Ocean Acidification Flashcards
what is ocean acidification?
the ongoing decrease in teh pH value of the earth’s ocean. it is the changing of the amount of carbonate minerals that are available to marine organisms
what is the normal pH of the ocean?
8.1
what causes ocean acidification?
anthropogenic interference. industrial revolution, has direct and indirect effects.
humans directly and indirectly influences the oceans chemistsry
what are the direct effects of anthropogenic causes of ocean acidification?
Fluxes of materials in the ocean
what are the indirect effects of anthropogenic causes of ocean acidification?
climate change and altered ocean acidification
what are the 4 anthropogenic sources of atmospheric CO2?
burning of fossil fuels
deforestation
changes in land use
energy and cement production
what are the 3 sinks of anthropogenic CO2?
atmosphere
ocean
land
what percentage of CO2 emissions does the ocean uptake?
20-35% , 1/3rd
what is the historical changes in atmospheric CO2 measurement?
the past 800,000 years, it has been around 172-290 parts per million by volume.
what is the recent atmospheric CO2 measurement?
since the industrial revolution, it is now 280-410 ppmv
what does ppmv stand for?
this is what atmospheric CO2 is calculated in, it means parts per million by volume
what is the issue with CO2 in the ocean?
it has a knock on effect to marine ecosystems and animals
how does the CO2 enter ocean water?
the CO2 diffuses passively into ocean surface water.
how does the CO2 in the ocean cause the pH to be lowered?
there, it combines with the sea water and forms acrbonic acid, which is a weak acid. it dissociates to create biocarbonate and H ions. the H ions cause the sea water pH to fall due to it being acidic.
the H ions react with other H ions, which produces bicarbonate. this is a natural buffering capacity.
the dissociation of carbonic acid causes a lot of the H ions, which lowers the pH. due to the buffering capacity, the carbon ion concentration is LOWERED substantially.
what is natural bufering capacity?
this is the natural buffering that oceans do to reduce the impact of an increase in H ions. this natural buffering capacity causes the ocean to be stable at 8.1 pH
what happens to H ions if there is more CO2 in the ocean?
the more CO2 in the ocean, the more H ions combine with the carbonate, and lowers the pH
what is the chemical equation for ocean acidification?
CO2 > CO2 + H20 > H2CO3 > HCO3- + H+ > More H+ , Buffering > HCO3-
CaCO3 > CA2+ + CO3^2-
(this goes into H+ addition)
why is the decrease of carbonate and increase of H+ an issue for marine life?
many marine organisms use this for shells and skeletal structures
what is carbonate saturation?
atmospheric CO2 can only be absorbed if enough CaCO3 dissolves in the water column or sediments
what is the chemical equation for carbonate saturation?
CaCO3 < > CO3^2- + Ca^2+
what is the chemical equation for CaCO3 formation and dissolution rates?
weird symbol O = [Ca^2+] [CO3^2-]/K’sp
what level of carbonate saturate causes calcification?
must equal more than 1, this is supersaturation and is a biotic process which forms shells and skeletons
what level of carbonate saturate causes undersaturation?
must be less than 1, which is undersaturation. this is dependent on abiotic environment. and dissolution of shell and skeleton
what is aragonite?
a form of CaCO3, which is soluble.
where is aragonite found?
in many tropical corals, cold-water corals, pteropods and mollusks
what is calcite?
a form of CaCO3, soluble
where is calcite found?
coccolithophores, foraminifera, echinoderms and crustaceans
which is more soluble, aragonite or calcite?
aragonite
which form of CaCO3 does coral growth benefit from being high in?
aragonite, benefits from high aragonite saturation states above 3
what are abiotic controls of carbonate saturation state?
CO2 solubility depends on:
temperatrue
salinity
pressure
is CO2 less or more soluble in warmer temperatures?
LESS soluble
where does a higher CaCo3 saturation state occur?
shallow, warm tropical waters
where does a lower CaCo3 saturation state cause?
cold, high latitude regions and at depth
where is the effect of enhanced CO2 in the oceans?
colder, deeper regions
what level of CaCO3 does warm waters have?
higher carbon concentration, and are more saturated with carbon minerals
in polar regions, what do organisms do to ensure survival?
organisms will have to use more energy to maintain their shell and prevent the dissolution of their shells
what does the ocean imbalance mean?
that the ocean is reducing in pH, causing it to be acidic
what does the solubility of CO2 and CaCO3 depend on?
temperature, salinity and pressure
where is CO2 more soluble?
in cold waters and higher pressures. more is taken up, and the effect of enhanced CO2 is going to be stronger.
what is the relationship between CO2 concentration in the atmosphere and the surface ocean?
linked increase, steadily increasing over tha past 30 years.
what is the relationship between seawater pH and carbonate concentration
concomitant decline
when was the important Royal Society Report published which introduced carbonate chemistry research?
2005