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Glossary

Abstractions
Removal of water from surface waters (lakes, reservoirs, rivers) and groundwaters for domestic, commercial and industrial use. DoE (1992).

Adsorption
The adhesion of atoms, ions or molecules from a gas, liquid, or dissolved solid to a surface.

Aeons
The largest division of geological time. Chambers (1994)

Anaerobic
An environment in which air (oxygen) is absent. Allaby & Allaby (1990).

Antarctic Bottom Water (AABW)
A dense bottom-water mass, formed in the Weddell and Ross Seas, which moves in an easterly direction around Antarctica. The high salinity and dense nature is caused by the removal of pure water as sea ice. Allaby and Allaby (1990)

Anticyclone
An area of high pressure around which the wind blows clockwise in the northern hemisphere and counter-clockwise in the southern hemisphere. Also called a high. Ahrens (1994)

Atmosphere
The gaseous envelope surrounding planets. Chambers (1994). The term is generally applied to the whole body of terrestrial air. The Earth's atmosphere is composed mainly of nitrogen, oxygen, argon and carbon dioxide.

Atmospheric convection cells
Formed in low latitudes and known as Hadley cells. Warm, equatorial air rises, moves away from the equator and cools, and then descends over the subtropics. Allaby and Allaby (1990)

Biodiversity
The diversity of the natural world, ecological variety and richness. Chambers (1994).

Biomes
Broad, regional types of naturally occurring communities characterized by distinctive life forms which are adapted to the broad climatic and soil types. Mayhew (1997).

Biosphere
The zone of air, land, and water (both in lakes and in the sea) at the surface of the earth that is occupied by organisms.

Carbon dioxide (C0₂)
A colourless, odourless gas at normal temperatures, composed of one atom of carbon and two of oxygen. It makes up about 0.03% of the atmosphere by weight. Carbon dioxide is consumed in photosynthesis by green plants and produced by the respiration of plants and animals and the burning of fossil fuel.

Charged ions
Atoms, or groups of atoms, which have gained or lost one or more electrons, and thus carry a negative or positive charge.
Abercrombie, Hickman and Johnson (1980)

Chemosynthesis
Chemosynthesis is the biological conversion of one or more carbon atoms and nutrients into organic matter using the oxidation of inorganic molecules (e.g. hydrogen sulphide) as a source of energy, rather than sunlight as in photosynthesis.

Community
A general term applied to any grouping of populations of different organisms found living together in a particular environment; essentially, the biotic component of an ecosystem. Allaby (1994)

Continental shelf
The part of a continent which is submerged beneath the sea to a maximum depth of 200m

Coral polyp
Individual coral animals responsible for the construction of coral reefs. A coral polyp is very similar to a tiny sea anemone with tentacles and stinging cells, but unlike the anemone the polyp extracts calcium carbonate from the water to form a calcareous skeletal cup around itself.

Deforestation
The removal of forests. Deforestation is often the result of human activities such as logging or farming and may lead to desertification.

Demographic
See demography.

Demography
A study in the measurement of certain characteristics of human populations, e.g. the size of a population and its distribution by age, sex, occupation, industry, location etc. And trends in these characteristics. Gilpin (1977).

Deoxygenation
The process whereby oxygen is removed from a substance, some chemical pollutants have the ability to cause this.

Deserts
Areas receiving less than 25cm of rain a year. The term is more generally applied to any arid area. Deserts do not necessarily have a hot climate: cold deserts do occur.

Ecocentric
A position or ideology which advocates environmentally benign development, typically through small scale, localised initiatives and practices. Contrast with technocentrism

Ecology
The study of environment factors and how organisms interact with them.

Ecosphere
See Biosphere.

Ecosystem
A community of plants and animals within a particular physical environment which is linked by a flow of materials through the non-living (abiotic) as well as the living (biotic) sections of the system. Thus, ecosystems can range in size from the whole earth to a drop of water, although in practice, the term ecosystem is generally used for units below the size of biomes, such as sand dunes, or an oak woodland. Mayhew (1997).

Effluent
Liquid wastes from industrial, agricultural or sewage plant outlets. DoE (1995).

El Niño
El Niño is a complicated atmospheric-ocean phenomenon which causes anomalously high sea surface temperatures in the western Pacific basin, when compared with the average (warm phase). The opposite phenomenon, La Niña, causes anomalously cooler sea surface temperatures in the western Pacific basin (cool phase) The cause of El Niño/La Niña is not fully understood, however both can effect the weather and climate of the Pacific area.

Equilibrium
A state of even balance. Chambers (1994)

Eutrophication
The process of nutrient enrichment (usually by nitrates and phosphates) in aquatic ecosystems, such that the productivity of the system ceases to be limited by the availability of nutrients causing a rapid increase in the population of one or more organisms in an ecosystem. It occurs naturally over geological time, but may be accelerated by human activities (e.g. by fertilisers being washed from fields into rivers and lakes.): such activities are sometimes termed ‘cultural eutrophication’. The rapid increase in nutrient levels stimulates algal blooms. Allaby (1994).

Evaporite minerals
Sedimentary rocks which have formed by the precipitation of salts from natural brines during evaporation (e.g. gypsum and rock salt.)
Allaby and Allaby (1990)

Freshwater
Water in the global hydrological cycle which has a low content of dissolved solids (less than 1g per l), as is found in most rivers, lakes and as ice.

Greenhouse effect
The absorption and re-radiation of terrestrial infrared radiation by atmospheric water vapour, carbon dioxide and ozone. The greenhouse effect suggests the earth will undergo a warming trend as carbon dioxide from fossil fuel combustion and other heat trapping gases accumulate in the atmosphere. A notable argument has arisen as to the importance of the role this effect will play in global climatic change and warming.

Groundwater
Water held in gravel deposits or porous rock below the earth's surface. Groundwater does not include water of crystallisation held by chemical bonds in rocks, or moisture in the upper soil layers.

Gulf Stream
The most important ocean current system in the northern hemisphere, which stretches from Florida to north-western Europe. The temperature and salinity tend to be seasonally constant, unlike neighbouring coastal water masses. Allaby and Allaby (1990)

Gyre
Circular or spiral motion of water, the term usually being applied to a semiclosed current system. A major gyre exists in each of the main ocean basins. Gyres are generated mainly by surface winds and move clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere.
Allaby and Allaby (1990)

Heat capacity
The ratio of the heat absorbed (or released ) by a system to the corresponding temperature rise (or fall). Ahrens (1994)

Heat of vaporization
Also called 'enthalpy of vaporization'. The heat that must be supplied, per mole of molecules, at constant pressure, in order to vaporize a specific substance. Atkins (1992)

Holistic
From HOLISM - the theory that the fundamental principle of the universe is the creation of wholes. The theory that a complex entity, system, etc. is more than merely the sum of its parts. Chambers (1994).

Hot springs
A continuous flow of hot water through a small opening on to the earth's surface. The water is usually groundwater heated at depth by hot rocks and recycled to the surface by convection. Hot spring waters are rich in dissolved minerals which are often precipitated around the spring mouth. Allaby and Allaby (1990)

Hurricane
A severe tropical cyclone having winds in excess of 74 miles per hour.
Ahrens (1994)

Hydrogen bonds
Hydrogen attached to an electronegative element (e.g. oxygen) gives a highly polarizable bond. If this bond is directed towards another atom with a lone pair of electrons, a weak bond is formed known as a hydrogen bond.
Sharp (1990)

Hydrological cycle
The circulation of water - in liquid, solid, or vapour form - through a series of reservoirs in the environment.

Hydropower
Energy produced as generators are turned by the power of running water. Necessary conditions are a constant supply of water from rivers and lakes, steep fall of water and stable geological conditions for the construction of dams. Mayhew & Penny (1992).

Hydrosphere
The total body of water of the earth, i.e. the oceans, rivers, lakes, underground and atmospheric water.

Infrastructure
The component systems of a larger structure. Often refers to the system of transport (road, rail etc.) and services (water, sewerage, power etc.) in a city or region.

Infra-red Radiation
Radiation of frquency less than about 1013 per second. It is invisible to the human eye. Heat-seeking and night-viewing devices rely on detection of infra-red radiation. Sharp (1990)

Ionic bond
An ionic bond is a type of chemical bond formed through an electrostatic attraction between two oppositely charged ions.

Ions
Atoms or molecules that have aquired an electric charge by the loss (cation; positive charge) or gain (anion; negative charge) of one or more electrons.
Allaby and Allaby (1990)

Irrigation
To provide water by means of canals or watercouses. Chambers (1994)

Limiting nutrient
All organisms require certain nutrients in order to develop at a healthy rate. Any single factor that limits a biochemical process, the growth of an organism or its abundance or distribution is known as the limiting nutrient.

Lithological
The science of rocks as mineral masses. Chambers (1994)

Lithosphere
The rigid uppermost portion of the mantle plus the overlying crust of the earth comprising surface rocks.

Manganese nodules
These are rounded, layered lumps that are found on the deep ocean floor and which contain around 20% manganese and smaller amounts of iron, nickel and copper.

Marine
Of, in, near or concerned with the sea. Chambers (1994)

Micro-organism
Any microscopic organism, including bacteria, viruses, unicellular algae and protozoans, and microscopic fungi (yeasts and moulds). Lawrence (1995)

Molecule
A molecule is composed of two or more bonded atoms. Molecules are converted into other molecules during chemical reactions by breaking chemical bonds between atoms: new chemical bonds between different atoms are usually formed to create the product of a chemical reaction.

North Atlantic Deep Water (NADW)
A water mass whose main source is the Norwegian Sea, from which deep water flows over the sills between Scotland, Iceland and Greenland, and cascades into the depths of the Atlantic. Allaby and Allaby (1990)

Nucleus
The nucleus is the central part of any atom and is generally composed of protons and neutrons.

Oxygen (O)
A gas without taste, colour or smell, forming part of the air, water, etc., supporting most forms of life and also necessary for combustion. (Atomic number 8). Chambers (1994).

Ozone (O₃)
In the lower atmosphere it forms a dangerous pollutant but in the stratosphere (upper atmosphere) ozone is essential for the continuation of life of earth because it forms an ultraviolet absorbing shield which is needed to protect the biosphere from mutagenic radiation.

Peat
A nutrient rich soil with a very high percentage of organic matter

Photosynthesis
The process by which green plants convert light energy into chemical energy (food), through the use of chlorophyll. The main chemical components are water and carbon dioxide.

Phytoplankton
The small plants such as diatoms which float passively in seas and lakes. They form the base of many marine food chains.

Plankton
Minute aquatic organisms that drift with water movements, generally having no method of independent movement. The phytoplankton (plants) are comprised mainly of diatoms, which form the basis of aquatic food chains.The zooplankton (animals) which feed on the diatoms include protozoans, small crustaceans and the larval stages of many larger organisms. Allaby and Allaby (1990)

Polar molecules
A molecule in which, though it does not carry a net electric charge, the electrons are unequally shared between the nuclei. In the water molecule, for example, the pull of the oxygen nucleus on the shared electrons is greater than the pull of the hydrogen nuclei. As a result, the oxygen end of the molecule is slightly negatively charged, and the hydrogen ends of the molecule are each slightly positively charged. The molecule is said to have a dipole moment and can attract other molecules with a dipole moment. Allaby (1998).

Pollution
Chemical substances released to the environment at levels exceeding standards or background concentrations and considered harmful to the natural environment and/or humans.

Population
The number of inhabitants, a group of persons, considered statistically. Chambers (1994).

Porous
Permeable by fluids. Chambers (1994)

Precipitation
With reference to the water cycle: Rain, hail, snow etc. Chambers (1994)

Predator
A predator is any species which uses another species, the prey, as a source of food. This ranges from algae feeding on bacteria through herbivores feeding on food plants to carnivores feeding on herbivores. The difference between a predator and a parasite is that a parasite can only survive if its host survives, whereas a predator eats and thereby kills its prey.

Pure water
Water which contains no dissolved ions and consists only of water molecules.

Relative humidity
The ratio of the amount of water vapour in the air compared to the amount required for saturation, at a particular temperature and pressure. Ahrens (1994)

Reservoir
a) An artificial body of water maintained to support human activities. For example, the Kielder reservoir in Northumberland. b) A integral body of accessible oil, normally defined by its economic viability. For example those within the Ekofish Oil Fields in the North Sea. c) A store for material within the environment which is part of a cycle. For example, the biosphere is a reservoir for carbon within the carbon cycle.

Residence time
The average time spent by a component, e.g. carbon, within a given reservoir, before it is transferred by a flux into a different reservoir.

Riparian rights
The (legally binding) rights of owners in relation to watercourses which flow above or below their land eg rights to angling or to abstract water from a borehole. Riparian owners do not own the water flowing in the relevant watercourse but they have rights to receive water in its natural state.

Saline
Containing salt; a salt solution. Chambers (1994)

Salinity
See Saline

Sedimentation
The deposition of organic materials or minerals by chemical, physical, or biological processes. Sediments can be transported from their source to their place of deposition by gravity, wind, water or ice. Time, burial and chemical reactions convert sediments into solid sedimentary rock.

Solvent
In a solution, the substance which makes up the bulk of the solution is usually termed the solvent. Sharp (1990)

Species
A population of morphologically similar organisms that can reproduce sexually among themselves but cannot produce fertile offspring when mated with other organisms.

SSSI
Site of Special Scientific Interest - A designated area for conservation and species protection.

Steady state
The condition where the inputs and outputs (fluxes) of a reservoir balance one another.

Subduction Zones
Regions where one section of a lithospheric plate is forced beneath an adjoining plate. Associated with deep trenches in the earth's crust, they are responsible for the removal of crust by forcing it into the mantle beneath.

Surface tension
The molecules in the body of a liquid are equally attracted in all directions by other molecules. Those at the surface, on the other hand, will have a residual inward attraction, creating a surface tension which causes the surface to behave like a stretched elastic membrane. Chambers (1994) and Sharp (1990)

Sustainable
Capable of being sustained, to support, to maintain, to keep going. In ecology, the amount or degree to which the earth's resources may be exploited without deleterious effects. Chambers (1994).

Technocentric
Having faith in technological progress and continued economic growth as the means for social progress, development and betterment.

Topography
The detailed study, description or feature of a limited area. With reference to land or the ocean bottom: a description of relief. Chambers (1994)

Treaties
Negotiation; a formal agreement, especially between states. Chambers (1994).

Trophic level
A step in the movement of energy through an ecosystem: an organism's feeding status in an ecosystem.

Tropical storms
Organised thunderstorms with a cyclonic wind circulation between 35 and 64 knots. Ahrens (1994)

Vents
Openings or appertures, e.g. volcanic vents. Chambers (1994)

Waste
Both the Control of Pollution Act 1974 and the Environmental Protection Act 1990 refer to 'controlled waste'. This is defined as household (but not waste from a private dwelling), industrial and commercial waste or any such waste. Waste is defined by reference to the producer of waste. If the producer considers the material to be waste then it is 'waste'. Thus waste may be something which is surplus or otherwise unwanted. It may be waste because the character of the material changes - e.g. it becomes contaminated or broken. If something is waste then the new duty of care will apply to the producer, keeper, transporter or disposer of that waste.

Water balance
The relationship between the input of water, from direct rainfall or floods, and the output, from evaporation and transpiration.

Water column
A term used to describe the cross section of a body of water, with particular reference to the different processes taking place at various depths, e.g. the photic zone.

Water vapour
A suspension of water, as a liquid, in air. Water vapour is not the gaseous form of water since that would be steam.

Weathering
The process by which rocks are broken down and decomposed by the action of external agencies such as wind, rain, temperature changes, plants, and bacteria. Note that the process acts in situ with no transportation taking place and is therefore different from erosion. Two forms of weathering, chemical and physical, can take place and both may act at the same time.

Wetlands
A comprehensive term for landforms such as swamps, salt marshes, bogs and vernal pools. Their common feature is that they are wet at least part of the year and as a result have a particular type of vegetation and soil. Wetlands form important habitats for many species of plant and animal life.

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