Marine Science: Salinity, Water Cycle, Ocean Zones, and Upwelling

Vocabulary practice flashcards covering ocean salinity, chemical terms, pelagic zones, density and convection, dissolved gases, and upwelling dynamics from the marine science notes.

Diffusion

The net movement of particles from an area of higher concentration to an area of lower concentration.

Surface run-off

Water flowing over land to return to rivers and oceans, which can occur on natural surfaces (such as rocks, soil, and vegetation) or artificial surfaces (such as roads and buildings).

Element

A substance found in the Periodic Table that is made up of only one type of atom, such as oxygen ($O_2$).

Compound

A substance formed when two or more different elements are chemically bonded together, such as water ($H_2O$), calcium carbonate ($CaCO_3$), or sodium chloride ($NaCl$).

Mixture

A combination of two or more elements or substances that are not chemically bonded together, such as air or seawater.

Solute

A substance that dissolves in a liquid (the solvent) to form a solution.

Solvent

The liquid that dissolves the solid solute to form a solution.

Solution

The homogeneous mixture formed when a substance (solute) dissolves into another substance (solvent).

Insoluble

A description of a substance that does not dissolve in a particular solvent.

Salts

Ionic compounds that can be formed by the neutralisation reaction of an acid with an alkali.

Ions

Charged particles made from an atom or a group of atoms.

Salinity

A measure of the quantity of dissolved salts in water, typically measured in parts per thousand ($\text{ppt}$).

Land ice

Ice situated on land (such as mountain glaciers and ice sheets) that adds extra freshwater to the oceans when melting, causing sea levels to rise.

Sea ice

Frozen ocean water (such as Arctic sea ice) that is already floating in the water, causing little to no increase in sea levels when it melts.

Sunlight zone

The uppermost pelagic ocean zone that receives abundant sunlight, supporting high rates of photosynthesis by producers and maintaining high dissolved oxygen levels.

Twilight zone

The middle pelagic ocean layer beneath the sunlight zone where light levels are insufficient for photosynthesis to occur.

Midnight zone

The deep ocean layer below $1000\,m$ that is completely dark, characterised by temperatures around $2\text{--}5^\circ\text{C}$, little dissolved oxygen, and very high hydrostatic pressure.

Thermocline

The transitional ocean layer between two layers of water of differing temperatures, where water temperature rapidly decreases as depth increases.

Temperature gradient

The change in ocean temperature with increasing depth; it shows a more gradual change in polar regions compared to tropical regions.

Density

The measure of mass per unit volume, defined by the formula $\text{density} = \frac{\text{mass}}{\text{volume}}$ ($\text{kg/m}^3$); colder and saltier water contains more particles in the same volume and is denser.

Convection currents

The movement that transfers heat energy within a liquid, occurring when denser (cooler) water sinks and is replaced by rising, less dense (warmer) water.

Solubility

The maximum amount of a solute that can dissolve in a solution; for gases in seawater, gas solubility increases as water temperature decreases.

Photosynthesis

The daytime process used by marine plants and algae to convert carbon dioxide and water into glucose and oxygen: $\text{Carbon dioxide} + \text{water} \rightarrow \text{glucose} + \text{oxygen}$.

Respiration

The continuous cellular process in plants and animals that consumes oxygen and glucose to release energy, producing carbon dioxide and water: $\text{Oxygen} + \text{glucose} \rightarrow \text{carbon dioxide} + \text{water}$.

Upwelling

The wind-driven process where deep, cold, nutrient-rich water rises to the sunlit surface to replace warm, nutrient-poor surface water that has been pushed offshore by winds and the Coriolis effect.

Condensation stage in the water cycle (Fig. 7.1)

Letter $C$, which indicates atmospheric condensation where rising water vapour cools and forms clouds.

Pacific Ocean salinity range

The geographic range of seawater salinity across the Pacific Ocean, which varies between $33\,\text{ppt}$ and $36\,\text{ppt}$.