Chemical Reference Materials: Setting the Standards for Ocean Science (2002)

Accelerator mass spectrometry:

Instrumental technique for direct enumeration of low-level radioactive nuclides.

Accuracy:

The closeness of agreement between a test result and the accepted reference value.

Algaenans:

Hydrolysis resistant macromolecules of algal origin.

Alkenones:

Long-chain, unsaturated ketones that are synthesized exclusively by certain haptophyte microalgae (e.g., Emiliania huxleyi).

Analyte:

The substance being measured in an analytical procedure.

C3 photosynthetic pathway:

Also known as the Calvin cycle. A series of enzymatically mediated photosynthetic reactions during which CO₂ is reduced to 3-phosphoglyceraldehyde and the CO₂ acceptor, ribulose 1,5-bisphosphosphate, is regenerated.

C4 photosynthetic pathway:

The set of reactions through which CO₂ is fixed to a compound known as phosphoenolpyruvate (PEP) to yield oxaloacetate, a four-carbon compound.

CAM (Crassulacean Acid Metabolism) photosynthetic pathway:

A variant of the C₄ pathway; phosphoenolpyruvate fixes CO₂ in C₄ compounds at night, and then, the fixed CO₂ is transferred to the ribulose bisphosphate of the Calvin cycle within the same cell during the day. Characteristic of most succulent plants, such as cacti.

Carotenoids:

Organic molecules that function as accessory pigments in phytoplankton photosynthesis.

Certified Reference Material:

Reference material, accompanied by a certificate, one or more of whose property values are certified by a procedure that establishes its traceability to an accurate realization of the unit in which the property values are expressed, and for which each certified value is accompanied by an uncertainty statement at a specified level of confidence.

Certified Value:

For a certified reference material, the value that appears in the certificate accompanying the material.

Chromatography:

Analytical technique to separate chemical species by continuous partitioning between a mobile and stationary phase.

Colloids:

Material in the nanometer to micrometer size range whose characteristics and reactions are largely controlled by surface properties.

Consensus Value (of a given quantity):

For a reference material, the value of the quantity obtained by interlaboratory testing, or by agreement between appropriate bodies or experts.

Cosmogenic Nuclides:

Isotopes of elements produced by the action of cosmic rays (often radioactive).

Deltaic:

Of or pertaining to river deltas.

Diatoms:

Fucoxanthin containing phytoplankton characterized by the presence of a silica-impregnated cell wall.

Dinoflagellates:

Peridinin-containing phytoplankton characterized by a “rotating” swimming movement produced by the combined action of their flagellae.

Fallout or bomb-produced nuclides:

Isotopes of elements produced from nuclear reactors or by detonation of nuclear devices (often radioactive).

Foraminifera:

Micrometer-size animals that possess calcium carbonate tests.

Haptophyte:

Hex-fuxoxanthin­−containing phytoplankton whose representatives include calcium carbonate plate-forming species (e.g., E. huxleyi).

Heterotrophic activity:

A mode of nutrition based on the oxidation of organic matter.

Homogeneity:

Condition of being of uniform structure or composition with respect to one or more specified properties. A reference material is said to be homogeneous with respect to a specified property if the property value, as determined by tests on samples of specified size, is found to lie within the specified uncertainty limits, the samples being taken either from different supply units (bottles, packages, etc.) or from a single supply unit.

Hopanoids:

Membrane stabilizing chemical components found in the cell membranes of bacteria.

Hydrolysis-resistant biomacromolecules:

Large organic compounds of biological origin that can not be broken into subunits by heating with acid or base.

Hydrous Minerals:

Minerals that contain water within their matrices.

Hygroscopic Salts:

Salts that have a high affiinity for water.

Information Value:

Value noted for the concentration of a substance in a reference material, however insufficient information exists to assess the associated uncertainty. Nevertheless, it is believed that this information is of substantial interest to potential users of the reference material.

Interlaboratory Test:

Series of measurements of one or more quantities performed independently by a number of laboratories on samples of a given material.

Isotope:

Two or more species of atoms of a chemical element with the same atomic number and different atomic mass or mass number.

Isotope Dilution:

Condition that occurs when a stable isotope of the analyzed metal is added to the seawater. After equilibrium with the sample,

the isotope can be expected to behave in the same way as the metal being determined, and can be used to establish the recovery of the preconcentration steps used prior to detection. Instead of the absolute quantity, the isotopic ratio is determined.

Labile:

Prone to reaction or easily degraded.

Lyophilization:

Freeze-drying.

Macromolecular:

Pertaining to large organic molecules.

Macronutrients:

Elements or compounds (like nitrate, phosphate, and silicate) that are necessary to sustaiin life and that are typically present in larger amounts than the micronutrients.

Matrix:

The immediate environment (milieu) surrounding an element or compound. For example, seawater, sediment, and particulate material are general matrices of interest in this report. Also, organic matter, opal, carbonate and aluminosilicate are more specific solid-phase matrices of interest.

Micronutrients:

Elements or compounds (like iron, other trace metals, and vitamins) that are necessary to sustain life and that are present in smaller amounts than the macronutrients (see above).

Mycosporine-like Amino Acids (MAA):

Small molecular weight organic compounds that absorb UV light and are thought to function as natural sunscreens.

Non-bioactive metals:

Elements that do not take an active role in biological cycles.

Paleoenvironmental Indicators:

Elements or compounds that reflect ocean history.

Paleovegetation Indicators:

Elements or compounds that reflect historic vegetation patterns.

Photoautotrophic:

Mode of nutrition based on the use of solar energy to synthesize organic compounds.

Photobioreactors:

Light-controlled chambers used to grow microalgae in mass culture.

Photoheterotrophy:

A mode of nutrition based on sunlight and the oxidation of organic compounds.

Phytoplankton:

Small (often microscopic) aquatic plants suspended in water.

Plant Chars:

A form of black carbon obtained by burning plant materials.

Polymerization:

The act of forming a larger molecule from a combination of smaller structural units.

Polynuclear Aromatic Hydrocarbons (PAH):

Organic molecules composed of 2 or more fused benzene rings.

Precision:

The closeness of agreement between independent test results obtained under prescribed conditions.

Primary Standard:

Standard that is designated or widely acknowledged as having the highest metrological qualities and whose value is accepted without reference to other standards of the same quantity, within a specified context.

Protists:

Single-celled organisms more complex than bacteria that include protozoans and some types of algae.

Radionuclides:

Isotopes of elements characterized by spontaneous nuclear interconversions.

Reference Material:

Material or substance one or more of whose property values are sufficiently homogeneous and well established to be used for the calibration of an apparatus, the assessment of a measurement method, or for assigning values to materials.

Reference Method:

Thoroughly investigated method, clearly and exactly describing the necessary conditions and procedures for the measurement of one or more property values that has been shown to have accuracy and precision commensurate with its intended use and that can therefore be used to assess the accuracy of other methods for the same measurement, particularly in permitting the characterization of a reference material.

Salinity:

A measure of the salt content of seawater (approximately the weight (g) of the dissolved inorganic matter in 1 kg of seawater.

Secondary Standard:

Standard whose value is assigned by comparison with a primary standard of the same quantity.

Secular Equilibrium:

A condition that occurs when a chain of radionuclides has reached a steady state condition, in which the rate of decay of daughter nuclides is balanced by their rate of formation by decay of each parent. In this condition, the radioactivity (measured in disintigrations per minute) of each radionuclide in a chain is the same.

Spectroscopic Analysis:

Measurement of chemical species based on the detection of electromagnetic radiation.

Stability:

Ability of a reference material, when stored under specified conditions, to maintain a stated property value within specified limits for a specified period of time.

Traceability:

Property of the result of a measurement or the value of a standard whereby it can be related, with a stated uncertainty, to stated references, usually national or international standards, through an unbroken chain of comparisons.

Uncertainty of a Certified Value:

Estimate attached to a certified value of a quantity which characterizes the range of values within which the “true value” is asserted to lie with a stated level of confidence.

Uncertified Value:

Value of a quantity, included in the certificate of a CRM or otherwise supplied, which is provided for information only but is not certified by the producer or the certifying body. (Also see Information Value).

Zooplankton:

Assemblage of drifting or feebly swimming animals that are often minute in size.