The Effect of Acid Precipitation on Water Quality in Cove River
Top 14 Acid Precipitation
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Transcript of Top 14 Acid Precipitation
7/30/2019 Top 14 Acid Precipitation
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CHEM115 Environmental Chemistry
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CHAPTER 14 (part 1)
ACID PRECIPITATION
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CHEM115 Environmental Chemistry
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Acid Precipitation
Acid precipitation involves deposition of
hailstones, rain and snow.
The main causes include the presence of
sulfuric (H2SO4) and nitric (HNO3) acid
which are formed by oxidation of sulfur
dioxide (SO2) and nitrogen oxides (NOx).
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CHEM115 Environmental Chemistry
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Formation of Acid Rain
Source: Botkin&Keller, 2003. Environmental Science. 4th ed. Chapter 23.
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CHEM115 Environmental Chemistry
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Sulfur dioxide and nitrogen oxides in theatmosphere reacts with water vapor to form
sulfuric and nitric acids.
i. SO2 + H2O H2SO3 (sulfurous acid)
ii. SO3 + H2O H2SO4 (sulfuric acid)iii. 2 NO2 + H2O HNO2 + HNO3 (nitrous and nitric acids)
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• These acids travel long distances with
prevailing winds and be deposited as acid
precipitation.
• Sulfate and nitrate particles can also be
deposited as dry deposition and changes
into sulfuric and nitric acid later where
there is moisture.
CHEM115 Environmental Chemistry
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CHEM115 Environmental Chemistry
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Negative effects on:
• Lake and aquatic ecosystems
• Trees and soils• The atmosphere
• Architecture
• Materials• Humans
Consequences
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Effect on Aquatic Ecosystem
Acidic chemicals can enter the water directly.
Surface run-off which washes nutrients out of soil thatenters the water.
Spring acid-shock can occur. The aquatic ecosystem doesnot have enough time to adjust to the sudden change.
Acid in water may affect the fish direct and indirect ways of which both will lead to death of fish and weak reproductionof fish.
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• Spring acid-shock :When snow melts rapidly in
spring due to a sudden temp change, any acids
and chemicals in the snow are released into thesoil. The melted snow then runs off into streams
and rivers and gradually makes its way into lakes.
The introduction of these acids and chemicals
causes a sudden dramatic change in the pH of the lakes – hence, the term ‘acid shock’
Example: fish have disappeared from lakes in Scandinavia.
Records show that an increase in acidity has been traced
to acid rain, the result of industrial processes in other
countries particularly Germany and Great Britain.
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Effects on Trees and Soils
•Minerals such as calcium and magnesium
in soils can be washed away.
•Overtime, when soil becomes too acidic.
• Aluminum from clay minerals is freed and
taken up by the plants. The plants gradually
become starved of their vital nutrients and
poisoned by aluminum.
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Acidic aerosols affect stomata in leaves and
hinder photosynthesis.
Ammonium sulfate
further increases soilacidification which
encourages the growth
of pests.
Source: http://www.grandfather.com/conservation_interpretation/images/acidrain.jpg
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• Ammonia from ground-level biological decay
processes reacts with droplets of atmospheric
sulfuric acid to form ammonium sulfateH2SO4 + 2NH3 > (NH4)2SO4
which can form on the surfaces of trees. When
ammonium sulfate reaches the soil, it reacts to
form both sulfuric and nitric acids, further
increase soil acidification. These conditions also
stimulate the growth of fungi and pests because
trees under stress release chemicals such asterpenes, with the latter attracting pests such as
ambrosia beetle.
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Loss of nutrients also results in weakeningof trees, making them more susceptible todisease.
As trees weaken and die, there is lesshabitat and food for birds and animals.
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The dying trees also allow more light through to
the forest floor , changing the temperature andwater content of soil at the surface. This affects
the ecosystem.
The trees allow more light as they are stripped of
leaves. It affects the ecosystem because the
amount of light reaching the ground can affect
the surface temperature and water and thuschange what grows on the floor and what lives in
the soil
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Effects on Atmosphere
Atmospheric sulfates, nitrates and acids can
cause haze.
It reduces visibility and interfere withatmospheric energy processes by absorbing
sunlight.
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Effects on Architecture
Acid particles and precipitation depositedonto stone buildings, monuments causestone damage
Limestone and marble turn into gypsum(calcium sulfate) upon contact with the acid.
Gypsum is soluble and can be washed off the stone by rain.
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Building materials such as paint, plasticsand steel may be damaged by acid. Iron
exposed to acid and oxygen will rapidly
dissolve and be washed away.
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Effects on Materials
Acid rain can damage materials like fabric,
books, works and water pipelines.
Metals leaching from water pipelines may
enter and accumulate in human bodies.
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Effects on Humans
Long-term exposure to acidic aerosols issaid to cause:
dry coughs
Headaches
eye irritation
nose and throat irritation
aggravating respiratory
pulmonary diseases.
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Control of Acid Precipitation
The main one:Decrease the emissions of sulfur dioxide
and nitrogen oxides.
-Reducing electricity consumption
-Reducing on-road vehicle exhaust
-Reducing manufacturing shipping
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Thank you