420ALGAE: Microscopic plants that are free-living and usually live in water. They occur as single
cells floating in water, or as multicellular plants like seaweed or strands of algae that attach to
rocks.
ALKALI METALS: The metals of Group 1 on the periodic table.
ALKALINITY: Alkalinity or AT is a measure of the ability of a solution to neutralize acids to the
equivalence point of carbonate or bicarbonate. Alkalinity is closely related to the acid neutralizing
capacity (ANC) of a solution and ANC is often incorrectly used to refer to alkalinity. However, the
acid neutralizing capacity refers to the combination of the solution and solids present (e.g.,
suspended matter, or aquifer solids), and the contribution of solids can dominate the ANC (see
carbonate minerals below).
ALKANLINE EARTH METALS: The metals of Group 2 on the periodic table.
ALLOMER: A substance that has different composition than another, but has the same crystalline
structure.
ALLOTROPY: Elements that can have different structures (and therefore different forms), such as
Carbon (diamonds, graphite, and fullerene).
ALPHA AND BETA RADIOACTIVITY: Represent two common forms of radioactive decay.
Radioactive elements have atomic nuclei so heavy that the nucleus will break apart, or
disintegrate spontaneously. When decay occurs, high-energy particles are released. These high-
energy particles are called radioactivity. Although radioactivity from refined radioactive elements
can be dangerous, it is rare to find dangerous levels of radioactivity in natural waters. An alpha
particle is a doubly-charged helium nucleus comprised of two protons, two neutrons, and no
electrons. A beta particle is a high-speed electron. Alpha particles do not penetrate matter easily,
and are stopped by a piece of paper. Beta particles are much more penetrating and can pass
through a millimeter of lead.
ALTERNATIVE DISINFECTANTS: Disinfectants - other than chlorination (halogens) - used to
treat water, e.g. ozone, ultraviolet radiation, chlorine dioxide, and chloramine. There is limited
experience and scientific knowledge about the by-products and risks associated with the use of
alternatives.
ALUMINUM SULFATE: The chemical name for Alum. The molecular formula of Alum is
Al2(SO4)3~14H2O. It is a cationic polymer.
AMMONIA: NH3 A chemical made with Nitrogen and Hydrogen and used with chlorine to
disinfect water. Most ammonia in water is present as the ammonium ion rather than as ammonia.
AMMONIATOR: AA control device which meters gaseous ammonia directly into water under
positive pressure.
AMMONIATOR:
AMOEBA: Amoeba (sometimes amœba or ameba, plural amoebae) is a genus of protozoa that
moves by means of pseudopods, and is well-known as a representative unicellular organism. The
word amoeba or ameba is variously used to refer to it and its close relatives, now grouped as the
Amoebozoa, or to all protozoa that move using pseudopods, otherwise termed amoeboids.
ANAEROBIC CONDITIONS: When anaerobic conditions exist in either the metalimnion or
hypolimnion of a stratified lake or reservoir, water quality problems may make the water
unappealing for domestic use without costly water treatment procedures. Most of these problems
are associated with Reduction in the stratified waters.
ANAEROBIC: An abnormal condition in which color and odor problems are most likely to occur.
ANEROID: Using no fluid, as in aneroid barometer.
ANION: Negatively charge ions.
ANODE: The positive side of a dry cell battery or a cell.
AQUIFER PARAMETERS: Referring to such attributes as specific capacity, aquifer storage,
transmissivity, hydraulic conductivity, gradient, and water levels. Refers to all of the components
of Darcy’s Law and related parameters.
AROMATICITY: Chemical property of conjugated rings that results in unusual stability. See also
benzene.
AS NITROGEN: An expression that tells how the concentration of a chemical is expressed
mathematically. The chemical formula for the nitrate ion is NO3, with a mass of 62. The
concentration of nitrate can be expressed either in terms of the nitrate ion or in terms of the
principal element, nitrogen. The mass of the nitrogen atom is 14. The ratio of the nitrate ion mass