7 - Acidification Flashcards
What is acid deposition? Includes…
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
Slides 6,7**
Look
7 =steps
First step in in acid deposition? Sources?
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
Trends in SO2 emissions in Canada? NOx?
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
Major emissions of CO2 come from… What is absorbing it? What is happening to this sink?
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
Major CO2 emissions come from… Trends in emissions?
Oil and gas then transport
Slight decrease in 2020/21
Slide 12
Second step in acid deposition
Transformation into acid particles and transport over long distances
Slides 14,15
Third step in acid deposition? Types?
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
Fourth step in acid deposition
Harmful effects to soils, forests, lakes and structures
How does acid deposition damage soils?
- depletes calcium and other base cations
- mobilizes aluminum, heavy metals from soil to water
- accumulate sulfur, nitrogen in soils (can lead to eutrophication)
Direct and indirect effects of acid deposition on forest ecosystems
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)
Acid deposition damage to stream and lake ecosystems
- 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)
Slides 25-29
Experimental acidification of lakes
Damage of acid deposition on oceans
- chemical changes in the ocean as a result of CO2 emissions in the atmosphere
- decreasing pH
Slides 31, 32, 33
How is climate change affecting oceans
- warming ocean
- sea level rise
- changes in storm patterns
- changes in precipitation
- altered ocean currents
- ocean acidification
Acid deposition legislation in Canada
- 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
Goals of the 1985 Eastern Canada Acid Rain Program
- Cap SO2 emissions in seven easternmost provinces
- Establish monitoring
- Updated in 2000 with additional national cap
Goals of the 1991 Canada-United States Air Quality Agreement
- cut SO2 and NOx emissions
- increase monitoring
Goals of the Canada-Wide Acid Rain Strategy Post-2000?
- continued reductions in SO2 emissions
- even more monitoring
- regulate reports to the public
- prevent clean/undamaged areas from being degraded
Findings of the 2004 Acid Rain Science Assessment
- need to reduce emissions even further
- need to address acidification in the West and North (east has longer history of reducing emissions)
What is chemical recovery?
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
What is biological recovery?
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
Is chemical recovery occurring? Dependent on…
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
Slide 42
Potential of soils to reduce acidity
Chemical recovery of the 202 lakes originally targeted in 1985
- 33% have reduced acidity (increased pH)
- 56% show no change
- 11% have increased acidity (decreased pH)
How is acidity of soils changing?
- further acidification is not occurring
- aluminum levels are decreasing
- pH is increased
Is biological recovery occurring?
Probably, but it is slow and data is still limited
Slides 46, 47
Biological recovery of diff species
