickel)
DATE Branches Bark Branches Bark
1994 October 13 27 10 23
1994 November 8 11 7 15
1994 December 21 32 23 27
Discussion
As can be recognized from the high
evidence of Pb and Ni concentrations in the
control and experimental trees on which we
studied in our research work, the main source
for Pb and Ni pollution in nature is the
motorized vehicles traffic. Together with
other living beings especially the plants on
the street sides are influenced and largely
harmed by the Pb and Ni pollution in the
environment. Various researches have shown
that this pollution of which the main source
are motorized vehicles, cause the
accumulation of heavy metals like Pb and Ni
in plants, and that the amount of Pb and Ni
decreases as you get away from the street.
The findings also show that the amount of
Pb and Ni in different plant organs, though
within 3 months, exhibits monthly changes
depending on the traffic. This indicates that
the amount of Pb and Ni in different organs
of the plants depends in short periods, even if
monthly, on traffic, monthly rainfall, and
various climatic conditions. Monthly total
precipitation (Pi) is shown in Table 8.
Table 8. Monthly total precipitation (Pi) mm*
October 1994 48.1
November 1994 13.2
December 1994 66.7
The fact that there was a little more
evidence of Pb and Ni in the control tree then
had been expected, shows that Pb and Ni
granules, very little of size, are carried over
long distances by the ascending and
circulating air. Similar evidence, which
prove this result, was by Lagerwerf (1971).
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Kastamonu Üni., Orman Fakültesi Dergisi, 2008, 8 (1): 93-96 Bingöl et al.
Kastamonu Univ., Journal of Forestry Faculty
Furthermore, it has been proved through the
studies that these heavy metals (Pb and Ni)
can be carried over up to 100 km per year,
and ever hundreds of km away traces of them
have been found. Another reason for the high
values in the control tree is that Turgut Reis
Street nevertheless has a little traffic
circulation. That we carried out our study in
the rainy months and that in these months
there was evidence of high Pb and Ni
concentration is because there is more traffic
in the rainy months. Türkan (1982) and
Bingöl (1992) came in his study to a similar
result, which supports these findings.
According to the results, there are different
accumulation of Pb and Ni in different
tissues in different months. This shows that
the surface structures of the plant organs
affect the ability of accumulating Pb and Ni.
In examinations of bark with rough surfaced
plant tissues, the highest amount of
accumulation was found directly proportional
to the tree's age. And in branch samples
again directly proportional to the tree's age
2. degree accumulation was proved. Similar
studies with ours have been carried out (Page
et al., 1971; Bingöl, 1992; Fidora, 1972;
Hampp, 1973; Türkan, 1982; Öztürk ve
Türkan, 1982; Özörgücü ve Türkan, 1985;
Başlar et al., 2003). Pb and Ni concentrations
at branches and barks according to months
are shown in Table 3-8. As it is known many
motorized vehicles enter traffic every day in
Turkey and cause the traffic to grow heavier
day by day. Experts point out, that tetra ethyl
lead and tetra methyl lead will continue to be
use in gasoline as anti-knock material as long
as no material of equal value can be found
(Bingöl, 1992; Türkan, 1982). It is not
difficult to predict that if it continues in this
way, the amount of Pb and Ni accumulation
in plants, which we tried to prove, will reach,
in near future, the amount of some other
countries. But in spite of all these, the use of
unleaded gasoline has increased in recent
years, especially in our country and in the
U.S.A. Regarding the fact that approximately
200 ppm of lead can kill growing up small
animals, it becomes clear how great the
danger is. In our opinion, increase in this
danger can be prevented, by certain measures
against the accumulation and pollution of Pb
and Ni in the most valuable creatures in our
ecosystem the plants, which we tried, though
in a limited extent, to exhibit.
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