O3, CO2, Ocean acidification Flashcards
Ocean acidification
A decrease in the pH of ocean waters caused by the uptake of CO2
3 steps of ocean acidification
1) In seawater, CO2 + H2O to H2CO3 (carbonic acid)
2) H2CO3 dissolves, yielding H (acid) + HCO3 (bicarbonate, weak base)
3) Seawater is already supersaturated with CO3 (carbonate) essential for maintaining CaCO3 structures for ocean dwellers and neutralizes H acid (H + CO3 to HCO3)
Net reaction: CO2 + H2O + CO3 to 2HCO3 (weak base)
Normal pH of the ocean
8.5
Ozone
O2 has a double bond (2 oxygens sharing 4 electrons), making it very stable because it requires lots of energy to break double bonds (495 KJ/mol), therefore, a photon must have at least 8.2 x 10^-19 J to break apart O2
Chlorofluorocarbons
Invented by Thomas Midgley in 1930s, they are not flammable, non-toxic, not soluble in water, stable, and replaced ammonia in refrigerators. Then, in 1970s Rowland and Molina studied the impact of CFCs in the atmosphere and won the Nobel Prize in chemistry in 1995 for discovering that CFCs were causing ozone depletion by releasing large amounts of Cl to the stratosphere.
Production of ozone
C-Cl to C + Cl
Cl + O3 to O2 + ClO
ClO + O to Cl + O2
Net: O3 + O to 2O2
Sources of air pollutants
SPM, CO, NOx, O3, Hydro-carbons, VOCs, SOx
Controlling air pollutants
Use fuel efficient cars, scrubbers, wet soil before moving it, Low S fuels, decrease combustion temp, decrease tillage, increase combustion temp (increases CO2)
Interesting facts about UV radiation
On the earth’s surface, there are larger ozone holes at the earth’s poles, and there is more surface UV found in rural areas than in urban areas
Montreal Protocol
Signed in 1987 with the goal to eliminate CFCs by 1996 and HCFCs by 2030, no with 191 signatories
2 major sources of carbon
1) Combustion of fossil fuels
2) Deforestation/changes in land use (agriculture/development)
2 sides of climate change
1) Human activity
2) Natural phenomenon due to earth’s orbit, volcanic activity, etc.
Ocean acidification: concerns for ocean life
1) Supersaturation is essential for calcifying organisms to produce skeletons/shells
2) Acidosis (increased carbonic acid in body fluids causing lower blood pH) in fish
3) Coral reefs are eroded and bleeched
4) Squids use swimming to supply oxygen to their blood, which is impaired by lower blood pH
Ocean acidification: Canadian research results
1) Atlantic pH has decreased
2) Pacific is already undersaturated
3) Arctic uptake of CO2 is accelerated in cold water and rapid sea ice melt, making the Arctic particularly vulnerable to ocean acidification
