9.7 ocean acidification

what percentage of CO2 is dissolved into the ocean

30-40% (rest is in atmosphere or body parts)

what does the p in pH stand for? and what does it mean

• potential

  • power or potential of a liquid to make charged hydrogen atoms

The Industrial Period occurred between ___ and ___. During the time, the average surface ocean pH decreased from____to ____. This translates to a ____ ______ concentration in the ocean.

• 1751-1990s

• 8.25 to 8.14

• 30%

• increase in hydrogen ion

chemical equation of ocean acidification process and explain it.

CO2 + H2O —> H2CO3 (carbonic acid)

—> HCO3 (-1) (bicarbonate) —> CO3(-2) (carbonate ion)

as carbon dioxide from atmosphere interact with water, it produces carbonic acid. as it breaks down into bicarbonate and carbonate, it is releasing/losing H+ ions, which increases the H+ concentration in the water (acidity).

the problem isn’t that pH levels are changing, it is ____

the rate at which they are changing

what does increased acidity do in the ocean?

• drops metabolic rate

• drops immune response

• destruction of coral by triggering chemical reactions that result in an overall drop in the amount of carbonate ions available

what is the building arterial used by marine organisms?

calcium carbonate (CaCO3)

equation of producing calcium carbonate

Ca2+ +CO3(-2) —> CaCO3

(calcium ion + carbonate ion —> calcium carbonate)

which organisms depend on calcium carbonate

corals, mollusks, crabs, single celled organisms (foraminifera), coccolithophores

what happens to the free carbon ions? what is its impact on calcium carbonate?

they recombine with free hydrogen ions to make more bicarbonate, reducing the available calcium carbonate organisms need to build or repair skeletons

what does cocco and lith mean

berry shaped and rock

Coccolithophores

• single celled algae

• important as phytoplankton producers

• produce chemical that promotes creation of clouds

what happens if cloud cover decreases

reduces reflectivity (albedo) of earth, increasing rate of global warming (positive feedback loop)

how can the increase of CO2 above ocean water impact skeletons?

increasing CO2 above ocean water could cause an increase in the rate that some skeletons will dissolve

What else can happen with an increase in ocean acidity?

• hypercapnia can happen in fish and squid and mess with their immune response 

• excess CO2 can make it difficult for clownfish to distinguish smell of preys/predators/friends

• echolocation is affected (CO2 increases noise)

• impact construction of ear bones and balance origins (statoliths)

• change in behavior

What are some anthropogenic activities that contribute to ocean acidification + increased CO2 in the atmosphere? 

• Burning of fossil fuels

• Vehicle emissions 

• Deforestation

what does the ocean act as?

a carbon sink, absorbing much of the CO2 produced from burning fossil fuels

why are oceans a large reservoir of carbon

CO2 from atmosphere dissolves into them

what does the color of bromothymol blue indicator show us about the pH in the ocean?

• blue in basic (alkaline) solutions, blue/green in neutral water and yellow/green in acidic solutions 

  • adding CO2 to water containing bromothymol blue causes the solution to turn yellow/green as CO2 dissolves 

what 2 minerals do calcium carbonate occur as

• calcite

• aragonite

what is stronger? aragonite or calcite?

• aragonite

  • forms an equilibrium with its ions Ca2+ and CO3(-2)

  • if CO3(-2) is removed from solution by adding H+, then the aragonite splits into more Ca2+ and CO3(-2) ions

  • this has effect of dissolving or removing aragonite from its crystal form

  • reducing available CO3(-2) makes it difficult for marine organisms to build aragonite shells

why is the pH of the open ocean surface layer likely to ever become acidic?

because seawater is buffered by dissolved salts

relationship of changes in pH and carbonate chemistry + energy of marine organisms

marine organisms are using more energy to regulate chemistry in their cells.

for some organisms, this may leave less energy for other biological process.

impact of OA at any life stage and population growth/recovery

reduces populations ability to grow or to recover from losses due to disturbance or stress

what areas are particularly vulnerable to OA

• natural upwelling of colder, low, pH, deep water onto continental shelves (west coast of North America)

• oceans near poles

• coastal regions that receive freshwater discharge

effects of long term pH in tolerance of marine species

long term pH decline could exceed the tolerance limits of marine species that live in coastal water

why do geo-engineering proposals seek just to cool the

planet and not address OA?

they do not tackle its cause : excess atmospheric CO2

how is blue carbon offsetting CO2 levels

blue carbon is CO2 captured from the atmosphere or seawater by salt marshes, mangroves, and seagrass meadows.

these environments store it as organic material for decades.

what could reducing nutrient runoff do?

might offset some of the local changes caused by OA, and could increase the overall health of marine ecosystems.