Ch.5 Ocean Acidification & Marine Carbonate System

Ocean Acidification

The decrease in the pH of the Earth's ocean.

Dissolved Gases

Gases such as O2 and CO2 that are present in seawater.

Carbon Dioxide's Role in Seawater

Determines the acidity of seawater and is needed for primary producers to photosynthesize.

Carbon Dioxide & pH Reaction

CO2(g) → CO2(aq) + H2O ↔ H2CO3 (Carbonic Acid) ↔ HCO3^-1 + H+ ↔ CO3^-2 + 2H+.

Marine Carbonate System

A system that buffers pH in seawater by using calcium carbonate (CaCO3) from marine organisms.

Carbonate Ion Addition

Dissolving shells adds carbonate ion (CO3^2-) to seawater, buffering pH.

Carbon Sink

A process that removes carbon dioxide from the atmosphere, such as the growth of shells.

Biogeochemical Cycles

Natural pathways by which essential elements of matter are circulated between biological, geological, and chemical components.

Sinks

A reservoir/process that provides storage for a substance.

Sources

A reservoir/process in which a substance is output.

Carbon Cycling

Processes that remove and add CO2 to the atmosphere.

Processes that Remove CO2

Photosynthesis, burial of organic carbon, uptake of carbon in the ocean.

Processes that Add CO2

Burning of fossil fuels, volcanic outgassing, respiration, and decomposition.

Inversely Correlated Gases

CO2 and O2 are inversely correlated in seawater.

Primary Producers

Organisms that photosynthesize and use CO2 in the surface ocean.

Decomposition

The process that takes up O2 and releases CO2 back into the water column.

Impact of pH < 7

Indicates an acidic condition.

Impact of pH > 7

Indicates a basic condition.

Impact of pH = 7

Indicates a neutral condition.

H+ Ion Concentration

The more H+ you have, the lower your pH is.

Gases in Ocean Water

Gases like CO2 and O2 get mixed into the mixed layer of the ocean.

Dominant Carbonate Species at pH 5

We'd have more CO2.

Negative Impacts of Dissolving Shells

Can destroy marine food chains.

Ocean Sink for CO2

If the ocean can no longer act as a sink, CO2 will continue to build up in the atmosphere.

Temperature and CO2 Relationship

As CO2 goes up, temperature goes up.

What impact do changes in dissolved O2 and CO2 in ocean water have?

They affect the livability for marine life and global climate.

What are the two major roles of carbon dioxide (CO2) in seawater?

It determines the acidity of seawater and is needed for primary producers to photosynthesize.

What is the chemical reaction involving CO2 and seawater?

CO2(g) → CO2(aq) + H2O ↔ H2CO3 ↔ HCO3^-1 + H+ ↔ CO3^-2 + 2H+.

How does increased CO2 in the atmosphere affect seawater?

It increases the amount of H+ ions in seawater, leading to lower pH.

What materials do many marine organisms use to form their shells or skeletons?

Calcium carbonate (CaCO3), including minerals like calcite and aragonite.

What effect does the dissolution of shells have on seawater chemistry?

It adds carbonate ions (CO3^2-) to seawater, buffering pH and preventing it from getting too low.

What is a carbon sink in the context of marine environments?

A process that removes carbon dioxide from the atmosphere, such as the growth of shells that lock away carbon.

What are biogeochemical cycles?

Natural pathways by which essential elements are circulated between biological, geological, and chemical components of Earth's system.

What are sinks and sources in biogeochemical cycles?

Sinks provide storage for a substance, while sources are processes that output a substance.

What processes remove CO2 from the atmosphere?

Photosynthesis, burial of organic carbon, and uptake of carbon in the ocean.

What processes add CO2 to the atmosphere?

Burning of fossil fuels, volcanic outgassing, respiration, decomposition, and methane contributions.

How are CO2 and O2 correlated in seawater?

They are inversely correlated; as primary producers use CO2, deeper water organisms consume O2 and release CO2.

What role do bacteria play in the carbon cycle in seawater?

They respirate, taking up O2 and releasing CO2 back into the water column.

What happens during the decomposition of organic matter in seawater?

It consumes O2 and releases CO2 back into the water column.

What happens to the dominant carbonate species in the ocean if pH drops to 5?

More CO2 would be present in the ocean.

What are the potential negative impacts of dissolving shells of ocean critters?

It could destroy marine food chains.

What will occur if the ocean can no longer act as a sink for atmospheric CO2?

CO2 will continue to build up in the atmosphere, leading to increased temperatures.

How does an increase in CO2 levels affect ocean temperature?

As CO2 levels go up, ocean temperatures also increase.