Oceanography Chapter 7

Front 1

A compound found in the ocean and atmosphere in quantities greater than can be accounted for by the weathering of surface rock. Such compounds probably entered the atmosphere and ocean from deep crustal and upper mantle sources through volcanism.

Back 1

excess volatiles

Front 2

In seawater, the condition in which the proportion and amounts of dissolved salts per unit volume of ocean is nearly constant

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chemical equilibrium

Front 3

Those characteristics of a solution that differ from those of pure water because of material held in solution

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colligative properties

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A substance dissolved in a solvent. See solution

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solute

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A minor constituent of seawater present in amounts less than 1 part per million.

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trace element

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A measure of the acidity or alkalinity of a solution. Numerically, the negative logarithm of the concentration of hydrogen ions in an aqueous solution. A pH of 7 is neutral; lower numbers indicate acidity, and higher numbers indicate alkalinity

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pH scale

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The average length of time a dissolved substance spends in the ocean

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residence time

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A group of substances that tends to resist change in the pH of a solution by combining with free ions

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buffer

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An element whose proportion in seawater varies with time and place, depending on biological demand or chemical reactivity. An element with a short residence time. For example, iron, aluminum, silicon, trace nutrients, dissolved oxygen, and carbon dioxide

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nonconservative constituent

Front 10

The proportions of major conservative elements in seawater remain nearly constant, though total salinity may change with location. Also called Forchhammer's principal.

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principle of constant proportions

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A homogeneous substance made of two components, the solvent and the solute

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solution

Front 12

A chemical bond resulting from attraction between oppositely charged ions. These forces are said to be "electrostatic" in nature

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ionic bond

Front 13

The movement-driven by heat-of molecules from a region of high concentration to a region of low concentration

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diffusion

Front 14

A measure of the content of chloride, bromine, and iodide ions in seawater. We may derive salinity from chlorinity by multiplying by 1.80655.

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chlorinity

Front 15

See principle of constant proportions. (principle of constant proportions: The proportions of major conservative elements in seawater remain nearly constant, though total salinity may change with location. Also called Forchhammer's principal.)

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Forchhammer's principal

Front 16

A substance that combines with a hydrogen ion (H+) in solution

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base

Front 17

A substance able to dissolve other substances. See solution.

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solvent

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A solution containing a base (a substance that combines with a hydrogen ion in a solution)

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alkaline

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The time necessary to mix a substance through the ocean, about 1,000 years

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mixing time

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A close intermingling of different substances that still retains separate identities. The properties of a mixture are heterogeneous; they may vary within the mixture

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mixture

Front 21

An electronic device that determines salinity by measuring the electrical conductivity of a seawater sample

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salinometer

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A substance that releases a hydrogen ion (H+) in solution

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acid

Front 23

State of a solution in which no more of the solute will dissolve in the solvent. The rate at which molecules of the solute are being dissolved equals the rate at which they are being precipitated from the solution.

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saturation

Front 24

A measure of the dissolved solids in seawater, usually expressed in grams per kilogram or parts per thousand by weight. Standard seawater has a salinity of 35 at 0°̊C (32°̊F)

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salinity

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An atom (or small group of atoms) that becomes electrically charged by gaining or losing one or more electrons

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ion

Front 26

An element that occurs in constant proportion in seawater. For example, chlorine, sodium, and magnesium.

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conservative constituent

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A water-sampling instrument perfected early in this century by the Norwegian scientist and explorer Fridtjof Nansen.

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Nansen bottle:

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(1) A solid substance formed in an aqueous reaction. (2) The process by which a solute forms in and falls from a solution. The falling of water or ice from the atmosphere

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precipitate

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Water-sampling device suspended from a ship or platform

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Niskin bottle

Front 30

A compact optical device that determines the salinity of a water sample by comparing the refractive index of the sample to the refractive index of water of known salinity

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refractometer