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Toxicology Reports
journal homepage: www.elsevier.com/locate/toxrep
Application of Mulberry nigra to absorb heavy metal, mercury, from the
environment of green space city
Seyed Armin Hashemi
a,⁎
, Sahar Tabibian
b
a
Department of Forestry, Lahijan Branch, Islamic Azad University, Lahijan, Iran
b
Department of Agriculture and natural resources, Payame Noor University, P.OBox, 19395-3697, Tehran, Iran
ARTICLE INFO
Keywords:
Mulberry nigra
Mercury
Heavy metals
North of Iran
ABSTRACT
Phytoremediation is one of the methods for Bioremediation of the soils which has been noticed in recent dec-
ades. Two years sapling of Mulberry nigra selected and Mercury(II) nitrate solution with 30, 50 and 70 mg/L
concentrations, after add solutions in to soil of sapling Mulberry nigra, eight months’later leaf, stem and roots
were selected and Measuring mercury was determined by Atomic Absorption Spectrometer. The maximum level
of mercury accumulation in the leaf, stem and root was 55.67, 50 and 65 mg/kg, respectively. Mercury could be
absorbed easily by the plant’s root and accumulated in the plants.
1. Introduction
Human sources for releasing the mercury to the environment is by
secondary products of various industrial processes like coal burning,
combustion of fossil fuels, mercurial vapor lamps and producing
Chloralkali [1]. Phytoremediation is one of the methods for Bior-
emediation of the soils which has been noticed in recent decades. In this
method, resistant plants are used for refining the soils contaminated by
organic and inorganic components. The advantages of this method
among the others are its simplicity, inexpensiveness and exploiting
possibility in a broad level. Selection of plant has a great importance in
this method. Plant selection depends on climate conditions and also the
level of pollution [2,3]. The mercury is toxic and is absorbed easily by
respiratory system and damages Stomach and intestines. Existence of
this element in the air is harmful. By initiation of industrial era, the
level of mercury has been increased significantly. The mercury has
harmful effect of the human beings and wildlife as well as various
mediums and food (especially fish) all around the world [4]. The level
of entered mercury into the environment has increased from the be-
ginning of industrial era. The mercury contamination is first due to man
activities from which 60–90% of total mercury released from man ac-
tivities is caused by industrial activities in 1995–1999. Mercury emis-
sion caused by man activities in Asia has increased from about 30% of
total universal emission to 56% [5,6,7].
The most important way for mercury emission is its emission in the
air. However, the mercury is also released from various sources in the
water and earth. In the case of releasing, the mercury is remained in
various forms and circulates among the air, water, deposits, soil and
plants. The study of heavy metals’distribution in the dusts of the streets
and the soil of industrial towns’workshops in Jordan suggested that
heavy metal density is more accumulated in surface soil and it is de-
creasing in the lower level of the soil. The man and industrial activities
in the town workshops are possible sources for accumulating the heavy
metals of Zn, Cu, Ni and Pb from which a significant portion was related
to industrial sources in the town [8].
Mulbery nigra is a fast-growing species from medium to high trees, is
resistant towards various soils and prefers visors to shade-friendly sites.
In this research it was studied that how much a Mulbery nigra could
absorb the mercury from the environment.
2. Method and materials
Two years saplings were transited into greenhouse and were
maintained there for 20 days in order to adapt to new condition. Non-
contaminated soil (applied natural soil in this analysis) was provided
from 0 to 30 depth of one of plantations. Then they were dried and
passed from a 2 mm sieve.in order to provide a soil contaminated by
Mercury(II) nitrate, spraying on the soil by 30, 50 and 70 mg density
was used in this study and the required amount of the solution was
sprayed on the soil gradually, then it was contaminated by the soil
uniformly and the vases were filled by them. The seedlings with the
same age and size were chosen in sufficient number and were planted in
the vase. Afterward, the vases were maintained in the greenhouse and
the soil moisture was kept in the capacity level by weighted method.
Watering was done by distilled water when requiring and eight months
after seedlings growth, the aerial organs were harvested and washed by
https://doi.org/10.1016/j.toxrep.2018.05.006
Received 7 August 2017; Received in revised form 6 May 2018; Accepted 13 May 2018
⁎
Corresponding author.
E-mail address: hashemi@liau.ac.ir (S.A. Hashemi).
Toxicology Reports 5 (2018) 644–646
Available online 21 May 2018
2214-7500/ © 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/BY/4.0/).
T
water, then they were dried in the oven by 70 °C. The level of mercury
in plant samples was determined by dry digestion method after samples
digestion with atomic absorption spectrometry. The obtained data from
plants tests were organized in SPSS software. In order to analyze data
for determining metal accumulation level in aerial organs and the root
of plant, ANOVA test and in order to compare the effect of mercury
concentration on the leaf, stem and root, Duncan test were used.
3. Results
Comparison of mercury level among the studied concentrations,
using Duncan test suggested that there is significant difference in ac-
cumulation level of mercury among 30, 50 and 70 mg/l concentrations
in probability level of 95%. Such that the highest level of mercury ac-
cumulation was 55.67 mg/kg and the lowest level was 22.2 mg/kg in
20 mg/l density (Fig. 1).
The comparison of mercury among studied concentrations using
Duncan test suggested that there is significant difference among 30,
50,70 mg/L by 95% probability in accumulation level of mercury in the
stem m so that the highest level of Mercury accumulation is 50 mg/kg
and the lowest level was 28.6 mg/kg (Fig. 2).
Comparison of the mercury means among the studied
concentrations, using Duncan test suggested that there is significant
difference among 30, 50, and 70 mg/L by 95% probability in mercury
accumulation. Such that the highest level of mercury accumulation is
65 mg/kg and the lowest level of mercury accumulation is 35.3 mg/kg
(Fig. 3).
4. Discussion
The obtained results from the research suggest that aerial organs of
Mulberry nigra have had significant difference for mercury accumula-
tion in various concentrations. By increasing the concentration of soil
mercury, the amount of its accumulation in aerial organs of leaf, stem of
Mulberry nigra has increased as well. By studying the effect of mercury
on some physiology parameters in eucalyptus and also comparing the
accumulation and mercury transition in this study suggested that the
absorption of this metal in the root is more than it in leaf and stem
[9,10]. About mercury accumulation in Acer velutinum, the results
suggest that various contamination densities have been effective and by
increasing mercury, accumulation level in the root is increased as well
(Fig. 2) concluded in their research that although the mercury is not a
nutrient, could be absorbed easily by the plant’s root and accumulated
in the plants with some concentrations which is harmful for food chain.
Fig. 1. The mean of mercury absorption in aerial organ of leaf in Mulberry nigra sapling.
Fig. 2. The mean of mercury absorption in the stem of Mulberry nigra sapling.
S.A. Hashemi, S. Tabibian Toxicology Reports 5 (2018) 644–646
645
5. Conclusion
The factors of stems, roots, soil, are a significant difference in terms
of mercury accumulation and this significant difference shows the
amount of mercury absorption in Mullberry nigra tree species and the
ability of Mullberry nigra in the amount of contamination accumulation
is appropriate. Study revealed that concentrations of lead, zinc, mer-
cury, cadmium and nickel were measured in the leaf of seven species of
deciduous trees (Indian horse-chestnut, maple, Acer cappadocicumGled,
ash, Platanus orientalis, poplar and acacia) in urban areas which the
highest accumulation amount of cadmium and zinc, lead, mercury and
nickel was in poplar, Indian horse-chestnut and acacia, and acacia and
ash, respectively [11,12]. The mercury accumulation in plant tissues in
cell surface also may be toxic and cause growth decrease. Therefore,
preventing mercury absorption by plant’s roots, could be a strong
strategy for minimizing biologic side effects of this element. In phy-
toremediation topics of heavy metals, tolerance factors of the plant
against metals, plants’root system, and the capability of transition from
underground organs to aerial organs (transition factor), growth speed
and high biomass must be considered. In this research, according to
mentioned points, Mulberry nigra is an appropriate species for refining
soils contaminated by mercury.
Transparency document
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Fig. 3. The mean of mercury accumulation in the root of Mulberry nigra sapling.
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