7 - Acidification

Question 1

What is acid deposition? Includes…

Answer 1

The settling, or deposition, of acidic or acidic-forming pollutants form the atmosphere onto the Earth’s surface

Acidic precipitation (rain, slow, hail), fog, gases, dry particles

Question 2

Slides 6,7**

Answer 2

Look
7 =steps

Question 3

First step in in acid deposition? Sources?

Answer 3

Sulfur dioxide, nitrogen oxides and carbon dioxide are released

SO2 = largest source in Canada is oil and gas, used to be ore and mineral

NOx = largest source in Canada was transportation, now its oil and gas industry

Question 4

Trends in SO2 emissions in Canada? NOx?

Answer 4

Have decreased significantly since 1991 (around 80%)
Oil and gas emissions highest
Slide 9

Also decreased, oil and gas most prominent, followed by transportation
Slide 10

Question 5

Major emissions of CO2 come from… What is absorbing it? What is happening to this sink?

Answer 5

Oil and gas
1/4 of CO2 produced by burning coal, oil and gas dissolves into the ocean

Ocean has absorbed 525 billion tons of CO2 from the atmosphere since the beginning of the industrial era (minimizing atmospheric CO2)
Ocean has become 30% more acidic

Question 6

Major CO2 emissions come from… Trends in emissions?

Answer 6

Oil and gas then transport
Slight decrease in 2020/21

Slide 12

Question 7

Second step in acid deposition

Answer 7

Transformation into acid particles and transport over long distances

Slides 14,15

Question 8

Third step in acid deposition? Types?

Answer 8

Fall as wet and dry depositions

Wet deposition: acids removed from the atmosphere in the form of water (rain, sleet, snow, hail)

Dry deposition: acids removed from the atmosphere in the form of particulates or gases (= no water). Often in the form of fly ash, sulphates, nitrates, and SO2 and NOx gases

Question 9

Fourth step in acid deposition

Answer 9

Harmful effects to soils, forests, lakes and structures

Question 10

How does acid deposition damage soils?

Answer 10

• depletes calcium and other base cations
• mobilizes aluminum, heavy metals from soil to water
• accumulate sulfur, nitrogen in soils (can lead to eutrophication)

Question 11

Direct and indirect effects of acid deposition on forest ecosystems

Answer 11

Direct effect: leaches calcium out of needles (lose calcium in cell membranes, more susceptible to cold and freezing)

Indirect effect: alters soil chemistry (less Ca to uptake, more toxic aluminum)

Question 12

Acid deposition damage to stream and lake ecosystems

Answer 12

• increased leaching of aluminum into surface waters as runoff from soils
• if pH too low, can be lethal for fish and other aquatic organisms
• aluminum + low pH, can disrupt osmotic balance in fish, eventually leading to heart attacks
• dissolution of calcium shells of aquatic invertebrates and prevents them from growing strong shells (e.g. zooplankton)

Question 13

Slides 25-29

Answer 13

Experimental acidification of lakes

Question 14

Damage of acid deposition on oceans

Answer 14

• chemical changes in the ocean as a result of CO2 emissions in the atmosphere
• decreasing pH

Slides 31, 32, 33

Question 15

How is climate change affecting oceans

Answer 15

• warming ocean
• sea level rise
• changes in storm patterns
• changes in precipitation
• altered ocean currents
• ocean acidification

Question 16

Acid deposition legislation in Canada

Answer 16

• 1985 Eastern Canada Acid Rain Program
• 1991 Canada-United States Air Quality Agreement
• Canada-Wide Acid Rain Strategy Post-2000
• 2004 Acid Rain Science Assessment

Question 17

Goals of the 1985 Eastern Canada Acid Rain Program

Answer 17

• Cap SO2 emissions in seven easternmost provinces
• Establish monitoring
• Updated in 2000 with additional national cap

Question 18

Goals of the 1991 Canada-United States Air Quality Agreement

Answer 18

• cut SO2 and NOx emissions
• increase monitoring

Question 19

Goals of the Canada-Wide Acid Rain Strategy Post-2000?

Answer 19

• continued reductions in SO2 emissions
• even more monitoring
• regulate reports to the public
• prevent clean/undamaged areas from being degraded

Question 20

Findings of the 2004 Acid Rain Science Assessment

Answer 20

• need to reduce emissions even further
• need to address acidification in the West and North (east has longer history of reducing emissions)

Question 21

What is chemical recovery?

Answer 21

Decrease in damaging chemicals (e.g. sulfate, nitrate and aluminum) concentrations in soils and waters. If the decrease is sufficient, will lead to increase in pH

Question 22

What is biological recovery?

Answer 22

Multi-step return and/or increase in health of organisms (animals and vegetation) in previously acidified ecosystems (aquatic or terrestrial)
Cannot occur without chemical recovery

Question 23

Is chemical recovery occurring? Dependent on…

Answer 23

Yes - rate dependent on the resistance and resilience of the ecosystem to acid precipitation; it is mostly about the amount of calcium naturally found in soils and surface waters

Lots of Ca = more resistant and resilient (enough stores to resist Ca depletion by acid rain) e.g. Limestone

Low Ca = less resistant and resilient

Question 24

Slide 42

Answer 24

Potential of soils to reduce acidity

Question 25

Chemical recovery of the 202 lakes originally targeted in 1985

Answer 25

• 33% have reduced acidity (increased pH)
• 56% show no change
• 11% have increased acidity (decreased pH)

Question 26

How is acidity of soils changing?

Answer 26

• further acidification is not occurring
• aluminum levels are decreasing
• pH is increased

Question 27

Is biological recovery occurring?

Answer 27

Probably, but it is slow and data is still limited

Question 28

Slides 46, 47

Answer 28

Biological recovery of diff species