DEFINITIONS

Some of the scientific and technical terms used in the publication are defined below.

Chapter 2: Land Sedimentary rocks (map 2.1)	These are formed from material either derived from pre-existing rocks by weathering (e.g. and stone), or composed mainly of particles of in organic origin (e.g. coal).
Igneous rocks (map 2.1)	These are rocks which have solidified from a liquid state. There are 2 types of igneous rocks: intrusive (solidified before reaching earth's surface) and extrusive or volcanic (solidified above the earth's surface).
Metamorphic rocks changed (map 2.1)	These are rocks which were originally igneous or sedimentary but whose state has been by heat and pressure within the earth's crust.
Pesticides (table 2.13 and 2.14)	A product or substance used in the control of pests which may affect public health or attack resources of use to man (e.g. paraquat and lindane).
Chapter 4: Atmosphere Ozone (table 4.10) compounds and	A blue pungent strong gas which is an irritant to eyes, nose and throat, and toxic by inhalation. It is produced by phototchemical reactions involving volatile organic nitrogen oxides. It contributes to phototchemical smog.
Nitrogen oxides (table 4.11)	There are a number of nitrogen oxides of different composition, emissions normally being expressed in terms of nitrogen dioxide equivalent. Nitrogen dioxide is a brown toxic gas which is involved in photochemical reactions with other air pollutants to give irritant products.
Sulphur dioxide (map 4.7, table 4.12)	A colourless gas with a choking smell, the main product of the combustion of sulphur contained in fuels. Globally, much of the sulphur dioxide in the atmosphere comes from natural resources, but in highly developed and populated regions the greater part comes from combustion of sulphur containing fossil fuels (coal and oil).
Chapter 5: Water Harmonised monitoring (table 5.17, chart 5.4)	This is measuring the quality of river water and its capacity to support fish life: three of the sanitary determinands from measuring quality are the levels of dissolved oxygen, ammoniacal nitrogen, and suspended solids.
Ammoniacal nitrogen (table 5.17, chart 5.4)	High levels of ammoniacal nitrogen can be toxic to fish because it removes oxygen from the water.
Dissolved oxygen (table 5.17, chart 5.4)	Low levels of dissolved oxygen are inimical to fish life.
Suspended solids (table 5.17, chart 5.4)	High levels of suspended solids cause silt formation.
Acidity (table 5.17, chart 5.4)	Acidity is expressed on pH scale which indicates acidity/alkalinity: a neutral substance has a pH of 7.0 and the lower the pH the greater the acidity.
Biochemical oxygen demand or BOD (table 5.17, chart 5.4)	A standard water-treatment test for the presence of organic pollutants, and is a measure of the oxygen required by the microbes which reduce the wastes to simple compounds.
Chapter 7 : Radioactivity Radiation (general to chapter)
Activity	Attribute of an amount of a radionuclide. Describes the rate at which transformations occur in it. Unit bequerel (Bq). 1Bq = 1 nuclear transformation per second.
Radioactive	Possessing the property of radioactivity.
Radioactivity	The property of radio nuclides of spontaneously emitting ionising radiation.
Radiation	The process of emitting energy as waves or particles. The energy thus radiated.
Alpha particle	A particle consisting of 2 protons plus 2 neutrons. Emitted by a radionuclide.
Beta particle	An electron emitted by the nucleus of a radionucleide. The electric charge may be positive in which case the beta particle is called a positron.
Gamma ray	A discrete quantity of electomagnetic energy, without mass or charge. Emitted by a radionucleide.
Specific radionucleides (general to chapter)
Argon-41	Radioactive isotope of Argon, which has a half life of only 110 minutes, is produces mainly from the activation of the argon present naturally in the air to cool the outside surfaces of the reactor vessels and their shields. It is discharged from high stacks to ensure its rapid dispersal in the atmosphere and, being inert, it is not re-concentrated by biological systems.
Caesium-137	Radioactive isotope of caesium produced in nuclear reactions, with a half life of 30 years. It is chemically similar to potassium; when absorbed in the body, it spreads throughout, but especially to muscular tissue.
Strontium-90	Radioactive isotope of strontium produced in nuclear reactions, with a half life of 28 years. It is chemically similar to calcium and tends to be concentrated in milk; when absorbed into the body it is concentrated in the bones.
Tritium	Radioactive isotope of hydrogen produced in nuclear reactions, with a half life of 12.3 years. It has a very low radiotoxicity and is not subject to reconcentration in marine organisims and therefore relatively large actvities may be discharged with relatively little radiological effect.
Measurements (general to chapter)
Bequerel (Bq)	The standard international unit for radoioactvity, equal to one-radioactive transformation per second. Multiples of the bequerel are frequently used such as the terabequerel, Tbq, which is one million million bequrerels. For exposure to radon in homes 20 Bqm-3 is equivalent to 1mSv per year.
Gray (Gy)	The standard unit of absorbed dose. A microgray is one-millionth of a gray.
Sievert (Sv)	The standard unit off effective dose equivalent, which is obtained by multiplying the dose equivalent to various tissues and organs by the risk weighting factor appropriate to each and summing the products. A multi-Sievert (mSv) is equal to one-thousandth of a Sievert.