Effect of Acid Rain on
Germination of Plant Seeds
346 BOT
Amal Alghamdi
Background:
• Pollution from burning fossil fuels included
nitrogen and sulfur compounds.
• They combine with water vapor in the
atmosphere to form low pH solutions, like
sulfuric acid and nitric acid. When this water
falls to the ground it is called acid rain. It affects
any organism living there, especially plants.
• It can damage forest, crops, soil, and buildings.
Background
• "Acid rain" is a popular term referring to the
deposition of wet (rain, snow, sleet, fog,
cloudwater, and dew) and dry (acidifying
particles and gases) acidic components
• Distilled water, once carbon dioxide is removed,
has a neutral pH of 7. Liquids with a pH less
than 7 are acidic, and those with a pH greater
than 7 are alkaline.
CHEMICAL PROCESSES
• Combustion of fuels produces sulfur dioxide and
nitric oxides. They are converted into sulfuric
acid and nitric acid.
• Gas phase chemistry
• In the gas phase sulfur dioxide is oxidized by
reaction
• SO2 + OH· → HOSO2
• HOSO2· + O2 → HO2· + SO3
CHEMICAL PROCESSES
• In the presence of water, sulfur trioxide (SO3) is
converted rapidly to sulfuric acid.
• SO3 (g) + H2O (l) → H2SO4 (l)
• Nitrogen dioxide reacts with OH to form nitric
acid:
• NO2 + OH· → HNO3
ACI
D
RAI
N
CYC
LE
Seed Germination
• Seed germination is the growth of a plant inside
its pod.
• All developed seeds have an embryo inside.
• Water, oxygen, light, and certain temperatures
are required for seed germination.
Example: EFFECT OF ACID RAIN ON
SEED GERMINATION OF RICE
• The germination test showed that seed
germination was absolutely inhibited at pH 2.0 for
three species, Rice and wheat seeds germinated
abnormally at pH 2.5.
• Inhibition index of shoot and root length of three
kinds of seeds decreased in relation with increased
pH values.
Aim
In this investigation, you will perform an
experiment to simulate and test the effect of acid
rain on the germination of plant seeds.
How does acid rain affect the germination of
seeds?
Materials:
•
•
•
•
•
•
•
•
Monocotyledons seeds, as wheat and lentils.
Dicotolydons seeds as beans, .
Cotton bags, filter paper,
Hydrochloric acid (HCl), and Sodium hydroxide
(NaOH).
Water.
pH meter
Foriceps.
Pipettes.
Procedure
• A filter paper and cotton should rinse with each pH
and placed in the bottom of separate petri dish.
• Seeds (20 monocotyledons and 10 cotyledons) were
placed separately on the paper and covered with
cotton soaked in each pH and the lid was placed on
top.
• All plates were observed over a week period.
• The investigation include: the rate of germination
and/or the amount of seeds that germinated.
Hypothesis:• How do you think the seeds placed in each pH of
will germinate?
• compared to seeds placed in normal water
(pH=7) ?
• In addition, the experiment will show whether or
not the acids have a corrosive on the seeds.
Nuber of seeds germinated
Data
12
10
8
replica 1
replica 2
replica 3
6
4
2
0
2
5
7
pH Value
9
12
Discussion
• The hypothesis stated that the seeds soaked in
water (pH=7) would germinate first.
• However, all of the seeds sprouted after 48
hours, but the number varied for each solution.
References
• "Acetic Acid." EdInformatics. N.p., n.d. Web. 29 Nov. 2009.
<http://www.edinformatics.com/
math_science/science_of_cooking/acetic_acid.htm>. "Acid Rain
Experiments- Experiment 7- Observing the Influence on Acid Rain on Plant
Growth."
Environmental Protection Agency. U.S. Environmental Protection Agency,
8 June 2007. Web. 20
Nov. 2009. <http://www.epa.gov/acidrain/education/experiment7.html>.
Carpi, Anthony. "Acids and Bases: An Introduction." Vision Learning. N.p.,
2003. Web. 29 Nov. 2009.
<http://www.visionlearning.com/library/module_viewer.php?mid=58>.
Cummins, R. Hays. "Final Presentation of the Effect of Acid Rain on Plants."
Jr. Science. Miami
University, 10 Dec. 2008. Web. 20 Nov. 2009.
<http://jrscience.wcp.muohio.edu/nsfall02/
FinalArticles/FinalPresentationofTheEff.html>. Holt, S. A. "How to Grow
Mint Indoors." eHow.com. N.p., n.d. Web. 13 Nov. 2009.
<http://www.ehow.com/how_4493938_grow-mint-indoors.html>.