Acidification Flashcards
_____ _____= the settling, of deposition of acidic or acidic-forming pollutants from the atmosphere onto Earth’s surface
acid deposition
Acid deposition includes:
(list 4)
- acid precipitation (rain, snow, sleet, hail)
- acid fog
- acidic gases
- acidic dry particles
acid deposition is mostly caused by ____ activities, but can be ____
- it occurs when pH < ___
anthropogenic
natural
5.6
T/F
precipitation is naturally slightly acidic
What’s the usual pH of rain?
true!
rain pH= 5.6
What’s the first step in the acid deposition pathway?
SO2, CO2, and NOx emissions are released
What are the largest sources of carbon dioxide, sulfur dioxide and nitrogen oxides in Canada?
CO2: oil and gas industry
SO2: largest source is oil and gas industry
NOx: largest source is transportation
___ of CO2 released by burning coal, oil, & gas dissolves into the ocean
As a result, in the past 200 years, oceans have become __% more acidic
1/4
30%
What’s the second step in the acid deposition pathway?
How does it happen?
The pollutants are transformed into acid particles
- Oxidizes in the atmosphere
- oxidized form dissociates in water vapor (in the atmosphere) to release H+ and form acid
___ transport these acids long distances (no matter the source)- usually go toward the poles
winds
what’s the 3rd step in the acid deposition pathway?
the acid particles fall to the earth as wet or dry depositions
wet deposition=
acids removed from the atmosphere in the form of water (rain, snow, sleet, hail)
dry deposition=
acids removed from the atmosphere in the form of particulates or gases (no water).
- often in the form of fly ash, sulfates, nitrates, and SO2 and NOx gas
What is the 4th step in the acid deposition pathway?
May cause harmful effects to soils, forests, streams, lakes, and more
*some areas get the worst of it as it accumulates over time
List 3 ways in which acid deposition damages soils
- depletes calcium and other base cations (nutrients in the soil)
- mobilizes aluminum, heavy metals from soil to water
- accumulates sulfur, nitrogen in soils –> can lead to eutrophication
How does acid deposition damage forest ecosystems?
- list 1 direct effect and 1 indirect effect
direct effect: leaches Ca out of needles
- lose calcium in cell membranes= more susceptible to freezing, so they usually die in the winter
indirect effect: alters soil chemistry
- even less calcium to uptake, more toxic aluminum
Acid deposition causes increased leaching of ___ into surface waters as runoff from soils
aluminum
What happens to aquatic animals if the pH is too low in streams and lake ecosystems?
can be lethal
- can disrupt osmotic balance in fish, eventually leading to heart attacks
Explain what happens to aquatic invertebrates (zooplankton) when streams and lake ecosystems acidify
- usually, zooplankton take up calcium from the water to build their shells
- but, if the water is acidic (therefore less Ca in the water), then the water takes back the calcium from the zooplankton, dissolving their shells
What experiment helped us figure out that acidification is a huge problem?
The experimental acidification of Lake 302 and 223 at ELA in Ontario
After lake 302 recovered from acidification, what happened to the phytoplankton species that were in the lake before acidification?
most of the species almost died off when it was very acidic, and once the lake was recovered back to normal pH, there was a slight shift in the species that returned
zooplankton biomass overall ____ (inc/ dec) as lake 302 acidified
decreased
some species of zooplankton were more tolerant than others though
T/F
all but 2 species of fish disappeared from lake 302 when it was acidified to pH= 4.6
Did they all return naturally once pH was brought back up?
false
all but 1 species! (meaning that 1 species is tolerant to acid)
No, they did not return naturally. They only returned because the lake was restocked.
Which are acidifying faster- oceans or freshwater?
freshwater is acidifying faster
BUT oceans are still seeing a significant decrease in pH!
Ocean pH is normally= __
- could go down to __ this century
- This would have a huge impact on ___
8
7.5
biodiversity
There have been 4 pieces of acid deposition legislation in Canada.
List all 4 (names and dates)
- 1985 Eastern Canada Acid Rain Program
- 1991 Canada-US Air Quality Agreement
- Canada-wide Acid Rain Strategy Post- 2000 (signed 1998)
- 2004 Acid Rain Science Assessment
What did the 1985 Eastern Canada Acid Rain Program do?
- capped SO2 emissions in the 7 easternmost provinces (updated in 2000 to adjust cap on emissions)
- established monitoring
*this was the first time Canada stepped in and did something about the problem
What did the 1991 Canada-US Air Quality Agreement do?
- cut SO2 and NOx emissions in CAN and US
- increased monitoring
What did the Canada-wide Acid Rain Strategy Post- 2000 (signed 1998) do?
- continued reductions in SO2 emissions
- even more monitoring
- regulate reports to public- must be accessible
- prevent clean/ undamaged areas from being degraded (+start recovery)
What did the 2004 Acid Rain Science Assessment find?
- need to reduce emissions even further (stricter caps)
- need to address acidification in the west & north (where the most emissions happen)
There are 2 parts to ecosystem recovery from acid deposition:
1. ____ recovery
2. ____ recovery
chemical
biological (can’t happen until chemical recovery is well underway)
chemical recovery=
decrease in damaging [chemical] in soils and waters.
if the decrease is sufficient, pH will increase
*chemical recovery must begin before biological recovery can start
Biological recovery=
*can’t begin until chemical recovery is well underway
= multi-step return and/or increase in health or organisms in previously acidified ecosystems
Is chemical recovery occurring?
What is the rate of chemical recovery dependent on?
yes!
rate depends on resistance on the ecosystem to acid deposition- determined by the amount of calcium naturally found in soils and surface waters
If an ecosystem has lots of ____, it’s most resistant/ resilient to acid rain
calcium
If an ecosystem has low Ca, it’s less resistant/ resilient to ____ ____
acid deposition
*if Ca has been depleted, ecosystem takes a really long time to recover
202 lakes were originally targeted in ___ with legislation.
__% have reduced acidity :)
56% show ___ _____
__% have increased acidity :(
1985
33%
no change
11%
Do soils appear to be chemically recovering?
yes, but slowly
- further acidification isn’t occurring
- pH slowly increasing again
- Al levels decreasing
Is biological recovery occurring?
probably, but slowly
data is still limited
____ recover faster from acidification because they have a short life
_____ (like __)take a long time to biologically recover
microorganisms
macroorganisms like trees
why is it hard to tell is recovery is happening?
it takes several years for recovery to happen- we only started paying attention to acidity in the 1990’s, so we need more time to tell
- It can take __+ years for zooplankton to recover from acidification
- 10-20+ years for ___ populations to recover
- > __ years for trees to recover
10
fish
20
