Definitions for Chapter 7
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- algicide
- Compound designed to kill algae in water
- alkalinity
- property related to the buffering capacity of the water, relates to the amount of acid
which can be neutralized before the pH drops to a set value (see Ch. 3) As a water
pollutant, excessive alkalinity is usually due to dissolving salts from alkaline soil and
rock. Human contribution is often due to such activities as strip mining which expose the
alkaline soil to groundwater.
- alpha particle
- a helium nucleus with a mass of 4 AMU and a charge of 2+. Alpha particles are relatively
heavy and cause serious damage to materials. But, they also cannot penetrate through more
than a few mm of material.
- beta partcle
- a particle with the mass of an electron and either a positive or negative charge. These
electrons or positrons can ionize materials and penetrate more deeply than alpha particles
can.
- biochemical oxygen demand (BOD)
- a method of determining the amount of oxidizible material in water, by examining the
amount of dissolved oxygen which remains after the sample has been incubated under set
conditions. BOD is important because injection of high BOD wastes into water can consume
such amounts of oxygen that organisms in the water die.
- biorefractory organic compound
- organic compounds which resist decomposition by ordinary biological mechanisms.
- carbamate
- a class of insecticides derived from carbamic acid. These acetylcholinesterase
inhibiters tend to be less toxic and more biodegradable than many organophosphate
insecticides.
- detergents
- synthetic detergents are surfactant compounds which do not form insoluble
precipitates with Mg2+ or Ca2+ ions, as soaps do. They are compounds
such as long chain alkyl sulfates or linear alkyl sulfonates which have a hydrophyllic
group at one end and a long hydrophobic group.
- dioxin
- a side product in the manufacture of some pesticides, dioxin is formed of two benzene
rings attached together by two oxygen atoms. Dioxins vary from fully chlorinate to no
chlorine at all. The most toxic of the dioxins is 2,3,7,8, tetrachlorodibenzo-p-dioxin
(TCDD). It is extremely toxic to some animals and there is considerable controversy about
its effect in humans. It does cause a skin condition known as chloracne.
- eutrophication
- excessive growth of plants and algae in a body of water which tends to reduce fish and
aquatic animal populations and cause decay. A heavily eutrophied lake will eventually fill
up with sediment and plane detritus and become a marsh
- fertilizer elements
- nitrogen, phosphorous and potassium, the major elements in soil which plants need to
grow. These may become a problem in water if they lead to excessive plant growth or
eutrophication
- fungicide
- compound designed to kill fungus
- gamma ray
- high energy radiation( emitted by some decaying radioactive nuclei
- growth regulator
- substance which affects the growth of plants, often used to prevent excessive growth,
without killing plants
- half life
- the time it takes for 1/2 of a radioactive substance to decay. Radiochemicals decay
according to first order kinetics, so the half life is a constant
- heavy metals
- mostly transition metals, which have great affinity for sulfur, and disrupt enzyme
function. Most are toxic, but some, e.g. iron, are essential for life
- herbicide
- a compound used to kill plants
- insecticide
- any compound designed to kill insects
- ionizing radiation
- radiation of sufficient energy to remove electrons from matter. These include alpha,
beta, and gamma radiation
- metalloid
- elements such as arsenic and selenium, which have both metallic and non-metallic
properties
- Minamata disease
- mercury poisioning named after a serious epidemic due to ingestion of contaminated fish
from Minamata Bay in Japan
- organometallic
- an organic compound or complex which contains a metallic atom
- pesticide
- a compound designed to kill or retard the growth of some unwanted living organism
- phosphates
- compounds used in detergent formulations, which cause eutrophication when not removed in
sewage treatment
- pollutant acid
- acidic pollution arises from acidic industrial wastes, air emissions of sulfur and
nitrogen oxides which cause acid rain, and mine drainage which can contain acidic products
of oxidation of pyrites and other sulfide minerals
- polychlorinated biphenyl
- a biorefractory organic compound consisting of two benzene rings linked together and
containing varying amounts of chlorine substituents
- pyrethrin
- insecticide formulations derived from the pyrethrum plant. These are less toxic and more
biodegradable than some of the more synthetic organophosphorous insecticides
- radionuclide
- a natural or artificial atom with an unstable nucleus which will decay, forming daughter
products and emitting alpha, beta or gamma radiation as they decay
- rodenticides
- pesticide formulation designed to kill rodents, primarily rats and mice. One of the most
effective and widely used is Warfarin, a compound which reduces the clottong of blood, and
causes death from internal bleeding in rodents. The same compound is used medically to
reduce unwanted blood clotting.
- salinity
- quantity of salt in water. increased by human activities such as industrial wastes,
irrigation and recharging of water softeners.
- soap
- a natural surfactant formed from the reaction of sodium or potassium hydroxide with fat
or oil. They are salts of long chain fatty acids. Soaps are biodegradable, but form
insoluble salts with Mg2+ or Ca2+ ions, forming 'soap scum' in hard
water.
- surfactant
- a compound which has both polar and nonpolar character. It helps solubilize emulsions of
oily material in water. Surfactants may be cationic, anionic or nonionic in character.
Surfactants will form micelles in water when their concentrations are sufficiently high
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