ACID DEPOSITION
• the wet or dry deposition of acid
• “Acid rain”
1. Acid rain refers to all types of precipitation--rain,
snow, sleet, hail, fog--that is acidic in nature
2. precipitation that is polluted by sulphur dioxide
(SO2) and nitrogen oxides (NOX)
•
Link to the Fossil Fuels
– Combustion of fossil fuels
1. sulphur is harmful in excessive amounts
2. Much of Europe and North America are suffering from
sulphur deposition that exceeds critical loads as a
result of the large amounts of such compounds
generated by human activity
3. http://imgur.com/a/CnXGL
Key concepts:
1. The amount of CO2 in the atmosphere is increasing
Currently 30%
higher than since
last 650,000 years
Mauna Loa , Hawaii (13,677 ft = 4169 m)
Acid Deposition
• Reactions to convert to
acid take place in ~2 days travel 1000 miles
• Down wind - Acid rain
• Dry Dep. vs Wet Dep.
• Dry Deposition
– 50 % of total
– Can react with plants strip nutrients
– Tree dieback
Acid Rain and Trees
Forests affected by Acid Rain
Northeast US
Canada
Northern Europe
Asia
Acid Rain and Buildings
Many buildings are made of concrete and or stone
These compounds act as bases and react with acid
The building technically “weathers” very fast, or
Non technically “crumbles”
Europe
The US Capitol
• Acid Rain Damage to Buildings and Cultural Monuments
– In urban areas, acid deposition is rapidly deteriorating buildings, sculptures,
paintings, metal, glass, paper, leather, textiles and rubber
– European officials say that "ancient buildings and sculptures in a number of cities
have weathered more during the last 20 years than in the preceding 2,000"
(Green Issues, pg. 16).
– Sandstone, limestone and marble are the easiest victims of sulphur dioxide
because they contain calcium, and when the two react they form gypsum which
washes away easily with rainfall.
– Paper and textiles are also damaged by SO2 and NOx pollution because paper
absorbs these gases and become more and more brittle as they absorb more
pollutant. "About 5% of the British Library’s collections are thought to be seriously
damaged by sulphur-contaminated air" (Green Issues, pg. 16)
• Bridges are corroding at a faster rate
– in 1967,the bridge over the Ohio River collapsed killing 46 people-the reason was
corrosion due to acid rain
– 70,000 bridges across the country are classified as structurally deficient
• How atmospheric acids form
1. S + O2-->SO2 and N + O2-->NO2 and CO2
2. In the atmosphere, sulphur dioxide reacts with
oxygen to produce sulphur trioxide gas:
2SO2 + O2-->2SO2
3. Some of this sulphur trioxide dissolves into water
droplets in the atmosphere to produce tiny beads of
sulphuric acid
i.
SO3+ H2O-->H2SO4
ii.
NO3 + H20 –> H2NO4
iii.
CO2 + H20  H2CO3
• What causes the problem
– Public power generation. These are, in general, large plants
burning fossil fuel to generate electricity.
– Commercial, Institutional, Residential Combustion Plant
– Industrial Combustion Plant and Processes with Combustion
- pulp mills, metal smelters (when metal sulfide ores such as
lead sulfide are roasted or smelted to convert the metal ore
to free metal), refineries, heating boilers.
– Extraction and Distribution of Fossil Fuels
– Road Transport
– Natural Sources - volcanic eruptions, oxidation of sulfurcontaining by-products of decomposition of organic matter
• Other hazards of Sulphur pollution: Sulphurous smogs
1. Produced by high output of SO2, converted to
acids on contact with atmospheric moisture. Very
prevalent in Europe and North American cities during
first part of 20th Century
2. London. 4-10th December 1952: Cold, highpressure conditions trapped coal smoke in foggy air.
Output of smoke increased by cold. Sulphuric acid
droplets resulted in pH estimated as 1.4 to 1.9: as
acidic as car battery acid. Visibility reduced to 5m at
times. Smog lasted for 5 days, eventually extending
over 50km radius. Approx. 4,000 people died as result
of inhaling pollution, mainly old and sick and those
with chest problems.
• Donora, USA: October 1948: industrial
town of 14,000, with zinc smelter, steel
mill, and sulphuric acid plant, all of which
introduced sulphuric acid into atmosphere.
Anticyclonic conditions trapped emissions,
which continued to be produced. Air
became highly acidic, with sickening smell
of sulphur. Over five day period, over half
of population suffered ill effects, and 22
died
• Effects on Ecosphere
1. Terrestrial Ecosystems
i.
Acid rain damages the protective waxy
coating of leaves and allows acids to diffuse into them
ii.
interrupts the evaporation of water and gas
exchange so that the plant no longer can breathe
iii.
This stops the plant's conversion of nutrients
and water into a form useful for plant growth and affects
crop yields.
(1) acid precipitation destroys, overall, $1.3
billion annually in the eastern part of the nation
(2) $1.75 billion yearly in forest damage, $8.3
billion in crop damage in the Ohio River basin
alone by about the year 2000
2.
$40 million in health costs in the State of Minnesota
• Aquatic Ecosystems
i. Aquatic plants grow best between pH 7.0 and 9.2
ii. As acidity increases submerged aquatic plants decrease and
deprive waterfowl of their basic food source.
iii. At pH 6, freshwater shrimp cannot survive.
iv. At pH 5.5, bottom-dwelling bacterial decomposers begin to
die and leave undecomposed leaf litter and other organic
debris to collect on the bottom...water becomes
malnourished
v. This deprives plankton--tiny creatures that form the base of
the aquatic food chain--of food, so that they too disappear
vi. Below a pH of about 4.5, all fish die.
vii. Most of the frogs and insects also die when the water
reaches pH 4.5.
Key concepts:
2. The chemistry of the ocean is dependent on the chemistry of the atmosphere
Key concepts:
3. Water becomes more acidic the more CO2 it contains.
CO2 reacts with H20 to produce:
bicarbonate (HCO3)
hydrogen (H): makes ocean more acidic
Key concepts:
4. Increased ocean acidity affects marine organisms’ abilities to make and keep
their hard parts. Hard parts = calcium carbonate (CaCO3) shells, skeletons, etc.
Key concepts:
4. Increased ocean acidity affects marine organisms’ abilities to make and keep
their hard parts. Hard parts = calcium carbonate (CaCO3) shells, skeletons, etc.
Many marine organisms have CaCO3 hard parts
• They use their ATP (energy) to make their hard parts using calcium
(Ca) and carbonate (CO3) they get from the sea water
Key concepts:
4. Increased ocean acidity affects marine organisms’ abilities to make and keep
their hard parts. Hard parts = calcium carbonate (CaCO3) shells, skeletons, etc.
Many marine organisms have CaCO3 hard parts
• They use their ATP (energy) to make their hard parts using calcium
(Ca) and carbonate (CO3) they get from the sea water
BUT, hydrogen also naturally reacts with CO3
Key concepts:
4. Increased ocean acidity affects marine organisms’ abilities to make and keep
their hard parts. Hard parts = calcium carbonate (CaCO3) shells, skeletons, etc.
Many marine organisms have CaCO3 hard parts
• They use their ATP (energy) to make their hard parts using calcium
(Ca) and carbonate (CO3) they get from the sea water
BUT, hydrogen also naturally reacts with CO3
• The more acidic the ocean, the more CO3 reacts with hydrogen, and
the LESS CO3 left for marine organisms to convert into their hard parts
Key concepts:
4. Increased ocean acidity affects marine organisms’ abilities to make and keep
their hard parts. Hard parts = calcium carbonate (CaCO3) shells, skeletons, etc.
Many marine organisms have CaCO3 hard parts
• They use their ATP (energy) to make their hard parts using calcium
(Ca) and carbonate (CO3) they get from the sea water
BUT, hydrogen also naturally reacts with CO3
• The more acidic the ocean, the more CO3 reacts with hydrogen, and
the LESS CO3 left for marine organisms to convert into their hard parts
“Battle” for carbonate!
• Organisms must use more energy or
make less hard part material
• Existing hard parts dissolve (chemical
reaction goes “the wrong way”)
Ocean acidification: Impacts on individual marine organisms
Thinner, smaller and weaker shells in shellfish
• Especially larval stages, which already have thin shells
Mussels
Mussel
larva
Normal
Acidic
Gaylord et al. 2011
Really
acidic
Ocean acidification: Impacts on individual marine organisms
Reduced hearing ability in anemone fish (clown fish) larvae
• Deformed morphology of CaCO3 fish ear bones (otoliths)?
• Disruption of acid-base balance in neuro-sensory system?
• Fitness effect: lower survival due to higher predation.
Normal
Simpson et al. 2011
Acidic
Ocean acidification: Impacts on individual marine organisms
Growth
Photosynthesis
Chen & Durbin 1994
Non-calcifying marine algae: Increased photosynthesis and growth
• Lower pH means more dissolved CO2 for photosynthesis to fuel growth
• Fitness effect: higher survival and pop’n growth
Lots
Little
Lots
Amount of dissolved carbon
Little
Ocean acidification: Impacts on ecological communities
Tropical Oceans Predictions:
• Corals will become increasingly rare
• Algae will become more abundant
• Because coral reefs support so many animals,
biodiversity will decline
Hoegh-Guldberg et al. 2007
Could this cause coral extinctions?
•
High
coral
growth
A distinct possibility if ocean acidification continues
Earth’s two most recent mass extinction events
Both associated with high CO2 levels
First
modern
corals
Veron 2008
Million years ago
Present
Borrowed Heavily From:
http://oceanacidification.msi.ucsb.edu/resources/educators/CrowWhite_OA_Lecture.ppt/view