Ocean pH Levels

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Equilibrium Noun

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[ee-kwuh-lib-ree-uhm]

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Equilibrium

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A state of balance where the concentration of a substance is stable between two connected systems, like the ocean and atmosphere.

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Example: This image shows a balance scale with equal weights on both sides, representing a state of mechanical equilibrium where opposing forces are balanced.

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Ocean Acidification Noun

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[oh-shuhn uh-sid-i-fi-kay-shuhn]

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Ocean Acidification

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The ongoing decrease in the pH of Earth's oceans, caused by the absorption of excess atmospheric carbon dioxide.

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Example: This diagram shows how carbon dioxide (CO2) from factories dissolves into the ocean, which is the first step in the process of ocean acidification.

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pH Noun

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[pee-eych]

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pH

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A scale used to specify the acidity or basicity of an aqueous solution, where lower values indicate higher acidity.

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Example: This diagram shows the pH scale from 0 to 14, where values below 7 are acidic and values above 7 are basic. It shows seawater is slightly basic.

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Carbonic Acid Noun

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[kahr-bon-ik as-id]

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Carbonic Acid

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A weak acid that forms when a carbon dioxide molecule reacts with a water molecule in seawater, lowering the pH.

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Example: This image shows how a water molecule (H₂O) combines with a carbon dioxide molecule (CO₂) to form carbonic acid (H₂CO₃), a key step in ocean acidification.

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Ionize Verb

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[ahy-uh-nahyz]

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Ionize

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The process by which a neutral atom or molecule is converted into a charged particle, or ion, by losing or gaining electrons.

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Example: This diagram shows an ionic solid dissolving in water. The water molecules pull the solid apart into separate positive (cations) and negative (anions) ions.

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Hydrogen Ion Noun

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[hahy-druh-juhn ahy-on]

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Hydrogen Ion

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A positively charged hydrogen atom (H+) whose increased concentration in a solution makes the solution more acidic.

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Example: A hydrogen ion (shown as a proton) joins a water molecule to form a hydronium ion, which determines the acidity (pH) of ocean water.

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Hydrogen Carbonate Ion Noun

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[hahy-druh-juhn kahr-buh-neyt ahy-on]

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Hydrogen Carbonate Ion

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An ion (HCO₃⁻), also known as bicarbonate, formed when a carbonic acid molecule loses one hydrogen ion in water.

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Example: This diagram shows how a carbonic acid molecule can release a hydrogen particle (H+) to become a hydrogen carbonate ion, a key step in balancing ocean pH.

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Carbonate Ion Noun

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[kahr-buh-neyt ahy-on]

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Carbonate Ion

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An ion (CO₃²⁻) that is an essential building block for marine organisms to construct their shells and skeletons.

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Example: This diagram shows a carbonate ion, which is made of one carbon atom and three oxygen atoms and has an overall negative charge.

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Calcium Carbonate Noun

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[kal-see-uhm kahr-buh-neyt]

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Calcium Carbonate

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A chemical compound (CaCO₃) used by marine organisms like corals and shellfish to build their hard shells and skeletons.

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Example: A calcium ion and a carbonate ion combine to form the compound calcium carbonate, which makes up the shells and skeletons of many marine organisms.

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Partial Pressure (pCO₂) Noun

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[pahr-shuhl presh-er]

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Partial Pressure (pCO₂)

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A measure of the pressure exerted by a single type of gas, like carbon dioxide, within a mixture of gases.

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Example: This image shows that the total pressure of a gas mixture is the sum of the individual pressures (partial pressures) of each gas in it.