Definitions for Chapter 7

 
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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