This thesis is the one that i submitted to the 2012
ICY(International Conference of Youth) as my project. I am in the
Moon-Kwa(humanities) section, not the natural science section, but I am
interested especially in the environment field(&the protection of it)
indeed. (Which made 'The Age of Stupid' especially special to me) I wrote an
paper about how mosses can reflect the severeness of environmental pollution
for several weeks.
***I couldn't post the pictures because of some
mechanical problems within the Word file. But thank god; I did have some in a
separate folder!
Mosses; Useful Indicators for Environmental Pollutions
ABSTRACT
Mosses are environmentally
sensitive organisms, and so far have been intensively used for biomonitoring of
water and air pollution. It is known that
the sensitivity largely comes from their unique structure, for example moss
leaves are usually only a single cell in thickness, which leads to ready
absorption of water from the environment. In this study, we have examined the effects
of exposure to environmental pollution on the growth and development of mosses.
We have evaluated the growth of mosses exposed to 5 kinds of the artificial and
realistic pollutants such as artificial acid rain, artificial domestic
wastewater, and car exhaust gas, which are common pollutants in our lives. In
the artificial acid rain experiment, we found that the growth of mosses was
sensitively affected by pH of the pollutants rather than total amount of the
acidic pollutant treated. Interestingly the study on the effect of artificial
domestic wastewater revealed that total amount of the pollutant treated was
proportional to dead portion of moss samples. Fumes of a mosquito repellent
coil used as an artificial air pollution led to partial damage on the growth of
mosses. On the contrary, the pollutants collected around our town did not
affect on the growth of mosses. We concluded that the growth of mosses were sensitive not only to relatively strong acid pollutants
but also to wastewater. However, the growth of mosses was not affected by
pollutions around our town, indicating the degree of pollution around our town
would be quite low.
INTORDUCTION
Mosses are environmentally sensitive organisms, and so
far have been intensively used for bio-monitoring of water and air pollution.
Recently, through researches conducted by developed countries such as Japan and
the USA, the ecological function of mosses is being greatly recognized. Acting
as a healing poultice over the barren nature, they provide protection for
germinating seeds in the natural reforestation of environmentally sterile
areas. Also, their functions of absorbing and storing water form a suitable
environment for diversified forms of life, contributing to the maintenance of
the ecosystem.
Mosses are small and soft that at are typically 1–10 cm
tall, although it varies depending on the species. Because they are unicellular
plants, they do not have flowers or seeds, and their root, stem, and leaves are
not clearly distinguished. Instead of the root, fine brown filaments called
rhizoids are used for anchoring the plant. With a few exceptions, mosses have
no central core in the stem for conducting moisture and nutrients throughout
the plant, which is a major difference from other higher vascular plants. Thus,
they depend largely on the atmosphere and rainwater full of nutrients washed
from the forest canopy overhead. Some species have the stems covered in a brown
woolly coat called tomentum, an extension of the rhizoid system. In certain
conditions of humidity, this coat becomes a swollen gelatinous mass feeding
water to the stem and leaves externally. Mosses are affected more than other
plants by pollution because of this ready absorption of substances from the
atmosphere.
Mosses are typically found in environments of moist and
low light, such as wooded areas and at the edges of streams. They are also
found in cracks between paving stones in damp city streets. Some types have
adapted to urban conditions and are found only in cities. Their photosynthesis
mostly takes place in approximately 25℃, and they grow adequately in 400Lux of
light.
Main functions of mosses include the formation and
maintenance of the ecosystem, the prevention of soil erosion and the use of raw
materials for medicine.
Firstly, mosses play a critical role in the ecosystem.
They absorb and retain moisture, and spread a healing poultice over the raw
wounds of nature. They prevent erosion of the soil from slopes and open spaces,
and provide cover for germinating seeds in the natural reforestation of burned
areas. Also, they form an adequate environment for myriad forms of life active
in the maintenance of the ecosystem. Secondly, mosses prevent soil erosion.
Whenever heavy rain falls the rhizoids retain a thick blob of mud. The reason
for this is that the cell walls of the rhizoids secrete a mucilaginous
substance that literally sticks them to soil particles and insures the plant a
secure footing wherever it grows, including earth, rock or wood. This ability
to anchor makes moss most effective in its earth binding role. Finally, mosses
can be used for raw materials of novel medicine. Due to their great absorption
of water, the Indians and Inuit used the moss for dressing wounds, and the
natives of northern Alaska still make a salve from Sphagnum leaves and animal
fat for this purpose. During the First World War, thousands of tons of Sphagnum
mosses were used as surgical dressing. It was found to be far more efficient
than cotton for this purpose, absorbing 10 to 20 times its dry weight in moisture.
And whereas cotton absorbs moisture only locally to the point of saturation,
Sphagnum moss, by its peculiar cellular structure, absorbs the moisture into
every cell of its mass. Also, the extracts of mosses are also used for treating
bronchitis, cardiovascular diseases, and making diuretics.
The main aim of this study is to find out the effects of
exposure to environmental pollution on the growth and development of mosses
quantitatively. We have examined the growth and self purification ability of
mosses where they receive pollutants such as artificial acid rain, artificial
domestic wastewater, river water and car exhaust gas, which are common
pollutants in our lives. We have also attempted to figure out whether mosses
are particularly useful as pollution indicators.
EXPERIMENTAL
Materials.Mosses
(Thuidium Kanedae SAK species) were collected randomly on October 3, 2010, from
a park area on Bundang-Gu, Gyeonggi-Do, KOREA. Plastic bottles made from PET
were used as growing pots for moss samples. Artificial acid rain was made from
acetic acid and water. The pH of the water solutions were adjusted to pH 3, 4,
5, 5.6 using a pH meter. Soapy water (Liquid soap) was used as artificial
domestic wastewater. The pH of the artificial domestic waste water was adjusted
to pH 6. River water was collected from Bundang creek on Bundang-Gu,
Gyeonggi-Do, KOREA. Artificial air pollution samples caused by forest fire were
prepared by using a mosquito repellent coil. The car exhaust gas was collect
into a seal plastic bag directly from an exhaust pipe of a car.
Methods. The
collected mosses were planted to plastic pots. The pots were kept under sun
light at room temperature for 3 days with giving fresh water in order to
confirm that the environment of testing place was good enough for growing the
mosses. The growth status of mosses was determined by the observation of color
change in moss leaves. In the water pollution experiments, the treatment
condition of artificial acid rain and domestic wastewater are listed in Table
1~2. The moss samples were given 5 ml of fresh water or the pollutant solution
one time a day. In the river water experiments, moss samples were exposed to 5
ml of the Bundang creek water for 10 days. To examine the effect of air
pollution on the growth of mosses, fumes of a mosquito repellent coil and car
exhaust gases were collected into seal plastic bags, and the moss pots were put
in the bags contained the pollution for 5 days.
Table 1. Treatment
condition of artificial acid rain and domestic wastewater
Sample number
|
Treated
pollutants
|
Total Treatment days
|
Day 1
(Oct. 10)
|
Day 2
(Oct.
11)
|
Day 3
(Oct.
12)
|
Day 4
( Oct.13)
|
Day 5
(Oct.14)
|
Day 6
( Oct.15)
|
Day 9
( Oct.
18)
|
Day 12
( Oct.
21)
|
1
|
control
|
-
|
W
|
W
|
W
|
W
|
W
|
W
|
W
|
W
|
2
|
artificial acid rain
(pH 3)
|
1
|
A
|
W
|
W
|
W
|
W
|
W
|
W
|
W
|
3
|
2
|
A
|
A
|
W
|
W
|
W
|
W
|
W
|
W
|
4
|
3
|
A
|
A
|
A
|
W
|
W
|
W
|
W
|
W
|
5
|
4
|
A
|
A
|
A
|
A
|
W
|
W
|
W
|
W
|
6
|
artificial domestic waste- water
(pH 6)
|
1
|
D
|
W
|
W
|
W
|
W
|
W
|
W
|
W
|
7
|
2
|
D
|
D
|
W
|
W
|
W
|
W
|
W
|
W
|
8
|
3
|
D
|
D
|
D
|
W
|
W
|
W
|
W
|
W
|
9
|
4
|
D
|
D
|
D
|
D
|
W
|
W
|
W
|
W
|
Temp(°C)/Humidity (%)
|
22/63
|
20/71
|
21/71
|
19/65
|
18/64
|
18/39
|
17/46
|
20/57
|
*W: fresh water; A: artificial acid rain (pH 3); D:
artificial domestic waste water (pH 6)
*Giving 5 ml of fresh water or the pollutant solution one
time a day
Table 2. Treatment
condition of artificial acid rains with different pH
Sample number
|
Treated
pollution material
|
pH
|
Day 1
(Oct. 21)
|
Day 2
(Oct.
22)
|
Day 3
(Oct.
23)
|
Day 4
( Oct.
24)
|
Day 7
(Oct.
27)
|
Day 10
( Oct.
30)
|
10
|
control
|
-
|
W
|
W
|
W
|
W
|
W
|
W
|
11
|
artificial acid rain
|
3
|
A
|
W
|
W
|
W
|
W
|
W
|
12
|
4
|
A
|
W
|
W
|
W
|
W
|
W
|
13
|
5
|
A
|
W
|
W
|
W
|
W
|
W
|
14
|
5.6
|
A
|
W
|
W
|
W
|
W
|
W
|
Temp(°C)/Humidity (%)
|
21/67
|
18/55
|
18/50
|
19/60
|
14/41
|
23/44
|
*W: fresh water; A: artificial acid rain (pH 3, 4, 5 or
5.6)
RESULTS AND
DISCUSSION
The current research provides a detailed description of
common water and air pollutions and their effects on moss species. The overall
aim of this study was to evaluate the effects of exposure to artificial and
realistic pollutants on the growth quantitatively. Table 3 shows classification
of pollutants used in this study.
Table 3.
Classification of pollutants used in this study
|
Water
pollution
|
Air
pollution
|
Artificial
pollutants
|
Acetic acid
solution of pH 3, 4, 5, 5.6 (acid rain)
Soapy water
(pH 6)
|
Fume of a
mosquito repellent coil (Air pollutants caused by forest fire)
|
Realistic
pollutants
|
River water
|
Car exhaust
gas
|
Water pollution.As artificial acid rain and domestic wastewater, we used acetic acid
solution and soapy water, respectively. Acid rain has harmful effects on plants
and is mainly caused by sulfur and nitrogen gas from fuels such as coal and
petroleum. In some places the acidification is so severe that the pH drops to
around 4.0. Rare cases have been reported of acid rain having pH of around 2 -
2.5. Because the definition of acid rain is a rain with a pH less than 5.6, we
chose 4 solutions having different acidity under pH 5.6. Domestic wastewater
generally includes material disposed of through toilets, sinks, tubs and
showers, washing machines and the like. Therefore surfactants, which are the
base component for making soap, are one of the main pollutants of wastewater. Figure1
shows the effect of artificial acid rain and wastewater exposure on the growth
of mosses. Treatment conditions of the pollutants are listed in Table 1. As
shown in Figure 1a, the moss samples before treatment are appeared to be bright
green color indicating a healthy status. On day 9 (Figure 1d), the color of the
acid rain-treated samples (sample number 2~5) completely changed to yellow,
suggesting all the moss samples died regardless of treated amount (days) of the
artificial acid rain of pH 3. On the contrary, the color change of the
wastewater-treated samples (sample number 6~9) depends on the amount of the
pollutant. As shown in Figure 2 (a picture of the moss samples on day 12), the
sample (sample number 9) treated with wastewater one time is healthy, whereas
the sample treated with wastewater 4 times has almost died. In this experiment,
we concluded that acidity of the artificial acid rain of pH 3 was so strong
that only one dose led to severe result. However the effect of wastewater
treatment was sensitive to the amount of the pollutant. In this case, mosses
would be affected by the soap ingredients, not by the acidity because pH of the
wastewater was 6.
Figure 1. The effect of artificial acid rain and waste
water exposure on the growth of mosses (a: picture of moss samples before
treatment; b: on day 2; c: on day 4; d: on day 9, the number on the growing
pots represents the sample number listed in Table 1).
|
Figure 2. The effect of artificial acid rain and waste
water exposure on the growth of mosses (on day 12, the number on the growing
pots represents the sample number listed in Table 1.).
|
Figure 3. The effect of exposure of artificial acid
rain of pH 3 (sample number 11), 4 (sample number 12), 5 (sample number 13)
and 5.6 (sample number 14) on the growth of mosses (a: picture of moss
samples on day 1; b: on day 4; c: on day 10, the number on the growing pots
represents the sample number listed in Table 2).
|
Figure 3 shows the
samples exposed to artificial acid rains with different pH. The treatment
conditions are listed in Table 2. Compared to the sample 11, which was exposed
to artificial acid rain of pH 3, the sample 12, 13 and 14 exposed to acid rain
of pH 4, 5 and 5.6, respectively did not result in significant changes in
growth. The result suggests mosses are susceptible to acidity of pollutants. In
order to evaluate the effect of the total amount of acid exposed, a moss sample
was treated with an acid rain of pH 4 for 15 days. Interestingly the color of
the moss sample did not differ from controlled sample (Figure 4). Although the
total amount of acid exposed to sample number 16 (pH 4 for 15 days) was larger
than that of sample number 11 (pH 3 for 1 day) (the acid concentration of a
solution of pH 3 is ten times higher than that of pH 4), the sample exposed to
pH 4 for 15 days did not result in significant changes in growth. The result
suggests that mosses have the self-purification ability when exposed to low
concentration of an acid pollutant.
In order to
examine the degree of the water pollution near our town, we collected river
water from two different places of Bundang creek, and moss samples were treated
with the river water for 10 days. As shown in Figure 5, no significant changes
were detected even after being exposed for 10 days. The result indicates that
pollution of the river water was not serious.
Figure 4. The effect of exposure of artificial acid
rain of pH 4 for 15days (a: picture of moss samples on day 1; b: on day 6; c:
on day 10; d: on day 15, sample number 15: control, sample 16: sample exposed
to artificial acid rain of pH 4)
|
Figure 5. The effect of exposure of 5 ml of the river
water for 10 days (a: picture of moss samples on day 1; b: on day 4; c: on
day 10, sample number 17: control, sample 18, 19: sample exposed to Bundang
creek water collected at two different places)
|
Air
pollution. To examine
the effect of air pollution on the growth of mosses, fumes of a mosquito
repellent coil as an artificial air pollutant caused by forest fire were
collected into transparent seal plastic bags, and the moss pots were put in the
bags contained the pollution for 5 days. It is known that fumes of a mosquito
repellent coil contain toxic chemicals such as formaldehyde, which is also
found in the fume of forest fire and car exhaust gas. Figure 6b shows picture
of moss samples exposed to the fume for 5 days. As shown in Figure 6b, the
color of middle part of the sample (sample number 21) changed to yellow,
suggesting mosses are sensitive to the chemical fume. Using car exhaust gases,
we also examine the effect of real air pollutants on the growth of mosses. Car
exhaust gases were collected directly from the exhaust pipe of a car into seal
plastic bags, and the moss pots were put in the bags contained the pollution
for 5 days. As shown in Figure 7, no significant changes were detected after
being exposed to car exhaust gas. We believe that while the gas should contain
toxic air pollutants, the concentration of the pollutants collected in the
plastic bag is likely to be quite low.
Figure 6. The effect of artificial air pollutant
exposure on the growth of mosses. Moss samples are placed into a plastic bag
containing fumes of a mosquito repellent coil (a: on day 1, pollutant; b: on
day 5, pollutant; c: on day 1, control; d: on day 5, control).
|
Figure 7. The effect of car exhaust gas exposure on the
growth of mosses (a: picture of moss samples before treatment; b: a moss
sample is inside a plastic bag containing exhaust gas; c: after exposed to 5
days, sample number 22: control).
|
CONCLUSIONS
In this study, we
have examined the effects of exposure to environmental pollution on the growth
and development of mosses. We have evaluated the growth of mosses exposed to 5
kinds of the artificial and realistic pollutants such as artificial acid rain,
artificial domestic wastewater, and car exhaust gas, which are common
pollutants in our lives. In the artificial acid rain experiment, we found that
the growth of mosses was sensitively affected by pH of the pollutants rather
than total amount of the acidic pollutant treated. The result suggests that
mosses have the self-purification ability when exposed to low concentration of
an acid pollutant. Interestingly the study on the effect of artificial domestic
wastewater revealed that total amount of the pollutant treated was proportional
to dead portion of moss samples. Fumes of a mosquito repellent coil used as an
artificial air pollution led to partial damage on the growth of mosses. On the
contrary, the pollutants collected around our town did not affect on the growth
of mosses. For example, no significant changes were detected after being
exposed to river water and car exhaust gas. We concluded that the growth of mosses
were sensitive not
only to relatively strong acid pollutants but also to wastewater. However, the
growth of mosses was not affected by pollutions around our town, indicating the
degree of pollution around our town would be quite low. The
moss is known to be one of the representative indicators for the environmental
pollution, but we found that our environment such as river and air was not so
polluted to measure with it. However, if the degree of acid rain or air
pollution gets worse, mosses, which plays an important role to keeps our
ecosystem, might be in danger of extinct. Therefore we should always keep an
eye on our environment and protect it.
REFERENCE
